岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-741432120262018年7月5日〜7日の西日本豪雨における広域降水特性3344ENKuranoshinKATOFaculty of Education, Okayama UniversityKengoMATSUMOTOOkayama Gakugeikan High SchoolKazuoOTANITV Setouchi Broadcasting Co., LTD.10.18926/ESR/70297 Large-scale rainfall characteristics at the heavy rainfall event around the western Japan for 5–7 July 2018 were analyzed with use of the 10-mimute precipitation data at the surface meteorological observation stations of the Japan Meteorological Agency, and so on. In this case, the area with 3 days total precipitation of near or more than 300 mm was distributed widely from northern Kyushu to Shiga and Fukui Prefectures. As in the many heavy rainfall events around Kyushu District in the mature stage of the Baiu season, contribution of the intense rainfall with more than 4 mm/10-minute (24 mm/h) attained about one third of the areal mean total precipitation. However, it is noted that the "not so intense rain" with less than 2 mm/10-minute (12 mm/h) also contributed to about one third of the huge total precipitation in the wide area. In short, this case could be characterized by the mixture of the western Japan type heavy rainfall event and the eastern Japan type one.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-7414321202610分間降水量から大雨の特徴の多様性を捉える大学での授業の試み（防災気象リテラシー育成へ向けて）2131ENKuranoshinKATOFaculty of Education, Okayama University10.18926/ESR/70296 In the disaster prevention education on the heavy rainfall around Japan, it is also important to promote the meteorological literacy on the seasonal and regional differences of their rainfall characteristics such as the convective rain or stratiform rain, together with their total amount of precipitation and their occurrence frequency. As the first step toward the above purpose, the present study made a lesson practice for the university students by utilizing the 10-minute precipitation data for the four heavy rainfall events, in which the types of the heavy rainfall (although all the cases examined in the lesson are relating to the deep convective clouds) are rather different from each other, such as the differences of the rainfall intensity at the peak time, short-period variation of the rainfall intensity and the persistency of the rainfall including the "not so intense rainfall". The reports by the students seem to perceive the different features among these events briefly, but the students' attention to how long the intense rainfall with short-period variation or "not so intense rainfall" lasted was not so sufficient.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026寒風古窯跡群須恵器の岩石学的研究919ENTaijiANAMIDepartment of Earth Sciences, Okayama UniversityToshioNOZAKADepartment of Earth Sciences, Okayama UniversityOsamuKIMURADepartment of Archaeology, Osaka University10.18926/ESR/70295 The Sabukaze kiln site, a representative ancient tunnel-kiln site in the Kibi region, worked during the Asuka period (from early 7th century to early 8th century) to produce Sue ware including jars, cups, coffins, and ornamental tiles. To determine the provenance of the materials used for the Sue ware, we carried out petrological analyses of 13 Sue sherds, including optical microscopy, X-ray diffractometry, X-ray fluorescence spectroscopy, Raman spectroscopy, and electron-probe analysis. In spite of the difference of production time, all the Sue sherds show close similarities in modal proportion of mineral inclusions with dominant quartz and feldspar, and minor volcanic glass, in chemical compositions of feldspar and interstitial matrix, and in whole-sherd chemical composition. These similarities suggest that the paste materials of the Sabukaze Sue ware were commonly derived from weathered rhyolitic rocks and obtained from the same or neighboring mining site(s) located near the kiln site.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026岡山平野児島湾岸部での微動アレイ探査17ENNobuyukiYAMADAFaculty of Science and Technology, Kochi UniversityHiroshiTAKENAKADepartment of Earth Sciences, Okayama University10.18926/ESR/70294 This report describes microtremor array observations conducted at two sites for deep exploration and three sites for shallow exploration around Kojima Bay area in the southern Okayama Plain. Based on these records, the ground velocity structures were estimated. The results yielded solutions indicating the depth of the top of the seismic base layer (equivalent to 3 km/s layer) ranges from 140 to 300 m, while the depth of the top of the engineering basement layer (equivalent to 0.6 km/s layer) is approximately about 13–14 m. The shallow exploration results also suggested the possible presence of an inversion layer. These estimated velocity structure models provided a reasonable explanation for the observed phase velocities.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143212026表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143112025裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143112025岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143112025南西諸島の前弧域における付加体を含む堆積層のモデル化115ENMasanaoKOMATSUOkayama Gakuin UniversitySoheiURAKAMIFormerly Department of Earth Sciences, Okayama UniversityTaroOKAMOTODepartment of Earth and Planetary Sciences, School of Science, Institute of Science TokyoHiroshiTAKENAKADepartment of Earth Sciences, Okayama University10.18926/ESR/68676 We combine the recent seismic reflection profiles to construct a new seismic velocity model of the sedimentary layer incorporating the accretionary prism along the Ryukyu trench. In constructing the new model, we refer to the zoning (ZONE1 to ZONE4) identified by Okamura et al. (2017, Tectonophys.). The construction process consists of the following steps: First, we digitize either unconformities or VP=4 to 5 km/s lines as the seismic basement, whichever is more clearly identifiable. Second, the digitized thickness data of the sedimentary layer from the reflection profiles are geometrically modeled and interpolated to make the three-dimensional structure model. Finally, we supplement the external region of the constructed 3-D sedimentary model using the J-SHIS model provided by the NIED to complete the velocity structure model in the entire Ryukyu arc. The main features of our model are as follows: In ZONE1, off Ishigaki-jima island, the thick sedimentary layer extends about 50 km wide from the Ryukyu trench. In ZONE2, off Miyako-jima island, the thinner layer compared to the other zones is found near the trench, with a thin sedimentary terrace covering the area behind it. In ZONE3, off Okinawa-jima island, the sedimentary layer deepens as it approaches the trench. In ZONE4, off Tokara islands, the deepest layer among all zones is identified. We then conduct 3-D finite-difference simulations of seismic wave propagation using the new and the previous models to confirm the improvement of the new model. In the simulations, the effects of the accretionary prism along the Ryukyu trench on the seismic wave propagation are clearly identified.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143112025Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143112025表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024A new insight into the driving mechanism for plate tectonics―the relationship between tectonic processes and the circumferential tensile forces associated with a rotating planet―2135ENRobertMAURERStuartHARKERShigeyukiSUZUKIAllanWHEELER10.18926/ESR/66846 Mantle convection currents are the currently accepted driving force for plate tectonics that have ripped apart the continents and created oceans. Because of these actions, continental collisions and ocean closures have resulted. Our paper challenges the conventional concept and provides an alternate, mathematically justified drive mechanism. The pull-push motions of such convection currents in the upper mantle are here concluded to be too weak to be the driving mechanism.<br>
Our proposal for such global scale forces concerns the effect of an offset centre of mass of the Earth that results in rotational wobbling. Kepler’s laws of planetary motion demonstrate the rotational behavior of the Earth to be aligned with the Sun on the outward and inward motions of the elliptical orbit. The unbalanced rotation on a fixed gravitational axis results in circumferential stresses on the outer Earth’s rim that is more than strong enough to pull the continental plates apart. The proposed unbalanced rotational stress force equation is shown to be sufficient to drive the cyclic breakup and reassembly of the continental plates, as well as the generation of new oceanic crust and subduction zones. Mantle convection currents are here demonstrated to have a passive rather than active role in the plate movements.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024岡山大学津島キャンパスおける微動探査1320ENNobuyukiYAMADAFaculty of Science and Technology, Kochi UniversityHiroshiTAKENAKADepartment of Earth Sciences, Okayama University10.18926/ESR/66845 In this report, microtremor array observations were conducted in the Tsushima Campus of Okayama University, and the subsurface velocity structure was estimated from the analysis of the records. The results indicate that a five-layer S-wave velocity structure from the surface to the seismic basement equivalent layer with thicknesses of 8, 24, 80 and 180 m and velocities of 150, 450, 1100, 1700 and 3200 m/s, respectively, is reasonable. This model explains to some extent the observed phase velocity and H/V spectral ratios. It is also consistent with the surface borehole results. Furthermore, the areal characteristics of the H/V spectral ratios were also presented, allowing us to estimate the trend of the ground structure in shallow areas.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024鳶尾塚古墳の石室石材の岩石学的特徴112ENTakahiroKANEKODepartment of Earth Sciences, Okayama UniversityToshioNOZAKADepartment of Earth Sciences, Okayama UniversityAkiraSEIKEDepartment of Archaeology, Okayama University10.18926/ESR/66844 Tobiotsuka Kofun, a tumulus built on the Misu Hills in the Kofun period, has a horizontal stone chamber made of huge stone blocks with a width up to 2 meters or more. To specify the source of the stone blocks, we carried out the measurement of magnetic susceptibility, petrographic observation, and chemical analysis of minerals. The stones are amphibole-biotite granite with phenocrystic large grains of K-feldspar. The back-wall stone of the chamber has higher magnetic susceptibility than ceiling and side-wall stones, which probably results from a higher amount of magnetite formed by the alteration of biotite in the back-wall stone. Furthermore, the back-wall stone is different from ceiling stone in that it has lower XMg [Mg/(Mg + Fe) mole ratio], lower Al, Ti, and Na + K contents and higher Si contents of amphibole, higher XMg of biotite, and shows a tendency to have higher Na (albite component) contents at rims of plagioclase crystals and lower Ti contents of zircon. These characteristics of the back-wall stone are similar to those of granite exposed in the Koshinzan area about 2 km northeast of Tobiotsuka Kofun, whereas the ceiling and side-wall stones are similar to granite outcrops in the vicinity of Tobiotsuka Kofun, e.g., in the Midoriyama area. It is concluded that the quarry for the back-wall was located at a different place from that for the ceiling and side-wall stones.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74143012024表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023訂正：地形を考慮した陸海統合3次元地震波速度構造モデルを用いた大分県周辺の長周期地震動シミュレーション6566ENTatsuyaOKUNAKAFormerly Department of Earth Sciences, Okayama UniversityMasanaoKOMATSUDepartment of Earth Sciences, Okayama UniversityHiroshiTAKENAKADepartment of Earth Sciences, Okayama UniversityMasayukiYOSHIMIGeological Survey of Japan, National Institute of Advanced Industrial Science and TechnologyTakeshiNAKAMURAFormerly Japan Agency for Marine-Earth Science and TechnologyTaroOKAMOTODepartment of Earth and Planetary Sciences, School of Science, Tokyo Institute of TechnologyNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-741429120232018 年北海道胆振東部地震の初期の破壊過程4963ENHirofumiKOWARIDepartment of Earth Sciences, Okayama UniversityMasanaoKOMATSUDepartment of Earth Sciences, Okayama UniversityHiroshiTAKENAKADepartment of Earth Sciences, Okayama University10.18926/ESR/65481The rupture process at the beginning stage of the 2018 Hokkaido Eastern Iburi, Japan, earthquake (MJ 6.7) is investigated by analyzing P-wave records from local strong-motion stations. The records show about 3 s of small amplitude arrival (so-called "initial rupture phase") followed by the onset of the main energy release ("main rupture phase"). In this paper we address the issue: where the seismic energy release corresponding to the main rupture phase started at the primary stage of the main rupture, by locating the main rupture onset position. For this aim we applied the 2D and the 3D search methods to estimate the relative location of the onset of the main rupture with respect to the hypocenter, and the time difference between them. The 2D method assumes a plausible initial fault plane and locates the main rupture onset position on the initial fault plane, while the 3D method does not require such assumed fault planes. In the 2D method we employed each of the nodal planes of the first-motion focal mechanism as the initial rupture plane. The 3D method was able to give a better solution than the 2D one. It suggests that the main rupture initiation point might not be on the same fault plane as the hypocenter is. The solution shows that the main rupture onset point is 5.8 km southward and 2.5 km upward from the hypocenter, with the rupture time of 3.3 s from the origin time. It is consistent with the previous studies on the relationship between the magnitude and the initial rupture duration.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023気候・文化理解教育の学際的ESD学習プラン開発へ向けた取り組み（日本とヨーロッパの季節サイクルや季節感に注目して）2948ENKuranoshinKATOFaculty of Education, Okayama UniversityHarukoKATOFaculty of Education, Gufu Shotoku Gakuen University (Former Affiliation)RikakoAKAGIFaculty of Education, Okayama University10.18926/ESR/65480We have continued the interdisciplinary integration of the knowledge on climate and music and have developed the crosscutting study plans on the climate and cultural understanding education. A part of these results had been summarized in a Japanese book titled “Climate and music (Cultural understanding and ESD spreading from the “Doors of Song”)” (Kato and Kato 2019), building mainly our papers written in Japanese. This article will re-integrate our above study results, mainly for the climate and songs/traditional seasonal events around Germany, Northern Europe and Japan, with special attention to (A) asymmetric seasonal progression from autumn to next spring around Japan, (B) winter climate around Germany in association with the seasonal feeling on the traditional events “Fasnacht” for driving winter away and (C) climate around Northern Europe in association with the seasonal feeling on the summer solstice festival “Juhannus” with comparison to the summer climate around Japan.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023岡山県吉備中央町賀陽周辺の古第三系〜新第三系の地質と吉備高原面のゆるやかな曲隆127ENHajimeTANAKASeibu Engineering Consultants Co., Ltd.ShigeyukiSUZUKIDepartment of Earth Sciences, Okayama University10.18926/ESR/65479The Paleogene to Neogene successions which are composed of the Paleogene Kayo Formation, the late Oligocene to earliest Miocene Yagane Formation and the middle Miocene Ukan Formation are sporadically distributed in the Kibi Plateau region, surrounding area of Kibichuou Town, Okayama Prefecture, Southwest Japan. The gravel of the Kayo Formation occupied paleo-valley of Pre-Paleogene basement. The Yagane and Ukan formations unconformably overlay Pre-Paleogene rocks and occupy the gentle valley on the Kibi Surface as valley fill deposits.<br>
The fluvial of the Kayo Formation is mainly composed of conglomerate with minor amount of sandstone and mudstone. The fluvial Yagane Formation is mainly composed of conglomerate and associated with sandstone, mudstone and coal beds. The marine Ukan Formation is subdivided into 3 members, the Yamagata Muddy sandstone Member (YMM), the Shimoyokomi Sandstone Member (SSM) and the Tsuneyama Mudstone Member (TMM) in ascending order. The YMM is characterized by the bio-disturbed very poorly sorted muddy sandstone with frequent burrows, which indicate tidal flat deposits. The SSM is mainly composed of parallel bedded well-sorted sandstone with occasional burrows, which suggest near shore deposits. The TMM is composed of homogeneous clay rich mudstone, which implies off shore deposits.<br>
The boundary between the SSM and TMM (the contact of the sandstone and mudstone) is distinctive and correlative throughout the study area. The boundary is considered to be formed under similar water depth. The variations of the boundary height indicate a later ground movement. From the north to the south in about 25km distance, the height of the boundary changes 260m (in Ukan), 300m (in Takeshou), 360m (in Kibikogentoshi) and 260m (in Nichiouji). It indicates that a very gentle upwarping of the Kibi Plateau Surface was formed after the deposition of the Miocene.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142912023表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022地形を考慮した陸海統合3次元地震波速度構造モデルを用いた大分県周辺の長周期地震動シミュレーション27103ENTatsuya OkunakaFormerly Department of Earth Sciences, Okayama UniversityMasanaoKomatsuDepartment of Earth Sciences, Okayama UniversityHiroshiTakenakaDepartment of Earth Sciences, Okayama UniversityMasayukiYoshimiGeological Survey of Japan, National Institute of Advanced Industrial Science and TechnologyTakeshiNakamuraFormerly Japan Agency for Marine-Earth Science and TechnologyTaroOkamotoDepartment of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology10.18926/ESR/63515Oita prefecture is located in northeastern part of Kyushu Island which is characterized by active subduction of the Philippine Sea plate (PHS) beneath the Eurasian plate and several active volcanoes along with the volcanic front. Oita area has frequently been damaged by large earthquakes and tsunamis since ancient times. From the point of view of disaster prevention, it is important to investigate the feasibility of strong ground motion prediction using realistic structural models. In this paper we use a land-ocean unified 3D (three-dimensional) structure model around Oita prefecture, which includes land and sea-floor topography and a seawater layer as well as subsurface structures of the arc side and the PHS slab to conduct the FDM (finite-difference method) simulations of strong ground motion in land and ocean areas for the 2015 Southern Oita, Japan, earthquake (MJMA5.7) whose hypocenter is located in the PHS slab. The simulated long-period (2–20 s) ground motions reproducing observed records demonstrate substantial contributions of thick low-velocity sediment layers in and around Beppu Bay and Oita basin to development of the motions. We also examine the topographic effects on the seismic motion by analyzing the simulation results to show the strong enhancement of the later phases.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022岡山市北部吉備高原地域に分布する古第三系・新第三系の分布・堆積相と古地理変遷125ENHajimeTanakaSeibu Engineering Consultants Co., Ltd.ShigeyukiSuzukiDepartment of Earth Sciences, Okayama University10.18926/ESR/63514No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学科Acta Medica Okayama1340-74142812022表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021メジアンフィルターを用いた2016年熊本地震の断層近傍における加速度記録の基線補正と変位波形の推定3950ENTomotsuguWatanabeGraduate School of Natural Science and Technology, Okayama UniversityMasanaoKomatsuGraduate School of Natural Science and Technology, Okayama UniversityHiroshiTakenakaGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/61959The 2016 Kumamoto earthquake sequence occurred on April 14 (MJMA 6.5) and April 16 (MJMA 7.3). Seismic intensity of 7 on the Japan Meteorological Agency (JMA) scale was observed in Mashiki Town, Kumamoto Prefecture for the both events and in Nishihara Village, Kumamoto Prefecture for the April-16 event. We estimate the displacement waveforms from these acceleration records. Since the acceleration seismograms include the long-period noise due to tilting of the ground and instrumental effects, the baseline corrections are required to derive the accurate velocity and displacement waveforms. We apply a median filter to the velocity waveforms to identify the linear trends on them due to the steplike noise on the acceleration records, and determine the time at which baseline shifts take place and the step value of each shift for the baseline correction through trial and error. Our baseline correction can successfully reconstruct the velocity and displacement waveforms from the acceleration records. The displacement waveforms show the static components consistent with the geodetic data.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021水平成層構造における地中の近地理論地震記象2938ENHiroshiTakenakaGraduate School of Natural Science and Technology, Okayama UniversityTomotsuguWatanabeGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/61956We extend the computational code of Takenaka and Sasatani (2000) for synthetic nearfield seismograms for horizontally layered elastic media, based on the reflection/transmission matrices and the discrete wavenumber summation method, to calculate seismic motion and its spatial derivatives at a subsurface position in the attenuative media. In this paper we describe the theory of this extension and show some numerical examples to verify the extended code.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021新・古第三系の分布に着目した岡山県中西部における 吉備高原地域の地形特性1927ENHajime TanakaFukken Co., Ltd., Okayama branch officeShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/61955The Kibi Plateau Surface is associated with the Paleogene gravel river bed deposits of the Kibi Group and the Miocene marine deposits of the Katsuta Group and the Bihoku Group. These Paleogene and Miocene units are valley fill deposits. The Kibi Group is composed of formations which is deposited by more than 7 different depositional events during earliest to latest Paleogene Period. Repeated cycles of “erosion - formation of new valley system - deposition and fill up the valley” created the low relief topographic surface. The deposition of
the Miocene deposits might complete the Kibi Plateau Surface. Detailed field works have done in middle western part of Okayama Prefecture. The Kibi Plateau Surface in study area is gently dipping from NW (about 600m high) to SE (about 100m high). The distributions of the Paleogene and Miocene deposits fit the surface.
