Journal of the Geological Society of Japan最新文献

{"title":"Desquamatia ( Seratrypa ) from the Upper Devonian Choanji Formation in the South Kitakami Belt, Japan, and its stratigraphical significance","authors":"J. Tazawa, I. Niikawa","doi":"10.5575/GEOSOC.2017.0057","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0057","url":null,"abstract":"The Choanji Formation is newly defined as an Upper Devonian (Frasnian ‒ Famennian) sandstone- and shale-dominanted formation, in the Choanji area, South Kitakami Belt, northeastern Japan. The Late Devonian brachiopods, Desquamatia ( Seratrypa ) and Cyrtospirifer occur within the middle and upper parts of the Choanji Formation, respectively. The former is described for the first time in Japan.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128232510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Miocene foraminiferal assemblage occurred from the lower part of the Josoji Formation, Shimane Peninsula, southwest Japan, and its geological implication","authors":"R. Nomura, Yuichiro Tanaka, A. Tsujimoto","doi":"10.5575/GEOSOC.2017.0063","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0063","url":null,"abstract":"The lower–middle Miocene biostratigraphy of the Shimane Peninsula is difficult to interpret due to limited fossil occurrences in the lower Josoji Formation. In contrast, the middle–upper Josoji Formation and the underlying Koura Formation are rich in deep-sea foraminifera and non-marine to brackish fossils, respectively. We identified a diverse microfossil assemblage in the lower Josoji Formation that indicates deposition in dee-water environment that transitioned to the oceanic conditions. The microfossil assemblage consists mainly of agglutinated foraminifera such as Martinottiella communis and Spirosigmoilinella compressa , and calcareous hyaline forms such as Ammonia honyaensis , Valvulineria masudai , Globobulimina auriculata , and Nonionella miocenica . We therefore define this as the Spirosigmoilinella compressa –G lobobulimina auriculata Zone. The assemblage indicates upper to middle bathyal paleodepths and a poorly oxygenated depositional environment. The first occurrences of Spirosigmoilinella compressa and Martinottiella communis were identified in ODP Site 797 (Japan Sea). These species co-occurred just before the appearance of calcareous-rich foraminifera, similar to their occurrence in the lower Josoji Formation. The indicated geological age of the lower S. compressa – G. auriculata Zone is about 17 . 75 Ma, based on the biochronology of Miocene calcareous nannofossils of Backman et al. ( 2012 ). The biostratigraphy indicates progressive deepening of the sedimentary basin during deposition of the Koura to Josoji formations. This resulted in deep brackish waters during the earliest depositional period of the Josoji Formation, which explains the lack of foraminifera in the lower section. The appearance of both benthic and planktonic foraminifera along with nannofossils is interpreted as indicating a large-scale inundation of seawater. The basin, which was initially filled with brackish water, was then completely filled by sea water. This geological event, indicating abrupt water exchange, has important implications for the initial opening of the Japan Sea.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"239 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113996676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Concentration and carbon-isotopic change of dissolved gas from Murono mud volcano in Tokamachi City, Niigata Prefecture (central Japan), just before and after the 2014 Kamishiro Fault Earthquake","authors":"Yoshihiro Kakizaki, G. Snyder, M. Tanahashi, N. Ishida, R. Matsumoto","doi":"10.5575/GEOSOC.2017.0065","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0065","url":null,"abstract":"Dissolved gas concentrations, compositions, and carbon isotopic values are compared between times immediately prior to and following the 2014 Kamishiro Fault Earthquake at the Murono mud volcano (Tokamachi City, Niigata Prefecture, central Japan). Immediately following the earthquake, concentrations of methane, carbon diox-ide, ethane, and propane increased, while carbon isotopic values of methane and ethane decreased, on average. Carbon isotopic values of methane and gas compositions (C 1 /[C 2 +C 3 ] ratio) indicate that the dissolved methane of the mud volcano originates from the thermo-genic decomposition of organic matter. As the carbon isotopic values of methane and ethane are significantly more positive than those of natural gas from the Niigata Oil and Gas Field, the dissolved gases of the mud volcano are thought to be derived from the deepest source rocks of the Niigata Oil and Gas Field. However, the supply of ethane generated from less mature source rocks possibly increased following the earthquake. Our results reveal that a change in behavior of fluid deep below the mud volcano was likely caused by fluctua tions in volumetric strain related to the earthquake. Theoretical strain at the mud volcano can be estimated as 687×10 – 8 , which is much higher than estimates from previous studies for the lower lim-its of strain triggered by anomalous activity at mud volcanoes. Murono mud volcano is an important case study for investigating the correlation between mud volcanoes and earthquakes, because it fre-quently experiences the large volumetric strain of earthquakes that are comparable to the 2014 Kamishiro Fault Earthquake.