Preliminary Approach on the Stratabound Lead—Zinc Deposits and Lithofacies Palaeogeographic Framework of the Dengyingxia Age, Sinian(Edicarian),in Western Hunan—Western Hubei Area

Based on field investigations, the sedimentary characteristics and horizontal correlation as well as two types of facies-changing surfaces and two types of diachronisms of the upper Sinian(Edicarian) for more than dozen main logged sections in the study area are comprehensively studied in this paper, all of them become the basis to establish the lithofacies palaeogeographic map of the Dengyingxia Ages of Sinian System in the light of dominant facies and in the way to make stratigraphic map. The feature of paleogeographical framework was that the southern formed in shallow water and the northern in deep water; the difference in lithology, color, grain type of the stratigraphic sediment-styles and the assemblages and the character of sediment-facies were all controlled by the sedimentary facies-changed and diachronism. Vertically, the stratigraphic succession from the dolomite of the Dengying Formation makes up of a larger scale upward-shoaling succession of sedimentary facies and demonstrates a growth process of the ramp carbonate platform. Horizontally, the principal lithofacies palaeogeographic units in the upper Yangtze region,i. e.carbonate tidal flat,subtidal facies of restricted platform and platform marginal facies as well as basin facies from the northern to the southern have been described. The stratabound lead—zinc deposits distributing between platform marginal facies and subtidal facies of restricted carbonate platform were dominated by the lithofacies palaeogeographic framework.