At the southern margin of the Kibi Plateau, the surface is a little inclined (from 400m high to 100m high) where the bottom of paleo-valleys of the Paleogene deposits are subparallel to the surface. It suggests that the gentle tilting of the Kibi Plateau is caused by an up-warping.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021気候変動に関するESD教師教育開発へ向けて：様々な時間スケールの地学現象の俯瞰117ENYujiKatoCenter for Advanced Marine Core Research, Kochi UniversityKuranoshinKatoGraduate School of Education, Okayama University10.18926/ESR/61954Since the recent climate change is an important topic in the context of SDGs (Sustainable Development Goals) and ESD (Education for Sustainable Development), teacher training course should produce educators with sufficient geo-literacy. In order to meet this requirement, the authors have designed a study plan that facilitates students’ better understanding of current climate change issues, which will be offered in a lecture at university by two speakers who have different specialties, paleoenvironmental science and meteorology. Summary of the lecture is as follows. At first, from the branch of paleoenvironmental science, a major cooling
event at the Eocene/Oligocene boundary and the glacial-interglacial cycles in the Quaternary will be explained. We will then instruct the participants to compare these climatic events with recent global warming, in order to remind them of the extraordinary higher speed of the recent climate change than climatic events in the geological past. Followed by these global topics, climatological features in East Asia including Japan (e.g. regional/seasonal difference in climate and year-to-year variations) will be demonstrated in order to relate local issues to global ones. By these efforts, the lecture aims to cultivate students’ ability to grasp geophenomena from various aspects and understand the true nature of problems, which may contribute producing educators who can execute ESD programs.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142712021表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019裏表紙・目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019岡山大学地球科学研究報告 投稿規定（約款）ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019高知・岡山間の降水量差形成に関わる暖候期の日々の降水や大気場の総観気候学的解析（瀬戸内式気候に関連して）3749ENKuranoshinKatoGraduate School of Education, Okayama UniversityYukiSUGIMURAGraduate School of Education, Okayama UniversityKengoMATSUMOTOGraduate School of Natural Science and Technology, Okayama University10.18926/ESR58577 In order to re-examine the formation process of the climatological precipitation difference between Kochi (Pacific side of Shikoku District) and Okayama (Seto Inland Sea side) characterizing the Seto Island Sea Climate in warm season, synoptic climatological analyses of the daily precipitation features and atmospheric fields were performed for the warm season (April to September) of 1985 - 2015, based on the daily and hourly precipitation data and weather maps by the Japan Meteorological Agency (JMA), and the NCEP/NCAR re-analysis data. The large climatological difference of precipitation at Kochi from that at Okayama throughout the warm season was greatly contributed to by the days with the precipitation difference between Kochi and Okayama (ΔPR) with greater equal to 30 mm/day. In addition, such large daily ΔPR was mainly due to the intense rainfall at Kochi with greater equal to 10mm/h throughout the warm season, except for a part of the cases in April when the “not so intense rain” with less than 10mm/h at Kochi contributed to the large ΔPR. However, it is noted that the features of the synoptic-scale atmospheric fields and possible roles of the mountain ranges in Shikoku District causing the large ΔPR were rather different among August (midsummer), September (Autumn rainfall season) and April (Spring) .No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019ドイツ・北欧と日本の「夏」の気候や季節感の違いに注目して音楽と連携した大学での学際的ESD授業開発2536ENKuranoshinKATOGraduate School of Education, Okayama UniversityHarukoKATOFaculty of Education, Gufu Shotoku Gakuen UniversityKazuoOTANITV Setouchi Broadcasting Co., LTD.KengoMATSUMOTOGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/58576 Climatological features and seasonal feeling in the season called by the same word such as “summer”would be rather different from region to region. Comparison of these features among the different regions, including the regions which are not so familiar to the students, would help to promote their fundamental ESD literacy, especially relating to the “Understanding of heterogeneous others”. Based on that concept, this paper will report an interdisciplinary lesson study for the university students on a theme how different the summertime climate and seasonal feeling among Germany, northern Europe and Japan are. In this study, the lesson practice was made in 2015 and 2018. In both classes, after the lecture on the summertime climate and seasonal feeling in these regions, the students created substitute songs with use of the melody of “Alles neu macht der Mai” (“The May makes all things new”, the same melody as a Japanese school song “Butterfly”) for the comparison between Germany and Japan. As for that between northern Europe, the melody of a Japanese school song “Furu-Sato” (“My country home”) was used for the creation of the substitute songs. It is noted that, not only the seasonal mean temperature or solar radiation condition, but also the features in association with the large day-to-day temperature variation was strongly reflected in the students’ works.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019美咲町川北地域に分布する三郡変成岩から見出された片岩化した断層岩1924ENMireiMATSUSHITAGraduate School of Natural Science and Technology, Okayama UniversityShigeyukiSUZUKIGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/58575 The crystalline schist which is representatively exposed in the Innerside of Southwest Japan is called the Sangun Metamorphic Rocks (SMR). In Kawakita area, Misaki Town, Okayama Prefecture, schistose fault rocks which is newly described in below are intercalated in the SMR. The rocks are composed of lenticular fragments of pelitic, basic siliceous rocks and quartz vein with siliceous to pelitic matrix. The fine-grained muscovites which define schistosity penetrate the rocks. Major direction of layer which though to reflect slip plane is subparallel to the schistosity. The long axis of some fragments are slightly oblique to the schistosity. The combination of the two sets of planes is considered to be a composite planar fabric. These occurrences suggest that the rocks are fault rock before the Sangun Metamorphism and named as schistose fault rocks. Lenses of cataclasite and myronite are accompanied. Planar thin (about 10cm in thickness) brittle fault rock is also associated. These shear deformed rocks form units of layer (shear zone) of 10 to 100m in thickness, and are concordantly intercalated in the surrounded normal schists. Active periods of the shear zones had several times from before and after the event of the Sangun Metamorphism.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019時間領域差分法による表層地盤の非線形応答の計算117ENYusukeTORIGOEDepartment of Earth Sciences, Faculty of Science, Okayama UniversityMasanaoKOMATSUGraduate School of Natural Science and Technology, Okayama UniversityHiroshiTAKENAKAGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/58574 We have developed a time-domain staggered-grid finite-difference code for modeling non-linear response of a one-dimensionally inhomogeneous subsurface structure to a SH plane-wave incidence. It employs the velocity-stress formulation of elastodynamic equation for the linear part, and adopts a elastoplastic rheology model for the non-linear relation between the stress and strain. In this paper, we apply this code to four constitutive models from linear-elastic to nonlinear: (1) linear elastic model, (2) linear viscoelastic model, (3) elastoplastic model, and (4) viscoelastoplastic model, which simulate shallow sand and clay structures and are vibrated by a vertically incident SH plane-wave of Ricker wavelet, to compare the linear and the non-linear soil behaviors including low strains damping (viscoelastic effect) and/or hysteretic attenuation (non-linear effect). We also apply it to a local strong-motion record of the 2000 Western-Tottori earthquake (MW6.8). We then simulate characteristics of non-linear site response such as reduction of the spectral amplitude in the high frequency band and shift of the peak frequencies to lower frequencies.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142612019表紙・英文目次ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018裏表紙・目次 ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018岡山大学地球科学研究報告 投稿規定（約款） ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018U-Pb single grain zircon ages for Sanbagawa Metamorphic Rocks in central Shikoku (Japan): the Sanbagawa Belt re-united3948ENUlrichKnittelClay and Interface Mineralogy, RWTH Aachen UniversityMonikaWaliaDepartment of Geosciences, National Taiwan UniversityShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama UniversityYuan-HsiLeeDepartment of Earth and Environmental Sciences, National Chung-Cheng University10.18926/ESR/56695 The high-P/low-T Sanbagawa Metamorphic Belt that traverses SW Japan, has been subdivided into two belts thought to have been metamorphosed at ca. 120 Ma and at ca. 65 Ma (‘Sanbagawa Metamorphic Rocks’ and ‘Shimanto Metamorphic Rocks’). The subdivision was based on the assumption that metamorphism occurred at ca. 116 Ma, largely based on an early Rb-Sr isotope study and zircon data obtained for the eclogite unit of the Sanbagawa Belt, whereas in some parts of the belt detrital zircons of late Cretaceous age (90-80 Ma) were discovered. Analysis of detrital zircons sampled from two sites within the area considered to expose the older ‘Sanbagawa Metamorphic Rocks’, including the area investigated by the Rb-Sr study, reveals the presence of zircons younger than 95 Ma in all samples and some grains as young as 80 ± 4 Ma. It is therefore concluded that the Sanbagawa Belt is one single tectonic entity that formed in the Late Cretaceous though it contains older components, including fossiliferous clasts, older basic meta-volcanics and eclogite units that may record earlier metamorphic events.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018A new method of terrace analysis to determine precise altitudes of former shoreline3138ENHidekiAmanoGraduate School of Natural Science and Technology, Okayama UniversityShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama UniversityMasaruSatoHanshin Consultants Co., Ltd.,MakotoYanagidaHanshin Consultants Co., Ltd.,10.18926/ESR/56694 The study area is situated in Japan Sea side margin of the Shakotan Peninsula, Hokkaido, Japan, where MIS5e Terrace is preserved along the cost. Numbers of tight drilling have done to establish new method for terrace analysis. Buried wave cut terrace and sea cliff (when the MIS5e Terrace was formed) are reconstructed by distribution of the terrace deposits and these bottom of unconformity planes. The precise site and altitude of former shoreline was also obtained. Altitudes of the former shoreline from the 7 sections are almost the same 22 to 27m in height. Previous data of the height of shoreline are obtained from the topographic MIS5e Terrace surface. The altitudes have variation from 30m to 60m. It suggests that the traditional method for the MIS5e terrace analysis had some errors in the study area.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018日本の秋から冬への季節の変化を捉える学際的指導法の開発（初冬の時雨に注目した附属中学校での実践）1930ENKuranoshinKatoGraduate School of Education, Okayama UniversitySariNishikawaToshimiNakakuraAttached Junior High School of Okayama University10.18926/ESR/56693 An interdisciplinary study plan on the seasonal transition from autumn to winter around the Japan Islands and the “seasonal feeling” associated with the shallow convective rainfall “Shi-gu-re” in that stage expressed in the Japanese classic poems called “Wa-ka” was developed, through a lesson study at junior high school. In that study plan, special attention was paid to the seasonal evolution of the larger-scale systems from autumn to winter, such as the Siberian air mass and the Siberian high, and the relation to the cold air intrusion into the Japan Sea and the Japan Islands. According to the analysis of the lesson practice results, students seem to understand that the winter-type weather pattern becomes dominant around November, together with the features of the intermittent rainfall in the winter-type pressure pattern called “Shi-gu-re” expressed in the “Wa-ka”. However, necessity of further improvement of the study plan was pointed out, so that the students can understand more exactly the role of the seasonal development of the Siberian high and Siberian air mass in the climate around the Japan Islands.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018ドイツ付近の冬における日々の大きな気温変動に関する総観気候学的解析（冬の追い出しの行事「ファスナハト」における季節感に関連して）717ENTatsuyaHamakiGraduate School of Education, Okayama UniversityKuranoshinKatoGraduate School of Education, Okayama UniversityKazuoOtaniTV Setouchi Broadcasting Co., LTD.HarukoKatoFaculty of Education, Gifu Shotoku Gakuen UniversityKengoMatsumotoGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/56692 Synoptic climatological analyses associated with the large day-to-day variation of air temperature around Germany in winter were performed based mainly on the NCEP/NCAR reanalysis data for 2000/2001 to 2010/2011 winters, with an interest in the relationship to the “seasonal feeling” in “Fasnacht”, the festival for driving the winter away. The intermittent appearance of the extremely cold days with rather large day-to-day variation in winter as pointed out by Kato et al. (2017) for around Germany was seen also to the north and to the east of Germany. According to a case study for the 2000/2001 winter, such large daily mean temperature fluctuation was closely related to the intraseasonal variation of the Icelandic low with about one month period, i.e., while the temperature around Germany was relatively higher at the eastward shift phase of the Icelandic low due to the strong warm air advection by the SW-ly wind, the temperature was extremely low there when the Icelandic low was weakened and retreated westward.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018福井県おおい町赤礁崎で見出された非石灰質ビーチロック15ENShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama UniversityYoichiAzuma平寺町松岡兼定島 4-1-1 **YasuyoDeyama平寺町松岡兼定島 4-1-1 **HirokazuYukawaFukui Prefectural Dinosaur MuseumMayumiUsuiFujigakuin-Okayama10.18926/ESR/56691 Beachrock which was formed about 0.5 meter higher than high tide is found in Akagurisaki, Ohi Town, Fukui Prefecture. The outcrops always get wet by spring water. The sediments are composed of well sorted rounded gravels and sands but calcareous shell is not found at all. Intergranular space is occupied by white amorphous cement. Magnesium and silicon rich composition of the cement is obtained by EPMA analysis. There is a conjecture that the magnesium rich cement was precipitated in spite of solution of calcareous shell under saturated state by spring water, because calcium has a higher tendency to ionize than magnesium.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018Title PageENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142512018表紙・英文目次 ENNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017日本の気候環境と愛唱歌などにみる季節感に関する高校での学際的授業の開発（冬を挟む日本の季節進行の非対称性に注目して）518ENKuranoshinKatoGraduate School of Education, Okayama UniversityHarukoKatoFaculty of Education, Gufu Shotoku Gakuen UniversityShojiMiyakeGraduate School of Education, Okayama UniversityTaizoMoriOkayama-Ichinomiya High School10.18926/ESR/56190 This study is a part of the activity to develop an interdisciplinary lesson plan for high school students on the climate environment around Japan and the "seasonal feeling". This time, we focused our attention to the asymmetric seasonal march from autumn to the next spring as proposed by Kato et al. (2013). Comparison of the climate between early winter and early spring was made in the class not only on that around the Japan but also on the relation to the larger-scale systems such as the Siberian air mass, including the brief data analysis. The students also compared the detailed "seasonal feeling" between the two seasons expressed in the school songs and the Japanese classic poems called "Wa-Ka". This paper reports the contents and results of this joint activity at the two high schools.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017岡山県吉備高原弥高山地域に分布する中新統礫岩から変成鉄鉱石礫の発見14ENShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama University晴男小網Okayama Prefectural Okayama Asahi Senior High Schoolまゆみ臼井Fujigakuin-Okayama10.18926/ESR/56189 The Kibi Plateau was a part of the Eurasian Continent and separated by the event of opening of Japan Sea. The rounded pebble which is considered to be continental origin was discovered. The pebble is siliceous and attracts magnets. Prepared thin-sections were observed under microscope. Selected minerals were analyzed by EPMA. The rock is composed of recrystallized quartz, magnetite, riebeckite, stilpnomelane and associated with very tiny minerals with very high relief and interference colors. The assemblage suggests that there is a possibility that the rock is a metamorphic rock of iron-formations and derived from continent.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142412017表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016ヨーロッパの冬から春にかけての 低気圧活動に関する事例解析（2000年を例に）3342ENYusukeKuwanaFaculty of Education, Okayama UniversityKuranoshinKatoGraduate School of Education, Okayama UniversityYumiTakigawaFaculty of Education, Okayama UniversityYumiKojimaFaculty of Education, Okayama UniversityKazuoOtaniGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/55324 Although the extratropical cyclone is one of the basic systems that characterize the weather and climate in mid-latitude regions with the large meridional temperature gradient, its activity and characteristics would be greatly influenced by the seasonal transition and regional differences of the mean atmospheric fields such as between Europe and East Asia. Furthermore, detailed knowledge of the daily cyclone activity would help to understand deeply the differences of regional climatology including seasonal cycles among various areas. In such interest, the present study performed a case study on the cyclone activity around Europe from winter to spring of 2000. In winter, intraseasonal variation of the Icelandic Low was dominant. In the stage when such intraseasonal-scale Icelandic Low approached to the northwestern Europe, the several lows passed eastward with a few days interval around the intraseasonal-scale low pressure area or its southern edge where the baroclinicity was relatively strong. It is also noted that their center pressure was rather low (below 980hPa). After April, when the seasonal mean Icelandic low had disappeared, different types of the intra-seasonal-scale cyclones and anticyclones were dominantly observed. In the lower SLP stage of the intraseasonal variation in Europe, the low to the southwest of England in the middle of April was of the equivalent barotropic structure and persisted for about ten days. On the other hand, high pressure area extending from England to the northern coast of Germany also persisted for about half month. The southern half of that high area was also of equivalent barotropic structure with warmer air there.