Composition and Texture of Surface Sediment Indicating the Depositional Environments off Northeast Taiwan

臺灣東北外海黑潮轉向區海床之表層沉積物所顯示之沉積環境

陳民本(Min-Pen Chen) ； 林庚鈴(Shen-Chung Lo) ； 羅圣宗(Ken-Ling Lin)

《Terrestrial, Atmospheric and Oceanic Sciences》 3卷3期 (1992/09) Pp. 395-417

摘要

從台灣東北外海黑潮轉向區(KEEP)之海床上所採集之46個表層沉積物中之研究得出東海陸棚西南緣之黑潮轉向區的沉積環境和沉積現象。黑潮在此區之轉向主要是受到地形上升的影響。東海的中國海岸沿岸流所挾帶之富含石英、長石和鐵—鎂礦物的砂質沉積物，主要僅堆積到北緯26度，東經122度附近，但泥質沈積可以越過123度。黑潮主流在台灣東北外海因地形的影響所產生的湧升流有二，一在蘭陽溪河口附近，一在北緯25.6度，東經122.4度附近。湧升流之下的沉積物以富含岩石碎片及高碳酸鈣含量為其特色。黑潮主流之下的沉積物中，生物殼體並不富集。東海陸棚上的湧升流與台灣之間，有一黑潮迴流所造成的富含岩石碎片和鐵—鎂礦物顆粒的砂質沉積帶。蘭陽溪所挾帶之陸源泥砂出海以後係往東南方向堆積在西北—東南走向的宜蘭海脊上。在黑潮主流下的沖繩海槽內之沈積是以非生物源的細粒泥質為主。

並列摘要

Surfacial sediments of 27 piston cores, 14 gravity cores and 5 dredged samples were taken form an offshore area of northeastern Taiwan for delineating the depositional features beneath the Kuroshio Current and around the southwestern edge of the East China Sea. The turn of direction from the Kuroshio Current in this area has resulted primarily from the effect of an ascent of the seafloor. The China coast current has spread coarse sediment in the East China Sea, Composed primarily of quartz, feldspar and mafic minerals toward the area of 26°N, 122°E. Fine sediments may, however, be distributed beyond the east of 123°E. Rock fragments and mafic have been concentrated in the north of Taiwan, as delivered by the Kuroshio Current. Two upwellings have possibly deposited calcareous biogeneous materials on the seafloor: one being located at the south of the depositional boundary in which the sediments are derived from mainlang China; and the other one being located at 25.6N°,122.4E°just on top of the lan-Yan Fan. In the Okinawa Trough, the sediments beneath the path of the main Kuroshio flow have been shown here to be composed of non-biogenic, fine-grained mud.