鄂西利川地区二叠系—三叠系界线地层沉积相研究
发布时间：2018-10-09 07:48
【摘要】：二叠纪末期发生了显生宙最大的生物集群灭绝事件,这次重大的地质突变导致了生态系统的彻底改变。同时,沉积环境也发生了剧变,被称为“错时相”的特殊沉积构造广泛在早三叠世浅海环境中出现,这为研究生物灭绝的原因提供了良好的证据。有关这次灾变事件,前人做了大量的研究,提出了一系列的假说,得到普遍认可的有火山喷发、缺氧、全球变暖和海平面变化等,至今仍没有一致的结论。 本文以鄂西利川的二叠-三叠系地层为研究对象,通过实地观察和测量、采集样品和室内显微镜观察,分析了碳酸盐岩微相类型,还原了二叠-三叠之交沉积环境的变化。通过整合已有的资料,理清现阶段生物灭绝的主流原因,并以此认为二叠-三叠之交生物大灭绝的真实原因,如下： 1、在利川地区瑞坪、夏家槽两个剖面共划分出6种微相类型(有孔虫微晶灰岩、藻纹层状钙质微生物岩、藻-有孔虫生物碎屑灰岩、树枝状钙质微生物岩、花斑状构造钙质微生物岩、含黄铁矿的泥晶灰岩、碳酸盐浊积岩)。邻近地区的过渡层补充了3种微相类型,具有环境恶化的特征,在此基础上对海平面变化进行了研究。 2、火山事件是三叠纪早期沉积环境恶化的主要原因。从煤山剖面和峨眉山剖面的地球化学资料分析得出,陆内火山活动仍然是生物灭绝事件的根本原因。扬子地台西缘至下扬子地区三叠系底部凝灰质泥岩成分与峨眉山玄武岩的岩石地球化学性质十分相似。峨眉山凝灰质泥岩火山物质中含有来自地幔楔(或下地壳)的物质成分。
[Abstract]:At the end of Permian, the largest Phanerozoic mass extinction event occurred, and this major geological change resulted in a complete change of ecosystem. At the same time, the sedimentary environment has changed dramatically, and the special sedimentary structures called "staggered facies" have appeared widely in the early Triassic shallow sea environment, which provides good evidence for the study of the cause of biological extinction. A lot of researches have been done on this catastrophic event and a series of hypotheses have been put forward. The generally accepted conclusions are volcanic eruption, hypoxia, global warming and sea level change, etc. In this paper, the Permian-Triassic strata in Lichuan, western Hubei Province are taken as the research objects. Through field observation and measurement, sample collection and microscopic observation, the types of carbonate microfacies are analyzed and the change of sedimentary environment at the intersection of Permian and Triassic is reduced. By integrating the existing data, we can clear up the main causes of the current biological extinction, and based on this, we can conclude that the real reasons for the mass extinction of the two Permian and Triassic organisms are as follows: 1. In Ruiping, Lichuan region, Six types of microfacies (foraminiferal microcrystalline limestone, algae-lamellar calcareous microbe, algae-foraminifera bioclastic limestone, dendritic calcareous microbe, flower porphyry calcareous microbe) were divided into six microfacies types. Pyrite-bearing mudstone, carbonate turbidite) Three microfacies types are added to the transition layer in the adjacent area, which is characterized by environmental deterioration. The sea level change is studied on this basis. 2. Volcanic events were the main cause of the deterioration of sedimentary environment in the early Triassic. From the geochemical data analysis of Meishan and Emeishan sections, it is concluded that intracontinental volcanic activity is still the root cause of bioextinction events. The composition of the tuffaceous mudstone at the bottom of the Triassic in the western margin of the Yangtze platform to the lower Yangtze area is very similar to the petrogeochemical properties of the Emeishan basalt. Emeishan tuffaceous mudstone volcanic material contains material from mantle wedge (or lower crust).
【学位授予单位】：中国地质科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.46;P534.51
[Abstract]:At the end of Permian, the largest Phanerozoic mass extinction event occurred, and this major geological change resulted in a complete change of ecosystem. At the same time, the sedimentary environment has changed dramatically, and the special sedimentary structures called "staggered facies" have appeared widely in the early Triassic shallow sea environment, which provides good evidence for the study of the cause of biological extinction. A lot of researches have been done on this catastrophic event and a series of hypotheses have been put forward. The generally accepted conclusions are volcanic eruption, hypoxia, global warming and sea level change, etc. In this paper, the Permian-Triassic strata in Lichuan, western Hubei Province are taken as the research objects. Through field observation and measurement, sample collection and microscopic observation, the types of carbonate microfacies are analyzed and the change of sedimentary environment at the intersection of Permian and Triassic is reduced. By integrating the existing data, we can clear up the main causes of the current biological extinction, and based on this, we can conclude that the real reasons for the mass extinction of the two Permian and Triassic organisms are as follows: 1. In Ruiping, Lichuan region, Six types of microfacies (foraminiferal microcrystalline limestone, algae-lamellar calcareous microbe, algae-foraminifera bioclastic limestone, dendritic calcareous microbe, flower porphyry calcareous microbe) were divided into six microfacies types. Pyrite-bearing mudstone, carbonate turbidite) Three microfacies types are added to the transition layer in the adjacent area, which is characterized by environmental deterioration. The sea level change is studied on this basis. 2. Volcanic events were the main cause of the deterioration of sedimentary environment in the early Triassic. From the geochemical data analysis of Meishan and Emeishan sections, it is concluded that intracontinental volcanic activity is still the root cause of bioextinction events. The composition of the tuffaceous mudstone at the bottom of the Triassic in the western margin of the Yangtze platform to the lower Yangtze area is very similar to the petrogeochemical properties of the Emeishan basalt. Emeishan tuffaceous mudstone volcanic material contains material from mantle wedge (or lower crust).
【学位授予单位】：中国地质科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.46;P534.51
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