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016九州南部における4月頃の大雨日の降水の特徴と 大気場に関する総観気候学的解析1732ENKuranoshinKatoGraduate School of Education, Okayama UniversityNozomiMorizukaFaculty of Education, Okayama University(KengoMatsumotoGraduate School of Education, Okayama UniversityKazuoOtaniGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/55323 Around April, total precipitation in southern Kyushu already attains rather large value due to the increase in contribution of the “heavy rainfall days” (with daily precipitation more the 50 mm/day, referred to as HRD). The present study examined the rainfall features and atmospheric conditions on the HRDs at Kagoshima in southern Kyushu, based on the operational observation data from 1990 to 2009. The HRDs there in April appeared mainly associated with the extratropical cyclone passage, together with tentative appearance of the stationary front. The mean daily precipitation on the HRDs was 82 mm and contribution of the intense rainfall more than 10 mm/h attained up to 38 mm, which accounted for 46 % of the daily total precipitation. In April, the high specific humidity area in the time mean field was still located far to the south of the Japan Islands and the stratification around the Japan Islands was very stable for deep moist convection. However, the zone with rather strong seasonal mean baroclinicity extended to rather southern area near 20°N. This would provide a favorable condition for the long-distance moisturNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016Prelithification shear structures of mélange unit in Shiofuki-iwa area, the upper Cretaceous Shimanto Belt, Wakayama Prefecture, Japan915ENNoritoTakesueGraduate School of Natural Science and Technology, Okayama UniversityShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama University10.18926/ESR/55322 Analyzing of sedimentary facies and structure together with regional field mapping were studied in the mélange unit, upper Cretaceous Shimanto Belt, Wakayama Pref., SW Japan. The field survey was concentrated in the coast of Shiofuki-iwa, Miyama Complex, Hidakagawa Belt where soft deformations penetrate throughout the mélange unit. Brittle to ductile faults associated as later deformations are excluded. The mélange unit is subdivided into the Y-shear zone (YSZ) and P-foliation zone (PFZ). The YSZ is composed of thick lenticular sandstone (trends subparallel to the direction of the mélange), intense shear band (thin layer with concentrated prelithification shear deformation) and mudstone dominant mélange. The PFZ is composed of mudstone dominant mélange (associated with foliations which slightly oblique to the direction of the YSZ) and lenticular sandstone (slightly oblique to the direction of the YSZ). The intense shear band separates the YSZ and PFZ. Preserved radiolarian fossils free from deformation in the intense shear band is the evidence of the prelithification shear deformation in the mélange. A remarkable-fact is that the structures of mélange unit are formed under sinistral sense of shear. The mélange unit in the Shiofuki-iwa is ascribed to be formed by sinistral sense of shear during sediments were prelithified.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016航空レーザ傾斜量図を用いた斜面・土石流危険箇所抽出の試み17ENShigeyukiSuzukiGraduate School of Natural Science and Technology, Okayama UniversityMasashiMiyashitaWESCO co.TakeshiHirakawaWESCO co.MiekoFujiwaraWESCO co.SatoshiNishiyamaGraduate School of Environmental and Life Science, Okayama University10.18926/ESR/55321 The slope gradation map which is obtained from airborne laser scanning is very important tool to detect hazardous sites of landslide, debris flow and others. The features of the images (what the images are represented) in the map were confirmed by field survey. The study area, Tamagashi is situated in the Kibi Plateau area, Okayama City, Japan. The map helps to distinguish between artificial microrelief and natural microtopography very well. Small scarps (even 0.5m high), rocky cliffs and large blocks (larger than 2m) are identified in the map. The detail images of the microrelief suggest threatening sites. The merit of the map leads us to find the site in the field easily. We will not miss the threatening sites by using the map.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016Title Page ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142312016表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama University No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015岡山県川上町地頭地域における上部三畳系成羽層群地頭層の層相解析3139ENYutoMasaokaShigeyukiSuzuki10.18926/ESR/54119Facies analysis and analysis of stratigraphy together with folded structure of the Norian Jito Formation were studied in Jito Area, Kawakami, Okayama Pref., SW Japan. Results of regional mapping and measured sections reconstruct three-dimensionally distribution of the Jito Formation. The Jito Formation is sub-divided into the four new members; the Shimohira Muddy Sandstone Member, the Otofuji Coarse-grained Turbidite Member, the Misawa Fine-grained Turbidaite Member, and the Ide Conglomerate Sandstone Member in ascending order. The shimohira Muddy Sandstone Member is interpreted to be deposited in an inner-bay. The Otofuji Coarse-grained Turbidite Member and The Misawa Fine-grained Turbidite Member are considered to be deposited on a continental shelf. The Ide Conglomerate Sandstone Member is inferred to be a shallow marine deposit. As a result, the Jito Formation is regarded as one transgressive-regressive package.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015備前国分寺礎石の岩石特徴と産地の推定2530ENShigeyukiSuzukiNorihideNishimuraYujiAriga10.18926/ESR/54117The Bizen Kokubunji Temple was constructed in the 8th century, in Maya, Akaiwa City, Okayama. Only foundation stones are preserved. Geological characteristics of the foundation stones suggest that they are collected from mountain area of Maya, about 300 to 800m west from the site. The similarity of the foundation stones and the rocks Maya are identified by the following characteristics. 1) Assemblage of rock types (high grade welded tuff breccia, tuff breccia, tuffaceous sandstone and conglomerate) are the same. 2) Lithology of the 3 rock type of the foundation stones and the rocks from Maya are the same. 3) Rheomorphic flow structures are developed in both high grade welded tuff breccia. 4)Mudstone fragments are contained in both high grade welded tuff breccia tuff breccia.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015焼きなまし法による初動発震機構解の決定923ENMasanaoKomatsuHiroshiTakenaka10.18926/ESR/54116Simulated annealing (SA) is known as one of the efficient methods for global optimization. It allows for getting an optimal solution by jumping out of local minimum. In this paper, we apply the simulated annealing to determination of focal mechanism solution. To investigate the feasibility of the application, we determine focal mechanism solution of the 14 March 2014 Iyo-Nada intermediatedepth earthquake. The computation of SA method is then 1278 times faster than that of the grid search method.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015地震波の減衰がS 波偏向異方性に及ぼす影響17ENHitoshiOda10.18926/ESR/54115We investigate the effect of the seismic attenuation on the shear-wave polarization anisotropy by numerical experiments. For the experiments, the P-wave receiver functions are synthesized by assuming that a plane P wave is incident on an anisotropic multi-layer structure with anelastic properties. The synthetic receiver function shows smooth Ps phase waveforms with small amplitudes due to the attenuation of high-frequency spectral components, compared to that calculated for a multi-layer structure with perfect elasticity. From the shear-wave splitting of the Ps converted phases in the synthetic receiver functions, the S-wave polarization anisotropies for the anisotropic layers are measured as a function of propagation direction of the incident P wave. Consequently, we conclude that the seismic attenuation has a minor influence on the measurements of the S-wave polarization anisotropy.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142212015表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014東日本の大雨日の降水特性や総観場の解析（盛夏期の気候学的特徴と梅雨最盛期に関する補遺）3343ENKengoMatusmotoKuranoshinKatoKazuoOtani10.18926/ESR/53196 Rainfall characteristics and large-scale atmospheric fields on the “heavy rainfall days” (with more than
50mm/day) in midsummer, and so on, at Tokyo in the eastern Japan were examined for 1971 to 2010,
succeeding to Matsumoto et al. (2013)
The present study firstly examined the rainfall features and the atmospheric fields for the “heavy rainfall
days” at Tokyo with rather lower appearance frequency than in the typhoon related patterns in Matsumoto et
al. (2013) and so on. In these cases (three cases in total), although the synoptic situations were rather
different among each other, they seem to occur under the systems with relatively small zonal scale
associated with the great meander of the upper-level westerly wind.
Next, the climatological analyses similar to Matsumoto et al. (2013) were performed for the "heavy rain
days" at Tokyo in midsummer (1~31 August). The precipitation on the “heavy rainfall days” at Tokyo in
midsummer was mainly brought by the intense rainfall with more than 10 mm/h, as in the western Japan in
the mature stage of the Baiu season. The detailed examination of the rainfall features for the case on 10
August 2009, with use of the 10-minutes precipitation data and the Radar AMeDAS Composite Data by the
JMA, revealed that the organized meso-β-scale convective rainfall systems as often appear in the western
Japan in the mature stage of the Baiu season were just to the east of the typhoon, and brought the intense
rainfall at Tokyo to result in the large daily precipitation.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014東アジアとの比較の視点でみたヨーロッパにおける低気圧活動と広域場の季節サイクル（序報）2332ENYumiTakigawaYuichiHagaKengoMatsumotoKuranoshinKato10.18926/ESR/53195 Preliminary analyses on the seasonal cycles of the large-scale atmospheric mean fields and the cyclone
activity in Europe were performed based mainly on the NCEP/NCAR re-analysis data, at the viewpoint
comparing with those in East Asia.
As for the climatological monthly mean fields (1981~2010), the meridional temperature gradient in East
Asia presents striking seasonal change with the maximum in winter and the minimum in summer. It is
interesting that such transition from winter to summer and that from summer to winter occur rather rapidly
accompanied by the great temperature increase around April to June and the decrease around October to
November, respectively, in a wide region of 40~70N. On the other hand, the temperature gradient in
Europe is significantly smaller with slight seasonal change than that in East Asian winter.
By the way, in spite of the above difference of the horizontal temperature gradient between Europe and
East Asia, the cyclone activity does not seem to be so weak even around Europe. Thus, the seasonal cycles
of the characteristics of the cyclones and their environmental fields around Europe were examined. At the
first step, we analyzed the daily cyclone activity in Europe for January and July of 2000. Many low pressure
centers at the surface level appeared in both January and July. Referring also to the daily maps of sea level
pressure and geopotential height at 500 hPa level, we found that not only the cyclones corresponding to the
baroclinic instability waves, but also to the cold vortices which amplitudes increased with height appeared
frequently. Moreover, it is interesting that the large-scale cold vortex, which embeds the shortwave trough
with the low center at the surface level, appeared in the northern Europe in July as in East Asian winter,
when such multi-scale systems sometimes bring the persisting heavy snowfall events in the Japan Sea side of
the Japan Islands.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014スカイラジオメーターとライダーを用いた岡山上空のエアロゾル観測1321ENSinpeiNagamatsuDaikiEgawaOsamuTsukamoto10.18926/ESR/53194 Aerosol is one of the controlling parameter for the global climate and also effects on local health hazards. The measurement of the aerosol was originally carried out as in-situ sampling and mass weight measurement including chemical analysis. Recently, remote sensing method is applied as satellite remote sensing and surface based remote sensing. Skyradiometer and LIDAR are surface based remote sensing system. Skyradiometer measures solar radiation as direct and scattered solar radiation affected by aerosols. LIDAR emit laser beam upward and it is backscattered by overlying aerosols. The backscattered light is received by a telescope and vertical distributions of the aerosols are obtained. These measurements require atmospheric
radiation physics.
A Skyradiometer and a LIDAR were operated continuously at Okayama University campus and aerosol parameters were obtained from both of the system. Seasonal variations of the AOT (Aerosol Optical Thickness) and Angstrom parameter (α) are evaluated. During some dust events (e.g. yellow sand and PM2.5), time variations of these parameters were identified from both of the measurement system.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014岡山県美咲町小原周辺に分布する中部中新統からのPaleoparadoxiaの産出報告711ENAkiraFukuchiShigeyukiSuzuki10.18926/ESR/53193 The partially preserved left humerus of the Desmostylia (Mammalia) has been collected from the riverbed in Obara, Misaki-cho, Okayama Prefecture in the western Japan. This specimen can be classified to the genus Paleoparadoxia by the following features: the absence of the supratrochlear foramen; the curved disto-lateral border of the shaft in the antero-posterior view; the medio-laterally expanded flat trochlea of
humerus. Moreover, this specimen can be referred to cf. P. media on the basis of its middle-sized dimensions. This is the second occurrence of Palaeoparadoxia from Okayama Prefecture.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014岡山県南部におけるPM2.5の高精度高解像度空間分布推定15ENAkihoOmoriJunjiYamakawa10.18926/ESR/53192 A relatively high precision and high resolution spatial distribution of the PM2.5 in the south part of the Okayama prefecture, Japan was estimated by the Universal Kriging method and the FOSS4G GIS softwares.
The observation data of the PM2.5 were obtained from the Environmental data service site of the Okayama prefecture. The geospatial open data about the research field that used in the research were served by the government research institutes. The spatial analysis were executed by the R (R core team, 2014) and its spatial libraries, maptools (Bivand and Lewin-Koh, 2014), rgdal (Bivand, Keitt and Rowlingson, 2014) and gstat (Pebesma, 2014). The geospatial representation and qualitative analysis of the estimated distribution were
performed by the QGIS (QGIS Development Team, 2014) and the Google earth (Google, 2014). The time
variant of the PM2.5 concentration by the each observatories in the area were show some cross correlation
factor to the SPM10 concentration data. The estimated PM2.5 distribution seems to show that the relatively
tight relation to the geospatial factors in the research area. The estimation of a time variant change of the
PM2.5 distribution will be required of the further research..No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142112014表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013梅雨最盛期における東日本の大雨日の降水特性や総観場に関する気候学的解析（序報）2534ENKengoMatsumotoKuranoshinKatoKazuoOtani10.18926/ESR/52167Rainfall characteristics and large-scale atmospheric fields on the “heavy rainfall days” (with more than 50
mm/day) in the mature stage of the Baiu season (16 June ~ 15 July) at Tokyo in the eastern part of the Japan
Islands were examined, based on the daily and the hourly precipitation data from 1971 to 2010.
Appearance frequency of the “heavy rainfall days” at Tokyo attained only about 1/3 of that at Nagasaki in
the western Japan. Furthermore, it is noted that about half of the “heavy rainfall days” at Tokyo were related
to the typhoon. In detail, about half of the typhoon cases were associated with the direct approach of a
typhoon (referred to as Pattern A, hereafter), the other half corresponded to the situation when the Baiu front
also stagnated around Kanto District with a typhoon to the southwest of Kanto (Pattern B).
Although the contribution of the intense rainfall with more than 10 mm/h to the total precipitation was
large in Pattern A, that with less than 10 mm/h was dominant in Patterns B and C (Pattern C: meso-α-scale
cyclone on the Baiu front approaching to the Kanto District). It is noted that about half of the “heavy rainfall
days” corresponded to these pattern. In other words, unlike the localized torrential rain in western Japan, the
“heavy rainfall days” due to the duration of “not-so-intense-rain” appeared rather frequently in the eastern
part of Japan even in the Baiu season.
In both Patterns B and C, relatively strong low-level southerly wind associated with the disturbance (a
typhoon or a meso-α-scale cyclone) invades into the baroclinic zone in the basic field sustained as the
sowthwestern edge of the cool Okhotsk air mass. It is interesting that the “heavy rainfall days” there due to
the contribution of the persistent “not-so-intense-rain” occur just in such situation.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-741420120132004年10月後半の台風23号に伴う日本列島での広域の降水（台風18号と比較して）1324ENAiSatakeKuranoshinKatoYoshinoriMoriYasuhiroGodaShoichiroIkedaOsamuTsukamoto10.18926/ESR/52166Rainfall distribution in the Japan Islands associated with the approach of Typhoon No.23 around 20 October
2004 (referred to Ty0423, hereafter) showed considerably different features from those in late summer of this
year. The present study examined the detailed rainfall features around the Japan Islands brought by Ty0423
and the atmospheric processes based on the operational observation data by the Japan Meteorological Agency
(JMA), comparing with those in association with Ty0418 around 7 September 2004.
During the stage when Ty0423 was approaching or landing on the western part of the Japan Islands, the
areal mean precipitation from Kyushu to Kanto District attained much larger than that for Ty0418, with wider
extension of the area with the large amount of precipitation. It is interesting that, although the intense rainfall
was observed only at the upstream side of the mountain range from Kyushu to Honshu District for Ty0418
except for the area near its center, strong rainfall with 10~30 mm/h persisted in wider regions from the western
to the eastern part of the Japan Islands, resulting in the considerably large total rainfall for Ty0423.
