| JaLCDOI | 10.18926/ESR/13828 |
|---|---|
| Title Alternative | Storm surge in the Seto Inland Sea accompanied by Typhoons in 2004 |
| FullText URL | earth_science_reports_014_1_1.pdf |
| Author | Asanuma, Tomomitsu| Tsukamoto, Osamu| Ogawa, Kouji| |
| Abstract | In 2004, Seto Inland Sea coast suffered severe damages of storm surge. This area never experienced storm surge damage in recent half century and people were not ready for the storm surge. In two typhoons of T0416 and T0418, surge anomaly were more than 150cm in Bisan-Seto area. Storm surges appeared after the maximum approach of typhoon not only due to surface low pressure but also due to wind stress as westerly. Because of geographical complexity of Seto Inland Sea, the surge process have not been well understood. Therefore, it is necessary to study the effects of the wind and the surface pressure using a numerical model. Atmospheric model MM5 and ocean model POM were used as a numerical experiment, including the astronomical tide model NAO. Aｓ the results of numerical simulation of the storm surge, atmospheric conditions were well simulated but ocean model was rather complex. There are a lot of island in Seto Inland Sea and sea water movement in the model was very much influenced by the topography and wind stress effect appeared much smaller. In the no-island model, storm surge height was a little improved. However the simulated surge height was still less than the observed height. Further improvement of the ocean model application should be considered in future studies. |
| Keywords | Typhoon Storm Surge Seto Inland Sea surface pressure wind stress |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2008-03-31 |
| Volume | volume14 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 9 |
| 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 | 120002310572 |
| JaLCDOI | 10.18926/ESR/13844 |
|---|---|
| Title Alternative | バングラディシュの更新世台地の地形と地質 |
| FullText URL | EAR_13_1_1.pdf |
| Author | Towhida Rashid| Md. hossain Monsur| Suzuki, Shigeyuki| |
| Abstract | With regards to the origin and evolution of the Pleistocene tracts (Lalmai, Madhupur and Barind tracts) of Bangladesh, two trends of thoughts are common. Most of the authors believed that the Madhupur, Barind and Lalmai tracts represent tectonically uplifted surface. Some researchers have different opinion and they believed that the Lalmai hills and the Madhupur locality represent tectonically uplifted blocks but the whole Barind tract and the major portion of the Madhuput tracts are not tectonically uplifted, rather these are originated by erossional-depositional processes. In order to solve the problems associated with origin and evolution of Pleistocene tracts of Bangladesh, further study is needed. Borehole data may be collected and fusion images can be prepared from aerial photographs and setellite images to detect netectonic imprins and geomorphological signatures of the areas. Elaborate laboratory analysis of sediment deposits, radiocarbon dating my indicate a new dimension about the origin and evolution of these tracts. |
| Keywords | Bangladesh Lalmai Hill Barind Tract Madhupur Tract Neotectonices Aerial photographs Satellite Image Fusion Image |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2006-03-31 |
| Volume | volume13 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 13 |
| 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 | 120002310445 |
| JaLCDOI | 10.18926/ESR/13847 |
|---|---|
| Title Alternative | Geology of Holocene deposits in Mizushima Area, Okayama Prefecture, Japan |
| FullText URL | EAR_13_1_15.pdf |
| Author | Suzuki, Shigeyuki| |
| Abstract | The study srea, Mizushima is occupied by polder and reclaimed land. The ground of this area is composed of the Holocene deposits below the surface. The deposits are mostly 10 to 20m in thickness and composed of 2 units, the B Unit and C&D Unit. The B Unit is composed of muddy sand with 2 to 3m in thickness. This unit is thought to be deposited in the mouth of paleoriver. The C&D Unit is composed of marine mud and sand with 10 to 15m in thickness. This unit is especially soft and will expand ground oscillations during an earthquake. |
