The desert deposits as a kind of unusual deposits developed under specific climatic conditions in the geologic history play a particular role in the approaches to global climatic changes and atmospheric circulation patterns. Numerous studies show that although gypsum and other salt deposits indicating xerothermal climates once occurred over a wide area of the eastern margin of the Qinghai-Xizang Plateau within the arid zone prior to the establishment of the modern Eastern Asian monsoon systems, especially during the early - middle Palaeogene, the presence or absence of deserts remain to be uncertain up to now. The recent results obtained in the research of the early - middle Palaeogene red strata in the sedimentary basins on the eastern margin of the Qinghai-Xizang Plateau with the aid of the integration of sedimentology, palaeoclimatology and palaeogeography have disclosed that there was indeed an enrichment zone of aeolian dunes with stable thickness on the eastern margin of the Qinghai-Xizang Plateau during the early - middle Palaeogene. This implies that the basin-range type desert depositional systems might be present in the study area during the Palaeogene on the basis of palaeogeographic and sedimentary model and palaeoclimatic proxy index analysis. The sedimentary facies and palaeocurrent analysis indicates that the presence of a transitional boundary from arid to humid and from planetary wind circulation to monsoon circulation in the study area may mark the occurrence of Eastern Asian monsoon events. For this reason,the results of research in the present paper may provide not only new sedimentological data for the approaches to the evolution of the Cenozoic arid zones in China and global climatic changes but also significant atmospheric circulation evidence for the uplift of the Qinghai-Xizang Plateau and the origin of the Eastern Asian monsoons.%沙漠沉积是地质历史演化过程中的一种特殊沉积,是特殊气候条件下的产物,对研究全球气候变化、大气环流样式具有独特的作用.沙漠沉积在地质历史中普遍存在但极少保存,它的发现和研究对恢复地质历史具有重要意义.研究表明,现代东亚季风系统建立前,尤其是古近纪早、中期,青藏高原东缘仍然处于行星环流所控制的干旱带内,发育了大量代表干旱炎热气候的石膏与盐类沉积,但至今尚未找到沙漠存在的确切记录.近年来,笔者采用沉积学、古气候学、古地理学等手段,并结合前人研究资料,对青藏高原东缘沉积盆地的古近纪早、中期红色地层进行了综合研究.结果表明,青藏高原东缘存在一个厚度稳定的古近纪早、中期风成沙丘富集带.在此基础上,通过古地理、沉积模式及古气候替代指标等分析,论证了青藏高原东缘存在古近纪盆山型沙漠沉积体系的可能性.沉积相、古流向分析揭示,青藏高原东缘存在一个由于旱向潮湿、由行星风系向季风风系转换的界面,可能暗示了东亚季风建立事件的发生.本研究相关成果可为新生代中国干旱带演化与全球气候变化研究提供可贵的沉积学资料,也可为青藏高原隆升与东亚季风起源研究提供重要的大气环流证据.
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