As for the case for Ty0423, the surface front with stable frontal surface was located just to the east of the
Ty0423 center just before its landing at the Japan Islands. Thus, the huge moisture inflow mainly in the eastern
region from the typhoon center seems to be redistributed widely over the Japan Islands area associated with
the large-scale convergence around the stable frontal surface. In late October, the colder air associated with
the high pressure system in the eastern Siberia can cover the northern part of the Japan Sea area as the seasonal
march. Such basic field might be favorable for sustaining the synoptic-scale front just around the southern
coast of the Japan Islands, even when the strong southerly wind invades associated with the typhoon approach
there.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013岡山県新見市の中新世備北層群からのPeriploma mitsuganoense Araki (Bivalvia: Mollusca)について ―特にその古地理学的意義―711ENEijiTaguchciShingoKishimotoShigeyukiSuzuki10.18926/ESR/52165In this paper, we deal with re-description of Periploma mitsuganoense Araki and it’s morphological
variation and significance of the molluscan fauna of it from the Miocene Bihoku Group in Niimi City,
Okayama Prefecture, Southwest Japan. Moreover, the paleogeographic significance of this species is analyzed.
The obtained results are summarized as follows:
1. The morphological variation of Periploma mitsuganoense Araki has a wide range on the basis of the
analysis of the morphological outline.
2. The occurrence of P. mitsuganoense Araki from the Pectinid fauna is the first record in the West Setouchi
Geological Province.
3. It is presumable that P. mitsuganoense Araki is an endemic species in the First Setouchi Geological
Province from a view point of it’s spatial distribution.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013岡山県倉敷市北村地域で発生した土石流災害の特徴と要因16ENYukiKimuraShigeyukiSuzuki10.18926/ESR/52164The debris avalanche occurred in Kitamura area, Kurashiki City, Okayama Prefecture caused by the hard
rain of Typhoon 12 of September, 2011. Furthermore, 11 small landslides occurred in the study area. In this
area, the altitude of mountainous are not so high (150m to 250m) and the amount of precipitation which
producted the debris avalanche was not very serious quantity with 230mm. However the debris avalanche
occurred. One private house collapsed, and the first floor part of the Kitamura Elementary School was buried
due to the debris flow. The purpose of this study is to examine causes of the debris avalanche disaster
occurred in Kitamura area using applied geological technique. The length of the debris avalanche scar is
about 250m, and alluvial fan is formed as a debris slope. The ground is composed of weathered granite and
the bottom of the valley was filled by soils derived from disintegrated granite. There are three small
landslides as head scarps with steep slopes at approximately 30°-35°. The debris avalanche was inferred to
have started as a shallow soil slip at the head by rainfall. 3 major causes are inferred which originated the
debris avalanche in the study area; steep slope, ground composed of weathered granite, existence of sandy
soil which occupied at the bottom of valley.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74142012013表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012岡山大学地球科学研究報告 投稿規定（約款）ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012地上梅雨前線の南方の九州における 線状降水帯の集団の維持について （2001年6月19日頃の事例解析）3950ENYasuhiroGodaKuranoshinKatoOsamuTsukamoto10.18926/ESR/49212A case study on persistent appearance of the ensemble of precipitation bands in the warm sector of the Baiu front in
Kyushu District, the western part of Japan around 19 June 2001 was performed based on the operational observational
data. Around 00UTC (09JST) 19 June when the Baiu front on the surface weather map was still located about a few
100kms to the north of Kyushu, the number and the total area of the meso-β or γ-scale line-shaped precipitation
bands increased around Kyushu rapidly. These precipitation bands had been sustained there and gradually gathered
each other to change into the Baiu frontal precipitation zone extending from the northern Kyushu to Seto-Naikai (Seto
Inland Sea) around 09UTC (18JST) 19 June (the intense rainfall zone was still located in the warm sector of the Baiu
front).
Until ~09UTC (18JST) 19 June, the moist air flow with the latently unstable stratification had been sustained
around Kyushu corresponding to the low-level southerly wind toward the surface Baiu front to the north of Kyushu.
This large-scale situation would contribute greatly to the maintenance of the ensemble of the line-shaped precipitation
bands in the warm sector of the Baiu front.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012上部三畳系成羽層群における 日本最古の化石林の発見 ―堆積環境復元および古植生復元における意義―2537ENHirokazuYukawaKazuoTeradaGeSunShigeyukiSuzuki10.18926/ESR/49211Erect fossil stumps were found from the outcrop of the Upper Triassic Hinabata Formation, the uppermost part of
the Nariwa Group at Hinabata, Nariwa-cho,Takahashi City, Okayama Prefecture, SW Japan. They are evidence of
the oldest fossil forest in Japan. The Upper Triassic Nariwa Group is mostly composed of non-marine deposits
except the marine Jito Formation and characterized by the abundance in plant fossils. The marine Jito Formation is
characterized by occurrence of Norian Monotis ochotica. On the basis of detailed observation of the occurrence of
erect fossil stumps, as well as sedimentary facies of fossil-bearing unit, the fossil forest was interpreted to have
grown on the top of the natural-levee units. One of the erect fossil stumps was identified as Xenoxylon sp.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012瀬戸内海中部上空におけるSPM濃度分布の推定1924ENTakahiroEbiHirofumiMatsumotoJunjiYamakawa10.18926/ESR/49210Ordinary Kriging, OK, and Regression Kriging, RK, are the spatial statistical methods that are possible to
estimate a horizontal distribution in a study area from discrete data. OK is the method which takes account of
only spatial auto-correlation structure of the data, while RK is the method which takes account of an interrelationship
between spatial auto-correlation structure and some auxiliary variables to minimize the estimation error.
Analytical processing for OK and RK methods was performed by the R-Language (R Core Team, 2012)
and its some additional libraries. The auxiliary variables required to perform RK method were prepared by a
GIS application, Quantum GIS (Quantum GIS Development Team, 2012). The 3-dimensional geographic representation
of the estimation maps was performed by the Google Earth (Google, 2012).
In this report, OK and RK methods were applied to one of the Earth scientific information, SPM (Supended
Particulate Matter). Then, these methods were considered by comparing two estimation maps, and finally
considered qualitatively by displaying these maps in the Google Earth.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012シベリア石とパラシベリア石の安定温度圧力条件1317ENMasahiroKanoJunjiYamakawa10.18926/ESR/49209Sibirskite (CaHBO ) and parasibirskite ₃ are in the relation of polymorphism, these are regarded as the alteration
products of takedaite (Ca₃B₂O₆), occurs at Fuka mine, Okayama Prefecture. The synthesis of parasibirskite was
reported by the Schäfer (1968a, b) etc. and the synthesis of sibirskite was reported by the Sun et al. (2011).
To determine the formation condition of sibirskite and parasibirskite in the natural, they were synthesized from
the natural takedaite (Ca₃B₂O₆). As a result, both of sibirskite and parasibirskite were formed by the duration
time of 7 days with 1000 kg/cm2 and 300 oC, on the other hand, only sibirskite was formed by the duration time of
14 days with the same condition.
In addition, the mixtures of sibirskite and parasibirskite were examined under the various temperatures and
pressures of hydrothermal conditions. As a result, the upper limit of the stable temperature and pressure
conditions of sibirskite was estimated between 350 oC and 400 oC at 1500 kg/cm2, and between 400 oC and 450 oC
at 500 kg/cm2 . In the higher temperature than the condition, sibirskite were changed into shimazakiite (Ca₂B₂O₅).No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012秋吉帯高山石灰岩層群の褶曲構造511ENNoriyukiInadaShigeyukiSuzukiKeisukeIshida10.18926/ESR/49208The fold structure of the Akiyoshi Belt was analyzed in Kawakami-cho, Okayama Prefecture, where the Lower
Carboniferous to Middle Permian Ko-yama Limestone Group (Yokoyama et al., 1979), Permian Yoshii Group
(Sano et al., 1987) and Triassic Nariwa Group (Teraoka, 1959) are distributed. The Nariwa Group unconformably
covers the Paleozoic successions (Otoh, 1985). The Lower Carboniferous to Middle Permian Ko-yama Limestone
Group, dated by foraminifers and fusulinids (Yokoyama et al., 1979), is mainly composed of massive limestone
with basic volcanics, acidic tuff and chert. The Paleozoic successions of the Akiyoshi Belt were folded during the
Middle to Late Permian (Suzuki et al., 1990). Strata of the Ko-yama Limestone Group generally strike E-W and
dip to the north. The Hoya section about 300 m thick is composed of limestone, basic tuff, chert and acidic tuff,
limestone, basic lava and tuff in ascending order. In this section, Ishida et al. (2012) recognized a nearly complete
conodont faunal succession ranging from the upper Visean to the lower Moscovian. The faunal succession
indicates younging southward, and the strata are overturned. A folded strucuture of tight overfold with
north-dipping axial plane was reconstructed. Similar style of small scale overfolds of banded chert and turbidite
were observed in the overlying Yoshii Group.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012岡山平野の泥炭層から推測される完新世の海水準変動と古環境変遷14ENShigeyukiSuzuki10.18926/ESR/49207Quaternary peat beds from bore-hole samples deliver information to reconstruct paleoenvironment. Altitudes of
dated non-marine peat beds and marine beds allow to be created a sea-level curve. 4 peat beds (A to D) are
identified from the uppermost Pleistocene to Holocene deposits of the Okayama Plain. They thought to be
deposited at stable events during sea-level change.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141912012表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011岡山大学地球科学研究報告投稿規定（約款）・奥付ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011初夏に日本列島付近へ北上する台風の進路や周辺場の特徴について1118ENNatsumiHamamotoKuranoshinKatoYuukiNakayamaOsamuTsukamoto10.18926/ESR/47748The number of typhoons approaching the Japan Islands is much smaller in May and June than in August to September. However, some typhoons abnormally approach to the Japan Islands in May or June as in 2004. The present study investigated the characteristics of the typhoon tracks and the large-scale fields in May and June associated with the approach of typhoons to the Japan Islands. Climatologically speaking, typhoons are generally formed in the lower latitude in May and early June, and tend to turn to ENE-ward before they reach ~ 20N in May by the upper- and middle-level westerly wind. In June, the upper-level easterly wind associated with the Tibetan high seems to prevent typhoons from approaching to the Japan Islands. However, when the cell-type subtropical high and the deep westerly trough in its western side are formed with the SW-ly from the lower to the middle latitude, a favorable situation for the northward invasion of the typhoon can be realized in May. On the other hand, the formation of the barotropic-like subtropical high to the southeast of the Japan Islands seems to enable a typhoon to approach to the Japan Islands by the S-ly wind around the subtropical high.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011岡山市北部吉備高原地域における地形区分―斜面防災のための試み―510ENShigeyukiSuzukiYunaOmizoMinoruHirataMakotoNishigaki10.18926/ESR/47747The Kibi Plateau is characterized by horizontal skylines and they are considered to be an uplifted peneplain. Landform of the plateaus in central part of Okayama Prefecture is divided into "Kibi plateau landform" and "Recent dissecting landform". The Kibi plateau landform is composed of low relief surface and relict mountain. The altitude of the low relief surface varies from 300 to 450m in Kayo area, and 200 to 350m in Kanayama area. The Recent dissecting landform is characterized by escarpment and cuts the Kibi plateau landform. Knick-point is formed at the boundary between two landforms and steep slope is distributed just below the knick-point. The steep slope of the recent dissecting landform is unstable and a potential of landslide is high.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011KED法を用いた地球科学情報の分布推定13ENJunjiYamakawaTakahiroEbiHirofumiMatsumoto10.18926/ESR/47746KED, the Kriging with External Drift, is one of the spatial statistical method for estimating some distribution from the discrete spatial sampled data set about the research field. The KED uses the kriging method (Matheron, 1973) with some auxiliary map to minimize the estimated error. The KED procedure was performed by the R-Language (Ihaka and Gentleman, 1996) using some geostatistical libraries. The auxiliary maps required by the KED were prepared by the authors with some GIS applications. The 3-dimensional geographic representations for the estimated distribution were performed by the Google Earth (Google, 2011). In this report, the KED was applied to some Earth scientific information to show the fundamental scheme of the method.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141812011表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010岡山大学地球科学研究報告投稿規定（約款）・奥付ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010Google(TM) Earthによる地球科学情報の表示2526ENJunjiYamakawaTakahiroEbiHirofumiMatsumoto10.18926/ESR/42460The Google(TM) Earth is a GIS application provided by the Google, with versatile and high performance visualization and manipulation capability for geographic information. The Google Earth is also a multi-platform application, so the installation and running cost for research and education site is relatively low. The Earth
scientific information also have a geographic information scheme, so the Google Earth has some potential to support the education and research field of the Earth science. In this report, some Earth scientific information were converted by the R-Language and its libraries for represent by the Google Earth. The 3-dimensional representation of the information will be able to support to understanding the specification of the data for the Earth scientific research and education field.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010DGEM: 数値地質標高モデル2123ENJunjiYamakawaTakahiroEbiHirofumiMatsumoto10.18926/ESR/42459DGEM, a Digital Geological Elevation Model, was developed using the digital geological map and the JPGIS DEM data with some GIS application and the R-Language. In the model, the information of the geological map was combined with the DEM by their coordinates. The integration of those two digital map was performed by the R-Language, so the model can be used by some useful presentation library of the language, such as the RGL, or
by some geographical calculation libraries. Moreover, the DGEM will be used by the spatial statistical libraries of the R-Language to investigate some geological spatial distributed specifications.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-741417120101993，1994，1995年における東アジアの秋雨前線帯付近の雲分布や大気場の総観的特徴の比較719ENShigekoFukudaKuranoshinKato10.18926/ESR/42458In order to examine year-to-year variability of the Akisame (autumn rainfall) frontal zone in East Asia, large-scale cloud distribution and atmospheric fields around the frontal zone were compared among 1993, 1994 and 1995, when their characteristics were rather different among each other. While the Akisame frontal zone extended zonally and the deep convective clouds tended to appear in that frontal zone near the southern coast of the Japan Islands in 1993, the frontal zone extends from southwest to northeast and the large amount of precipitation was brought mainly in the northern Japan. In 1995, although the surface front on the weather maps appeared frequently also around the southern coast of the Japan Islands, the rainfall amount there was not so large. The area with frequent appearance of the deep convective clouds in the Akisame frontal zone was seen only to the east of the Japan Islands. As such, it is noted that the active area of the Akisame frontal zone shows rather large year-to-year variability also in the zonal direction. It is also suggested that such great variability of the Akisame frontal zone in the zonal direction seems to correspond to the
variations of the subtropical high and the ITCZ in the western Pacific region around September.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010A note on compositional variation of olivine and pyroxene in thermally metamorphosed ultramafic complexes from SW Japan15ENToshioNozaka10.18926/ESR/42457This short article presents some diagrams showing the compositional variations of primary and metamorphic olivine, orthopyroxene and clinopyroxene in peridotites and serpentinites from thermally metamorphosed ultramafic complexes in SW Japan. In contrast to olivine, which shows a gradual change of chemical composition corresponding with metamorphic grade, orthopyroxene and clinopyroxene show clear differences in composition between primary and metamorphic phases. Compared with primary pyroxenes, even though their compositions could be variable depending on original rock composition, metamorphic orthopyroxene and
metamorphic clinopyroxene is clearly deficient in Cr(2)O(3) and CaO, and in Cr(2)O(3) and Al(2)O(3), respectively. These characteristics are useful for the discrimination between the pyroxenes of different origin.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141712010表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009裏表紙・目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009投稿規定（約款）, 奥付ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009Provenance of Early Cretaceous Hayama Formation, Okayama Prefecture, Inner Zone of Southwest Japan: constraints from modal mineralogy and mineral chemistry of derived detrital grains2942ENDaniel K.AsieduShigeyukiSuzukiTsugioShibata10.18926/ESR/19850Petrographic and phase chemistry studies of detrital grains were carried out on sandstones from the Lower Cretaceous Hayama Formation, Inner Zone of Southwest Japan, to determine their provenance and the tectonic setting during the early Cretaceous. The results of the modal mineralogy suggest that the Hayama Formation has magmatic arc provenance and that deposition of the sediments took place in the back-arc areas with detritus mostly derived from the magmatic arc and rifted continental margins. The chemical compositions of chromian spinel, chlorite and sphene indicate that significant proportions of the detrital grains were derived from mafic and/or ultramafic sources. The source areas are the mafic and ophiolitic rocks in the Sangun-Renge and Akiyoshi terranes and the felsic volcanic rocks probably from either the Akiyoshi terrane or a source not presently exposed in southwest Japan. However, minor amounts of the detritus were derived from the basement rocks; i.e., carbonates and siliciclastic rocks of the Akiyoshi terrane and the metamorphosed mafic rocks of the Chizu terrane.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009Sr–Nd isotopic compositions of Paleoproterozoic metavolcanic rocks from the southern Ashanti volcanic belt, Ghana928ENSamuelDampareTsugioShibataDanielAsieduOsamuOkanoJohnsonManuPatrickSakyi10.18926/ESR/19849Neodymium (Nd) and strontium (Sr) isotopic data are presented for Paleoproterozoic metavolcanic rocks in the southern part of the Ashanti volcanic belt of Ghana. The metavolcanic rocks are predominantly basalts/basaltic andesites and andesites with minor dacites. Two types of basalts/basaltic andesites (B/A), Type I and Type II, have been identified. The Type I B/A are stratigraphically overlain by the Type II B/A, followed by the andesites and the dacites. The analyzed volcanic rocks commonly have low initial (87)Sr/(86)Sr ratios consistent with previous studies on Paleoproterozoic rocks from the West African craton. The LREE-depleted, tholeiitic Type I B/A exhibit back-arc basin geochemical signatures and show high positive epsilon Nd (i.e., ε(Nd) (2.1 Ga) = +3.89 to +7.21), which suggest a long term depleted source and also indicate that they were produced in an entirely oceanic environment devoid of influence of continental crust. The isotope signatures are thus consistent with the previously published trace element data of the Type I basalts/basaltic andesites in suggesting that their parent magma was generated from a depleted mantle. The Type I B/A have Nd model ages (T(DM2)) of 1.83–2.09 Ga similar to their formation ages, suggesting that they were juvenile at their time of formation. The andesites and the Type II B/A andesites show LREE-enriched patterns and exhibit characteristics of subduction zone-related magmas, and show initial ε(Nd) (2.1Ga) values of –1.15 to + 1.35 and Nd model ages (T(DM2)) of 2.32–2.58 Ga. The LREE-enriched dacitic porphyry also exhibits characteristics of subduction zone-related magmas, and have initial ε(Nd) (2.1Ga) value of –2.24 and Nd model ages (T(DM2)) of 2.64 Ga. The Nd isotopic data confirms the juvenile character of the Birimian crust, but also suggests some contributions of a pre-Birimian crustal material (or Archean?) in the genesis of some of the metavolcanic rocks. Our isotopic result is consistent with the island arc complex model which views Paleoproteozoic terranes of West Africa in the context of subduction–accretion processes.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009日本最初の用語「地質学」の成立: 箕作阮甫（1799-1863）の貢献17ENHakuyuOkadaShigeyukiSuzuki10.18926/ESR/19848The first Japanese word "chishitsu-gaku" for the "geology" was proposed by Genpo Mitsukuri, a scientific contributor in the Tokugawa regime in the 19th century, who was born in 1799 in Tsuyama in Western Honshu, Japan and had worked for scientific activities of the Tokugawa government from 1839 to 1863. His major works for the first making of the "chishitsu-gaku" for the "geology" have been presented in this paper, also showing his contribution to Japanese sciences.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009Title PageENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141612009表紙・英文目次ENDepartment of Earth Sciences, Faculty of Science, Okayama UniversityNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141512009Estimation of daily solar radiation from sunshine durationin Ningxia region, China7986ENQinYangOsamuTsukamoto10.18926/ESR/15034For the estimation of daily solar radiation from sunshine duration, observation data of Yinchuan station in Ningxia, China was used. Using a linear relationship between solar radiation and extraterrestrial radiation including relative sunshine duration and daylength, we obtained local coefficients s a =0.18, s b =0.62 from past five years data(1981-1985). Using the same method, coefficients for Guyuan region were confirmed too as a representative of south part of Ningxia province. Applying the local
coefficients and calculation formula of solar radiation, we validated daily solar radiation of two years(1986-1987) of Yinchuan station and four years(1991-1994) of Guyuan station. The results showed high correlation coefficients of R2=0.94 in Yinchuan and R2=0.85 in Guyuan. Error analysis was applied using mean bias error(MBE), mean absolute bias error(MABE), root mean square error(RMSE)，mean absolute percentage error(MAPE) on solar radiation of Yinchuan(1973-2006) and Guyuan(1986-2006) stations.
