| Project/Area Number |
12573014
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | KANAZAWA UNIVERSITY |
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Principal Investigator |
TSUKAWAKI Shinji Kanazawa University, Institute of Nature and Environmental Technology, Associate Professor, 自然計測応用研究センター, 助教授 (00222133)
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| Co-Investigator(Kenkyū-buntansha) |
ODA Motoyoshi Tohoku University, Graduate School of Science, Professor, 理学部, 教授 (60108454)
KAMIYA Takahiro Kanazawa University, Graduate School of Natural Science and Technology, Associate Professor, 理学部, 助教授 (80194976)
KATO Michio Kanazawa University, Graduate School of Natural Science and Technology, Professor, 理学部, 教授 (10093741)
OKAWARA Masafumi Iwate University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80223741)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥10,100,000 (Direct Cost: ¥10,100,000)
Fiscal Year 2002: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2001: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥4,300,000 (Direct Cost: ¥4,300,000)
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| Keywords | Lake Tonle Sap / Cambodia / environmental changes / lacustrine sediments / natural environment / Indochina Peninsula / Mekong River / intergovernmental change of researchers (Cambodia) / 古環境 |
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| Research Abstract |
During the course of this programme, twelve short and six long cores were recovered from north Lake Tonle Sap to reconstruct environmental history of the lake and its environs. On the other hand, about 100 surface sediment samples were obtained to obtain compositional features of micro-organisms and surface sediments, and their spatial distribution in the present lake floor and adjacent fluvial systems such as the Tonle Sap and Mekong rivers. Although some studies are still under investigation, the environmental changes and geological development of Lake Tonle Sap and the lower Mekong River during the last 10,000 years can be summarized. Lake "Palaeo-Totue Sap" appeared at about 7.6 Ka, and it existed to 5.5 Ka. The lake was a considerably smaller freshwater lake or lakes, rather than the large lake of the present time, situated in the central axis area of the modern Lake Tonle Sap. At that time the palaeo-lake(s) was isolated from the major fluvial system in the Indochina Peninsula and muddy sediments derived mainly from alluvial plains were filling up the lake(s). Because of the connexion of the lake with the Mekong River, caused by the rapid rise of sea-level after the Last Glacial Maximum and its high-stand at the Holocene Climatic Optimum, the present environment of Lake Tonle Sap appeared at 5.5 Ka and the environment has existed continuously till the present day. The exact shape and topography of Lake Palaeo-Tonle Sap still remains in question. Thus, shallow water seismic surveys should be carried out in the whole area of the lake to reveal paleogeography of the lake during the period from 7.6 to 5.5 Ka. Further, since the basement strata in the long coring sites can be interpreted sedimentologically as sub-aqueous deposits, a long drilling programme in the central part of the lake should be made in order to develop the mult-history of the lake.
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