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对南海北部琼东南盆地BD19-2-2井中新世地层中的钙质超微进行了定量和半定量分析,发现井段上部1800~2550m地层化石较丰富,而下部2574~3100m化石丰度及分异度明显降低;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1800~3100m井段地层中识别出9个钙质超微化石带或联合化石带,地层时代为早中新世至晚中新世,同时探讨了钙质超微划分下中新统-中中新统、中中新统-上中新统界线的化石标志。依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逐渐变化,确认BD19-2-2井从早中新世至晚中新世经历了4个沉积环境演化阶段,海水深度由浅变深,海水变暖。
Quantitative and semi-quantitative analyzes of calcareous ultrastructure in the Miocene strata in the BD19-2-2 well in the Qiongdongnan Basin in the northern South China Sea found that the abundance of fossils from 1800 to 2550 m in the upper part of the well was abundant while that of the lower 2574 to 3100 m and According to the existence of calcareous microfossil marker species, the biostratigraphy of this well is divided into 9 calcareous microfossils or united fossils in the strata of 1800 ~ 3100 m, The stratigraphic age was from early Miocene to late Miocene. At the same time, we explored the fossil marks of the Miocene-Miocene-Miocene-Miocene-Middle Miocene lines under the calcareous ultra-fine division. Based on the gradual changes of total abundance, degree of differentiation and characteristic environmental indicator abundance of calcareous microfossils, it was confirmed that BD19-2-2 experienced four stages of sedimentary environment evolution from Early Miocene to late Miocene The depth of seawater changes from shallow to deep, and seawater becomes warmer.