扬子西缘新元古代冰川启动时间、期次及其构造—岩相古地理演化

发布时间：2018-03-31 14:47

本文选题：扬子西缘　切入点：新元古代冰川　出处：《中国地质大学(北京)》2016年博士论文

【摘要】：华南扬子古大陆存在两期新元古代全球性冰川和一期间冰期记录,依次为江口冰期(Sturtian)(ca.715-660Ma)、富禄间冰期(ca.660M-651Ma)和南沱冰期(Marinoan)(ca.651-635Ma)。扬子西缘康滇地区自1940年发现新元古代冰川记录以来一直与南沱冰期沉积南沱组相对比,因而认为缺失江口冰期和富禄间冰期记录。本文采用锆石U-Pb定年手段,对扬子西缘冰川启动时间与期次进行了制约。结果表明,扬子西缘新元古代冰川启动时间约为715Ma,与华南扬子古大陆江口冰期乃至国际上Sturtian冰期启动时间一致,存在江口冰期沉积记录。沉积特征与旋回对比分析表明,扬子西缘新元古代冰川沉积地层“南沱组”和列古六组下段可与江口冰期的江口群和长安组相对比,而“南沱组”和列古六组上段则可与间冰期富禄组、大塘坡组相对比。新的地层划分对比方案改变了近一个世纪以来形成的传统认识,对华南扬子古大陆重建具有深远的意义。“构造-岩相古地理图”是古大陆再造研究成果的载体和最理想的表达形式。本文在广泛收集、分析前人实测剖面的基础上,系统观察、研究了扬子西缘新元古代冰期、间冰期沉积特征和时空分布,参照现代大陆冰川沉积模式,引进了大陆冰盖、雪线、陆相冰缘、海相冰缘等地理学概念,建立了相应的构造模型和充填模式,编制了扬子西缘新元古代冰期、间冰期构造-岩相古地理图,重建了当时的构造-古地理演化史。本文的构造-岩相古地理演化研究成果对华南扬子古大陆构造-古地理演化和成矿背景研究具有重要的科学价值。
[Abstract]:There are two Neoproterozoic global glaciers and one interglacial record in the Yangtze ancient continent in South China. The order of order is Sturtianzao (715-660 Ma), Fulu interglacial (660M-651MaA) and Nantuo glacial (Marinoanzao. 651-635 Ma1). Since the discovery of the records of Neoproterozoic glaciers in Kangdian area, the western margin of Yangtze River, it has been contrasted with the Nantuo formation in the Nantuo glacial epoch since 1940, when the records of Neoproterozoic glaciers were discovered in Kangdian area. In this paper, zircon U-Pb dating method is used to restrict the onset time and duration of glaciers in the western margin of Yangtze River. The initiation time of Neoproterozoic glacier in the western margin of Yangtze is about 715Ma. it is consistent with the initiation time of Jiangkou glacial period and Sturtian glacial epoch in south China, and there are sedimentary records in Jiangkou glacial epoch. The lower member of Neoproterozoic glacial sedimentary strata "Nantuo formation" and Liegu formation can be compared with Jiangkou Group and Changan formation of Jiangkou glacial epoch, while "Nantuo formation" and upper member of Liegu formation can be compared with interglacial Fulu formation. Datangpo formation correlation. The new stratigraphic division and correlation scheme has changed the traditional understanding formed in the past century. The tectonic-lithofacies paleogeographic map is the carrier and the most ideal expression form of the paleocontinent reengineering research. Based on the extensive collection and analysis of the previous measured profiles, this paper makes a systematic observation. The sedimentary characteristics and temporal and spatial distribution of Neoproterozoic and interglacial epoch in the western margin of Yangtze were studied. The concepts of continental ice sheet, snow line, continental ice margin and marine ice margin were introduced according to the modern continental glacial deposition model. The corresponding structural model and filling model were established and the Neoproterozoic glacial and interglacial tectonic-lithofacies paleogeography maps of the western margin of Yangtze were compiled. The research results of tectonic-lithofacies paleogeography evolution are of great scientific value to the study of tectonic-paleogeographic evolution and metallogenic background in Yangtze, South China.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P531;P534.3

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