Records On Paleoenvironment From Mud In The Inner Shelf Of The East China Sea

The composition, source, formation and evolutionof mud off Fujian-Zhejiang coast oftheinnershelf inthe East China Sea were analyzed. The research shows that the mud in thestudy area records the high-resolution evolution of East Asian Paleo-Monsoon andPaleoclimate in China , especially in the Yangtze River drainage area. The relationshipbetween them was discussed. The heavy minerals, clay minerals, major elements, trace elements and Rare EarthElements (REE) of the mud in the study area are analyzed. The results show that theyaresimilar to those of the Yangtze River. Based on above studies, and combing with thecorrelation analysis of different elements and material source analysis with nonlinearprogramming model, the author concluded that the sediment in the mud area mainlyderived from Yangtze River instead of YellowRiver inthe last 2 ka. Thesedimentary environment of core DD2 and PC-6 was discussed, which are locatedin the north and center of the study area respectively. The grainsize compositions sensitiveto the sedimentary environment were taken by the analysis ofgrain size grade vs. standarddeviation. Comparative researchbetween grainsize compositions and suspended matterswas done. All above analyses show that the mud derived from the Yangtze River istransported with suspension by Fujian-Zhejiang coastal current. The further analysis of coresediments and shallow profiles indicate that the Fujian-Zhejiang winter coastal current hasformed and kept stable since about 8 ka before, but mud flux has changed drastically in thisperiod. This thesis studied Fujian-Zhejiang coastal current and mud transported by it, and theirresponse to the East Asian Monsoon and Palaeoclimate in China, especially in the Yangtze　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　River drainage area. The grain size sequence with resolution of 16 a and Rb/Sr ratiosequence were reconstructed with core DD2 in the continental shelf for the first time.Furthermore, the East Asian Monsoon and Chinese paleoclimate were discussed with highresolution in recent 2 ka. The research shows that there were 10 strong East Asian WinterMonsoonduring the period. Based on the rebuilding of grain size sequence of Core PC-6 in recent 8 ka, the EastAsian Monsoon was revealed completely, and their influence on the Paleoclimate wasdiscussed. Using power spectral analysis, centennial and millennial-scale cycles of Paleo-monsoon were extracted. In the cycles, 71 a is the basic cycle of East Asian Monsoon.