珠江口盆地渐新统—更新统钙质超微化石生物地层事件

CALCAREOUS NANNOFOSSIL BIO-EVENTS IN OLIGOCENEPLEISTOCENE IN THE PEARL RIVER MOUTH BASIN

依据珠江口盆地渐新统至更新统中28个重要的钙质超微化石生物地层事件划分出20个超微化石带,在此基础上明确了下第三系恩平组和珠海组,上第三系珠江组、韩江组、粤海组和万山组等岩石地层单元的钙质超微化石生物地层特征。NN1带内的Dictyococcites bisectus末现面,与珠海组顶界基本一致,为本区上、下第三系分界的钙质超微化石生物地层事件,其绝对年龄值为23.6～24.0Ma。本文还讨论了本区与邻区渐新统一上新统含超微化石地层的对比关系。

28 nannofossil bio-events and 20 zones in Oligocene-Pleistocene in the Pearl River Mouth Basin are recognized, the relationship between these bioevents and zones and 6lithostratigraphic units (formation) in the area has been defined in this paper as follows: The top of Wanshan Formation coincides with LAD Discoaster brouweri at top NN18 zone;The top of Yuehai F. with LAD Discoaster quinqueramus at top of NNll zone; The top ofHanjiang F. with LAD Discoaster hamatus at the top of NN9 zone; The top of Zhujiang F.with LAD Helicosphaera ampliaperta at the top of NN4 zone; The top of Zhuhai F. withLAD Dictyococcites bisectus within NNl zone and the top of Enping F. falls in the NP24-NP23 combined zone. This paper suggests that the top of lithostratigraphic Zhuhai Formation and biostratigraphic LAD of Dictyococcites bisectus can be considered as the Paleogene-Neogene boundary and Oligocene-Miocene boundary in the PRM Basin.