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西科1井0.10—1267.80m岩芯中钙质超微化石丰度低,属种比较单调。分析831个样品,仅在48个样品中发现钙质超微化石,共鉴定10属17种及1个未定种,主要化石种为Calcidiscus leptoporus,C.macintyrei,Coccolithus pelagicus,Cyclicargolithus floridanus,Gephyrocapsa caribbeanica,G.oceanica,Helicosphaera carteri,H.euphratis,Pontosphaera multipora,Pseudoemiliania lacunosa,Reticulofenestra minuta,R.minutula,Sphenolithus abies,S.moriformis和S.neoabies等。根据钙质超微化石生物事件及组合特征,结合有孔虫和大型底栖钙藻等研究结果,对西科1井0.10—1267.80m地层进行了划分,大致可划分为5段:1)0.10—212.20m地层属于第四系NN21—NN19带;2)214.29—328.69m归属于更新统NN18带至上新统;3)330.97—598.12m属于上新统NN15带至上中新统;4)599.53—1231.62m归属于中中新统至下中新统;5)1233.62—1267.80m为下中新统。由于化石丰度和分异度均较低,未建立完整的钙质超微化石带序列。根据钙质超微化石标志种及组合特征,确定研究井段的地层时代为早中新世至第四纪。西科1井生物礁地层中钙质超微化石的发现,对该井生物地层的划分起到了十分关键的作用。
West Branch 1 well 0.10-1267.80m core calcareous microfossils abundance is low, more monotonous species. Among 831 samples, calcareous nanofossils were found in only 48 samples. A total of 10 genera and 17 species were identified in 10 genera. The major fossil species were Calcidiscus leptoporus, C.macintyrei, Coccolithus pelagicus, Cyclicargolithus floridanus, Gephyrocapsa caribbeanica, G. oceanica, Helicosphaera carteri, H.euphratis, Pontosphaera multipora, Pseudoemiliania lacunosa, Reticulofenestra minuta, R. minutula, Sphenolithus abies, S.moriformis and S. neoabies and the like. Based on the biological events and assemblages of calcareous nannofossils, combined with the research results of foraminifera and large-scale benthic calcareous algae, the strata of 0.10-1267.80 m in West Section 1 well are divided into 5 sections: 1) 0.10 -212.20m strata belong to the Quaternary NN21-NN19 zone; 2) 214.29-328.69m belonged to the Pleistocene NN18 zone to the Pliocene; 3) 330.97-598.12m belonged to the Pliocene NN15 zone to the Upper Miocene; 4) 599.53- 1231.62m belongs to the Middle Miocene to the Lower Miocene; 5) 1233.62-1267.80m is the Lower Miocene. Due to the low abundance and differentiation of fossils, no complete sequence of calcareous microfossils was established. According to the characteristics and characteristics of calcareous microfossils, the stratigraphic period of the study section was determined to be Early Miocene to Quaternary. The discovery of calcareous microfossils in the reef strata of the West Section-1 well has played a crucial role in the division of the biostratigraphy of the well.