南海西沙群岛西科1井中新世石珊瑚

MIOCENE SCLERACTINIA FROM WELL XK-1,XISHA ISLANDS, SOUTH CHINA SEA

南海西沙群岛西科1井374. 95 1 257.5 m井段发现石珊瑚化石19属,分别为Acropora,Antillo-phyllia , Astreopora, Caryophyllia, Coenangia, Cricocyathus, Cyphastrea, Diploastrea, Enallopsammia Favia ,Favites, Fungia,Goniastrea ,Leptastrea ,Meandrina ,Montipora, Phyllangia, Porites 和 Turbinaria 等,主要分布于黄流组二段和一段顶部、梅山组二段上部和一段以及三亚组二段。其中Antillophyllia分布于渐新世到中新世,Cricocyathus的分布时代为始新世至中新世,说明含上述2属珊瑚的地层时代不晚于中新世。综合有孔虫、大型底栖钙藻和钙质超微化石等的时代划分结果,推断374. 95-1 257. 5 m井段的时代属于中新世。对Cricocyathussp.,Antillophyllia sp.和Phyllangia sp.等单体珊瑚和群体珊瑚Goniastrea sp.的主要特征进行了描述。

About 19 genera of scleractinian corals were found in the interval 374. 95 m to 1257. 52 m of the Well XK-1 from Xisha Islands, South China Sea. They are Acropora, Antillophyllia,Astreopora, Caryophyllia, Coenangia, Cricocyathus, Cyphastrea, Diploastrea, Enallopsammia, Favia,Favites,Fungia,Goniastrea,Leptastrea, Meandrina, Montipora, Phyllangia, Porites, Turbinaria. The scleractinian corals mainly occurred in the member 2 and at the top of member 1 of Huangliu Formation, ranging from the upper part of member 2 to member I of the Meishan Formation and in the member 2 of the Sanya Formation as well. Among them, the genus Antillophyllia has hitherto been known from Oligocene to Miocene, while the genus Cricocyathus has been recorded from Eocene to Miocene. It means that the age of the strata is not younger than Miocene. Concluding from the stratigraphic division of foraminifera,calcareous algae and calcareous nannofossils,the interval of 374. 95一1257. 52 m of the Well XK-1 is assigned to the Miocene in age. Furthermore,the main characteristics of solitary corals such as Cricocyathus,Antillophyllia,Phyllangia and the compound coral Goniastrea are described in this paper.