Results showed that mean absolute bias error(MABE) was less than 13% and 17% in Yinchuan station and Guyuan station
respectively. Then we have applied this method to the estimation of daily solar radiation at ‘Yongning’ station(near Yinchan) with the sunshine duration data at ‘Yongning’. The estimated values were compared with observed daily solar radiation at Yinchuan as past twelve
years data(1989-2000). The results showed good linear relationship with high correlation coefficient of R2= 0.88.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-741415120091990年代における東北日本の冷夏に関わる大規模場について（1970年代との比較）6777ENYukariSenooKuranoshinKato10.18926/ESR/15033It is pointed out by the previous studies that the Baiu front tends to stagnate around the Japan Islands even in
midsummer season in 1990s, although the global warming is going on. The present study examined the climatological
features of the appearance of daily fronts on the surface weather maps and the large-scale factors associated with the
activity of the polar frontal zone to the north of the Baiu frontal zone based on the observational data in the summer of 1971-2000. It was found that the midsummer when the Baiu front tends to stagnate around the Japan Islands appeared
rather frequently in 1970s as in 1990s. However, the baroclinicity around the Eurasian polar frontal zone was stronger in 1970s than in 1990s. Thus while the fronts around the Japan Islands in midsummer were greatly due to the southward invasion of cold front associated with the disturbances on the polar frontal zone in 1970s, the Okhotsk High tends to stagnates to the northeast of the fronts around the Japan Islands in 1990s.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141512009吐喝喇列島・小宝島の完新世隆起サンゴ礁段丘地形と堆積構造3365ENNozomuHamanakaHironobuKanYosukeNakashimaNobuyukiHoriTakehiroOkamotoTomoyaOhashiHiroshiAdachi10.18926/ESR/15025Well-developed Holocene raised coral reef terraces are formed in Kodakara Island (29°13'N 129°19'E), Tokara
Islands, northwestern Pacific, Japan. Detailed morphology and sedimentary structure of the raised reef terraces are
observed by field survey through the terraces surface and core drillings. The Holocene raised reef in Kodakara
Island are divided into three terraces (TI to III). The surface geo-biological facies and paleo-morphology such as
spur and groove system or reef mounds are well preserved on these terraces. The raised coral reefs in Kodakara
Island consist of reef flats and reef slopes. No lagoon formed in these terraces. On the raised reef surface, we
observed five distinct reefal facies (S-f1-5). The platy and encrusting Acropora facies is the major constituent of
the terrace surfaces. We obtained seven drilling cores (B1 to 7) from Terraces I and II along a transect in the
southern part of the island. The thickness of the Holocene reef is more than 14m which is approximately
equivalent to the Holocene reefs in the middle and southern Ryukyu Islands. Sedimentary structure consists of
seven facies (C-f1-7: five reefal and two non-reefal facies). The drilling cores indicating the shallowing sequence at the upward of the cores which characterized by platy-encrusting Acropora facies overlying massive Porites,
favid and/or encrusting-foliaceous coral facies. It may indicate the environmental change such as wave-energy
gradients and turbidity during the reef development.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141512009現世土壌の岩石学的記載 ： 古土壌研究への応用の一例932ENShigeyukiSuzuki10.18926/ESR/15024The microscopic observations of the recent soil horizons were conducted in Okayama, Japan (moderate climate). The several soil horizons, including two surface (epipedon) and three subsurface horizons, were recognized in the forest, poorly vegetated hill, and riverside around the Okayama University. The umbric epipedon can be segregated from the organic-rich subsurface horizons by the scattered organic materials in thin sections. The ochrich epipedon shows the sandy matrix without any cements and the illuviation of
clay minerals. The subsurface horizons identified in the study area are as follows: albic, argillic, and cambic horizons. Each subsurface
horizon shows the specific structures in thin sections. The albic horizon is characterized by the absence of the illuviation. The argillic horizon definitely shows the clayey matrix and the illuviation of clay minerals. The primary structures may be retained in the cambic
horizon.
The microscopic examination of the Miocene paleosols from the Ukan-cho, Okayama, was attempted. By comparing the recent soils, the cambic horizon and spodic horizon, which is characterized by the concentration of sesquioxides, are identified in the paleosols. This attempt suggests that the microscopic observations of the recent soils is a useful guide to understanding the paleosolsNo potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141512009岡山市北部の舞鶴帯から産出した二枚貝・巻貝化石18ENKeijiNakazawaShigeyukiSuzukiHidetoUwada10.18926/ESR/15022Permian and Triassic molluscan fossils are found from Mitsu-area, Okayama City, Southwest Japan. Permian
bivalve and gastropod fossils are collected from mudstones of the Upper Formation of the Maizuru Group. 4
species of bivalves (Nuculopsis? sp. ind., Leptodesma sp. ind., Streblopteria cf. eichwaldi, Posidonia sp. ind.)
and 5 species of gastropods (Worthenia cf. corrugata, Callitomaria n. sp. cf. stanislavi, Apachella n. sp.
ind., ??Eunemopsis like trochid, ??Yunnania sp.) are identified. Lower Triassic bivalve fossils are collected from sandstones of the Oono Formation. Neoschizodus cf. laevigatus and Bakevellia (Maizuria) kambei are identified.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994単結晶強度データーリスト作成プログラムLISTHKL4952ENJunjiYamakawaAkiraKawahara10.18926/ESR/13959LISTHKL, a Fortran 77 program listing up the data for deposit is submission to Acta Crystallo-graphica has been written. The program requires a computer set with a printer utilizung the LIPS3 page description language.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994CALCOMPからLIPS3への変換ライブラリの作成3748ENJunjiYamakawa10.18926/ESR/13958CALLIP, a CALCOMP compatible Fortran 77 library using the Canon LIPS3 page description lan-guage, has been written. As a result, the graphic output of programs with CALCOMP plotting routines used for crystal structure analyses, such as ORTEP2, Rietveld analyses and others can be used under the printer equipped with LIPS3 PDL. The details of the library was given with some graphic examples.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994Determination of Rb-Sr age for separated chondrules from the Allegan chondrite2736ENOsamuOkanoNanayoNishiyaHirooKagami10.18926/ESR/13957Rb-Sr isotopic study as well as petrologic investigations have been done on sixteen individul chondrule samples separated from the Allegan (H5) chondrite. The Rb-Sr chondrule isochron does not define a very precise age (4.42±0.17 Ga) and 87Sr/86Sr initial ratio (0.6997±0.0014) due to the very small variation in Rb/Sr ratio for the chondrules, whereas the model ages give a much more speciffic value (4.42±0.02 Ga). These ages may probably be indicative of the time of primary process (es) (e.g. chondrule formation) rather than secondary (metamorphic reheating) or tertiary (shock heating) processes in and/or on the H-chodrite parent body (or bodies). Chemical compositions of oliveines (Fa=17.5mol%, mean deviation (MD)=1.3%) and orthopyoxenes (Fs=15.4mol%, MD=3.2%) are moderately homogenized among the chondrules, while certains chemically uneguilibrated features are also distinctly preserved in this chondrite. Homogeneity of the mineral compositions, therefore, could not have been caused by thermal metamorphism but were probably inherited from processes prior to aggregation of the components. The overall implications of the chondrule isochron and model ages in relation to the petrological features and in comparison with Rb-Sr data of other chondrites of different chemical groups and petrologic types are discussed.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994瀬戸内海沿岸で観測されたScSp相について1926ENMasakiNishiHitoshiOda10.18926/ESR/13955Observation of ScSp phase, P wave converted from ScS phase, has been made at a seismological observatory (SBK) located on the coast of the Seto Inland Sea, southwest Japan. The ScSp phases were found on the seismograms of earthqukes with long epicentral distances, but not observed for those with short epicentral distances. Such dependence of appearance of the ScSp phase on epientral distance is interpreted as being due to the Philippine Sea plate horizontally lying beneath the Shikoku and Chugoku districts.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994Gradational development of slaty cleavage to schistosity -an example from the Iberian Pyrite Belt, Spain-918ENshigeyukiSuzuki10.18926/ESR/13953The Iberian Pyrite Belt is an Upper Paleozoic succession which has been divided into the Phyllite-Quartzite Group, the Volcanic-Sliceous Complex and the Culm Group in ascending order from base to the top. The contacts among them are conformable. These Groups are tightly folded and metamorphosed un-der low-grade conditions during Hercynian times. The first stage folds of the Volcanic-Siliceous Complex and the Culm Group are associate with slaty cleavages (S1), while the Phyllite-Quartzite Group is asso-ciate with schistosities (S1). Fold analysis using cleavages and minoe folds has been utilized in the analysis of the stratigraphy. This led to systematic horizontal collection of specimens (pelitic rocks). S1 texture is defined by paralled alignment of secondary platy minerals which tend to grow larger and together, forming zonal domains toward the Phyllite-Quartzite Group. The clay matrices change to recrystallized quartz toward the Phyllite Quartzite Group. Textural modifications are evidenced by gradational changes from slaty cleavages to schistosities. This shows that recrystallization is the important deformation mecha-nism responsible for S1 development. It also reflects that the deformation was contemporaneous with metamorphism.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414111994Petrography of primary peridotites from the Ohsa-yama area, Okayama Prefecture18ENToshioNozakaTsugioShibata10.18926/ESR/13952Ultramafic rocks exposed around Mt. Ohsa(= Ohsa-yama), Okayama prefecture, designated as "Ohsa-yama ultramafic body" all together, are one of the Alpine-type peridotites in the Sangun metamorphic belt. They are intensely serpentinized and locally suffered contact metamorphism by younger granitic intrusions. In a por-tion of the ohsa-yama body where it has been affected by the contact metamorphism, the constituent minerals, texture and structure of primary ultramafic rocks have been locally preserved. Petrographic studies revead that the primary ultramafic rocks of the ohsa-yama body consist domimantly of dunite and harzburgite possessing no obvious layering, and their constituent minerals are similar in composition to those of the Tari-Misaka and Ashidachi ultramafic bodies. These features indicate that unlike the Ochiai-Hokubo body, the Ohsa-yama ultra-mafic body belongs to the "massive group" of the Arai's (1980) classification.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995X線発生装置真空度監視システムの試作 （8ビットパソコンの有効利用)103108ENJunjiYamakawaAkiraKawahara10.18926/ESR/13950An used 8 bit personal computer is utilized for an instrument for continuous monitoring of the vacuum valuses of X-ray genrators. The interface board, programmable peripheral interfacial LSI, 8255A and some IC's for address decoding are assembled into a completed unti. The concept of the construction of this interface unti is profitable for the inexpensive layout of experimental laboratories.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995Yamato-74442 LLコンドライトにおけるアルカリ分別年代91102ENNanayoNishiyaOsamuOkanoHirooKagamiNoboruNakamura10.18926/ESR/13949Yamato-74442, a brecciated LL-group chondrite, consists of fragments with igeous texture, chondrules, mineral fragments, and host. The fragments involve K-rich fragments as well as normal ones. Typically, both fragments consist mainly of euhedral porphyritic olivines and a few orthopyroxenes in a glassy grundmass. EPMA analyses for these fragments indicate that olivines and orthoptroxenes have a range of Fe/(Fe+Mg) ratio of 27.19〜31.33 and 20.10〜26.91 mol%, respectively. There is no significant difference in these rations between K-rich (Na2O/K2O<1) and normal framents. The K2O contents of groundmass for K-rich fragments range from 0.51 to 4.89 wt% and that of the normal fragments is 0.38〜090 wt%. K2O contents of groundmass vary from fragment to fragment but are rather homegeneous in a single fragment.
Rb-Sr isotopic determination on eighteen K-rich fragments (1.5 to 9.5mg in weight) gave an internal isochron age of 4.514±0.022 (2σ) Ga (λ87Rb=1.42×10-11y-1) and initial 87Sr/86Sr ratio of 0.7016±0.0024. This age is somewhat old compared with a whole rock isochron age of LL chondrites (4.493±0.18 Ga; Minster and Allegre, 1981). From a comoarison of the present result with others so far reported, it is inferred that the alkali differentiation as observed in Yamato-74442 probably occurred prior to or during a process of accumulation from LL chondrite parent material in the early solar nebula. No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995A geochemical study of the Ashanti gold deposit at Obuasi, Ghana8190ENShilohOsaeKatsuoKaseMasahiroYamamoto10.18926/ESR/13948The Ashanti gold deposit at Obuasi occurs in the Early Proterozoic Birimian formation. The orebodies consist of gold-sulphides disseminated in metasediments and metavolcanics, and gold-bearing quartz veins. Gold occurs mainly as native gold normally with arsenopyrite, pyrrhotite and pyrite in the metasediments and metavolcanics. In the quartz veins, however, it is associated with tetrahedrite and sphalerite. Microprobe analysis of gold grains gave an Ag content of about 8 wt.%.
Textural relationships among the various mineral associations suggest that pyrrhotite, pyrite, arse-nopyrite and possibly gold may have been formed esrlier in the paragenetic sequence. The precipitation of some amounts of gold may have occurred during the later stages of the mineralisation sequence.
Average arsenopyrite composition determined from electron microprobe study is: Fe: 33.6 ± 0.5 at.%, As: 29.3 ± 1.2 at.%, S: 37.1 ± 1.1 at.%, This suggests an average temperature of formation of less than 300℃ for the sulphides and possibly the gold assuming equilibrium was attained between pyrite, pyrrhotite and arsenpopyrite. The δ34S values for sulphide mineral separates are in the range between -4.1 and -10.8%. The values were, however, constrained between -4.1 and -7.0%. The narrow range and the depleted nature of the δ34S values may suggest a sedimentary sourcc of sulphur which may have undergone high temperature homegenisation before deposition. Sulphides from quartz vein samples had the most depleted δ34S values. This may indicate a different mineralisation history of the sulohides in the quartz veins from those dissemi-nated in metasediments and metavolcanics.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995Occurrence and composition of manganese oxide minerals from the Nauta manganese deposit, Western Ghana7180ENNyameFrank kKatsuoKaseMasahiroYamamoto10.18926/ESR/13947X-ray diffraction, ore microscopy, and electron microprobe studies have been done on ore samples obtained from the mine site at Nsuta, Ghana. Manganese ore minerals identified include nsutite, cryptomelane, pyrolusite, and lithiophorite. Except for pyrolusite, all these minerals are poorly crystalline. Chemical compositions of the minerals indicate little contamination by other elements. Quartz, muscovite, and clay minerals feature prominently as gangue in most samples. Textures are varied, and modes of occurrence are prinicipally by replacements, cavity or fracture fills, leaching and precipitaion. Mineral associations seem rather complex, as a result of which definitive paragenetic relations could not be established.
