Distribution characteristics and paleo-climatic significance of continental climate-sensitive sediments in the Late Cretaceous in China

The Cretaceous is a typical period for studying the greenhouse climate and the earth system interactions, and the world's most extensive terrestrial strata are mainly in East Asia, especially in China. Continental sediments can effectively reflect the paleo-climate change, but the previous studies of the Late Cretaceous paleo-climate, based on the combined characteristics of continental climate-sensitive sediments, were barely found in China. To obtain the Late Cretaceous paleo-climate characteristics of China, the distribution characteristics of different continental climate-sensitive sediment types in the early, middle and Late Cretaceous in China were studied in detail. According to the distribution and combination characteristics and types of continental climate-sensitive sediments, seven climate types can be divided: 1) warm-humid and warm-dry climate; 2) hot and dry climate; 3) hot-dry and arid climate; 4) hot-dry and semiarid climate; 5) hot-dry and hot-wet climate; 6) hot-dry and warm-humid climate; 7) hot-dry and warm-dry climate. The results show that in the early Late Cretaceous, the hot and dry climate was the most widespread, followed by warm-humid and warm-dry climate, but the climate was drier than the paleo-climate of the previous study of Early Cretaceous. Hot and dry climate zone became wider in the Coniacian and Maastrichtian; furthermore, it covered Xinjiang to the east of China from east to west after the Santonian Period. The hot-dry and semiarid climate zone was nearly latitudinally distributed from the northwest to the southeast and it shows a further increase in aridification. Global geological events, paleogeographic features and regional tectonic evolution had significant impacts on the paleoclimate of China in the Late Cretaceous, such as global eruptive events of volcanoes led to the temperature increase in China in the early Late Cretaceous; coastal mountain ranges in southeastern China led to the drying of the Late Cretaceous climate in southern China; Xuefeng Mountains, Wuling Mountains, Nanling Mountains and Tai-hang Mountains were the dividing line between the hot and dry climate zone and hot-dry and arid climate zone in the early Late Cretaceous, and Altun Mountains were the dividing line between the southeastern section of the hot and dry climate zone in western China in the middle Late Cretaceous.