The Study On Mesozoic And Cenozoic Lithofacies Paleogeography In The South Of China And The Indochina Peninsula

Based on IHS database data,published literature and limited amount of seismic,drilling and outcrop data,and using relevant theoretical knowledge of plate tectonics,petrology,sedimentology and lithofacies paleogeography,the characteristics and evolution of Mesozoic and Cenozoic lithofacies paleogeography in the south of China and the Indochina Peninsula have been discussed in this paper.There are 223 basic tectonic units such as basins and mountain belts in the south of China and the Indochina Peninsula.These basic tectonic units can be grouped into six large tectonic stratigraphic zones: the Northern Continent and its peripheral deformation zone,the Himalayan Meso-Cenozoic deformation area,the western of Indochina Peninsula Meso-Cenozoic deformation zone,the central Indochina Peninsula Meso-Cenozoic deformation zone,the South China Sea and its peripheral Meso-Cenozoic deformation zone,Northeast Indian plate and its peripheral area.The basement of main part of the Northern Continent and its peripheral deformation zone is the pre-Sinian metamorphic rocks,on which developed the Sinian and the Paleozoic,Mesozoic and Cenozoic.The Mesozoic is a lacustrine environment dominated by clastic rocks,and the Cenozoic is developed with clastic rocks of alluvial facies.The basement of the Himalayan Meso-Cenozoic deformation area is the Precambrian metamorphic complex rocks,on which developed the Phanerozoic.The Mesozoic is a shallow sea environment dominated by clastic and carbonate rocks,and the Cenozoic is dominated by lacustrine and alluvial clastic rocks.The basement of the western of Indochina Peninsula Meso-Cenozoic deformation zone is the kimeri metamorphic complex rocks,the upper Cretaceous-Quaternary developed on it is mainly composed of shallow marine-alluvial clastic rocks.The mainly basement of the central Indochina Peninsula Meso-Cenozoic deformation zone is the Indosinian metamorphic rocks,and the Meso-Cenozoic on it is mainly composed of lacustrine-alluvial clastic rocks.The basement of the South China Sea and its peripheral Meso-Cenozoic deformation zone is the Indosinian metamorphic rocks.The Middle Triassic-Cretaceous is generally absent,and the Paleogene is composed of alluvial-lacustrine clastic rocks.The Neogene is composed of clastic rocks and carbonate rocks of shallow marine facies.The mainly basement of the Northeast Indian plate is the Precambrian metamorphic complex rocks,In Cretaceous,there are littoral and shallow marine volcanic rocks and clastic rocks.In Cenozoic,there are shallow marine-alluvial carbonate rocks and clastic rocks.There are 13 lithologic associations of paleogeographic significance in the Mesozoic and Cenozoic in the south of China and the Indochina Peninsula,represented by clastic rocks,carbonate rocks and evaporites.Eight paleogeographic environments were identified,including uplift erosion area,alluvial area,lake area,coastal shallow sea and salt marsh area,shallow sea area,semi-deep sea to deep sea area,submarine fan and island arc area.In Triassic,most of the sedimentary areas in the study area are characterized by shallow sea area with sandstone and mudstone and carbonate rocks,and island arc area dominated by volcanic rocks.In Jurassic,the area of shallow sea area decreased,mainly distributed in the Tibetan Plateau and the western of Indochina Peninsula;the area of uplift and denudation area increased,mainly distributed in the periphery of the northern continent and around the central Indochina Peninsula;the sedimentary areas of the northern continent and the central part of Indochina peninsula were mainly lake area and alluvial area.In Cretaceous and Paleogene,the uplift and denudation areas,lake area and alluvial area gradually expanded.In Neogene,the area of uplift and denudation area continued to increase,the area of lake area and alluvial area decreased,the South China Sea has formed,and the southern shallow sea area gradually expanded.The distribution and evolution of this lithofacies palaeogeography are closely related to the closure of the Paleo,Meso and Neotethys oceans and the formation of the South China Sea.