论文部分内容阅读
本文对南海北部珠江口盆地PY30井早中新世―更新世地层中的钙质超微化石进行了系统研究,发现490-690m和1 040-1 170m井段化石丰度和分异度均较高,700-1 035m和1 179-1 809m化石丰度中等,井段下部1 818-3 478m化石稀少,种类单调。根据钙质超微化石标志种的存在,对该井的生物地层进行了划分。在490—3 478m地层中识别出12个钙质超微化石带或联合化石带,地层时代为早中新世―更新世,据此建立了该井的钙质超微化石生物地层框架,探讨了下中新统与中中新统、中中新统与上中新统、上中新统与上新统以及上新统与更新统界线划分的钙质超微化石标志。根据钙质超微化石总丰度、分异度及特征性环境指示种丰度的变化,划分了8个沉积环境演化阶段,从而讨论了早中新世至更新世沉积环境演化特征。
In this paper, we systematically studied the calcareous microfossils in the Pli30 well of the Pearl River Mouth Basin in the northern South China Sea in the Pleistocene-Pleistocene strata and found that the fossil abundance and the degree of differentiation in the 490-690m and 1 040-1 170m wells were both high , 700-1 035m and 1 179-1 809m with medium fossil abundance. There are few fossils of 1818-3 478m in the lower part of the well, with monotonous species. According to the existence of calcareous microfossil marker species, the biostratigraphy of this well is divided. In the 490-3 478m strata, 12 calcareous microfossils or associated fossil zones were identified. The stratigraphic age was Early Miocene-Pleistocene, and the framework of the calcareous nannofossil biostratigraphy was established The calcareous fossil marks of the Lower Miocene and Middle Miocene, the Middle Miocene and the Upper Miocene, the Middle Miocene and the Pliocene, and the Pliocene and the Pleistocene boundary. Based on the changes of total abundance, degree of differentiation and abundance of characteristic environmental indicators of calcareous microfossils, eight stages of sedimentary environment evolution are divided, and the evolutional characteristics of sedimentary environment from Early Miocene to Pleistocene are discussed.