Cretaceous-Eogene Desert Facies in Southern Sichuan and Northern Guizhou and Its Significance

This paper deals with Cretaceous-Eogene desert environments in southern Sichuan and northern Guizhou in terms of large amount of depositional indicators and features. It also discusses sedimentary environments, environmental evolution and their relations to palaeontology, palaeoclimate and palaeogeography based on a variety of sedimentary structures and textures in dune, sand sheet, interdune and extradune deposits as well as their geologic background. The well-sorted thick-bedded dune deposits(the maximum thickness=35m)were deposited in Cretaceous-Eogene desert environments in southern Sichuan and northern Guizhou, but the wet interdune deposits were not developed at that time, indicating a very dry climate. The ecologic environments are responsible for the early retreat of some large reptiles such as dinosaurs from the southern Sichuan-northern Guizhou area. The authous maintain in this paper that eolian sandstones in the study area not only have cerated very good hydrogeological conditions, but also may serve as a kind of industrial material of good quality. It is undoubted that the occurrence of the depositional events in Cretaceous-Eogene deserts will occupy a remarkable position in geological history of China and that the study of the events has also great significance for the division of sedimentary facies types and the interpretation of sedimentary environments in China.