Geochemistry of the dolomite from Dengying Formation in Xichuan, southwest Henan Province:Implications for paleoenvironment

The Qinling orogen has been an active geological unit since Proterozoic, of which the study about its origin and evolution has been a hot issue in geology for a long time.In this paper, we presented the trace and rare earth geochemical data from the dolomite of Neoproterozoic, the Dengying Formation, in the Huwo section of Xichuan area.Field work shows that the Dengying Formation mainly consists of dolomite, and can be divided into three sedimentary facies, i.e.the subtidal slope zone, intertidal zone and supratidal flat.Geochemical data indicate that the dolomite in Dengying Formation was mainly formed in a marine environment of high salinity, under hot climate and low latitudes.The Dengying Formation started from deep-water and reduction environment then changed into shallow-water and weak oxidation environment and finally exposed, showing agenerally process of regression.