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Studies on the Paliogine tephron in Northwest Kyushu and West Chugol

Research Project

Project/Area Number 06804026
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Geology
Research InstitutionKYUSHU UNIVERSITY

Principal Investigator

MIYACHI Mutsuai  Post-graduate school of Social and Cultural Stadia Kyushu University, 大学院・比較社会文化研究科, 教授 (70038470)

Co-Investigator(Kenkyū-buntansha) SAKAI Harutaka  Post-graduate school of Social and Cultural Stadia Kyushu University, 大学院・比較社会分化研究科, 助教授 (90183045)
Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
KeywordsTsuyazaki Formation / pyroclastic flow deposits / Oligocene / fusinite / phreatomagmatic oruption / zircon / fission-track age / volcanic front / フィッショ・トラック / 火砕流 / 水中火砕流 / 炭田第三系 / 津屋崎層 / 漸新世火砕流堆積物 / マグマ水蒸気性プリニアン型 / 福岡層群残島層 / 古第三系の堆積環境
Research Abstract

The Koinoura Tuff Member of the Early Oligocene non-marine Tsuyazaki Formation consists of three non-welded rhyolitic and dacitic pyroclastic flow beds (KP-A, -C and -D), and possible pyroclastic surge and phreatoplinian ash fall beds (KP-B), two fluvial interbeds, and a volcanic debris flow bed at the top. The pumice flow beds of KP-A and -D and the ash flow beds of KP-C contain charred and silicified fossil tree trunks which show a typical fusinite exture. The KP-D has degassing pipes in the upper part and a ground layr in the basal part. The volcanic debris flow bed, referable to a lahar, is deposited in a channel dccply croded in the KP-D and contains a great number of fossil tree trunks whose reflectances are very mauch varied.
The KP-B comprises thin-bedded fine-grained tuff in the lower part and conformably succeeding 1.6m thick accretionary lapilli tuff in the upper part. The former contains abundant carbonized wood-trunks which are often coated with ash-spray. The latter compri … More ses densely packed coarse accretionary lapilli, and show no lithologic differences throughout the thickness. These features indicate that the lower part of the KP-B is referable to surge deposits and that the upper part formed by phreatoplinian ash-fall.
Reflectance of the charred trees in the pumice and ash flow beds of the KP-A and -D indicate that the temperature of the beds at the time of deposition was about 550゚C, and that of the surge of the KP-B was about 330゚C.
Flow directions of pyroclastic flow and surge obtained from the preferred orientation of the contained fossil tree trunks are W to E and NW to SE.They are concordant with flow directions of the fluvial interbeds. These data suggest that the source of the pyroclastic flows was situated to the west of the Tsushima-Goto Islands, in consequence of the paleogeographic adjustment of Kyushu and the Tsushima Islands in Late Eocene and Early Oligocene times. The volcanoes there constituted a volcanic chain that is connected to the San'in district. It is very likely that global lowering of sea level during Late Eocene and Early Oligocene time caused a major regression, called the Onga regression. As a result of expansion of fluvial land area and narrowing of the sea between the Tsushima Islands and mainland Kyushu during the regression, torrential pyroclastic flows could have rushed over these land and sea areas, and reached to North Kyushu. The pyroclastic flows and co-ignimbrite ash falls were spread over the whole Paleogene coalfield basin in North Kyushu and West Chugoku, and formed a thick sequence of tuff beds. Less

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] 宮地六美: "九州の新生代源成表類・火山表類・火砕表類のフィッション・トラック年代の総括(1)" 九州大学比較社会文化研究科紀要. 1. 61-65 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 宮地六美: "九州の新生代源成表類・火山表類・火砕表類のフィッション・トラック年代の総括(2)" 九州大学比較社会文化研究科紀要. 2. 117-124 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 酒井治孝: "九州北西冲全、対馬の古第三紀茂木、穿岩水中火砕流堆積物" 地質学雑誌. (投稿中).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 酒井治孝: "北九州の下部漸新統津屋崎層中の意ノ浦火砕流堆積物" 地質学雑誌. 100. 692-708 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 宮地六美: "福岡炭因残島層のジルコンのフィクショントラック年代" 九州大学教養部地学研究報告. 30. 39-42 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Miyachi Mutsumi: "Zircon Fission-track Age of the Nokonoshima Formation of the Fukuoka Coal Field, Kyushu, Japan" Reports on Earth Science, College of General Education, Kyushu University. No.30. 39-42 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Sakai Harutaka: "Koinoura pyroclastic deposits in the Lower Oligocene Tsuyazaki Formation, North Kyushu" Journal of Geological Society of Japan. Vol.100, No.9. 692-708

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Miyachi Mutsumi: "Summary of the fissiontrack ages of the plutonic, volcanic and pyroclastic rocks in the Cenozoic Era of Kyushu, Japan (1)" Bulletin of the Graduate School of Social and Cultiral Studies, Kyushu University. Vol.1. 61-65

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Miyachi Mutsumi: "Summary of the fissiontrack ages of the plutonic, volcanic and pyroclastic rocks in the Cenozoic Era of Kyushu, Japan (2)" Bulletin of the Graduate School of Social and Cultural Studies, Kyushu University. Vol.2. 117-124

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Sakai Harutaka: "Paleogene Mogi and Ugetsuiwa subaqueous pyroclastic flow deposits in the Tsushima Islands, northwestern off Kyushu" Journal of Geological Society of Japan. (under preparation).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] 宮地六美: "九州の新生代源成岩類・火山岩類・火砕岩類のフィッション・トラック年代の総括(2)" 九州大学比較社会文化研究科紀要. 2. 117-124 (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] 酒井治孝: "北九州の下部漸新統、津屋崎層中の恋ノ浦火砕流堆積物" 地質学雑誌. 100. 692-708 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 宮地六美: "福岡炭田残島層のジルコンのフィッション-トラック年代" 九州大学教養部地学研究報告. 30. 39-42 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] 酒井治孝: "相浦・佐世保層群に記録された30-20Maの氷河性海水波変動とミランコビッチサイクル" 日本地質学会第101年大会講演要旨. 150 (1994)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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