从孢粉学论证东海盆地下第三系的存在

传统的地质学观点,将东海盆地与台湾海相地层相提并论,以至误解东海盆地只有上第三系沉积。而在东海海域龙井构造中首钻的龙井一井和次钻的东海一井下部地层中所获得的孢粉组合证明,东海盆地龙井构造史前的早第三纪时曾与苏北相连成陆,只是在晚渐新世一早中新世时才全面解体接受海侵,这一事实表明,其成盆历史大体与南海相仿。

THE EXISTENCE OF PALEOGENE SEDIMENTS IN EAST CHINA SEA BASIN BY PALYNOLOGICAL EVIDENCE

The Paleogene deposits in the East China Sea Basin may be divided into the Yangzijiang and Lower subformation of the Qiangtajiang Formation in ascending order.The mudstone and shale are rich in sporopollen fossils.They may be divided into two palynological assemblages as follows: 1.Ulmipollenites minor-Ulmoideipites krempii assemblage(In the Yangzijiang Formation). The Sporepollen assemblage is charactezied by the absolute predominance of Angiospermous pol- len,while Gymnospermous and Pteridophytous are second.The pollen of Angiosperae is do- minated by Quercoidites(Q.asper,Q.henrici,Q.microhenrici,Q.minor),Ulmaceae(Ulmipolle- ninites undulosus,U.minor,U.granulatus,Ulmoideipites krempii,U.tricostatus),Rutaceae(Ru- taceoipollis ovatus,R.rotundatus,R.oblongatus),Meliaceae(Meliaceoidites minor,M.rhomboi- porus and M.rotundiporus)and Hydrocaryaceae(Sporotrapoidites minor and S.medius),with also some Caryapollenites,Juglanspollenites,Plicapollis,Tiliaepollenites,Krutzipites and Trilo- bapollis.The pollen of Gymnospermae are more aboundant in Pinuspollenites.As to Pterido phyta,the Spores Polypodiaceae,Magnastriatites howardi and Pterisisporites are relatively com- mon. 2.Pinuspollenites-Trilobapollis assemblage(In the Lower subformation of Qiangtangjiang Formation).The Sporepollen assemblage is also characterized by the absolute predominance of Angiospermous pollen Quercoidites,Ulmaceae,Rutaceae and Hydrocaryaceae,and less in pollen of Gymnospermae and Spores of Pteridophyta,but it is different from that of the Yangzijiang Formation,the major difference lie in acute attenuation of Podocarpidites,Quercoidites minor, Rutaceoipollis ovatus,Ulmipollenites minor and Ulmoideipites krempii,and well development of Pinuspollenites,Ulmipollenites undulosus and Trilobapollis. Based on the fact that Spore pollen assemblage of the Eocene-Oligocene in the coastal region of the Bohai Sea,and the provinces of Jiangsu,Anhui,Zhejiang,Jiangxi,Hubei and Guangdong,the South Yellow Sea and northern shelf of the South China Sea are characterized by the great abundance of Ulmaceae,Rutaceae,Meliaceae and Quercoidites.The Yangzijiang Formation can probably be defined as Eocene,the climate was marine,central-south subtropical type.The lower subformation of the Qiangtangjiang formation is identified as Oligocene,dry and cool,central subtropical climate.