Sequences and lithofacies paleogeographic features of the eastern Guizhou province,western Hunan province,and northern Guangxi Zhuang autonomous region during the Nanhua Period
A set of wedge-shaped strata overlying the Xuefeng tectonic interface deposited in a cold climate during the Nanhua Period has been developed in eastern Guizhou province,western Hunan province,and northern Guangxi Zhuang autonomous region.These wedge-shaped strata distribute along the rift basins of Hunan,Guizhou,and Guangxi,crossing the southeastern edge of the Upper Yangtze Block and the southwestern segment of the Jiangnan Orogenic Belt.The scope and distribution characteristics of paleoshoreline changes,paleocurrent directions,and paleogeographic features were inferred via comparative studies of typical lithofacies stratigraphic sections at different locations within the region as well as conducting research on depositional facies and micro-facies.This research reconstructs the lithofacies paleogeography and sedimentary models of the basin evolution at different stages.Lithofacies paleogeographic features indicate that the study area is in a rift cover deposition period during the Nanhua Period,with basin filling evolution divided into three stages:uplift and erosion with early glacial till deposition,interglacial filling stage,and late gla-cial till deposition stage.The Nanhua glaciation(Chang'an and Nantuo glaciations)involves glacial,preglacial,and postglacial grav-ity flow deposits.The interglacial period,especially the Fulu interglacial,is dominated by fluvial,lagoon,and deltaic deposits,with the development of manganese-bearing clastic rock deposits.This research provides new fundamental data for studying the rift basin filling evolution,lithofacies paleogeographic features,and mineralization effects in the Hunan-Guizhou-Guangxi rift basin and also sheds some light on the stratigraphic understanding,mineral exploration,and the tectonic geological background study of its formation.
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