Supergene formation of the manganese oxide ore is shown by the abundance of manganese minerals in solution channels such as fractures and cavities within silicate gangue. Much of the ore, howver, appears to have been enriched by leaching of gangue minerals and the later addution of manganese.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995塩溶液中の溶解性シリカの平衡濃度と重合速度について6370ENHajimeSugitaMasahiroYamamoto10.18926/ESR/13945The solubility of amorphous silica was determined in sodium chloride,potassium chloride, magnesium chloride and calium chloride solutions from 0.01 to 1moI/I and at temperatures of 21,36,50 and 65℃. The Setchenow equation was applied to the results, which enabled us to estimate the equilibrium concentration of "dissoloved silica" (molybdate-reactive silica) in the studied chloride solutions.
Next, the effects of pH, supersaturation of silica and salt concentration on the polymerization rate of silica were investigated at 35℃. In the pH range from 6.4 to 7.9, the maximum polymerization rate increased with increasing pH. The maxima occurred when dissoloved silica decreased by 25% of the initial supersaturation concentrations irrespective of pH. The polymerization rate was found to be dependent on the supersaturation degree rather than on the supersaturation concentration of silica. The results in magnesium chloride solutions suggest that magnesium ions may act as nuclei in the formation of colloidal silica in geothermal waters.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995雲仙火山1990〜94年の火山活動に伴う火山灰水溶性物質5562ENSeishiAkagiMasahiroYamamoto10.18926/ESR/13943Water-soluble materials on volcanic ash from the Unzen volcano collected from February, 1991 to July, 1994 were chemically analyzed. They were similar in chemical characteristics to those obtained from other volcanoes. Chemical compositions varied even for materials from the same pyroclastic flow. C1 contens increased with increasing residence time of volcanic ash in air, but SO4 contents were almost fixed. It therefore seems that the reaction of volcanic ash with HC1 proceeds even at low temperatures, whereas the reaction with SO2 takes place only at high temperatutes.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995瀬戸内海地域領家帯の黒雲母片麻岩の起源に関する1つの提案 : 玖珂層群とは別の地質単元から由来した黒雲母片麻岩がある2354ENTerukazuNureki10.18926/ESR/13941The Kuga group is a Jurassic accretional complex that has been believed by many workers to be a unique geologic unit transformed into the Ryoke gneisses in the Seto Inland Sea region. I will now suggest the presence of a different geologic unti in addition to the Kuga group. Most of the biotite gneisses found at the Iwakuni-Yanai area are probably derived from rocks of the Kuga group, but the rest biotite gneisses that occur in the Murotu Peninsula, the Yashiro-jima, the E-no-shima, and the other several islands in the Seto Inland Sea region were derived from a un-known and a different geologic unit to the Kuga froup.
Some pieces of evidence proving the distinct origin of the latter biotite gneisses are: (1) the biotite gneisses commonly occur as small to large fusiform bodies generally enclosed in the older Ryoke granite or as large masses contacting only with the older Ryoke granite; (2) tight folds with parallel axial surfaces are very common, and dupli-cated fold systems are found in many localities; (3) microtextures of some minerals, e.g. garnet and K-feldspar, often suggest a plural metamorphic history of the gneisses (Nuraki et al., 1982a; Miyashita % Komatsu,1993); and (4) the sillimanite zone (Ikeda,1991 : Okudaira et al.,1993) is only a metamorphic zone that can be found. The sillimanite zone is interpreted to be excluded from the progressive metamorphism in the Iwakauni-Yanai area (Wallits et al.,1992).
Biotite gneisses of the sillimanite zone are found here and there and show no zonal arrangement of distribu-tion in the Ryoke belt. The estimated metamorphic temperature and pressures for the biotite gneisses of the silliman-ite zone are 530-710℃ and 2-4kb respectively, both of which are lower than of the peak metamorphism, estimated as 550-820℃ and 5-6kb, at the Iwakuni- Yanai area.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995水中テレビロボットによる瀬戸内海での海底地質調査1322ENShigeyukiSuzukiTakashiInada10.18926/ESR/13940Submarine geological survey using the remotely operated TV vehicle (RV100), was carried out in 4 offshores of the Seto Inland Sea in Kagawa Prefecture. The study areas are west of Kosei Island of Sakaide City, south of Okado-bana of Nankai Town, west of Misaki of Takuma Town and north of Nou-Misaki of Sakaide City. TV vehicle transmite clear pictures of bottom of the sea to the monitor on board. The submarine geology of the study areas are composed of Cretaceous granitic basements and Quaternary sedimentary covers. By using these pictures Recent and Pleistocene deposits could be distinguished and lithology of sediments could also be identified. Lithology of sediments was however difficult to identify using the usual sonic prospecting method. Furthermore, pictures suggesting that ripples are just forming have been obtained. The TV vehicle is convenient in submarine survry, because it can travel much longeer and deeper than human diver. A new method of mapping submarine geology using TV vehicle was developed.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414211995Mineral paragenesis in thermally metamorphosed serpentinites, Ohsa-yama, Okayama Prefecture112ENToshioNozakaTsugioShibata10.18926/ESR/13938The Ohsa-yama ultramafic body, which consists of several types of serpentinized peridotites, underwent contact metamorphism caused by a Cretaceous granite intrusion ; this metamorphism resulted in the formation of contact aureole, 1.5-2.0 km wide, around the granite intrusion, and produced progressive mineral changes in metaserpentinites toward the contact between the Ohsa-yama body and the granite intrusion. On the basis of analysis of mineral paragenetic relations, the Ohsa-yama ultramafic body can be divided into three zones with progressive changes in mineral assemblages as follows :
Zone T : serpentine ± chlorite ± brucite
Zone U : olivine + talc ± tremolite ± chlorite
Zone V : olivine + orthopyroxene ± tremolite ± spinel
Zone T corresponds to the parts unaffected by the thermal event, and Zones U and V correspond to the thermally metamorphosed parts of the Ohsa-yama body. The results obtained in this study are generally consistent with those of the previous studies on metamorphic peridotites from the Sangun and Muzuru zones.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996マイコンを使用した水熱合成炉徐冷制御装置の作成6570ENJunjiYamakawaAkiraKawahara10.18926/ESR/13937A used 8 bit microcomputer is applied for an instrument of controlling the heating temperatures of hydrothermal reactor furnaces. The temperatures were changed into appropriate values of voltage by thermocouples and additional devices. The interface board, programmable peripheral interface LSI and some IC's for addres decording are assembled into a complte unti. The device is useful for the inexpensive way of the construction of the accurate temperature control system.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996Interpretation of the Crystad Structure of Synthetic Kaliophilite from the Domain Structure of Kalsilite5764ENAkiraKawahara10.18926/ESR/13936The syntheses of kaliophilite have been carried out from the starting materials of near kalsilite compotions (KAISiO4), of which the AI2O3/SiO2 ratio is greater than 1/2. The X-ray powder deffraction pattern fit well to those of previous investigators. The crystal structure of synthetic kaliophilite was proposed by using the model consisting of four different types of kalsilite structure. The positions and intensities of the X-ray powder pattern were able to be explained on the basis of these four domains, belonging to thr twinning by merohedory. As a result of the conditions of the syntheses, it may be supposed that the violation of the AI-O-AI avoidanice rule can possibly exist along the domain boundaries.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996Ca-bearing Rectorite Mineral from Roseki Deposits, Japan4756ENToshihikoMatsudaMakotoKurosaki10.18926/ESR/13934Several specimens of rectorite-type regularly interstratified mineral (including Ca-rich one of hydrother-mal origin) from roseki deposits together with a few rectorites were examined by chemical analysis, X-ray diffraction and IR spectroscopy.
These specimens are rich in SiO2, AI2O3 and H2O in addition to considerable amounts of CaO, Na2O and K2O. The Ca content in mica-like layers ranges from a slight amount to exceeding 50% of the total interlayer population. For the Ca-bearing specimens, AI-for-Si substitution in the tetrahedral sheets of mica-like layers increases in proportion to the Ca contents. Characteristic absorption bands of 950-900 cm-1 and 700-670 cm-1 are observed in IR spectra. The bands are due to AI-for-Si substitution in the tetrahedral sheets. Judging from the chemical analysis and IR spectra, the component of mica-like layer rich in Ca is not that of mica but mainly that od margarite (brittle mica). Expansion characteristics of the Ca-rich mineral are similar to rectorite and expandable layer is close to beidellite. The mineral is somewhat less expandable than rectorite under the condition of RH70-80% (Na-saturation) and EG treatment (K-saturation).
The rectorite-type Ca-rich mineral reported here is simlar to rectorite in its expansion characteristics, but the component of mica-like layers is different from that of rectorite. Mica-like layer of the mineral must be mainly composed of margarite-like layer. The mineral is mainly composed of a 1 : 1 regular interstratification of dioctahedral britlle mica (margarite) and smectite (beidellite). The mineral does not strictly correspond to rectorite, defined as a 1 : 1 interstratified mineral of dioctahedral mica and smectite.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996西南日本内帯のろう石鉱床の硫黄同位体比4346ENMasahiroYamamotoToshihikoMatsudaRaikiNakagawa10.18926/ESR/13933Sulfur isotope ratios of pyrite and alunite from 5 Roseki deposits in the Inner Zone of Southwest Japan were determined. The δ34S values of all pyrite samples were in the range from -13.2 to +2.3%, the variation range for each deposit being within 8%. In each deposit δ34S values of alunite were always higher than those of pyrite, which may be interpreted as that alunite was precipirated under more oxidizing conditions than pyrite. Sulfur isotope rations of the Roseki pyrite showed a distribution similar to that of ore sulfur from skarn and vein deposits in the same Zone. This suggests that the origin of sulfur of the Roseki deposits is also host igneous rocks.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996固有周波数のインバージョンによる地球内部構造の不均質性の推定 ―数値実験―3342ENSeijiOnishiHitoshiOda10.18926/ESR/13931An investigation was made on effect of lateral heterogenity of the earth's elasticity structure on the normal mode frequencies. The lateral heterogeneity is expressed by an expansion of spherical harmonic functions, Pιm(cosθ)sinmΦ and Pιm(cosθ)cosmΦ, up to the second order harmonics (ι≤2). Free oscillation freguencies of the heterogeneous earth were computed by the xyz algorithm. Further we derived an analytic expression of partial derivatives of eigenfrequency with respect to the expansion coefficients, and performed a numerical test to verify whether or not it is possible to estimate the heterogeneity of the earth's structure by the inversion of noemal mode frequencies.
When the earth is assumed to be elastically isotropic spheroid with short polar and long equatorial radii, frequency spectra affected by longitudinal heterogeneity terms, Pιm(cosθ)(sinmΦ, cosmΦ) (m≠ 0), for given values of ι and m coincide with each other, because these two terms describe the same heterogeneity when the earth is rotated by π/2m around rotation axis. In such a case, we cannot determine accurately the expansion coefficients of tha two heterogeneity terms by inversion of normal mode frequencies, whereas the coefficients of the latitudinal heterogeneity Pι0(cosθ) can be precisely determined. Therefore it is difficult to estimate of lateral heterogeneity of the earth's elasticity structure by the inversion of normal mode frequencies.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996Thermal Expansion of Forsterite, Mg2SiO4 : 1. Measurements2532ENKojiKajiyoshiIsaoSuzuki10.18926/ESR/13930Thermal expansion of forsterite, Mg2SiO4, is measured up to 1,600 K by the dilatometric method. The present results of volume thermal expansion Yv is 3.20 percent from 300 to 1,200 K and expansion coefficient αv is 40.5 × 10-6 K-1 at 1,200 K. They are close to those of a natural olivine (Suzuki, 1976), but are 4.4 and 11 percent smaller as compared with those reported in the former paper (Suzuki et al., 1984). The Yv and αv of forsterite are 5.00 percent and 46.7 × 10-6 K-1 respectively, at 1,600 K.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996Paleogene talus deposits, Okayama City, Southwest Japan1724ENShigeyukiSuzuki10.18926/ESR/13928In eastern Chugoku area, Paleogene deposits have not been recognized until fission-track dating of so called "Mountain Gravels" was carried out (Suzuki et al. 1995). Two sedimentation events in Paleogene time (27Ma and 34-35Ma) are inferred by the F-T dating Major lithology of the Paleogene deposits in the study area is graved which is mainly composed of subrounded to rounded cobbles. The "Mountain Gravels" were previously thought to be lower Quaternary deposits. The "Mountain Gravels" is associsted with coal bearing mud, sand, gravel and breccia deposits.
The breccia deposits is distributed sporadically between the "Mountain Gravels" and basement rocks. The deposits are mainly composed of poorly sorted breccia and associated granitic sands. It is inferred that the breccia deposits are talus deposits.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414311996Provenance of Lower Cretaceous sediments in the Nariwa and Hokubo areas, Okayama Prefecture, deduced from detrital modes and geochemistry of sandstones116ENShigeyukiSuzukiTsugioShibata10.18926/ESR/13927Petrographic and geochemical study of sandstones from the Kenseki Formation have shown that the sandstones are compositionally immature. The immaturity is reflected geochemically by their low SiO2 contents (52-66 wt%) and petrographically by low modal percents of quartz and K-feldspar, and high modal percents of plagioclase and volcanic lithic fragmants. The Kensaki sandstones are, however, poor in Na2O (up to 2.1 wt%).
Both petrography and geochemistry suggest a heterogeneous source lithologies of acidic and basic volcanics, sedimentary, and ultramafic rocks. Petrographic evidence is supplied by quartz and plagioclase of volcanic origin, acidic volcanic fragments, basic volcanic fragments, volcanic glass, serpentinite fragments and detrital spinel grains. Geochemical evidence is provided by high FeO* (total iron as FeO), MgO, TiO2, CaO and K2O contents.
Petrographic and geochemical study of the Kenseki sandstones indicate calc-alkaline oceanic island are provenance. The sediments were locally derived, with Alpine-type ultramafic rocks exposed in the north and volcanic materials of the Akiyoshi Belt supplying the bulk of the detritus.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997Trial calculation of relating the equilibrium state of minerals to the descriptive mineralogy7996ENAkiraKawahara10.18926/ESR/13922Statistical calculation have been carried out on the volumes of the asymmetric unit of minerals. This treatment is related to the origin of the symmetry and periodicity of the crystals, and to the equilibrium conditions of these crystals. From the view point of the cohesion energy, if the crystals were grown under the condition of nearly perfect equilibrium states, than all the volumes of the asymmetric unit of each crystal structure will be approximately equal, and if the volume of the asymmetric units of a certain mineral is larger than the average value, this mineral is considered to be grown in a metastable condition. The calculation of the cell dimensions of minerals have been carried out by the use of deta from previous investigations. The statistical consideration of the volumes of the asymmetric unit of minerals is considered to be an appropriate criterion to relate the stability of minerals to their descriptive mineralogy.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997On the plasticity of Si-O framawork of alkali zinc silicates7378ENShizuoKoharaAkiraKawahara10.18926/ESR/13921The configuration of the Si-O framework in alkali zinc silicates has been investigated on the basis of recently determined structures. The results have shown that there is a linear correlation between the ionic radii of alkali ions and the molar abundance of ZnO+SiO2 per one alkali ion in the structure. This indicates that in the case of zinc silicates, the configuration of the Si-O frameworks is largely influenced by the ionic radii of alkali ions in the structure. On the contrary, in the case of alumino-silicates, the configuration of the Si-O framework is independent of ionic radii of alkali ions. In the former, the Si-O framework is considered to be plastic, while in the latter, it could be called rigid. The latter extreme cases are those of zeolites. In this case, the configuration on frameworks is not entirely influenced by the ionic radii of alkali atoms present. These results are discussed in connection with the historical investigations of silicate structures.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997Structural Modification of KAISiO4 Minerals4172EN10.18926/ESR/13919Kalsilite, a polymorph of KAISiO4 is an end member of nepheline-kalsilite series and the mineral was syn-thesized by hydorhermal methods. The synthetic kalsilite is hexagonal, P63, with a=5.151(5), c=8.690(8) A. The structure was refined by full-matrix least-squares methods to a R-value 0.084, using 373 observed reflections. The obtained structure agrees well with those of the natural and the alkali-exchanged specimens reported in the previous literatures. The oxygen atoms are disordered at two mirror-equivalent sites, constructing the domain structure. The average domain structure shows P63mc symmetry and the strctural relation between the two P63 structure corresponds to the twinning by merohedry.
The domain structure was considered to be caused accompanied with the high-low inversion of the kalslite structure. Heating experiments of kalsilite reveal that the X-ray powder pattern changes at 865℃, and that cell dimensions vary discontinuously at this temperature. It was confirmed that kalsilite underwent a displacive transition like those observed in quartz or tridymite. The high-form is refered as 'high-kalsilite', and a possible simulate model is proposed.
The structure of the high-kalsilite at 950℃ was refined byfull-matrix least-squares methods to a R-value 0.095, using 115 observed reflections. The high-kalsilite is also hexagonal, P63mc or P63/mmc, with a=5.288(1), c=8.628(5) A at 950℃. The structure almost prefectly coincides with that of the simulated model. Based on the interatomic distances, the distribution of silicon and aluminum atoms is found to be or-dered and the space group is determined to be P63mc.