| Keywords | Holocene deposits Mizushima Area Ground oscillation |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2006-03-31 |
| Volume | volume13 |
| Issue | issue1 |
| Start Page | 15 |
| End Page | 18 |
| 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 | 120002310562 |
| JaLCDOI | 10.18926/ESR/13848 |
|---|---|
| Title Alternative | Eastward extension of the Baiu Front on the surface weather maps in ralation to zonal scale of the area with strong low-level southerly wind toward the front |
| FullText URL | EAR_13_1_19.pdf |
| Author | Nakayama, Yuuki| Owada, Michio| Ikeda, shoichiro| Kato, Kuranoshin| |
| Abstract | Eastward extension of the Baiu front in relation to zonal scale of the area with strong low-level southerly wind toward the front was examined based on the operational surface weather maps and the NCEP/NCAR re-analysis data mainly for the mature Baiu period (15 June to 31 July) from 1991 to 2000. During that period, the Baiu front on the surface weather maps appeared from the Changjiang River Basim to the east of the Japan Islands accompanied by the strong low-level southerly wind toward it in a wide zonal scala(～3500km), in many cases. However, the situations when the appesrance of the Baiu front was limited to the western part of the Japan Islands or limited to its eastern part are sometimes found with relatively narrow zonal acale of the strong low-level southerly wind toward the front, although the appearance frequency of such cases was not so high. As such the present results illustrate the importance of the zonal scale of the subtropical high for the spatial activity of the Baiu front. |
| Keywords | variation of the Baiu front southerly wind in the subtropical high area zonal extension of the Baiu front |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2006-03-31 |
| Volume | volume13 |
| Issue | issue1 |
| Start Page | 19 |
| End Page | 25 |
| 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 | 120006211873 |
| JaLCDOI | 10.18926/ESR/13850 |
|---|---|
| Title Alternative | 沖縄トラフ第四与那国海丘海底熱水系チムニーの錫を含む黄銅鉱と白金を含む輝蒼鉛鉱 |
| FullText URL | ESR_12_1.pdf |
| Author | Gena, Kaul| Chiba, Hiroshi| Kase, Katsuo| |
| Abstract | The active sulfide chimney ore sampled from the flank of the active Tiger chimney in the Yonaguni Knoll IV hydrothermal system, South Okinawa Trough, consists of anhydrite, pyrite, shalerite, galena, chalcopyrite and bismuthinite. Electron microprobe analyses indicated that the chalcopyrite and bismuthinite contain up to 2.4 wt. % Sn and 1.7 wt. % Pt, respectively. The high Sn-bearing chalcopyrite and Pt-bearing bismuthinite are the first occurrence of such minerals on the submarine hydrothermal systems so far reported. The results confirm that the Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn 4+ Fe 2+ for Fe 3+ Fe 3+ while Pt enters the bismuthinite structure as a solid solution during rapid growth. The homogenization temperature of the fluid inclusions in anhydrite (220-310℃) and metasured end-member temperature of the vent fluids (325℃) indicate that the minerals are precipitated as metastable phases at temperature around 300℃. The Sn-bearing chalcopyrite and Pt-bearing bismuthinite expess the original composition of the minerals deposited from a hydrothermal fluid with temperatures of about 300℃. |
| Keywords | Sn-bearing chalcopyrite Pt-bearing bismuthinite Active sulfide Chimmey Yonaguni Knoll IV Okinawa Trough seafloor hydrothermal system |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 5 |
| 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 | 120002310444 |
| JaLCDOI | 10.18926/ESR/13851 |
|---|---|
| Title Alternative | ガーナ, ビルム・ダイヤモンド産地のアクァティア地域に分布する沖積層の重鉱物分析 |
| FullText URL | ESR_12_7.pdf |
| Author | Samuel Dampare| Daniel Asiedu| Bruce Banoeng-yakubo| Shibata, Tsugio| |
