result 9297 件
| JaLCDOI | 10.18926/14059 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_48.pdf |
| Author | Totsuji, Chieko| Miyake Takashi| Nakanishi Kenta| Tsuruta, Kenji| Totsuji, Hiroo| |
| Abstract | Based on the mapping introduced by the classical-map hypernetted-chain (CHNC) method, classical numerical simulations, Monte Carlo and molecular dynamics, have been applied to the twodimensional electron fluid and the results are compared with those of quantum Monte Carlo simulations hitherto reported. It is shown that polarization properties of the ground state obtained by the diffusion Monte Carlo method are reproduced within the accuracy of quantum simulations by both of two mapping functions for the quantum temperature which have been proposed within the CHNC method. These results may serve as the basis of numerical simulations based on the CHNC method which are applicable to finite non-periodic systems like quantum dots and systems at finite temperatures. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 48 |
| End Page | 52 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308425 |
| JaLCDOI | 10.18926/14058 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_44.pdf |
| Author | Ogawa Takafumi| Tsuruta, Kenji| Totsuji, Chieko| Totsuji, Hiroo| Hiroshi Iyetomi| |
| Abstract | To analyze vibrational properties of Si crystal with a single charge-neutral vacancy, we perform large-scale simulations based on tight-binding molecular-dynamics method. Vibrational modes and frequencies are obtained by diagonalizing dynamical matrix within a harmonic approximation. Results indicate that there exist vibrational modes spatially localized around the vacancy and large frequency shifts associated with the localized modes contribute significantly to reduction of the vibrational free energy. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 44 |
| End Page | 47 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308412 |
| JaLCDOI | 10.18926/14057 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_36.pdf |
| Author | Kato, Hidehiro| Nekado, Kenta| Nogami, Yasuyuki| Morikawa, Yoshitaka| |
| Abstract | This paper proposes an exponentiation method with Frobenius mappings. Our method is closely related to so-called interleaving exponentiation. Different from the interleaving exponentiation methods, our method can carry out several exponentiations using same base at the same time. The efficiency to use Frobenius mappings for an exponentiation in extension field is well introduced by Avanzi and Mihailescu. This exponentiation method is based on so-called simultaneous exponentiation and uses many Frobenius mappings. Their method more decreased the number of multiplications; however, the number of Frobenius mappings inversely increased. Compared to their method , the number of multiplications needed for the proposed method becomes about 20% larger; however, that of Frobenius mappings becomes small enough. |
| Keywords | exponentiation Frobenius mapping extension field |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 36 |
| End Page | 43 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308105 |
| JaLCDOI | 10.18926/14056 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_18.pdf |
| Author | Kanatani, Kenichi| Yasuyuki Sugaya| |
| Abstract | We classify and review existing algorithms for computing the fundamental matrix from point correspondences and propose new effective schemes: 7-parameter Levenberg-Marquardt (LM) search, EFNS, and EFNS-based bundle adjustment. Doing experimental comparison, we show that EFNS and the 7-parameter LM search exhibit the best performance and that additional bundle adjustment does not increase the accuracy to any noticeable degree. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 18 |
| End Page | 35 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308468 |
| JaLCDOI | 10.18926/14055 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_10.pdf |
| Author | Kanatani, Kenichi| |
| Abstract | The author introduced the "geometric AIC" and the "geometric MDL" as model selection criteria for geometric fitting problems. These correspond to Akaike’s "AIC" and Rissanen's "BIC", respectively, well known in the statistical estimation framework. Another criterion well known is Schwarz’ "BIC", but its counterpart for geometric fitting has been unknown. This paper introduces the corresponding criterion, which we call the "geometric BIC", and shows that it is of the same form as the geometric MDL. We present the underlying logical reasoning of Bayesian estimation. |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 10 |
| End Page | 17 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308447 |
| JaLCDOI | 10.18926/14053 |
|---|---|
| FullText URL | Mem_Fac_Eng_OU_42_1.pdf |
| Author | Asatani Jun| Koumoto, Takuya| Toru Fujiwara| Tadao Kasami| |
| Abstract | Two typical examples, the (32, 21, 6) and (64, 45, 8) extended code of primitive permuted BCH codes, are considered. The sets of minimum weight codewords are analyzed in terms of Boolean polynomial representation. They are classied by using their split weight structure with respect to the left and right half trellis sections, and for each class, the standard form is presented. Based on the results, we can generate a proper list of the minimum weight codewords of the codes. |
| Keywords | Boolean polynomial representation extended BCH codes minimum weight codewords binary shift invariance property |
| Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
| Published Date | 2008-01 |
| Volume | volume42 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 9 |
| ISSN | 0475-0071 |
| language | English |
| File Version | publisher |
| NAID | 120002308333 |
| Author | Tsutsui, Hideta| |
|---|---|
| Published Date | 1994 |
| Publication Title | 岡山医学会雑誌 |
| Volume | volume106 |
| Issue | issue3-4 |
| Content Type | Journal Article |
| JaLCDOI | 10.18926/ESR/13959 |
|---|---|
| Title Alternative | LISTHKL : List h, k, l, Fo and σFo tables |
| FullText URL | ESR_1_49.pdf |
| Author | Yamakawa, Junji| Kawahara, Akira| |
| Abstract | LISTHKL, 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. |
| Keywords | LISTHKL Acta Crystallographica reflection data |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 49 |
| End Page | 52 |
| 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 | 120002310510 |
| JaLCDOI | 10.18926/ESR/13958 |
|---|---|
| Title Alternative | CALCOMP to LIPS3 convert library |
| FullText URL | ESR_1_37.pdf |
| Author | Yamakawa, Junji| |
| Abstract | CALLIP, 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. |
| Keywords | CALLIP CALCOMP LIPS3 Fortran 77 |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 37 |
| End Page | 48 |
| 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 | 120002310211 |
| JaLCDOI | 10.18926/ESR/13957 |
|---|---|
| FullText URL | ESR_1_27.pdf |
| Author | Okano, Osamu| Nishiya, Nanayo| Kagami, Hiroo| |
| Abstract | Rb-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. |
| Keywords | chondrule age Rb-Sr isochron Allegan H- chondrite meteorite metamorphism olivine pyroxene |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 27 |
| End Page | 36 |
| 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 | 120002310261 |
| JaLCDOI | 10.18926/ESR/13955 |
|---|---|
| Title Alternative | ScSp Phase observed on the Coast of the Seto Inland Sea |
| FullText URL | ESR_1_19.pdf |
| Author | Nishi, Masaki| Oda, Hitoshi| |
| Abstract | Observation 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. |
| Keywords | ScS Phase ScSp Phase Philippine Sea Plate Southwest Japan |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 19 |
| 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 | 120002310571 |
| JaLCDOI | 10.18926/ESR/13953 |
|---|---|
| FullText URL | ESR_1_9.pdf |
| Author | Suzuki, shigeyuki| |
| Abstract | The 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. |
| Keywords | Slaty cleavage Schistosity Recrystallization |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 9 |
| End Page | 18 |
| 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 | 120002310428 |
| JaLCDOI | 10.18926/ESR/13952 |
|---|---|
| FullText URL | ESR_1_1.pdf |
| Author | Nozaka, Toshio| Shibata, Tsugio| |
| Abstract | Ultramafic 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. |
| Keywords | petrography dunite harzburgite massive ultramafic body |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1994-09-20 |
| Volume | volume1 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 8 |
| 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 | 120002310594 |
| JaLCDOI | 10.18926/ESR/13950 |
|---|---|
| Title Alternative | System for monitoring the vacuum of X-ray generators (Available use of 8 bit personal computer) |
| FullText URL | ESR_2_103.pdf |
| Author | Yamakawa, Junji| Kawahara, Akira| |
| Abstract | An 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. |
| Keywords | X-ray generator vacuum monitoring personal computer |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 103 |
| End Page | 108 |
| 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 | 120002310492 |
| JaLCDOI | 10.18926/ESR/13949 |
|---|---|
| Title Alternative | Rb-Sr age of K-rich LL-chondrite Yamato-74442 |
| FullText URL | ESR_2_91.pdf |
| Author | Nishiya, Nanayo| Okano, Osamu| Kagami, Hiroo| Nakamura, Noboru| |
| Abstract | Yamato-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. |
| Keywords | LL-chondrite Rb-Sr age Sr isotope K-rich fragment |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 91 |
| End Page | 102 |
| 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 | 120002310270 |
| JaLCDOI | 10.18926/ESR/13948 |
|---|---|
| FullText URL | ESR_2_81.pdf |
| Author | Osae, Shiloh| Kase, Katsuo| Yamamoto, Masahiro| |
| Abstract | The 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. |
| Keywords | Birimian Ashanti gold arsenopyrite |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 81 |
| End Page | 90 |
| 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 | 120002310561 |
| 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 |
| JaLCDOI | 10.18926/ESR/13941 |
|---|---|
| Title Alternative | A suggestion on the origin of biotite gneisses of the Ryoke belt in the Seto Inland Sea (Seto-nai-kai) region : Some biotite gneisses were derived from a different geologic unit to the Kuga froup |
| FullText URL | ESR_2_23.pdf |
| Author | Nureki, Terukazu| |
| Abstract | The 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. |
| Keywords | Kuga group Ryoke belt biotie gneisses Sillimanite Zone Iwakuni-Yanai area |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 1995-09-20 |
| Volume | volume2 |
| Issue | issue1 |
| Start Page | 23 |
| End Page | 54 |
| 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 | 120002310501 |
