| Summary: | 碩士 === 國立臺灣大學 === 海洋研究所 === 99 === Abstract
In study area, 18 core samples were collected throughout the Eastern waters off Taiwan using box corers, including in the estuary of Lanyang River, Hualien River, Siouguluan River, and in southern OkinawaTrough, Ilan Shelf, Hoping Basin, Hoping Rise, Hsincheng Ridge, Hualian Valley and Southern Longitudinal Trough. This study hoped to find out the feature of grain size and the transportation of sediment through the analyses of cores collected from those physiographic units.
Depending on water depth and physiographic features, these core can be divided into three categories: 1. estuaries and shelves, 2. slopes 3. valleys, basins and troughs. X-ray photographs indicated that sediment cores from estuaries and continental shelves often contain convolute, lenticular, and also find turbidite layer; in the 2nd and 3rd categories, could also discover some turbidite records. Through the result of the grain size analyze, we ascertain that particle size range between 0~10ψ,mass median diameter range between 2.5~7.5ψ,and sorting of all cores varies between moderate, poor and very poor. The value of sand is decreasing northward; the value of silt and clay is increasing northward. That means the northward currents, such as Kuroshio current could carry sediments in similar topography. The 1st category with sediments in estuaries and shelves’s mass median diameter range between 2.5~7ψ, and moderately and very poorly sorted. Sediments in slopes’s mass median diameter range between 4.5~7.5ψ, with moderately and poorly sorted. The 210Pb data shows that the sedimentation rate range between 0.936~0.049 cm per year. Category in estuaries and shelves, only Site 757-14 could count the sedimentation rate in 0.486 cm per year. Cores in slopes’s sedimentation rate range between 0.936~0.056 cm per year. The 3rd category’s sedimentation rate range between 0.632~0.049 cm per year.
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