| Abstract | Heavy mineral analysis was carried out on Pliocene to Recent alluvial sediments from the Birim diamondiferous field od Ghana. The main objective of the study was to examine the mineral composition of heavy fractions in order to identify : (1) the heavy mineral assenblage that occur in the sediments, (2) particular diamond indicator minerals associated with the diamonds, and (3) the provenance of the alluvial sediments. The heavy minerals are essentially composed of staurolite, ilmenite and magnetite in varying proportions, with trace amounts of leucoxene, rutile, garnet and zircon. The heavy mineral assenblage and chemical composition of ilmenite and gamet suggest their derivation from phyllites and schists which reflect directly the composition of the basement rocks developed in the study area. The absence of diamond indicatior minerals such as apatite, pyrope garmet, chromian spinel, and picroilmenite in the heavy fraction is unlikely to be due to their destruction during intense weathering and/or diagenesis but rarher their non-occurrence in the area. |
| Keywords | Heavy minerals provenance sediments diamonds Ghana |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| Issue | issue1 |
| Start Page | 7 |
| End Page | 14 |
| 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 | 120002310657 |
| JaLCDOI | 10.18926/ESR/13853 |
|---|---|
| Title Alternative | ガーナ,南部アシャンティ帯の原生代プリンスタウン・グラニトイド岩体に関する主成分地球化学 |
| FullText URL | ESR_12_15.pdf |
| Author | Samuel Dampare| Shibata, Tsugio| Daniel Asiedu| Shiloh Osae| |
| Abstract | The Pateoproterozoic metavolcanic rocks of the southern Ashanti greenstone belt of Ghana are intruded by three major suites of granitoids, locally called Prince's Town, Dixcove and Ketan plutons. The Prince's Town pluton is the largest intrusive body in the Axim area, and tends to separate the Axim volcanic branch from the Cape Three Points branch. The Pluton consists of granitic to dioritic rocks, which are generally massive but occasionally display alignment of ferromagnesian minerals. The rocks contain mainly plagioclase, K-feldspar, quartz, amphibole, biotite and opaques. The feldspars are mostly sericitized and saussuritized, and alteration of amphibole and biotite to epidote and chlorite is common. Accessory minerals include apatite, sphene and zircon. The geochemical data indicate that the rocks are tonalitic to granodioritic in composoition, metaluminous (ASI<1) and have I-type characteristics. The granitoids have the SiO2 content of 63-70% ; total iron, as Fe2 O3 of 3.10-5.80% ; (Na2O+K2O) content of 5.01-6.96% and Na2O/K2O ratios from 1.34 to 2.70 ; and are characterized by Mg# ranging from 53 to 48. The Fe*(=FeOtot/FeOtot+MgO) and modified alkali-lime index (MALI) of the rocks indicate that the Prince's Town pluton is dominantly magnesian and calcic in nature. Higher values in molar CaO/(MgO+FeOtot) coupled with low molar AI2O3/(MgO+FeOtot) may suggest their derivation from partial melting of metabasaltic to metatonalitic sourcc, with a possible contribution from metagreywacke, but preclude any contribution from metapelitic sources. The Birimaian metavolcanic rocks are the likely source material candidate for the rocks. CIPW norm calculations yielded a crystallization temperature of～650-685℃ and a pressure of 4-7kb for the rocks, suggesting a lower crustal souree. The Prince's Town plutonic rocks also show characteristice of plutons emplaced in a volcanic are tectonic setting environment. This observation is largely consistent with previous studies conducted on granitoids from other parts of the southern Ashanti greenstone belt c and the belt-type granitoids of Ghana as a whole. |
| Keywords | Geochemistry tectonic setting granitoids Birimian Ghana |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| Issue | issue1 |
| Start Page | 15 |
| End Page | 30 |
| 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 | 120002310649 |
| JaLCDOI | 10.18926/ESR/13855 |
|---|---|
| Title Alternative | 中国淮河流域付近の入梅前の時期における大気場や陸面状態の季節進行 (1998年の事例解析) |
| FullText URL | ESR_12_31.pdf |
| Author | Ikeda, Shoichiro| Kato, Kuranoshin| Tsukamoto, Osamu| |
