Paleo-Environmental Information Study Of Loess On Islands In East China Sea And Xiashu Loess

Systemic and overall researches are made on the loess,which is one kind of good carrier of paleo-environmental information of land,distributed on Loess Plateau Northwest China and on the hills in west of Yangtze Delta which named Xiashu Loess. It has been an agreement that loess on Plateau is the sediment of aeolian dust and so with Xiashu Loess. All of the proxies which are used in the research of loess distributed in Northwest China to reflect the variation of paleoclimate have been widely used in the research of Xiashu Loess. Hard Clay distributed under the plain in east part of Yangtze Delta and the loess covered on the Shengshan Islands which locates in East China Sea were found that they were the same kind of aeolian sediments deposited in late Pleistocene by Prof.Zheng XM. For the reason of thin stratum and the great effects made by contemporary environment, it is an valuable research whether the proxies which are widely used in northwest to reflect paleoclimatal fluctuations could be used in the loess research successfully in this area. Paleo-environmental changes and the sedimentary mode of loess on islands are discussed in this paper and compared with the profile of Taishan New village on the proxies of grain size, magnetism,geo-chemistry and pedogenesis.Results and acknowledgements of this paper include five aspects as follows: 1.Through the analysis of experimental outcome of grain size , it's confirmed that the three profiles have the same components carried by wind which consistent with the rule of belt distribution about Loess in China except loess on Langgangshan Islands. The clay content of Xiashu Loess and Loess on islands is higher than that in Northwest China, which indicates that primary components of Xiashu loess and loess on islands are the fine particles carried by westerlies and fine partiles formed by pedogenesis. Being the concentration of sand in Langgangshan loess is 13.81%,which is even higher than that in loess distributed in Northwest China, the loess on Langgangshan Islands including much dust nearby are confirmed.2.The content of magnetic minerals of loess on Shengshan Island is less comparatively. The top part about 60cm thickness of the profile contains more anti-ferromagnetic minerals which indicates the violent pedogenesis and weathering. Concentration of stable singe domain (SSD) magnetic minerals...