result 2452 件
| JaLCDOI | 10.18926/ESR/13947 |
|---|---|
| FullText URL | ESR_2_71.pdf |
| Author | Frank k, Nyame| Kase, Katsuo| Yamamoto, Masahiro| |
| Abstract | X-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. |
| Keywords | Nsuta nsutite cryptomelane pyrolusite lithiophorite |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 71 |
| End Page | 80 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310527 |
| JaLCDOI | 10.18926/ESR/13945 |
|---|---|
| Title Alternative | solubility and polymerization of silica in salt solutions |
| FullText URL | ESR_2_63.pdf |
| Author | Sugita, Hajime| Yamamoto, Masahiro| |
| Abstract | The 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. |
| Keywords | amorphous silica solubility polymerization |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 63 |
| End Page | 70 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310447 |
| JaLCDOI | 10.18926/ESR/13943 |
|---|---|
| Title Alternative | Water-soluble materials on volcanic ash from the 1990-94 eruption of the Unzenn volcano |
| FullText URL | ESR_2_55.pdf |
| Author | Akagi, Seishi| Yamamoto, Masahiro| |
| Abstract | Water-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. |
| Keywords | volcanic ash volcanic gas Unzen volcano C1/SO4 ratio water-soluble material |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 55 |
| End Page | 62 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310484 |
| Author | Ishizu, Hideo| Miyaishi, Satoru| Yamamoto, Yuji| Takata, Shingo| |
|---|---|
| Published Date | 1993-10 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume105 |
| Issue | issue9-10 |
| Content Type | Journal Article |
| JaLCDOI | 10.18926/ESR/13933 |
|---|---|
| Title Alternative | Sulfur isotope ratios of some Roseki deposits in the Inner Zone of Southwest Japan |
| FullText URL | ESR_3_43.pdf |
| Author | Yamamoto, Masahiro| Matsuda, Toshihiko| Nakagawa, Raiki| |
| Abstract | Sulfur 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. |
| Keywords | sulfur isotope ratio Roseki deposit pyrite alunite |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1996-09-20 |
| Volume | volume3 |
| Issue | issue1 |
| Start Page | 43 |
| End Page | 46 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310309 |
| Author | Kuroda, Masahiro| Asaumi, Junichi| Nishikawa, Koji| Tanaka, Seiryo| Gao, Xian Shu| Yamamoto, Michinori| Makihata, Eiichi| Hiraki, Yoshio| Kawasaki, Shoji| |
|---|---|
| Published Date | 1993-02 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume105 |
| Issue | issue1-2 |
| Content Type | Journal Article |
| Author | Yamasu, Kiyofumi| |
|---|---|
| Published Date | 1993-10 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume105 |
| Issue | issue9-10 |
| Content Type | Journal Article |
| Author | Shiiki, Shigeo| Nakagawa, Kazuhiro| Sasaki, Hiroshi| Yamashita, Yutaka| Yumura, Masahito| Kodani, Johji| Yunoki, Yasuhiro| Orita, Kunzo| |
|---|---|
| Published Date | 1993-02-27 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume105 |
| Issue | issue1-2 |
| Content Type | Journal Article |
| JaLCDOI | 10.18926/ESR/13912 |
|---|---|
| FullText URL | ESR_5_17.pdf |
| Author | Yamamoto, Masahiro| Kase, Katsuo| Harada, Kaori| |
| Abstract | Sulfur 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. |
| Keywords | Sulfur isotope ratio Besshi-type deposit Tsuchikura mine Pyrite Chalcopyrite |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1998-09-20 |
| Volume | volume5 |
| Issue | issue1 |
| Start Page | 17 |
| End Page | 22 |
| ISSN | 1340-7414 |
| language | English |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310378 |
| JaLCDOI | 10.18926/ESR/13907 |
|---|---|
| Title Alternative | Chemical and Rb-Sr isotopic features of the shock-melted chondrite Yamato-793533 |
| FullText URL | ESR_6_29.pdf |
| Author | Okano, Osamu| Katayama, Hiroko| Nakamura, Noboru| |
| Abstract | The 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. |
| Keywords | LL-chondrite Shock-melting Sr isotope |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1999-09-20 |
| Volume | volume6 |
| Issue | issue1 |
| Start Page | 29 |
| End Page | 38 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310391 |
| JaLCDOI | 10.18926/ESR/13901 |
|---|---|
| Title Alternative | Tidal notch cut into the Namigata Limestone, 240m above sea level, Ibara City, Okayama Prefecture |
| FullText URL | ESR_7_41.pdf |
| Author | Fujiwara, Takao| Suzuki, Shigeyuki| Maeda, Yasuo| |
