The Eogene Surface Texture of Quartz Sand and PaleoclimaticChange in Northern Margin of Tibetan Plateau

Key words: 
• surface texture of quartz sand /
• paleoclimatic /
• Eogene /
• Northern Margin of Tibet Plateau

Abstract: The start time of the Asian interior aridification and East Asian monsoon is a research hotspot. The quartz sand grains which are taken from the Eogene red sandstones in the northern margin of Tibet Plateau were examined under Electronic Scanning Microscope for their external morphological characteristics in the paper. The result shows that the samples almost have the texture of subaqueous polished surface and Vshape impact pits which is the typical feature of hydraulic action, and it is obviously different with the quartz sands from modern sand dunes of Taklimakan and northern margin of Altun Mountain. Also, the variations of the grain size indicate the Eogene red sandstones are different from the loess and modern sand dunes. To combine the sedimentary characteristics, we conclude that it does not widely present aeolian sediments in the northern margin of Tibet Plateau, and the Asian interior aridification and East Asian monsoon not started during the Eeogene. The aridity of Western China may be controlled by the planet wind system and global cooling during Eogene.