| Abstract | Seasonal evolution of atmospheric and land surface conditions around the Huaihe River Basin in China in the pre-Meiyu stage of 1998 were examined, mainly based on the GAME re-analysis data. Around the Huaihe River Basin in China (just to the nront of the Changjiang River Basin), although the air temperature increased rapidly already in early June (the Meuyu front was located to the south of that region), the specific humidity did not increas so much at time. In addition, the latent heat supplied from the ground there decreased from late May to early June, compared to that before early May. The time mean southerly wind component across the low-level baroclinic Zone (although not so strong as in the mature stage of the Meiyu) invaded into Central Cjina during late April to early May. On the other hand, the relatively strong wind region once retreated southward in the middle of May associated with the onset of the Southeast Asian monsoon, and the calm wind region with frequent appearance of the surface high was seen around the Huaihe River Basin from late May to early June. Thus the present study shows that the Huaihe River Basin once experiences the rather drier stage just before the onset stage of the mature Meiyu there. |
| Keywords | arid region in China and the Meiyu front seasonal evlution in East Asia Land surface condition around the Meiyu front |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| Issue | issue1 |
| Start Page | 31 |
| End Page | 37 |
| 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 | 120002310602 |
| JaLCDOI | 10.18926/ESR/13856 |
|---|---|
| Title Alternative | Local wind storm (Hirodo-kaze) in northern Okayama caused by Typhoon 0421 & 0423 |
| FullText URL | ESR_12_39.pdf |
| Author | Kataoka, Fumie| Tsukamoto, Osamu| |
| Abstract | In 2004, ten typhoons had landed over Japan and a lot of damages were reported due to heavy rain, storm surge and wind storms. In the north eastern part of Okayama prefecture, local high wind "Hirodo-kaze" caused severe wind damages due to typhoon passage. During Typhoon 0421, high winds were recoreded in the south foot of Mt.Nagi as typical local wind atrom, " Hirodo-kaze". While, during Typhoon 0423, severe wind damages expanded west of the typical Hirodo-kaze srea as well as a new extreme. In the present report, a lot of surface meteorological data were coollected and compared the meteorological fields among two typhoons. |
| Keywords | Wind Storm Hirodo-kaze Typhoon Local high wind |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| 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 | 120002310608 |
| JaLCDOI | 10.18926/ESR/13857 |
|---|---|
| Title Alternative | Drilling Research of a high-latiude coral reef in Mage Island, Stsunan Islands, Japan |
| FullText URL | ESR_12_49.pdf |
| Author | Kan, Hironobu| Nakashima, Yosuke| Ohashi, Tomoya| Hamanaka, Nozomu| Okamoto, Takehiro| Nakai, Tatsuo| Hori, Nobuyuki| |
| Abstract | Four drilling cores are observed from a high-latitude coral reef at the northwestern Mage Island (N30゜45' 40"). The thickness of the Holocene reef is around 2.5m in the reef edge and 4m in back reef. The Holocene thickness is relatively thin comparing to the modern reefs in the middle or the southern Ryukyu Islands. The reef structure Acropora facies, reworked coral rubble facies. This zonal structure conforms to the ecological coral-zonation corresponding to the wave-energy gradient. |
| Keywords | Holocene Coral Reef Sedimentary Structure Drilling Southwestem Japan |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2005-12-31 |
| Volume | volume12 |
| Issue | issue1 |
| Start Page | 49 |
| End Page | 58 |
| 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 | 120002310535 |
| JaLCDOI | 10.18926/ESR/13861 |
|---|---|
| Title Alternative | 重力異常データのカラムインバージョンから見積もったモホ不連続面の形状 |
| FullText URL | earth_science_reports_011_1_1.pdf |
| Author | Fukunaga, Mariko| Oda, Hitoshi| Shichi, Ryuichi| |
