| Project/Area Number |
15500696
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geography
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| Research Institution | National Institute of Advanced Industrial Science and Technology (AIST) |
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Principal Investigator |
KOMATSUBARA Taku AIST, Institute of Geology and Geoinformation, Chief researcher, 地質情報研究部門, 主任研究員 (50357026)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAMOTO Shinji Lake Biwa Museum, Department for research, Curator, 研究部, 学芸員 (60359271)
濱 修 財団法人滋賀県文化財保護協会, 調査普及課, 課長
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Lake Biwa / Water level change / environmental change / environmental history / active fault / deposition / laggon / Holocene / 琵琶弧 / 水辺環境 / 地殻変動 / 気候変化 / 湖水位変動 / 沿岸環境 |
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| Research Abstract |
We investigated depositional process and environmental history of inner lakes around Lake Biwa, by using of five boring cores.
The results are follows. 1) There are two types of inner lakes. One is the closed inner lake which bates behind the mountains, so sediment supply is not enough. The other type is open inner lake which locates in the delta, enough sediment are supplied intermittently. 2) Closed inner lake deposits consist of continuous humic soil and peat, containing Kikai-Akahoya tephra (c.a. 7.3ka). This means stable marshy or shallow water environments had been continued during late Holocene in the closed lagoon. The open inner lake deposits consist of alteration of sand and mud and gravels, containing thin humic layers. Such deposits indicate frequent environmental changes in the fluvial plain and delta. 3) Inorganic sediments are concluded in the uppermost part of some closed inner lake deposits which dated historical age. This suggests that human activities such as reclamation on the lowland surrounding the inner lake affected product of inorganic sediments. 4) In comparison with two closed inner lake deposits in the western side and eastern side of Lake Biwa, Minami-numa located western side and Sone-numa located eastern side, the same datum horizons are systematically deeper at the Minami-numa core than at the Sone-numa core, while both two deposits consist of peat containing rootlets of true grasses under c.a.4ka horizon. This means active faults near the western side of Lake Biwa acted before c.a.4ka, and western side of Lake Biwa subsided
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