湖南区域地质研究的新进展

    NEW PROGRESS IN THE STUDY OF THE REGIONAL GEOLOGY OF HUNAN

    • 摘要: 湖南省地跨新华夏系第二沉降带和第三隆起带,处在杨子和华南两个全国一级地层区内,是华南成矿区的重要组成部分,地层发育较全,沉积类型多样,岩浆活动频繁,地质构造复杂,成矿条件优越,矿产资源丰富,因而历来为地质界所瞩目。早在本世纪二十年代,我国地质界先辈即开始对湖南进行地质矿产调查,取得不少成果。新中国建立后,地质事业得到全面发展,获得丰硕成果。自1956年开始,湖南区调队开展了全省范围的区域地质调查工作,经过三十年的不懈努力,对省内的地层、沉积岩、岩浆岩、地质构造等有

       

      Abstract: This paper briefly elucidates the main fruitful results and understandings gained in the study of the regional geology of Hunan province in the past thirty years and presents the current research level of basic geology and geological sciences. In the aspect of stratigraphy, the paper gives a summary of four major stages of deposition and their general regularities, and introduces the significant advances in the study of the stratigraphic paleontology in the Yangtze and South China regions and the transional region between them (which are stratigraphically of nationwide order). In the aspect of magmatic rocks, six magmatic periods are established: Wulingian, Xuefengian, Caledoni- an, Indosinian, Yanshanian and Himalayan, and it is pointed out that all the intrusions are characterized by composite intrusions and contemporaneous polyphase and multiple intrusions. According to the sources of rock-forming material, granites in Hunan may be divided into two genetic types, the crust- derived anatectic type and the crust-mantle-derived transitional type. The paper summarizes the evolutionary regularity of the composite intrusions and contemporaneous multiple intrusions. The spatial and temporal distribution of the magmatic activity has a general tendency of southeast-directed migration. A comparison is made between the main characteristics of the two types of granite. In the aspect of geological structures, it is pointed out that the deve- lopment of the regional geological structures in Hunan progressed through three phases: the pre-Devonian activity, late Paleozoic stability and Meso- Cenozoic substability. The paper discusses the mode and direction of the cru- stal movements in Hunan, which are dominated by N-Sand E-Wdirected compression or shear. The crustal movements are characterized by nonisotasy, migration of the continental-crustal evolution and superposition of structures that occurred since the Mesozoic. Besides, the paper also analyses the impo- rtant controlling effect of the Jiangnania on the process of development of the geological structures of Hunan, and discusses the controlling effect of the crustal movements and major structural systems on rock and ore formation, earthquakes and geotherms.

       

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