Sources and Transport of Clay Minerals in Surface Sediments of the Northeastern East China Sea

The relative contents of clay minerals in 80 surface sediment samples were analyzed by X-ray diffraction. The results showed that the content of illite (65.1%) was the highest in the surface sediment clay minerals in the northeastern part of the east China sea, followed by chlorite (26.6%), kaolinite (8.9%) and smectite (4.3%). In mineral assemblages, illite-chlorite-kaolinite-smectite type is dominant, while illite-chlorite-kaolinite type is less. From the outer shelf to Okinawa Trough, the distribution of illite content was low-high-low-high. Chlorite distribution was low-high-low. The distribution trend of kaolinite is obviously different from that of illite and chlorite. The smectite was absent in some areas and the high value area was patchy in the outer shelf with water depth less than 100 meters. Fast clustering analysis shows that clay minerals can be divided into three types:Yangtze River-like, Yellow River-like and Taiwan-like, which covered in four regions. The "Yellow River-like" clay minerals are mainly transported from the Yellow River and the abandoned Yellow River by the coastal current of the Yellow Sea. They are distributed in the outer shelf area north of 29.5°N and west of 127°E, and don't cross the East China Sea shelf into the Okinawa Trough. The "Yangtze-like" clay minerals covered in the outer continental shelf were mainly paleo-Yangtze materials in the low sea level period, mixed with a small amount of suspended materials from the modern Yangtze River. The "Yangtze-like" clay minerals covered in the Okinawa Trough were mainly derived from the paleo-Yangtze materials in the low sea level period. The "Taiwan-like" clay minerals are mainly controlled by the Kuroshio, which are transported from Taiwan through the southern Okinawa Trough and deposited along the continental slope.