Study On The Sedimentary Environment And Foraminifera Diversity In The Muddy Area Of The Continental Shelf Of The East China Sea

The continental shelf muddy sedimentary area in the East China Sea records rich geological information such as sea-land changes,monsoon fluctuations,ocean current invasion,and changes in material sources in the study area.It is an ideal place to study the deposition process and the evolution of the climate and environment in this area.Through sedimentary particle size analysis,element geochemical characteristics and foraminifera characteristics analysis,the Holocene sedimentary and paleoclimate environmental records and response characteristics of the continental shelf of the East China Sea since 6420 a BP were systematically studied.This study established a chronological model for the S04-3 sample from the study area.The deposition rate is high in the study area,showing an unstable trend of deep and shallow layers;the results of the sediment particle size test indicate that the hydrodynamic environment in the study area is resolved.Changes,and the coarse-grained composition has a good response relationship with the East Asian winter monsoon;the analysis of the relative content of clay minerals determined that the main material in the study area came from the Taiwan warm current transport sediments in the Taiwan river and the Yangtze River material and coast under the control of the East Asian winter monsoon.For effluent sediments,the transport volume of the two main provenance areas varies according to the inter-annual differences and the flux of land-based materials into the sea.Using benthic foraminifer cold and warm water indicator species and Taiwan warm current representative species analysis,we obtain Cold water combination(Protelphidium tuberculatum?Cribrononion vitreum?Bulimina marginata?Florilus spp.?Eggerella advena)sensitive to climate change,has a good indicator,and uses the above replacement indicators to compare with the Dunde ice core ?18O,Greenland ice core GISP2?18O and Hongyuan peat ?18O related parameter indexes,and divides the three stages of monsoon fluctuations.According to the experiment As a result,the analysis concluded that 8 cooling events occurred in the study area:C1(5613±100 a B.P.)?C2(4472 a—4385 a B.P.)?C3(4122 a—4034 a B.P.)?C4(2806±40 a B.P.)?C5(2100±30 a B.P.)?C6(1400 a—1050 a B.P.)?C7(700±30 a B.P.)?C8(300±30 a B.P.).