四川盆地东北部二叠纪末有孔虫和（？）的分布及其环境意义

发布时间：2019-03-03 14:13

【摘要】：长久以来,有孔虫和(?)类在海洋地质研究中占有重要的地位。它们是记录海洋沉积环境信息的重要载体,同是也是研究古环境变化、恢复古海洋环境的指示生物之一。四川盆地东北部二叠纪末长兴组地层含有丰富的微体古生物化石,为论文的研究提供了丰富的材料。本文同时运用沉积学、地层学、古生物地层学、古生态地层学及海洋地球化学等学科知识,对有孔虫及(?)类分布及特征进行系统细致的分析,来研究有孔虫及(?)的演化与海洋环境变迁之间的关系。经统计,巫溪田坝剖面与巫溪尖山剖面共描述了有孔虫14个属,59个种；(?)类5个属,5个种,划分出5个古生物组合。通过对有孔虫及(?)的生物组合及分异度变化的研究,生物相的角度论证了海洋物理条件对有孔虫及蜓的纵向演化影响较小。生物地层分析表明：(1)区内两剖面长兴组均分别出现了两次生物骤减,并且都是第一次骤减后很快在上覆地层中富集起来；第二次的生物骤减发生后,上部的地层均不见有孔虫分布；(2)通过牙形石建立区内生物地层格架,与长兴煤山金钉子剖面对比,确定了巫溪尖山剖面与巫溪田坝剖面生物大灭绝的灭绝线,分别为巫溪尖山第4层和巫溪田坝第2层；(3)对有孔虫壳体大小变化规律的分析发现,在生物大灭绝发生之前,有孔虫壳体就出现了不同程度小型化的现象。通过地球化学特征指证,高温缺氧的古海洋环境可能导致了区内有孔虫壳体提前出现小型化现象,西伯利亚火山活动有可能是导致一系列灾难事件发生的最重要的原因。
[Abstract]:For a long time, foraminifera and Classification plays an important role in marine geological research. They are important carriers for recording marine sedimentary environment information. They are also one of the indicator organisms to study the change of palaeo-environment and restore the paleo-marine environment. The late Permian Changxing formation in northeastern Sichuan Basin contains abundant microfossils, which provides abundant materials for the study of this paper. Based on the knowledge of sedimentology, stratigraphy, palaeontology, palaeoecostratigraphy and marine geochemistry, this paper deals with foraminifera and foraminifera. In order to study foraminifera and foraminifera, the distribution and characteristics of the species were analyzed systematically and meticulously. The relationship between the evolution of the ocean environment and the evolution of the ocean environment. According to statistics, the Wuxi Tianba Section and the Wuxi Jianshan Section described 14 genera and 59 species of foraminifera. Class 5 genera, 5 species, divided into 5 palaeontological assemblages. For foraminifera and (?) From the angle of biological facies, it is proved that the marine physical conditions have little effect on the longitudinal evolution of foraminifera and flies. The biostratigraphic analysis shows that: (1) the Changxing formation of the two sections in the area has two biological sudden decreases respectively, and they are enriched in the overlying strata soon after the first sudden decrease; No foraminifera were found in the upper strata after the second sudden decrease of organisms. (2) the biostratigraphic framework of Wuxi Jianshan section and Wuxi Tianba section, which are the fourth layer of Wuxi Jianshan and the second layer of Wuxi Tianba, are determined by comparing it with Jinnail section of Changxing Coal Mountain by using conodont to set up the biostratigraphic framework in the area, and the extinction lines of Wuxi Jianshan Section and Wuxi Tianba Section are determined. (3) by analyzing the variation rule of the shell size of foraminifera, it was found that the shell of foraminifera appeared miniaturization in varying degrees before the occurrence of biological extinction. It is proved by geochemical characteristics that the paleo-marine environment with high temperature and hypoxia may lead to the miniaturization of foraminifera shell in the area, and the volcanic activity in Siberia may be the most important cause of a series of disaster events.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.46;Q915

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