【摘要】：二疊紀(jì)末期發(fā)生了顯生宙最大的生物集群滅絕事件,這次重大的地質(zhì)突變導(dǎo)致了生態(tài)系統(tǒng)的徹底改變。同時(shí),沉積環(huán)境也發(fā)生了劇變,被稱為“錯(cuò)時(shí)相”的特殊沉積構(gòu)造廣泛在早三疊世淺海環(huán)境中出現(xiàn),這為研究生物滅絕的原因提供了良好的證據(jù)。有關(guān)這次災(zāi)變事件,前人做了大量的研究,提出了一系列的假說,得到普遍認(rèn)可的有火山噴發(fā)、缺氧、全球變暖和海平面變化等,至今仍沒有一致的結(jié)論。 本文以鄂西利川的二疊-三疊系地層為研究對象,通過實(shí)地觀察和測量、采集樣品和室內(nèi)顯微鏡觀察,分析了碳酸鹽巖微相類型,還原了二疊-三疊之交沉積環(huán)境的變化。通過整合已有的資料,理清現(xiàn)階段生物滅絕的主流原因,并以此認(rèn)為二疊-三疊之交生物大滅絕的真實(shí)原因,如下： 1、在利川地區(qū)瑞坪、夏家槽兩個(gè)剖面共劃分出6種微相類型(有孔蟲微晶灰?guī)r、藻紋層狀鈣質(zhì)微生物巖、藻-有孔蟲生物碎屑灰?guī)r、樹枝狀鈣質(zhì)微生物巖、花斑狀構(gòu)造鈣質(zhì)微生物巖、含黃鐵礦的泥晶灰?guī)r、碳酸鹽濁積巖)。鄰近地區(qū)的過渡層補(bǔ)充了3種微相類型,具有環(huán)境惡化的特征,在此基礎(chǔ)上對海平面變化進(jìn)行了研究。 2、火山事件是三疊紀(jì)早期沉積環(huán)境惡化的主要原因。從煤山剖面和峨眉山剖面的地球化學(xué)資料分析得出,陸內(nèi)火山活動仍然是生物滅絕事件的根本原因。揚(yáng)子地臺西緣至下?lián)P子地區(qū)三疊系底部凝灰質(zhì)泥巖成分與峨眉山玄武巖的巖石地球化學(xué)性質(zhì)十分相似。峨眉山凝灰質(zhì)泥巖火山物質(zhì)中含有來自地幔楔(或下地殼)的物質(zhì)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).
【學(xué)位授予單位】：中國地質(zhì)科學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P534.46;P534.51

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