南黄海中部沉积物岩芯常量元素组成与古环境

南黄海中部三个晚第四纪沉积物岩芯的粒度和常量元素组成研究表明,岩芯YS1和YS2沉积物组成接近,而与YS3沉积物明显不同.根据元素地球化学参数推测沉积物的来源不同,YS1和YS2沉积物主要来自中国大陆,以长江沉积物为主;而YS3沉积物则主要来自朝鲜半岛,长江和黄河的细粒沉积物可能通过黄海暖流输运而影响该岩芯沉积.南黄海中部沉积物受黄海暖流的影响显著,暖流形成前后的沉积物物源及沉积环境并不相同.黄海暖流靠近中国大陆一侧沉积区域的沉积环境由于气旋型涡旋的影响,水动力环境较弱,粒径较细,沉积速率缓慢;而靠近朝鲜半岛一侧的粗粒沉积物则由于靠近南黄海东北部的潮成砂体区,水动力环境相对较强,沉积物颗粒较粗,沉积物的形成过程与中部明显不同.

Major elemental compositions and paleoenvironmental changes of the core sediments in the southern Yellow Sea

The analyses of grain size and elemental compositions of three cores in the southern Yellow Sea indicate that the sediments in cores YS1 and YS2 are similar in size and elemental compositions, but obviously different from those in core YS3. Provenances of these core sediments were identified by using geochemical proxy indices such as elemental ratios. Different sediment sources were recognized for the three cores, in which the sediments of Cores YS1 and YS2 are mainly sourced from the Changjiang and Huanghe Rivers, whereas the sediments of Core YS3 came primarily from the Korean Peninsula via river supply or coastal erosion. The finegrained sediments from the Changjiang and Huanghe, probably transported by the Yellow Sea Warm Current (YSWC), exert weak influence on Core YS3. Both Cores YS1 and YS2 are formed during the postglacial transgression, with sediment supply varying between the Changjiang and the Huanghe sources with different Holocene periods. The YSWC formed at about 7 000 a BP, has a great influence on the sediment deposition in the southern Yellow Sea, by having formed different sedimentary environments in the study area. Cores YS1 and YS2 are mainly influenced by the cyclonic gyre dynamic action under relatively weak hydrodynamic environments, causing finegrained sediments therein. In contrast, Core YS3 is just located in the west part of the YSWC and close to the tidal sand ridges of the northeastern Yellow Sea. The sediment deposited under the stronger hydrodynamic environment and lack of sediment supply, which accounting for the coarsegrained sediment deposition.