Benthic Foraminifera In The East China Sea Shelf That Recorded Rapid Climate Change Since The Deglaciation

The last deglaciation period has always been a hot spot in paleoclimatic research.During this period,a series of rapid climate change events took place in the Earth's climate system?Heinrich event-H1,B?lling-Aller?d,BA,Younger Dryas-YD?.Studying these climate events will help us understand the evolution of the global climate system and its driving mechanisms.The East Asian monsoon is an important part of the global climate system and plays an important role in the global and regional water cycle.The ups and downs of the East Asian monsoon affect the distribution of precipitation and the evolution of the ecological environment in East Asia,and in turn affect the socio-economic development and the succession of civilization in the monsoon region.Therefore,it is of great practical significance to study the evolution of the East Asian monsoon.The East China Sea continental shelf is located in the core area of the East Asian monsoon and belongs to a typical monsoon climate.This paper uses the drilling D02 and drilling D03 in the north and middle of continental shelf of the East China Sea for the study,perform particle size analysis,high Accuracy ¹⁴C Chronology Analysis,?based on single or mixed benthic foraminifera?and benthic foraminifera assemblage analysis,reconstruct the rapid climate change of the drilling D02since 1300a BP and the drilling D03 since17000a BP to date.It is compared with the sediment records of the East China Sea continental shelf studied by previous researchers and the rapid climate change in other parts of the world.The results show:the benthic foraminifera in the drilling D02 recorded seven cold events since 1300a BP,That is,1000⁹90a BP,820⁷80a BP,750⁷20a BP,700⁶30a BP,480⁴20a BP,280²30a BP,and 200¹70a BP.It may be a signal that the East Asian winter monsoon is increasing,and have a period of about 70a,the enhancement of the East Asian winter monsoon may be the same as the temperature change mechanism in Greenland and each cold event is accompanied by the occurrence of hypoxia.The benthic foraminifera in the drilling D03 recorded paleoenvironmental changes since about 17000a BP.Including the H1 cold event,the B?lling-early Aller?d and the Younger Dryas cold events.Taiwan warm current began to form on the 8500a BP,the strongest during the 8500⁵500a BP period,during this period,there is also an alternate enhancement of the centennial scale of East Asian winter monsoon and East Asian summer monsoon,that is,the increase of East Asian winter monsoon during8200⁸100,7600⁷500,7200⁷100a BP,6700⁶500a BP,6200⁶000a BP,and5800⁵600a BP;the increase of East Asiansummer monsoon during8100⁷600,7500⁷200,7100⁶700,6500⁶200,6000⁵800a BP.Between 5500 and800a BP,four enhancements of the East Asian winter monsoon at 4800⁴300,3600³500,1400¹300,and 800a BP.From 800a BP to the present,the East Asian winter monsoon increased during the period of 500⁴00a BP,during the period of700⁵00a BP and 400¹00a BP,there were two strong periods of Taiwan warm current,and the summer monsoon increased.It can be seen that the change of the East Asian monsoon has a cycle of about 500a.The enhancement of the East Asian winter monsoon may be the same mechanism as the cooling incident in Greenland.The enhancement of East Asian summer monsoon may be related to the movement of ITCZ to the north.The East Asian winter monsoon has a cycle of about 70 years since1300a BP,East Asian winter monsoon and summer monsoon have a cycle of about500a since 8500a BP.It is assumed that the East Asian monsoon has a cycle of about500 years since the mid-Holocene,And there is a minimum positive cycle of about 70a.