珠江口盆地西部渐新世以来钙质超微化石年代地层研究

CALCAREOUS NANNOFOSSIL CHRONOSTRATIGRAPHY IN THE WESTERN PEARL RIVER MOUTH BASIN SINCE THE OLIGOCENE

珠江口盆地西部保存记录了渐新世以来较为丰富的钙质超微化石,为生物地层学的系统研究奠定了基础。笔者以5口钻井为依托,根据经典钙质超微化石分带、国际年代地层表(2012,2015)以及ODP184航次等建立的西太平洋最佳深海地层剖面和微体古生物分析成果,识别出NP24—NN16共14个钙质超微化石带,重新厘定了研究区的生物事件年龄,建立了珠江口盆地西部渐新世以来钙质超微化石年代地层格架。并讨论了岩石地层单位的时代归属问题,将Sphenolithus ciperoensis,Zygrhablithus bijugatus,Reticulofenestra bisecta的末现面以及Helicosphaera carteri,Cyclicargolithus abisectus的初现面作为古近系与新近系界线的标志生物化石。

The relatively abundant calcareous nannofossil record in the western of Pearl River Mouth Basin, northern shelf of South China Sea, S. China provides the foundation for systemic research on the biostratigraphy. According to the ＂classical＂ calcareous nannofossil zones from five wells and recent progress of ODP Leg 184 which established the best western Pacific deep-sea stratigraphic section, 14 calcareous nannofossil zones from NP24 to NN16 have been recognized in this paper. Moreover, we also redefines the standard of the ages of biological events and establishes the chronostratigraphic frame of calcareous nannofossil in the western of Pearl River Mouth Basin since the Oligocene. With discussing the ages of each lithostratigraphic unit, the LAD of Sphenolithus ciperoensis, Zygrhablithus bijugatus, Reticulofenestra bisecta and the FAD of Helicosphaera carteri, Cyclicargolithus abisectus are used as the index fossils of the Paleogene- Neogene boundary.