Kaliophilite and the related orthorhombic from, polymorphs of KAISiO4, were synthesized by dry method. The synthetic kaliophilite (kaliophilite-H2) is hexagonal with a=5.17(1), c=8.49(3) A, and the orthorhombic KAISiO4 (kaliophilite-O1) is orthormbic with a=9.01(1), b=15.60(2), c=8.53(4) A. Detailed examina-tion of the obtained powder patterns together with that of simulated model indicates that the kaliophilite-H2 has a disorderd structure of four types of the low-kalsilite. The structure was refined by the X-ray powder pattern-fitting method (Rietvelt method) to a R-value 0.121.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997岡山県大佐山地域に産するフェロ藍閃石片岩3340ENToshioNozaka10.18926/ESR/13917A ferroglaucophane schist occurs in fault contact with serpentinites at the Ohsa-yama area, Southwest Japan. It consists of albite, ferroglaucophane and actinolite with small amounts of stilpnomelane, sphene, apatite and K-feldspar. Petrological studies reveal that the schist was originally igneous rock of felsic or intermediate composition and has suffered two stages of metamorphism : ferroglaucophane has been formed at the first stage and actinolite at the second stage. In a basic schist from the same outcrop that the ferroglaucophane schist occurs, tremolitic amphibole instead of alkali amphibole has been formed along with chlorite, phengite and albite. Such a difference in mineral association between the schists is ascribed to a difference in whole rock composition, particu-larly in Fe/Mg ratio.
Some of the schists from th Ohsa-yama area characteristically contain glaucophane or ferroglaucophane and have low Fe2O3/FeO ratios, forming a striking contrast to the crossite schists that commonly occur in the so-called "Sangun metamorphic terrane". These facts suggest that the alkali amphiboles of the Ohsa-yama schists were formed under higher P/T and more reducing conditions than those of the regional metamrphic rocks. On the other hand, development of the second-stage actinolite in the ferroglaucophane schist is consistent with the meta-morphic parageneses of greenschists from adjacent areas. Consequently the ferroglaucophane schist is considered one of the tectonic blocks that were captured by mobile serpentinites and have suffered the regional metamor-phism after the emplacement of the serpentinites into the present geologic position.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997三畳系成羽層群の地質と地すべり2132ENShuHotaniShigeyukiSuzukiHajimeTanakaTakuyaYamada10.18926/ESR/13916Geological and topographical study of landslides in the Triassic Nariwa Group has been carried out. Nariwa Group is mostly composed of non-marine deposites and is characterized by cycle of fining upward successions. Landslides abundantly occur in the non-marine successions. Slip surface occure in coaly mudstones that have conspicuously less strength than sandstones. Creeps immediately below slip surfaces contribute to the occurrence of landslides in the Nariwa Group.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414411997西南日本の地殻及び上部マントルの三次元P波速度構造120ENTakashiTanakaHitoshiOda10.18926/ESR/13915Trevel-time data of the P wave were inverted to study three-dimensional structure of the P wave velocity in the upper mantle and crust beneath the Shikoku and Chugoku districts, southwest Japan. Low-velocity and high-velocity regions were found in the upper crust of the eastrn and western regions in the Shikoku district, respectively. The activity of crustal earthquakes is high in the eastern region. Moreover a significant high-velocity region exists in the uppermost mantle, where the activity of small earthquakes is very high. A low-velocity region with velocity of 7.0km/s was found just above the descending Philippine Sea plate with high velocity of 8.0 km/s. This region is continued to oceanic crust in the vicinity of the Nankai trough and its velocity is nearly equal to the P wave velocity (6.7 km/s) of oceanic crust. Thus the low velocity is interpreted as the oceanic crust. A high-velocity region is found below the depth of 50km in the Shikoku district. This region suggests the Philippine sea plate lying horizontally from the Shikoku districts to the ocast of the Seto Inland Sea of the Chugoku district. A low-velocity zone suggesting the volcanic front is found around the depth of 50km at the coast of the Japan Sea of the Chugoku distrit.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414511998Sulfur isotope rations of sulfide minerals from the deposit of the Tsuchikura mine, Shiga Prafecture, Japan1722ENMasahiroYamamotoKatsuoKaseKaoriHarada10.18926/ESR/13912Sulfur isotope rations of sulfide minerals in the ore specimens from the deposit of the Tsuchikura mine are distrib-uted in a range from -0.8 to 5.4%, mostly from +0.5 to 3.0%, close to the previous data (from +1 to +3%) by Miyake and Sasaki (1980). The distribution range is also similar to the major Besshi-type deposites of the Sambagawa terrain. Sulfur isotope fractionation between coexisting pyrite and chalcopyrite is not uniform. This may be largely due to spatial tearrangament of the initial orebodies to the present form. Sulfide minerals mostly pyrite from host rocks (siltsones, sandstones, basaltic rocks) exhibit remarkably low δ34S values ranging from -49.3 to -2.6%, dis-tinctly different from the δ34S values for sulfide minerals of ores. The low δ34S values may indicate the bacteriogenic origin of host rock sulfides, although it seems peculiar that basaltic rocks also have extremely low δ34S values.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414511998児島湾干拓地におけるボーリング試料から得られた(14)C年代測定値1316ENHajimeSasakiShigeyukiSuzuki10.18926/ESR/13911Two 14C ages are obtained from drilled core samples in Kojima Lake area. One is 7920±250 y.B.P. from peat which is just below silty clay of bay sediments (-14.30-14.61 m) The other is 24900+3450,-2450 y.B.P. from pale milky gray clay of fluvial sediments (-24.15-24.45 m).No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414511998横浜町に発達する段丘に地形と堆積物112ENShigeyukiSuzukiAkikoMiyawaki10.18926/ESR/13909Higher, middle and Lower Terraces (Quaternary) have been distinguished in Yokohama Town, Aomori Prefecture. The Higher Terraces are subdivided into three terraces, H1,H2 and H3. They are distributed in hills. H1 and H2 deposites are composed of gravels of fan deposits. H3 deposits are composed of gravels, sands and mud of alluvial plain deposits. The Middle Terraces are subdivided into three terraces, M1, M1' and M2, and occupy almost all terraces in Yokohama Town. These deposits are composed of beach (sand with gravel) and fan (gravel) deposits. The Lower Terraces are subdivided into two terraces, L1 and L2. The L1 Terrace is distributed in limited area along coast and thought to be composed of beach deposits. The L2 Terrace is distributed in limited area along river and composed of braided stream deposits.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414611999Hydrogen and oxygen isotope ratios of thermal waters of Okayama Prefecture, Japan3944EN10.18926/ESR/13908Hydrogen and oxygen isotope rations of thermal waters from 46 spas in Okayama Prefecture range from -62.6 to -29.2% in δD and from -10.0 to -4.4% in δ18O, respectively. The isotope rations indicate that all but one of the thermal water in Okayama prefecture are meteoric in origin. The Ofuku thermal water is the only exception, which is probably a mixture of seawater and meteoric water with the ratio of about 1.
Sulfur isotope rations of dissolvel sulfate in the thermal waters range from -6.2 ti 59.3% in δ34S. The high δ34S values observed in some thermal waters may be due to bacterial reduction of sulfate.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414611999衝突溶融隕石Y-793533コンドライトの化学組成とRb-Sr系2938ENOsamuOkanoHirokoKatayamaNoboruNakamura10.18926/ESR/13907The Sr isotopic compositions and Rb and Sr abundances, as well as major element abundances in olivine, pyroxenes and glass, were determined for a chip and 21 fractions separated from a shock-melted chondrite Yamato-793533, a dark-colored, porous stone with glassy texture. Two lithologies were recognized for the 1.5g specimen studied (Yamato-793533, 67) ; L (Main portion) and L to LL (Dark portion) chondritic in terms of chemical compositions of olivine and pyroxenes. The chemical compositions of glass are relatively homogeneous (SiO2=67-77%) compared to those of other ordinary chondrites, suggesting a moderate cooling rate after shock-melting. The data points for fractions do not foem any isochron in a 87Rb/86Sr vs. 87Sr/86Sr diagram. However, it is noted that six out of nine points for the dark portion plot around a 1.2 Ga line, while most of points for the main portion plot around a 4.55 Ga chondrite isochron. The observed difference could be responsible for difference in melting degrees between the two portions. Similar Rb-Sr features have been found among shock-melted Yamato-79 LL-chondrites which are considered to be paired stones experienced the same shock-melting event at 1.2 Ga. Consequently, the Rb-Sr systematics as well as petrologic features strongly suggest that Yamato-793533 is a member of a series of the shock-melted Yamato-79 LL-chondrites.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414611999玉野市出崎海岸に露出した縄文時代の泥炭層2328ENShigeyukiSuzukiKoichiYukimoto10.18926/ESR/13906Peat bed remains isolated in the shoreline of western beach of Desaki peninsula. Collected samples gave radiocarbon data of 5790±80 and 5810±60 years BP.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414611999西太平洋における大気・海洋中二酸化炭素濃度の測定 ―MR98-04 次航海―1322ENTakehikoKonoEijiYamashitaTerumasaNogamiOsamuTsukamoto10.18926/ESR/13905It is well known that the ocean plays a very important role in the overall geochemical cycle of CO2. Over the ocean surface, CO2 is equilibrated between partial pressure of CO2 in the seawater (pCO2) and that in the atmosphere(PCO2).
The objectives of the present observation are to evaluate the following : (1) Horizontal distribution of pCO2 and PCO2, (2) Sea surface CO2 flux and (3) Vertical distribution of pCO2.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414611999Phlogopite and Hornblende in the Contact Metamorphosed Ultramafic Complex at Yanomine, Sangun Metamorphic Zone, Japan112ENYoshinoriInoueKatsuoKase10.18926/ESR/13904Phlogopite and hornblende were found in amall amounts in the contact-metamorphosed dunite-harzburgite complex at Yanomine. Phlogopite occurs in interstices of silicate minerals in dunite and harzburgite located near the contact with granite. Some phlogopite grains also occur as inclusions in chromian spinel of chromitite bands. Hornblende is present associated with such metamorphic minerals as talc, olivine and orthopyroxene. Interstitial phlogopite is characterized by lower TiO2 and higher K/(K+Na) atomic ratio compared to that included in chromian spined. Hornblende in dunite chages its composition from edenite associated with olivine-talc through edenitic hornblende to Si-poorer magnesio-hastingsitic hornblende and magnesio-hastingsite with olivine or olivine-orhtopyroxene.
The interstitial phlogopite is suggested to have been formed intimately connected with fluids generated in ralation to the intrusion of granite. On the other hand, included phlogopite is considered to have crystallized from the incompatible elements-enriched hydrous melt resulted from mantle-melt interaction. Hornblende should be a metamorphic mineral formed under high temperature conditions.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000A New Species of Lithostrotion (Siphonodendron)(Rugosa) from the Hina Limestone, Okayama Prefecture, Southwest Japan4750ENShigeyukiSuzuki10.18926/ESR/13902A new rugose coral species, Lithostrotion (Siphonodendron) hinensis is described in this paper. It was collected from the Carboniferous Hina limestone in Okayama Prefecture, Southwest Japan. Judging from the paleontological data, the age indicates probably Late Viaean, Early Carboniferous.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000岡山県井原市浪形の標高240mの石灰岩に残された海食地形4146ENTakaoFujiwaraShigeyukiSuzukiYasuoMaeda10.18926/ESR/13901The tidal notch and the sea caves which cut into the Namigata Limestone is stiuated in 240m above sea level, Ibara City. The notch assocciates the Namigata Terrace 200m to 240m high. These geomorphological features indicate an event of high sea level. However the age of the event has not been known.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000岡山市北部, 備前, 富原炭鉱の夾炭層と「山砂利層」との関係3540ENShigeyukiSuzukiKeijiNakazawaHajimeTanaka10.18926/ESR/13900The Bizen and Tomihara Coalfields which were situated in northern Okayama City, had produced lignite during 1940s. Distribution of coal measures indicates that the coal measures are intercalated in the middle of the so-called "Mountain Gravels". The "Mountain Gravels" is subdivided into two formations ; the older, about 34〜35Ma, and the younger, about 27Ma, of fission track ages. The older formation inculudes the Bizen Coal Measures. On the other hand, the Tomihara Coal Measures are intercalated in the younger formation.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000Chemical composition of clinopyroxenes associated with the gehlenite skarn from the Hirata outcrop, Kushiro, Tojo-Cho, Hiroshima Prefecture, Japan2734ENChiyokoHenmiIsaoKusachi10.18926/ESR/13899The clinopyroxenes of the hybrid rocks from the Hirata outcrop, Kushiro, Hiroshima Prefecture, Japan are grouped into(1)diopside, (2)aegirine, and (3)zoned pyroxene. The diopside occurs as isolated crystals enclosed in feldspars. The aegirine occurs along with late hydrous minerals in pore spaces. The zoned pyroxenes occur as discrete cryatals with wide rims growing interstitially between feldspar laths and show a continuous composition-al trend from diopside through hedenbergite and aegirine-augite to aegirine or titanian aegirine. The pyroxenes enclosed in feldspars and the cores of the zoned crystals have nearly same chemical composition. The late stage pyroxenes are characterized by extreme enrichment of sodium and sometimes titanium. The titanian aegirines studied hera are characterized by the predominance of the Na(Fe2+, Mg)0.5Ti0.5Si2O6 component over other Ti-bearing pyroxene components.
The compositional trend of clinopyroxenes from the Hirata hybrid rocks follows a typical trend of peralkalne rocks. The peralkaline neture of the Hirata samples is a result of compositional change of magma accompanied by the metasomatic skarn formation.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000火山岩とHCIおよびSO2ガスの反応により生成する水溶性物質2126ENSeishiAkagiMasahiroYamamoto10.18926/ESR/13897Experiments on the reaction of a volcanic rock, dacite with HCI and /or SO2 gases have been carried out at room temperature to 800℃ for understanding of the condition of the formation of water-soluble materials on volcanic ash. HCI reacted with the dacite mainly at low temperatures (≤200℃), whereas SO2 did at high temperatures (≥400℃). It was also found that CI/SO4 ratios of water-soluble materials were very high at low temperatures, but decreased rapidly with increasing temperature. In the experiments using a mixture of HCI and SO2, the cation composition at 600℃ and 800℃ was revealed to be significantly different from that at lower temperatures, suggesting the change in the reaction process with temperature.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000新潟県東蒲原郡三川村三川鉱山産の自然金1920ENJunjiYamakawaMitsuoTanabeKazumasaShimadaChiyokoHenmi10.18926/ESR/13894Native gold was found at Mikawa mine, Niigata Prefecture, Japan. The mineral was associated with quartz in a druse within quartz-vein in propyrite. The crystals were formed in filiform, reticulated and dendritic shapes with about 1 mm length with 0.1 mm width and 0.05 mm thickness. Very malleable and ductile, opaque and yellow with metallic luster. Qualitative and semi-quantiative analyses were performed by the wavelength dispersive EPMA. Quantitatively, the crystals contained Au, Ag and Hg. Semi-quantitative analyses were executed with ZAF correction algorithm. The results showed that these specimens had a average chemical composition Au0.77 Ag0.11Hg0.12. This specimen was archived at our site with a collection number ESO-M01001.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000S-wave velocity structure estimated from long-period coda waves1518ENHitoshiOda10.18926/ESR/13893Long-period coda waves were recorded on the vertical-component seismograms of aftershocks of the Hyogo-ken Nanbu earthquake, 1995. We identify the long-period coda waves as Rayleigh wave, because they appear after the S-arrival times and exhibit the normal dispersion that propagation velocity of the coda waves increases with an increase in period. By applying the moving window analysis to the coda waves from nine aftershocks, the group velocities are determined as a function of period within the range of 2 to 8 s. The group velocity dispersion data are inverted to investigate the S-wave velocity structure of the upper crust. The S-wave velocity structure is consistent with those obtained in previous studies using traval time analysis of bood waves.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414712000船舶を用いた海面乱流フラックスの自動観測114ENSatoshiTakahashiOsamuTsukamotoHiroshiIshidaKunioYoneyama10.18926/ESR/13891Sea surface eddy fluxes were evaluated with the eddy correlation method including ship motion correction for the wind vector components. Previous ship motion correction algorithm was revised as a simple scheme setting a motion sensor at the same place with the sonic anemometer. This revised eddy flux system was mounted as a routine continuous measurement system on the R/V 'Mirai' of Japan Marine Science and Technology Center.