| Abstract | We present an inversion method, called "column inversion", to retrieve two-dimensional variation of the depth to the Moho discontinuity from Bouguer gravity anomaly data, assuming that a density jump between the lower crust and upper mantle is regionally invariant. The inversion method is applied to reveal the apatial undulation of the Moho discontinuity in the Chugoku and Shikoku districts, southwest Japan. The result shows that the Moho is deep in the land area and shallow in the sea area. The Moho is anomalously deep in the west regions of Shikoku and Chugoku districts, where the prominent negative gravity anomaly is observed. The two-dimensional variation of the Moho depth is quite similar to that determined by inversion of the first P-arrival time data. The column inversion of the Bouguer gravity anomaly data is proved to be useful for determining the fine structure of the Moho discontinuity undulation. |
| Keywords | Bouguer Gravity Anomaly Column Inversion Moho Discontinuity Chugoku and Shikoku Districts |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 5 |
| 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 | 120002310563 |
| JaLCDOI | 10.18926/ESR/13862 |
|---|---|
| Title Alternative | β-, γ-相(Mg,Fe)2SiO4の弾性率の温度変化 : 補遺 |
| FullText URL | earth_science_reports_011_1_7.pdf |
| Author | Mayama, Norihito| Suzuki, Isao| |
| Abstract | We 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. |
| Keywords | Wadsleyite Ringwoodite Elastic moduli |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| Issue | issue1 |
| Start Page | 7 |
| End Page | 14 |
| 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 | 120002310650 |
| JaLCDOI | 10.18926/ESR/13863 |
|---|---|
| Title Alternative | Increase Rate of fCO2 in the Eastern Equatorial Pacific Ocean |
| FullText URL | earth_science_reports_011_1_15.pdf |
| Author | Kondo, Fumiyoshi| Tsukamoto, Osamu| Watanabe, Shuichi| |
| Abstract | In 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. |
| Keywords | fCO2 Increase Rate Eastern Equatorial Pacific Ocean E1 Nino La Nina |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| 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 | 120002310498 |
| JaLCDOI | 10.18926/ESR/13867 |
|---|---|
| Title Alternative | Paleoceanography of the Eastern Asia from the Last Glacial Maximum to the early Holocene |
| FullText URL | earth_science_reports_011_1_23.pdf |
| Author | Kan, Hironobu| |
| Abstract | A 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. |
| Keywords | Paleoceanography Last Glacial Maximum |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| 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 | 120002310301 |
| JaLCDOI | 10.18926/ESR/13869 |
|---|---|
| Title Alternative | Relative sea-level changes of the Okayama Plain Area during the Holocene, Southwest Japan |
| FullText URL | earth_science_reports_011_1_33.pdf |
| Author | Suzuki, Shigeyuki| |
| Abstract | Postglacial 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. |
| Keywords | sea-level change peat bed Holocene Okayama Plain |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2004-12-31 |
| Volume | volume11 |
| Issue | issue1 |
| Start Page | 33 |
| End Page | 37 |
| 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 | 120002310268 |
| 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 |
| JaLCDOI | 10.18926/ESR/13871 |
|---|---|
| FullText URL | earth_science_reports_010_1_1.pdf |
| Author | Tomiya, Hisashi| Inoue, Yoshinori| Kase, Katsuo| |
| Abstract | In 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. |
| Keywords | Magnetite-series Ilmentie-series Granitic rocks Zn contents Mafic minerals Ore deposit |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2003-12-20 |
| Volume | volume10 |
| Issue | issue1 |
| Start Page | 1 |
| End Page | 10 |
| 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 | 120002310429 |
| JaLCDOI | 10.18926/ESR/13873 |
|---|---|
| FullText URL | earth_science_reports_010_1_11.pdf |
| Author | Suzuki, Isao| Inouye, Yasushi| Oda, Hitoshi| Morioka, Masana| |
| Abstract | Resonant 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. |
| Keywords | diopside single crystal resonace sphere elasticity |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2003-12-20 |
| Volume | volume10 |
| Issue | issue1 |
| Start Page | 11 |
| End Page | 14 |
| 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 | 120002310552 |
| 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/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 |
