贵州织金剖面二叠纪—三叠纪之交有孔虫演化对古海洋化学状态的响应

发布时间：2018-05-30 06:39

本文选题：贵州织金 + 二叠纪-三叠纪　；参考：《中国矿业大学》2017年硕士论文

【摘要】：贵州织金剖面火山凝灰质黏土岩比较发育,地层连续,为华南地区二叠纪-三叠纪之交斜坡相地层或盆地相地层对比、沉积特征、生物演化与古海洋化学状态特征的研究提供了非常好的条件。本文以贵州织金剖面为研究对象,通过资料收集、野外勘查、实验室分析和镜下观察,对研究区的有孔虫类型以及对古海洋化学状态响应进行了研究。经统计,贵州织金剖面一共鉴定了有孔虫15个属36个种,划分出了3个有孔虫组合带。根据有孔虫演化揭示了:区内有孔虫一共出现了两次生物骤减,第一次骤减之后,有少量的有孔虫延续到了上覆地层,第二次骤减之后,上覆地层有孔虫极少或灭绝;与浙江煤山剖面的对比,确定贵州织金剖面第一次生物大灭绝灭绝线为第5层顶,第二次位于第8层,P-T界线确定在7-1小层顶,7-2小层底。通过铁组分和微量元素测试,分析了贵州织金二叠纪末-三叠纪初水体中的含氧量呈震荡的变化,总体上二叠纪末是氧化环境,三叠纪初是缺氧环境。有孔虫的演化与海水中的含氧量呈很好的相关性,当氧量相对增加,有孔虫繁盛,当含氧量相对减少,有孔虫衰减。探讨了造成二叠纪末生物大规模灭绝和古海洋化学状态变迁的原因有可能是二叠纪末大规模的火山活动。
[Abstract]:Volcanic tuffaceous clay rocks in the Zhijin section, Guizhou Province, are relatively developed and the strata are continuous, which is the correlation of slope facies and basin facies strata between Permian-Triassic in South China, with sedimentary characteristics. Biological evolution and the characteristics of paleooceanic chemical state provide very good conditions. In this paper, the foraminifera type and the response to paleooceanic chemical state in the study area were studied by data collection, field exploration, laboratory analysis and microscopic observation. According to statistics, a total of 15 genera and 36 species of foraminifera were identified and 3 foraminiferal assemblages were identified in Zhijin section of Guizhou Province. According to the evolution of foraminifera, the foraminifera occurred two times in the region. After the first dip, a small number of foraminifera continued to the overlying strata, and after the second dip, there were few or no foraminifera in the overlying strata. Compared with the coal-mountain section of Zhejiang Province, the first extinction line of the Zhijin section in Guizhou is determined to be the top of the fifth layer, and the second one is located at the bottom of the 7-1 layer top and the second layer at the P-T boundary of the 8th layer. Based on the measurement of iron composition and trace elements, the oxygen content in the water body of the late Permian to the early Triassic in Zhijin, Guizhou Province was analyzed. The oxygen content in the water was oscillating. In general, the late Permian was an oxidation environment, and the early Triassic was an anoxic environment. The evolution of foraminifera has a good correlation with the oxygen content in seawater. When the oxygen content increases, foraminifera flourish, and foraminifera decay when oxygen content decreases. It is discussed that the reason for the mass extinction of the late Permian organisms and the change of paleo-marine chemical state may be the large-scale volcanic activity at the end of the Permian.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q915;P534

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