The first cruise was conducted at the tropical weatern Pacific in June 2000. Continuous sea surface fluxes were obtained and the data quality was checked with some parameters. This system is planned to be developed as a automated data processing system including ship motion correction and real-time flux evaluation system. These eddy fluxes can be integrated with the bulk fluxes and radiation fluxes to understand sea surface heat balance over the global ocean.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414812001Hydrogen and oxygen isotope rations of thermal waters of Izu Peninsula, Shizuoka Prefecture, Japan3944ENDaijuKobyashi10.18926/ESR/13889Hydrogen and oxygen isotope ratios of thermal waters from 42 hot springs in Izu Peninsula, Shizuoka Prefecture, range from -51.7 to -24.7% in δD and from -7.9 to -4.1% in δ18O, respectively. The isotope ratios suggest that most of the thermal waters in Izu Peninsula are essentially meteoric in origin. Significantly deviated from the normal meteoric waters are thermal waters from Yumigahama, Kumomi, and Shimogamo hot springs which may be mixtures of seawater and local meteoric waters, and thermal waters from Izusan and Imaihama whose oxygen isotope ratios may have become heavier by water-rock interaction. No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414812001岡山県の主要3河川の水質と地質の関係2938ENtakuyaKinoshitaToshihikoMatsuda10.18926/ESR/13888Concentrations of inorganic major components (Ca2+, Mg2+, Na+, K+, ΣFe, AI3+, HCO3, SO4, CI-, NO3, F- and SiO2) were measured in 57 water samples from three main rivers, the Yoshii, Asahi and Takahashi Rivers and their tributaries. The water quality is discussed in relation to the geological environment in the drainage basin of three rivers. The following results were obtained from the investigation. The degree of influence of rocks on the water quality was limestone≫basic rocks>clastic rocks>andesite>rhyolite>gramite. The influence of geology is clear in the riverhead but it is obscure in the downstream. The concentration of each component increases generally from the upper stream to the lower stream but that of SiO2 only decreases in the lower stream. Kaolinite is a stable mineral as a weathering prodouct from the ion compositions of three rivers. In a rough estimation, Yoshii, Asahi and Takahashi Rivers weather 303,000t, 433,000t and 1,033,000t of the rocks respectively from their basins in a year. The syrface of their basins are scraoed off 0.06mm, 0.11mm and 0.15mm respectively in a year.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414812001四国東部, 美馬町地域の中央構造線1328ENYoshinobuMizuiToruTachibanashigeyukiSuzuki10.18926/ESR/13887Tracing outcrops of shear zone were used to describe the geometry and structure of the Median Tectonic Line in Mima area, eastrn Shikoku. A distinct new fault outcrop was discovered between the Mino and Ikuchi Faults at the northern slope of the Mt. Boso. These two faults are regarded as a single continuous fault.
The analysis of surface fabrics of quartz in fault in fault gauge has been carried out to determine relative fault activity events.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414812001有漢町に分布する中新統有漢累層112ENTakaoFujiwaraEijiTaguchishigeyukiSuzuki10.18926/ESR/13885In this paper, we deal with the Miocene Ukan Formation, sporadically distributed in Ukan-cho, Okayama prefecture, from a viewpoint of analysis of lithology and molluscan assemblages.
The Ukan Formation is lithostratigraphically divided into the Suzuoka Conglomerate, Yamagata Muddy Sandstone, Shimoyokomi Sandstone and Conglomerate, Azechi Sandstone and Conglomerate, Tsuneyama Siltstone Members in ascending order.
The following 6 molluscan assemblages are recognized.
The lower four members and the last member is correlative to the Lower Sandstone and Upper Shale Formation of the Bihoku Group, respectively judging from lithology and fauna.
The temporal chages of the above mentioned molluscan assemblages represents that gradual deeping of sea during the depositional period from the Suzuoka Conglomerate and Yamagata Muddy Sandstone Members to the Azechi Sandstone and Conglomerate Member via the Shimoyokomi Sandstone and Conglomerate Member, and abrupt deeping of sea seems to have happened between the Azechi Sandstone and Conglomerate Member and the Tsuneyame Siltstone Member.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002津山盆地における霧の観測4152ENMinoruJokoYasutomoKiyoharaOsamuTsukamotoTsuyama basin is the largest basin in the Chugoku District, and dense fog appears frequently in autumn/winter. The fog is considered as "radiation fog", mainly induced by radiation cooling and topographical effect as the basin, including "cold air lake". The mechanism of the fog was not studied based on field measurements. Some statistical analyses are found in the literature. So we made intensive observation of the radiation fog mainly focusing on space and time distribution for the fog appearance and disappearance. The field measurement included tethered sonde observation, mobile observation and multi-point visual observations in October, 1999 and November, 2000.
According to the observation, the appearance of the fog was identified both feom visual observation and upper air sounding data. The top of the fog layer was clearly found as temperature/humidity singularities. Additionally, it is successfully confirmed the usefulness of the upward looking radiation thermometer in the fog detection.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002中国西北部乾燥地域(HEIFE領域)の様々な地表面における気象要素と熱収支特性3140ENQinYangOsamuTsukamotoSurface meteorological and heat balance were analyzed based on various surface conditions over arid region in northwest China (HEIFE area). The different surface conditions were clearly observed in summer rather than in winter. Summer data were selected from the HEIFE database.
Significant evening peaks of vapor pressure were also observed in Linze oasis as well as Zhangye oasis. And the peak was accompanied by air temperature dip and relative humidity peak in the lower layer. However, the peak cannot be observed in high wind condition as the mechanical mixing reduces the vertical gradients of air temperature and humidity. The oasis can be characterized by low wind speed due to wind sheltering by plants. In winter, plant activities are reduced and surface conditions are almost similar for desert and oasis, leading to no peak of vapor pressure.
Surface heat balances were also analyzed based on 4-component radiation measurement and sensible and latent heat flux measurements by eddy covariance method. Net radiation in the oasis area is about 50% larger than desert area due to the smaller upwelling radiation in oasis. Heat distribution into sensible heat and latent heat was different between oasis and desert. This unbalance of heat can lead to local circulation between oasis and desert as "desart-oasis interaction".No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002傾斜区分図と第三紀層の分布でみた吉備高原の地形発達史2530ENTakaoFujiwaraShigeyukiSuzukiA peneplain is evident in Takahashi area from slope map presented in this paper. The map shows that older gentle valleys exist in the Kibi Plateau. Miocene marine deposits are colored on the slope map. The Miocene marine deposits mostly distribute along the older valleys. The distribution of the Paleogene gravel river deposits is not cintrolled by topography.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002京都府宇治田原町の丹波帯泥質岩のストレート劈開に沿って産出する黄鉄鉱スポットについて1924ENTeijiMikamiMakotoMusashinoshigeyukiSuzuki10.18926/ESR/13880Pyrite spots were identified in pelitic rocks from the Ujitawara area, southernmost part of Tamba belt. XMA analysis shows that the spots are composed of pyrite. The spots occur along slaty cleavage plane and form spotted shape of diameter of about 5mm.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002西表島船浦湾におけるマングローブ干潟の堆積環境 ―堆積物と生物遺骸の保存状況について―918ENHiroyukiAzumaMasayukiSaigusaHiroshiFukudaThe distribution of conch shell contained in clastic sediments in the mangrove swamps in the Funaura Bay, Iriomote Island, Okinawa Prefecture was studied. The sediments in the mangrove swamp are mainly composed of up to 90% sands. The sand clasts are inferred to be derived from the sandstone of Miocene Yaeyama Group. The conch shells are richer in the muddy fraction than the sandy fraction. Many Terebralia palustris inhabit the mangrove swamp. However few dead shells were also observed in the sediments. Effect of selective transportation hermit crabs is considered to be the cause of this distribution.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-7414912002Geology of high- to ultrahigh-temperature granulites from central Madurai block, southern India ; with emphasis on the evolution of Grt-Opx-Crd granulite18ENYasuhitoOsanaiThe geology of Ganguvapatti area situated at the central Madurai block of southern India consisting of varous high-grade metamorphic rock types. This contribution briefly describes the geology, field occurrences and petrography of metamorphic rock from Ganguvarpatti area. Ganguvarpatti is known for its occurrence of sapphirine-bearing UHT granulites while the surrounding granulites are less studied. So in this contribution we have discussed the pressure-temperature stability and evolution of granulites surrounding UHT granulites. The pressure-temperature estimation of garnet-orthopyroxene-cordierite granulite resulted a near peak temperature condition of>950゜ C at a pressure between 9-10 kbar. These results are in good agreement with the stability field in the KFMASH petrogenetic frid.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141012003サイの歯冠上の構造に対する用語について3337ENAkiraFukuchi10.18926/ESR/13876The terminology for the molars of rhinoceorses is mainly derived from Osborn (1888). However, there is often confusion surrounding nomenclature of cheek teeth and the measuring point of the teeth. The nomenclature for the teeth of rhinoceroses and the controversy were reviewed. In this paper, I suggest the new nomenclatures that are composed of 24 elements for the upper cheek teeth and 12 ones for the lower ones and I also suggest the measuring points of teeth of the Rhinocerotidae.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141012003津山盆地東部に分布する中新統勝田層群の堆積環境2331ENRyoYamasakiShigeyukiSuzuki10.18926/ESR/13875The Miocene Katauta Group of the Syohoku-cho area is subdivides into 6 members ; The Uetsuki Conglomerate Member, Nara Sandy Mudstone Member, Tai Gravelly Sandstone Member, Takatori Conglomerate Member, Ayabe Mudstone Member and Maruyama Mutstone Member from bottom to top.
The unconformity between Miocene deposits and basement rocks in this area was traced to obtain geometry of the Miocene basin. Contour maps of the bases of the Miocene Yoshino Formation and Takakura Formation indicate paleo-topography. The obtained topography demonstrates a valley, which flowed to north-west, and a few islands and bays. It indicates that these Miocene successuions were deposited in the topography which resemble to the present Seto Inland.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141012003吉備高原周辺の古第三系に関する最近の知見とその古地理学的意義1522ENHajimeTanakaShigeyukiSuzukiShuHotaniYasuoYamamotoTohruDanhara10.18926/ESR/13874The "Kibi Plateau" forms a unique geomorphic province with the gently-sloping and stable continental feature. Gravel deposites called the "Mountain Gravels", are distributed sporadically in the Kibi Plateau, and have been considered Pliocene deposits. However, recent fission-track ages of the tuff beds intercalated in the deposits have indicated that the ago of deposits are Paleogen in the age. So far, fission-track ages (using zircon) of 61 to 65, 55, 37, 34 to 35 and 27 Ma are obtained. Remaining the belt-like distributions of the Paleogene gravelly valley-full deposits suggest that the Kibe Plateau has been keeping as a stable block, and repeated periods of incision followed by sedimentation of valley-fill deposits are occurred in the area during Paleogene period.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141012003Elasticity of diopside CaMgSi(2)O(6) measured by means of the resonant sphere technique, RST1114ENIsaoSuzukiYasushiInouyeHitoshiOdaMasanaMorioka10.18926/ESR/13873Resonant frequencies for a single crystad diopside sphere are measured accurately and rhirteen elastic moduli are reluced by the least squares calculation, A set of mduli gives theoretical resonant frequencies close enough to the observed ones.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141012003Zinc Contents of Mafic Micerals in Granitic Rocks, with Special Reference to Ore Chemistry110ENHisashiTomiyaYoshinoriInoueKatsuoKase10.18926/ESR/13871In order to know the reason why the Cu/Zn-Pb ratios of skarn-type deposits related with the ilmenite-series granitic rocks are markedly higher than those related with the magnetite-series, comparative mineralogical studies were carried out for the two types of granitic rocks in the Chugoku district. An attention was focused on the be-havior of Zn during the crystallization of granitic magma, because Zn contents of mafic minerals can be obtained by non-destructive electron microprobe analyses.
Microscopic observation indicats that no sphalerite occurs in the magnetite-series granitic rocks, which im-plies that the magmas corresponding to the granitic rocks were undersaturated in respect to ZnS. Electron micro-probe analyses revealed that the Fe/(Fe+Mg) ratios of mafic minerals such as biotite and hornblende in the ilmen-ite-series granitic rocks are remarkably higher than those in the magnetite-series, and the Zn contents are posi-tively correlated with the Fe/(Fe+Mg) ratios in the ilmenite-series granitic rocks. Also the Zn/Fe rations seem to be slightly higher in the ilmenite-series granitic rocks. In contrast, the correlation between Zn contents and Fe/(Fe+Mg) ratios is ambiguous in magnetite-series granitic rocks.
With a progress of crystallization differentiation, therefore, Zn may be removed more effectively in the il-menite-series granitic magma, and the contents may be growing scarce in the fractionated ilmenite-series granitic magma. On the other hand, magnetite-series granitic magma probably increases the Zn-contents in the advanced stage of the crystallization. The hydrothermal fluids genetically related to the fractionated magnetite-series grani-tic magma are likely to be enriched in Zn, being favorable for the formation of Zn-rich deposits.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141112004岡山県玉野市出崎海岸に埋没する完新世中期の泥炭層の古環境解析3947ENMarikoMatsushitaHiroshiSatoShigeyukiSuzukiKoichiYukumotoArataMomoharaYayoiUedaShigehiroKatohYasuoMaeda10.18926/ESR/13870The buried peat deposit was foud in the sand beach on the Desaki coast (Tamano City, Okayama Prefecture), the northeastern coast of Seto Inland Sea. In this study, we performed sulfur and diatom analyses of the deposit. The results were used along with 14C dates and the eruption age (7300 cal BP) of Kikai-Akahoya tephra (K-Ab) to derive sedimentary environments of the deposit. K-Ah was detected just below the peat deposit. At the culmination of the Jomon transgression, the peat deposit had been formed in brackish environments of salt marsh for about 300 years. In order to reconstruct local paleovegetation, we analyzed pollen, wood and plant fossils in the deposit. The results show vegetational transition from a deciduous broadleaved forest mainly of Ouercus subgen. Lepidobalanus to Pinus forest. In spite of the Holocene thermal optimum, the vegetation dominated by Ouercus subgen. Cyclobanopsis was not recognized at the Desaki site, as has been shown in many other regions of regions of western Japan. Ouercus sect. Prinus was replaced by Ouercus sect. Aegilops as the dominant section of Ouercus subgen. Lepidobalanus, suggesting early establishment of traditional rural vegetation of 'Satoyama' in Japan. However, no evidence for human agency has been obtained from the mid-Holocene archaeological sites around the Desaki site. Thus it is more likely that this vegetational transition resulted from the succession caused by natural forces such as ecological disturbance and climatic and/or endemic situations rather than by cultural deforestation.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141112004岡山平野における最終氷期最盛期以降の海水準変動3337ENShigeyukiSuzuki10.18926/ESR/13869Postglacial relative sea-level change of the Okayama Plain Area has been analyzed. Former sea-levels were recognized by using peat beds and marine organisms which are also available for 14C dating. Peat beds were rhought to be formed under a stable sea-level condition. 14C ages of the analyzed peat beds were seprated by 4 groups ; 30〜18 ka BP, 11〜8 ka BP, 6〜4 ka BP and 3〜2.5 ka BP, indicate 4 stable sea-level periods. 2 transgressive events (18〜11 ka BP and 8〜6 ka BP) and one regressive event (3.5?〜3 ka BP) were also inferred.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141112004東アジアにおける最終氷期最盛期から完新世初期の海洋古環境2331ENHironobuKan10.18926/ESR/13867A series of marginal seas that are separated from the Pacific Ocean by island arcs developed in Eastern Asia. The environmental property of these marginal seas amplified under a sea-level lowstand during the Last Glacial Maximum (LGM). The Japan Sea was covered by low salinity water during the LGM. At the beginning of the post-glacial sea-level rise, the Oyashio Current firstly flowed into the Japan Sea throught the Tsugaru Strait. The influx of the Tsushima Current started around 10,000 yBP and become vigorously after 8,000 yBP. Meanwhile, the northward migration and influx of the Kuroshio Current into East China Sea started around 10,000 yBP and strengthened after 7,500 yBP. The route alternation of the Kuroshio Current might have contributed to the establishment of the Tsushima Current and acted as a trigger for the drastic environmental changes around the merginal seas in Eastern Asia at the time of the post-glacial sea-level rise.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141112004太平洋東部赤道海域における二酸化炭素分圧の増加速度1522ENFumiyoshiKondoOsamuTsukamotoShuichiWatanabe10.18926/ESR/13863In the Eastern Equatorial Pacific Ocean, increase rates of fCO2 in the air and the ocean were evaluated using the CDIAC data set. The fCO2 in the air was increasing about 1.28μatm/year during 1957-1995. This result is almost same as the rate at the Mauna Loa, Hawaii in Tropical Pacific Ocean. The increase rate of fCO2 in the seawater was estimated as 1.64μatm/year. In this study it is found that the increase rate of fCO2 in the seawater is the almost same as that of fCO2 in the air. This reault supports the result on the snapshot analysis of Takahashi et al. (1983) in thr North Atlantic Ocean during 1958-1982. It is smaller than the result including seasonal variation in the Eastern Subtropical Pacific Ocean. These reault indicated that the anthropogenic CO2 in the air has affected fCO2 in seawater through CO2 gas exchange between the atmosphere and the ocean. It is found that fCO2 in the seawater has increased in the Eastern Equatiorial Pacific Ocean in spite of the large CO2 source region. It suggested that CO2 source potential has not changed in this ocean durung 1957-1995.No potential conflict of interest relevant to this article was reported.岡山大学理学部地球科学教室Acta Medica Okayama1340-74141112004Temperature dependence of elastic moduli of β-and γ-(Mg,Fe)2SiO4 : Supplements714ENNorihitoMayamaIsaoSuzuki10.18926/ESR/13862We measured the resonant frequencies for sphere specimens of the high pressure phases, β-and γ-(Mg0.91Fe0.09)2SiO4 from 298 to 470 K. The adibatic bulk modulus Ks and shear modulus μ at 298 K were determined to be Ks=165.72(6), μ=105.43(2) GPa for the β-phase, and Ks=185.1(2), μ=118.22(6) GPa for the γ-phase, respectively. The average slopes of the moduli at the measured temperature ranges were found to be ∂Ks/∂T=-0.175(3), ∂μ/∂T=-0.0159(1) GPaK-1 for the β-phase and ∂Ks/∂T=-0.193(6), ∂μ/∂T=-0.148(3) GPaK-1 for the γ-phase. The numerals in parentheses indicate probeble errors in the last place. In this technical report, we describe the observed frequencies and calcuation method to obtain elastic moduli, in details.No potential conflict of interest relevant to this article was reported.