EOCENE MICROPALEONTOLOGY AND ITS EOENVIRONMENTAL SIGNIFICANCE IN WELL B1,XIHU SAG,EAST CHINA SEA BASIN
19 samples were collected for micropaleontology analysis from the interval 3 370～3 799 m of Well B1 in the Xihu Sag,East China Sea Basin.Abundant pollen,a small amount of foraminifers,dinoflagellates,discostellaria and calcareous nannofossils were found.The pollen are characterized by the flourishing taxaceae,moderate pinaceae and ulmus pollen,and less hamamelidaceae,betulaceae and fagaceae pollen and less hydrosauria spore.It can be recognized as Taxodiaceaepollenites-Pinuspollenites-Ulmipollenites-Quercoidites assemblage.Comparing with the sporopollen assemblage in the adjacent region,the age of this studied assemblage is the Middle Eocene.In addition,there are dinoflagellates Operculodinium centrocarpum and Hystrichokolpoma granulatum in this formation.Calcareous nannofossils such as Dictyococcites bisectus and Cyclicargolithus floridanus were found,as well as planktonic foraminifera Parasubbotina griffinae.Combined with the occurrence of foraminifers,dinoflagellates and calcareous nannofossils,the age of the interval 3 370～3 799 m from Well Bl is the Middle Eocene.According to the micropaleontological assemblages,it is interpretted that the middle Eocene strata was mainly deposited under the nearshore coastal bay.
micropaleontologypaleoenvironmentMiddle EoceneBaoshi FormationXihu SagEast China Sea Basin
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