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    湖南奥陶纪沉积演化特征

    Characteristics of Ordovician sedimentary evolution in Hunan Province

    • 摘要: 提要:根据湖南地区奥陶纪沉积地层的野外考察和室内分析,并总结吸收前人对该区的研究成果,将湖南奥陶纪的构造沉积演化划分成了早奥陶世镶边型碳酸盐台地-陆棚-深水盆地、中奥陶世碳酸盐缓坡-陆棚-深水盆地、晚奥陶世早期碳酸盐缓坡-陆棚-深水盆地-陆棚边缘、晚奥陶世晚期局限浅海-深水盆地-陆棚边缘4个沉积阶段。处于扬子克拉通内的湘西北地区经历了镶边型台地-碳酸盐缓坡-局限浅海的演化阶段,沉积岩性也由碳酸盐岩逐渐被黑色泥页岩沉积所替代。位于克拉通边缘及华夏陆块之上的湘中、湘南地区则始终处于碎屑浅海沉积环境,盆地中心由南东向北西不断迁移。

       

      Abstract: Abstract: Based on field survey, laboratory analysis of sedimentary strata and summarization of previous research results in Hunan Province, the authors divided the Ordovician tectonic and sedimentary evolution into four stages, i.e., rimmed carbonate platform-shelf-deep water basin in the Early Ordovician, carbonate ramp-shelf-deep basin in the Middle Ordovician, carbonate ramp-shelf-deep water basin-shelf margin at the early age of Late Ordovician, and confined shallow marine-deep water basin-shelf margin in the late period of the Late Ordovician. The northwestern Hunan in Yangtze craton experienced the evolution from the rimmed carbonate platform to carbonate ramp, and finally became a confined shallow sea, with the black shale gradually replacing carbonates in lithology. The central and southern Hunan located at the edge of the craton and the Cathaysia Block was always in a clastic shallow marine environment, and the center of the basin migrated constantly from southeast to northwest.

       

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