AN APPROACH TO THE CONTROLLING FACTORS OF THE CARBONIFEROUS GYPSUM DEPOSITS IN CENTRAL HUNAN

This paper discusses the favourable factors governing the Early Carboniferous gypsum deposits in central Hunan on the basis of the studies of palaeotectonics, palaeoclimates, palaeogeography and sedimentary facies.
The gypsum basins in central Hunan are fault basins intermediate between two rises. with a palaeolatitude of 10.7° north latitude and the palaeotemperatures ranging from 43 to 47℃ during the deposition of the late Datangian(Early Carboniferous) Zimenqiao Formation. These basins consist of three secondary-order basins separated by submarine rises, in which the salinized lagoon and sabkha-type tidal flat environments were formed due to regression. The evaporation and concentration of sea water resulted in the precipitation of gypsum. All these factors facilitate the formation of the large-scale gypsum deposits in central Hunan.