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《Earth Science Frontiers》 2006-06
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The Mesozoic intraplate orogeny of the Taihang Mountains and the thinning of the continental lithosphere in North China

LUO Zhao-hua, WEI Yang, XIN Hou-tian, KE Shan, LI Wen-tao, LI De-dong, HUANG Jin-xiangState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083,China  
Recently, the thinning of the continental lithosphere in the North China has become one of the main topics in modern geoscience. However, the timing and mechanism of lithosphere thinning are still poorly understood. The ambiguity of the known constraints and the apparent contradiction of the evidences used to explain the thinning processes has resulted in a somewhat poor understanding of the regional tectonic history. In this paper, the recognition of intraplate orogeny in North China is considered as a key for understanding the thinning of lithosphere, because the thinning process is initiated at the base of the lithosphere, and not the craton. Lithosphere thinning can be divided into four types: 1)delamination, 2)extension, 3)thermal thinning and 4)chemical erosion. The former is dependent on gravitational instability of the lithosphere and display a sudden change of the lithosphere thickness. The other three processes are continuous and influenced by asthenospheric upwelling. The thinning process in North China began at about 120~110 Ma and is marked by the emplacement of the post-orogenic dike swarms. The multistage convergence of the asthenosphere beneath the Asian continent induces asthenospheric extrusion eastward. These processes are the important bases of the continuous lithosphere thinning beneath Eastern China since the Meso-Cenozoic era. Therefore, one of the most important differences between the continental and oceanic geodynamics is that commonly lithosphere thinning, especially delamination is a character of subcontinental lithosphere. Based on this, the subcontinental asthenosphere can be subdivided into two subsystems: shallow contaminated and deep undepleted. The geochemical features of igneous rocks reflect the level of magma generation.
【Fund】: 国家重点基础研究发展计划“973”项目(G1998040807 2002CB412603);; 国家自然科学基金资助项目(40272033 40472038 40434010)
【CateGory Index】: P542.2
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