臺灣淺灘位於台灣海峽南部為一扇狀、水深約40公尺，面積約13000平方公里的淺水區域。過去研究指出，此區沉積物為末次冰期時中國東南部河流在此區堆積的三角洲。後經全新世海水面上升後，海床沉積物和現代沉積物混合而形成變餘沉積物。本研究利用2010至2016年間法國研究船R/V Marion Dufresne第178航次、海研一號OR1-1071、OR1-1138航次和海研三號OR3-1938航次在台灣淺灘及南海北部所採的沉積物，結合台灣西南部河流樣本，分析其沉積物特性和分布。研究方法包括X光繞射分析、薄片礦物鑑定、碎屑鋯石鈾鉛定年分析。台灣淺灘沉積物大多為黃褐色、中至粗顆粒砂且含有大量生物殼體碎屑；而位於其南側之陸棚沉積物，呈灰黑色細砂且含多量有孔蟲。台灣淺灘之粗顆粒沉積物以石英為主，愈靠近中國及澎湖群島，其長石比例愈高。黏土礦物以綠泥石和伊萊石含量最高，並含有少量高嶺石及膨潤石。板岩屑分布於澎湖水道以東、靠近台灣島的陸棚區，以及淺灘以南的外大陸棚。由此區潮汐與洋流傳輸方向以及礦物組成分布，推測從台灣輸出、含板岩屑之沉積物被黑潮支流往北沿澎湖水道輸送，部分往南海方向堆積於台南盆地的外大陸棚及大陸斜坡，有些沉積物則經由澎湖海底峽谷往南、向深海區輸送。除了台南盆地外大陸棚外，於澎湖水道以西的台灣淺灘沒有發現板岩屑，推論台灣淺灘沉積物皆來自中國東南，且未與台灣沉積物混合。台灣淺灘之碎屑鋯石鈾鉛定年分析顯示其主要以中生代燕山期 (65-200 Ma) 的鋯石為主。與鄰近河流之現代碎屑鋯石年齡分布比對後，發現其鋯石鈾鉛年齡分布最接近九龍江，也顯示台灣淺灘沉積物，主要由末次冰期時九龍江堆積所形成。;The Taiwan Shoal in the southern Taiwan Strait exhibits a lobe-shaped shallow water area, with a depth less than around 40 m and an area approximately of 13,000 km2. The Shoal consists of relict sediments remnant from deltaic deposits during the last glacial period and associated with the paleo-Jiulong River. We collected seafloor sediments in and around the Taiwan Shoal to study the sediment characteristics and provenance of the Shoal as well as Taiwanese river sediments to characterize sediment sourced from southern Taiwan. Sediments collected from the deep South China Sea are also studied to understand their provenance. Our results help to understand possible sediment delivery pathways in a source-to-sink context from the southern Taiwan Strait to the northern South China Sea. The method of X-ray diffraction is used to identify mineral compositions for muds and mineral compositions are examined under polarized microscope for sands. Detrital zircon grains are separated from heavy minerals for U-Pb dating in order to understand the sediment source terranes. Sediments of the Taiwan Shoal are mostly tawny-colored, medium to coarse-grained sands with abundant shell fragments and shallow-water benthic foraminifera. Sediments to the south of the Taiwan Shoal and in the outer shelf consist of dark brown-colored and fine-grained sands with rare shell fragments. Siliciclastic compositions of the Taiwan Shoal sediments are mostly quartz. Slate fragments are found to occur near Taiwan and in the outer shelf, especially in the Penghu Channel area. The sediment colors and mineral species are very different for the sediments of the Taiwan Shoal and outer shelf, revealing that these two areas featuring different oceanographic processes and sediment provenance. Zircon U-Pb dating reveals that sediments in the Taiwan Shoal are mostly sourced from the Jiulong River in the Fujian province; the sediments in the outer shelf, the Penghu Channel and the northern South China Sea receive more sediment inputs from southwestern Taiwanese rivers, however.