| Abstract | The 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. |
| Keywords | notch sea cave Namigata Okayama Prefecture |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2000-09-20 |
| Volume | volume7 |
| Issue | issue1 |
| Start Page | 41 |
| End Page | 46 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310395 |
| JaLCDOI | 10.18926/ESR/13897 |
|---|---|
| Title Alternative | Water-soluble materials formed by the reaction between a volcanic rock and HCI and/or SO2 gases |
| FullText URL | ESR_7_21.pdf |
| Author | Akagi, Seishi| Yamamoto, Masahiro| |
| Abstract | Experiments 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. |
| Keywords | Volcanic gas Volcanic ash Water-soluble material CI/SO4 ratio |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2000-09-20 |
| Volume | volume7 |
| Issue | issue1 |
| Start Page | 21 |
| End Page | 26 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310554 |
| Author | Yamamoto, Takako| Akhmad, Sabarudin| Noguchi, Osamu| Takayanagi, Toshio| Oshima, Mitsuko| Motomizu, Shoji| |
|---|---|
| Published Date | 2006-11-17 |
| Publication Title | 分析化学 |
| Volume | volume55 |
| Issue | issue9 |
| Content Type | Journal Article |
| JaLCDOI | 10.18926/ESR/13887 |
|---|---|
| Title Alternative | Trace of the Median Tectonic Line in Mima area, eastern Shikoku |
| FullText URL | ESR_8_1_13.pdf |
| Author | Mizui, Yoshinobu| Tachibana, Toru| Suzuki, shigeyuki| |
| Abstract | Tracing 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. |
| Keywords | surface fabrics fault gauge Mino-Ikuchi Fault Median Tectonic Line |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2001-09-20 |
| Volume | volume8 |
| Issue | issue1 |
| Start Page | 13 |
| End Page | 28 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310656 |
| Author | Miyashita, Katuhiro| |
|---|---|
| Published Date | 1993-08 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume105 |
| Issue | issue7-8 |
| Content Type | Journal Article |
| Author | Irie, Shoichiro| |
|---|---|
| Published Date | 1994-12 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume106 |
| Issue | issue11-12 |
| Content Type | Journal Article |
| JaLCDOI | 10.18926/ESR/13875 |
|---|---|
| Title Alternative | Depositional environments of the Katsuta Group, eastern Tsuyama Basin, Southwest Japan |
| FullText URL | earth_science_reports_010_1_23.pdf |
| Author | Yamasaki, Ryo| Suzuki, Shigeyuki| |
| Abstract | The 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. |
| Keywords | Katsuta Group Tsuyama Basin Miocene geometry of basin paleoenvironmental chage |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2003-12-20 |
| Volume | volume10 |
| Issue | issue1 |
| Start Page | 23 |
| End Page | 31 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310475 |
| JaLCDOI | 10.18926/ESR/13874 |
|---|---|
| Title Alternative | Distributions and ages of the Paleogene deposits in the Kibi Plateau Area, and Paleogene paleogeography |
| FullText URL | earth_science_reports_010_1_15.pdf |
| Author | Tanaka, Hajime| Suzuki, Shigeyuki| Hotani, Shu| Yamamoto, Yasuo| Danhara, Tohru| |
| Abstract | The "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. |
| Keywords | Kibi Plateau gravelly valley-fill deposites fission-track ages Paleogene palaeogeography |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2003-12-20 |
| Volume | volume10 |
| Issue | issue1 |
| Start Page | 15 |
| End Page | 22 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310517 |
| JaLCDOI | 10.18926/ESR/13870 |
|---|---|
| Title Alternative | Paleoenvironmental Analyses of the Buried Peat Deposit during the mid-Holocene at the Desaki Coast in Tamano City, Okayama Prefecture, Weatern Japan |
| FullText URL | earth_science_reports_011_1_39.pdf |
| Author | Matsushita, Mariko| Sato, Hiroshi| Suzuki, Shigeyuki| Yukumoto, Koichi| Momohara, Arata| Ueda, Yayoi| Katoh, Shigehiro| Maeda, Yasuo| |
| Abstract | The 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. |
| Keywords | Desaki coast diatom remains Jomon transgression Kikai-Akahoya tephra mid-Holocene Paleoenvironment peat deposit plant fossils |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| Issue | issue1 |
| Start Page | 39 |
| End Page | 47 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310603 |
| Author | Yui, Jiro| |
|---|---|
| Published Date | 1994-12 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume106 |
| Issue | issue11-12 |
| Content Type | Journal Article |
