从地球系统科学角度浅析中国地貌若干问题研究的新进展

SOME ASPECTS ABOUT CHINESE GEOMORPHOLOGY:RECENT PROGRESSES FROM AN EARTH SYSTEM SCIENCE PERSPECTIVE

以地球系统中各圈层的相互作用为主线,分析总结了我国沙漠地貌过程、流水地貌过程、冰川地貌过程及风沙地貌过程等领域研究的部分进展。由于我国沙漠地理位置的特殊性,其形成和演变与岩石圈构造变动即青藏高原隆升有着紧密的联系,所以,对我国沙漠形成、演变的研究能为探讨青藏高原隆升历史提供重要佐证。近30年来,有关我国沙漠形成时代的认识更新较快。新的沉积记录显示,我国西北地区的沙漠在中新世时就已经出现了,但沙漠沙丘大规模扩展可能是在中更新世才开始的。既使在晚更新世以来,我国沙漠地区的气候也有过明显波动、沙漠地貌的特征也发生过显著变化。沙漠通过为沙尘暴提供物源,对全球变化产生驱动作用。从地表过程来看,风沙地貌的形成演变不仅受风力作用,而且受流水、湖泊等多种地貌动力过程的影响,地貌类型是各种动力过程共同作用的缩影。古冰川地貌曾是最早发现的第四纪气候变化的证据。随着新的测年技术的出现,学术界对我国第四纪古冰川地貌演化过程有了较系统、全面的认识。流水地貌过程应该是地球上作用区域最广的一种地貌动力过程,对流水地貌过程的认识目前正在向微观和宏观深入。

From the perspective of interactions between various layers in the Earth System, the paper aims to review recent progresses in the fields of studies on desert geomorphology in China, fluvial processes, glacial processes as well as aeolian processes. Due to the special geographical location, the formation and evolution of Chinese deserts are closely linked with the uplifting of the Tibetan Plateau. Consequently, the research on formation and evolution of Chinese deserts would reveal significant evidence for understanding the uplifting of the Tibetan Plateau. In the last 30 years, the initial ages relating to the formation of the Chinese deserts have been updated several times. The newly studied records show that Chinese deserts have been formed already at Miocene. But the rapid extension of the dune fields in China started probably during the Middle Pleistocene. It is concluded that distinct climatic and geomorphological variations have occurred in the desert areas of China since Late Pleistocene. As the main sources of dust and sand storms, the deserts would have impacts on the forces triggering global changes. It should be emphasized that desert landforms of China undergo not only aeolian processes but also fluvial and lacustrine processes. Landforms are the final products of all dynamic processes. Glacial landforms are the firstly recognized evidence for interpreting Quaternary climate changes. As the dating techniques are being improved, scientists have now obtained a systematic and comprehensive picture about Quaternary glacial history in China. As a kind of geomorphological process, fluvial processes occur most widely on Earth. Studies on fluvial processes are being carried out nowadays in detail on various scales.