The Discovery of Cretaceous Eolian Deposits at the Eastern Margin of the Hengyang Basin, Hunan, and Its Paleoenvironmental Significance

Key words: 
• eolian deposit /
• paleoclimate /
• Cretaceous /
• Honghuatao Formation /
• Hengyang Basin

Abstract: This is the first report of Upper Cretaceous eolian deposits in the Honghuatao Formation at the eastern mar-gin of the Hengyang Basin in central southern Hunan,providing a new understanding of the paleogeographic environ-ment of this area in the Upper Cretaceous. The Honghuatao Formation comprises a set of medium to fine-grained ma-genta feldspar quartz sandstone and lithic quartz sandstone. Large plates,wedge-shaped staggered bedding,bi-direc-tional staggered bedding,parallel bedding and ventifacts are common,all indicating an eolian desert environment. Optical microscope examination shows that suspended components such as mud and mica are absent,and dish-shaped pits,crescent-shaped craters,and upturned (flat) jointed particles are visible under the electron microscope. Comprehensive analysis confirmed that the sandstone is an eolian deposit,which has important paleoenvironmental significance. The discovery indicates that the climate was dry and hot;desertification and saline lakes were obvious, and food shortage might have led to the migration of dinosaurs in the Hengyang Basin. The dip characteristics of the foreset laminae of sand dunes has enabled the characteristics of surface wind belts in Hunan province to be restored, which provides a new basis for supporting the connection between the Hengyang Basin and its surrounding red basins. The discovery provides valuable material for the study of eolian deposition in Hunan province.