Presenter: Wen-Shu Koo
Date: 2016/12/29
Abstract
Different lithologies between Taiwan and southeastern China lead to diverse mineralogical composition for weathering products derived from the two source- areas of the Taiwan Strait. Pyrrhotite and magnetite are respectively the dominant magnetic minerals associated with fluvial sediments from western Taiwan and southeastern China. Magnetic susceptibility (χ), saturation isothermal remnant magnetizer (SIRM), hard isothermal remnant magnetizer (HIRM) and S-ratio are used to distinguish the differences in magnetic properties and sediment provenances. The radionuclides of 210 Pb and 137 Cs were analyzed for elucidating sedimentation dynamics and accumulation rates for the past ~100 years. Results show that sedimentation in the Taiwan Strait is controlled by flood discharges, current and tidal flows. Higher sediment accumulation rates are associated with fine-sized sediment particles in low-energy areas. Based on sediment loads of surrounding rivers and the distribution of sediment accumulation rates, three major sediment dispersal systems can be defined in the Taiwan Strait. The presumably largest system is a series of northwestern Taiwan Rivers (including Choshui River). The second system is derived from other western Taiwan rivers to the south of the Choshui River and the third system is sourced from the Yangtze River and other Chinese rivers to its south.
Reference
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