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Special Session 2: Changing ocean environment: from the sedimentary perspective -- processes and records |
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Land-sea duel in the late quaternary at the river mouth on a high standing island
Wednesday 11th @ 1520-1535
Room 4
Rick J. Yang* , Department of Oceanography, National Sun Yat-Sen University, Kaohsiung, Taiwan ROC
James T. Liu, Department of Oceanography, National Sun Yat-Sen University, Kaohsiung, Taiwan ROC
Daidu Fan, State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
George S. Burr, Department of Physics, University of Arizona, Tucson, AZ, USA
Hui-Ling Lin, Department of Oceanography, National Sun Yat-Sen University, Kaohsiung, Taiwan ROC
Presenter Email: kindhearted1222@gmail.com
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| The transition between sedimentary environments is compressed along land-sea boundaries in space and time. At river mouths on a high standing island, sedimentary records with high temporal resolutions formed as a result of large sediment loads and pervasive post-glacial sea level rise. Here we report on sediment core records covering the late Quaternary from the mouth of a small mountainous river in Taiwan. Results show the study site was initially terrestrial under fluvial control. Beginning at about 10,000 yr BP (before present) the site became inundated by the rising sea and the environmental facies transitioned from a floodplain/incised river valley to a succession of marine environments, from shoreface to offshore. As the rising sea level came to a pause at 6,000 yr BP, fluvial processes became dominant and sediments began to aggrade at the river mouth. After 4,500 yr BP, the accumulated sediment began to prograde seaward, taking on the form of a river delta, and subtidal sand ridges appeared in the nearshore. This chronology expresses the duel between sea level and fluvial processes that determined the depositional environments along the land-sea boundary at the study site. |
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