Late Cretaceous Aeolian Deposits In Eastern China

Along with intensification of global warming,severe desertification has already impaired human sustainable development.In the arid climate conditions,the shield and platform ergs are mainly developed in the plain basins according to the classification of modern geomorphic units.However,the research on the formation of deserts and their types in intermontane basins,another geomorphic unit,is insufficient and lacks modern examples.Based on previous studies,a large-scale basin-range system was formed in Eastern China during the Late Cretaceous,and aeolian sedimentary records were widely developed.It is still unknown whether these aeolian deposits also formed in shield and platform erg environment,or belong to coastal dunes,or represent new type of ergs.Therefore,the confirmation of its formation environment is conducive to the discussion of the evolution of deserts in the greenhouse climate,the discussion of the genetic mechanism of ergs such as wind and tectonics,and the prediction of the desertification process of the near-future greenhouse world.During the Late Cretaceous,a large number of intermountain basins were formed in the Eastern China,north of Qingling and Dabie Orogenic belt and east of Xuefeng Mountain.Through systematic geological survey,the development of seolian deposits was confirmed in Xinjiang Basin,Jianghan Basin,Subei Basin,Jurong Basin,Hengyang Basin and Chaling Basin.Based on better outcrops,this paper selected the Xinjiang Basin as a representative,combined with other five Late Cretaceous intermontane basins as the research object,processed lithofacies and sedimentary facies analysis,architecture reconstruction from the margin to the center area,and reconstructed the depositional model of these intermountain basins.At the same time,the provenance analysis of the Upper Cretaceous in the Xinjiang Basin was carried out through sandstone grain analysis,zircon morphology analysis and detrital zircon U-Pb dating.Through lithofacies and sedimentary facies analysis,and combining with the evolution regularities of the aeolian dunes,geometry of the internal beddings,as well as the vertical sedimentary packing,we confirmed that the aeolian deposits in the Eastern China formed in intermountain ergs in Late Cretaceous and reconstruct the 3D depositional model of the intermountain erg-fluvial-alluvial system.We discussed the reason and developing mechanism of these intermountain ergs from the perspective of tectonic and sedimentary geomorphology.The results of provenance analysis provided evidence for long-distance dispersal ability for winds and the interaction between aeolian and fluvial-alluvial deposits.The reconstruction of paleowind belts and paleoclimate zone reveal that in Late Cretaceous,the Eastern China was under the control of the alternating prevailing westerlies and northeast trade winds.The paleo-subtropical zone takes the Eastern China as the central zone and extends northward and southward.