【摘要】：本論文以云南丘北地區(qū)下三疊統(tǒng)洗馬塘組為主要研究對象,系統(tǒng)研究了該地區(qū)洗馬塘組的巖石地層、生物地層及沉積環(huán)境。研究重點是洗馬塘組生物化石組合和環(huán)境意義,并在此基礎(chǔ)上探討其對P/T大滅絕后早三疊世生物復蘇的意義。本次研究主要采取野外調(diào)查與室內(nèi)實驗相結(jié)合的方法,運用巖石學、沉積學、古生物學等理論作為指導,實測了多條洗馬塘組剖面,采集了大量化石,取得了諸多新的發(fā)現(xiàn)和進展,全面提升了對洗馬塘組的研究認識。取得的主要認識有:(1)通過剖面實測,對洗馬塘組巖性有了新的認識。在洗馬塘組底部發(fā)現(xiàn)一套厚層鮞�；�?guī)r和數(shù)層火山成因的鉀質(zhì)斑脫巖,修正了前人在巖性描述方面的認識。(2)在洗馬塘組一段泥巖中發(fā)現(xiàn)了大量古生物化石,包括雙殼類、腹足類、腕足類、葉肢介、海蛇尾類棘皮動物、節(jié)肢動物、菊石、牙形石、分類不明動物化石,以及植物等。其中海蛇尾類棘皮動物和肋木系首次在洗馬塘組發(fā)現(xiàn)。這些化石的發(fā)現(xiàn)為研究P/T大滅絕后早三疊世生物復蘇提供了重要的材料。(3)對洗馬塘組生物地層進行了研究,識別出牙形石帶分子Isarcicella staeschei,重新厘定了雙殼化石帶,證實洗馬塘組時代屬于早三疊世印度期Gresbachian亞期,可與四川貴州等地廣泛分布的飛仙關(guān)組對比。根據(jù)碎屑鋯石U-Pb測年獲得了年齡數(shù)據(jù)為249±5Ma。(4)結(jié)合古生物學和沉積學特征,認為丘北地區(qū)洗馬塘組屬于淺海環(huán)境,離陸地較近,是P/T大滅絕及其后早三疊世全球極端環(huán)境下的一個生物避難所,屬于正常富氧環(huán)境,為當時生物的迅速復蘇提供了一個有利的場所。
[Abstract]:In this paper, the Lower Triassic Simatang formation is taken as the main research object, and the lithostratigraphy, biostratigraphy and sedimentary environment of the Qimatang formation in this area are systematically studied. The emphasis of this study is on the fossil assemblage and environmental significance of the Qimatang formation, and on the basis of this, the significance of the fossil assemblage to the early Triassic recovery after the P- / T mass extinction is discussed. This study mainly adopts the method of combining field investigation with laboratory experiments, using the theories of petrology, sedimentology and paleontology as the guidance, measuring several sections of Ximatang formation and collecting a large number of fossils. Many new discoveries and advances have been made, and the research knowledge of Ximatang formation has been improved. The main results are as follows: (1) the lithology of the Qimatang formation has been acquired through the measurement of the profile. A set of thick oolitic limestone and several layers of volcanogenic potash porphyry were found at the bottom of the Simatang formation, which modified the previous understanding of lithology description. (2) A large number of paleontological fossils, including bivalves, were found in the mudstone of the first member of the Simatang formation. Gastropods, brachiopods, phyllodes, sea serpentine echinoderms, arthropods, chrysanthemums, conodonts, fossils of unknown species, and plants. Among them, echinoderms of sea snaketail and Leymus were first found in Ximatang formation. The discovery of these fossils provides important materials for the study of early Triassic biorecovery after the P/ T mass extinction. (3) the biostratigraphy of the Ximatang formation was studied, the conodont zone molecule Isarcicella staeschei was identified, and the bivalve fossil belt was redefined. It is proved that the Simatang formation belongs to the early Triassic Indian Gresbachian substage, which can be compared with the Feixianguan formation widely distributed in Sichuan and Guizhou. According to the U-Pb dating of clastic zircon, the age data is 249 鹵5 Ma.The (4) combined with paleobiology and sedimentology, it is considered that the Qimatang formation in Qiubei area belongs to the shallow sea environment and is near to the land. It is a biological refuge in the P/ T extinction and the early Triassic global extreme environment, which belongs to the normal oxygen-enriched environment and provides a favorable place for the rapid recovery of life at that time.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：Q91;P534.51

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本文編號：2174699