Core Sedimentary Features Of Modern Muddy Deposits In The East China Sea And Yellow Sea

There are several modern muddy deposits with patch-shapes on the continental shelf of the Yellow Sea and East China Sea is a typical shelf sea, which forms by a continuous sedimentation with terrestrial sediment sources mainly from coastal rivers, i.g., the Huanghe, Changjiang, etc. The muddy deposits are good material to study the interaction between land and sea because of continuous sedimentation. The cores B44, B45 (in the northern Yellow Sea), YSZD01(in central part of the southern Yellow Sea), DH8-1 (on inner shelf of the East China Sea) are collected and used in this thesis. The 210Pb and 137Cs dating, sediment grain size and clay mineral measurements of the core samples are conducted on a high-resolution sampling (0.5 cm interval). The age and deposition rate, grain size composition, and relative abundance of clay mineral of these cores are analyzed and compared. Main conclusions are as the follows.According to 210Pb dating, the core B45 formed during 1927-2010 with a mean sedimentation rate of 0.49cm/a; the core YSZD01 formed during 1902-2012 with a mean sedimentation rate of 0.26cm/a; the core DH8-1 formed during 1950-2012 with a mean sedimentation rate of 0.69cm/a. For the mean sedimentation rate of these three cores, the lowest (0.26cm/a) is core YSZD01 in the southern Yellow Sea, and the highest (0.69cm/a) is core DH8-1 on the inner shelf of the East China Sea, mainly due to the impact of sediment runoff.According to grain size analysis, the main sediment type of core B45 is silt. The percent composition of core B45 is 4.19% of sand,69.42% of silt, and 26.39% of clay. The main sediment type of core YSZDOl is mud. The composition of the core YSZD01 is 9.58% of sand,54.18% of silt, and 36.35% of clay. The main sediment type of core DH8-1 is silt. The composition of core DH8-1 is 3.28% of sand, with an average of 67.67% of silt, and 29.05% of clay.The relative abundance of chlorite, illite, kaolinite and smectite are estimated by the Biscaye (1965) semi-quantitatively method. The results show that the relative composition of clay minerals of core B44 in the northern Yellow Sea is 61.67% of illite, 11.41% of kaolinite,14.88% of chlorite and 12.04% of smectite. The clay minerals of core YSZD01 in the central part of the southern Yellow Sea are composed of 60.4% of illite,11.36% of kaolinite,18.39% of chlorite and 9.86% of smectite. The clay minerals of core DH8-1 on the inner shelf of the East China Sea are composed of 61.07% of illite, 12.07% of kaolinite,17.45% of chlorite and 3.74% of smectite.