中国东海陆架盆地西湖凹陷生物地层初探

CENOZOIC BIOSTRATIGRAPHY OF THE XIHU SAG,NORTHEAST CONTINENTAL SHELF BASIN OF THE EAST CHINA SEA

根据中国东海陆架盆地西湖凹陷十余年来所钻探的探井中的微体古生物研究,初步得出如下结论:1)该地区普遍缺失晚上新世地层,2)目前在少数探井深部所发现的零星海相微古化石应属再沉积分子,不能作为可靠的地层确认证据,3)从本区所有探井中所发现的孢粉化石组合面貌来看,尚不能支持本区存在着确切无疑的前渐新世地层。据微体化石及孢粉组合的综合研究,可明显划分出七个不同的生物层组合段。

Cenozoic biostratigraphical succession of the Xihu Sag,Northeast Continental shelf basin of the East China Sea,has been established on the basis of recent study of microfossil assemblages from 17 drill cores.The new results indicate that.1）Late Pliocene strata are absentin the study area,2）rare marine fossils reported from the Huagang and Pinghu formations are reworked and redeposited,and thus cannot be used as biostratigraphic evidence for age determination,pre-Oligocene strata are absent in the Xihu Sag according to palynomorph biostratigraphic data,3）seven biostratigraphic zones can be recognized as follow：1.Polypodiaceae spores-Chenopodipollis-Artemisiaepollenites-Pseudorotalia-Gephyrocapsa oceanica assemblage zone.2.Graminidites-Persicarioipollis-Reticulofenestra pseudoumbilica-Asterorotalia-Ammonia assemblage zone.3.Magnastriatites-Liquidambarpollenites-Fupingopollenites-Graminidites-Persicarioipollis assemblage zone.4.Magnastriatites-Liquidambarpollenites-Fupingopollenites-GraminiditesPersicarioipollis-Rutaceoipollis assemblage zone.5.Magnastriatites-Pinnspollenites-Sporotrapidites minor assemblage zone.6.Magnastriatites-Pinuspollenites-Tsugaepollenites-Trilobapollis assemblage unit,and 7.Lygodiumsporites-Pinaceae pollen-Taxodiaceoepollenites-Alnipollenites assemblage zone.