The reconstruction of Paleogene wind direction and general atmospheric circulation style in Sichuan Basin, Southwestern China

A large amount of desert sediments were developed during the Cretaceous and Paleogene in Sichuan Basin which are valuable evidence for the wind direction and general atmospheric circulation style reconstruction. Based on measuring the foreset bedding dip directions of the large scale eolian dunes in the Paleogene Liujia Formation in Sichuan Basin, palaeolatitude, paleo-orientation and general atmospheric circulation model, the palaeowind direction and general atmospheric circulation style have been reconstructed in this paper. It is resulted that the Paleogene Sichuan Basin was prevailing westerlies and controlled by westerly belt. By integrating the existed results, it can be revealed that Sichuan Basin was controlled by north-east trade belt at first and later by westerly belt during the Cretaceous which was inherited from that of the Cretaceous during the Paleogene and the transformation of general atmospheric circulation style was occurred at about the middle Late Cretaceous. Meanwhile, it can be deduced that the eastern Asian monsoon system had not been founded and the planetary circulation was still controlling wind system over Sichuan Basin at least when the studied horizon was depositing.