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124056888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zircon U-Pb and reassessed zircon fission track ages of Miocene Mizunami and Iwamura Groups in the southeastern part of Gifu Prefecture, central Japan","authors":"E. Sasao, T. Danhara, H. Iwano, T. Hirata","doi":"10.5575/GEOSOC.2017.0067","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0067","url":null,"abstract":"Here U–Pb and reassessed fission track (FT) ages are presented for samples from the Miocene Mizunami and Iwamura groups in the southeastern Gifu Prefecture, central Japan. The U–Pb ages of three tuff samples coincide with the reassessed FT ages within the error range. These new U–Pb and reassessed FT ages are consistent with those reported in previous microfossil and paleomagnetic studies, which indicate the following depositional history: The Hongo and Akeyo formations of the Mizunami Group were deposited at ~19–18 Ma and ca. 18 Ma, respectively, and the lower part of the Toyama Formation of the Iwamura Group was deposited ca. 18 Ma.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130413610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoceanographic study of the Arctic Ocean:: its state and issues","authors":"Masanobu Yamamoto","doi":"10.5575/GEOSOC.2017.0075","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0075","url":null,"abstract":"","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115330912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoceanography of the Bering Sea advanced by IODP Expedition 323:: significant roles playing for global circulation and climate change","authors":"H. Asahi, Kozo Takahashi, Y. Okazaki, Jonaotaro Onodera","doi":"10.5575/GEOSOC.2017.0066","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0066","url":null,"abstract":"Our understanding of the paleoceanography of the Bering Sea has been considerably advanced by IODP Expedition 323. The expedition aimed to create a high-resolution record of changes in paleoceanography since the Pliocene in a relatively high-latitude region of the North Pacific, subject to polar amplification. The expedition recovered 660 cores, mainly high-quality Advanced Piston Cores (APC), with a total length of 5741 m of continuous cores from seven sites distributed around the perimeter of the Aleutian Basin, including the Bowers Ridge, the Bering Slope edge, and the Umnak Plateau. These cores are crucial to our understanding of sea-ice distribution, productivity, laminated sediments, input of detrital materials, the formation of the North Pacific Intermediate Water mass, the Pacific water mass entry, the history of the Arctic gateway, and the enigma of the intensification of the Northern Hemisphere Glaciation and the mid-Pleistocene Transition. The maximum ages of the cores are ~5 Ma at the Bowers Ridge sites and 2.5 Ma at the Bering Slope sites. Meltwater from the Alaskan Ice Sheet has influenced the Bering Sea since 4.3 Ma, increasing in influence at 3.3 and 2.8–2.5 Ma. The significant development of sea-ice formation was identified at two sites on the Bowers Ridge at 2.7 and 2.2–2.0 Ma, based on analysis of sea-ice related diatoms and silicoflagellates. Such sea-ice formation affected the extent of the North Pacific Intermediate Water in the Bering Sea, which was strengthened during cold intervals such as when the Bering Strait closed due to falling sea level.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123638138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"東北地方太平洋沖地震後の緊急調査掘削(IODP第343次航海:J-FAST)の成果","authors":"泰広 山田, J. Mori, 氏家 恒太郎, 為人 林, 秀一 小平","doi":"10.5575/GEOSOC.2017.0080","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0080","url":null,"abstract":"","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115075939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration of the deep-subseafloor-biosphere frontiers: Achievements and perspectives","authors":"F. Inagaki, Y. Morono, T. Hoshino, A. Ijiri, Nan Xiao, S. Suzuki, S. Ishii, G. Uramoto, T. Terada, H. Imachi, Y. Kubo","doi":"10.5575/GEOSOC.2017.0079","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0079","url":null,"abstract":"Scientific ocean drilling over the past half-century has significantly expanded our knowledge of life, ocean, and Earth. The discovery of the spatially vast deep-subseafloor biosphere, a milestone scientific achievement, has extended the planetary habitability of life on Earth. To date, multiple lines of evidence form the core samples have demonstrated that a remarkable amount of physiologically unknown microbial life is present deep beneath the ocean floor where water supply and energy substrates are severely limited. Although subseafloor microbial ecosystems generally function extremely slowly, the consequence of long-term activity on geological timescales may play significant ecological roles in global biogeochemical carbon and other elemental cycles.","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123112148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topics on carbonate relevant topics by IODP","authors":"H. Kawahata, Y. Yokoyama, J. Kuroda, Y. Iryu, A. Kano","doi":"10.5575/GEOSOC.2017.0081","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0081","url":null,"abstract":"","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116727489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"千倉層群白浜層(上部鮮新統)野島崎礫岩部層の珪質岩小礫から産する三畳紀・ジュラ紀放散虫化石","authors":"Fumiaki Utagawa, K. Sashida, Sachiko Agematsu, S. Kozu","doi":"10.5575/GEOSOC.2017.0033","DOIUrl":"https://doi.org/10.5575/GEOSOC.2017.0033","url":null,"abstract":"","PeriodicalId":264556,"journal":{"name":"Journal of the Geological Society of Japan","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122912674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}