Onset of Asian desertification by 22 Myr ago inferred from loess deposits in China
作者单位：Department of Environmental ScienceClark HallUniversity of VirginiaCharlottesvilleVirginia 22903USA
会议名称：《中国科学院地质与地球物理研究所2002学术年会》
会议日期：2002年
学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0818[工学-地质资源与地质工程]
关 键 词：loess desertification Tibetan Plateau Asian monsoon Miocene
摘 要：The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic *** the dating of this transition is uncertain,partly because desert sediments are usually scattered,discontinuous and difficult to *** we report nearly continuous aeolian deposits covering the interval from 22 to 6.2 million years ago,on the basis of palaeomagnetic measurements and fossil evidence.A total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish *** new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of Asia by the early Miocene epoch,at least 14 million years earlier than previously *** tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in Asia.