Tectonics of the North Qilian orogen, NW China
Tectonics of the North Qilian orogen, NW China
复制标题
中国西北北祁连造山带的构造
DOI：
10.1016/j.gr.2012.02.004
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发表时间：
2013-05-01
影响因子：
6.1
通讯作者：
Xia, Xiaohong
中科院分区：
文献类型：
--
作者：
Song, Shuguang;Niu, Yaoling;Xia, Xiaohong
青藏高原北缘的祁连造山带是一个典型的缝合带，记录了从新元古代到古生代从大陆裂解到洋盆演化，再到最终大陆碰撞的完整历史。祁连洋，通常被解释为代表“原特提斯洋”，实际上可能是波罗的海和劳伦西亚两块大陆之间的世界性“土卫八洋”的东部分支，由于罗迪尼亚超大陆的分裂，在≥710Ma时打开。祁连洋的俯冲可能发生在大约520Ma时，并发育了以类似的婴儿弧岩浆作用为代表的安第斯型活动大陆边缘。至 517-490 Ma。奥陶纪初期（约490 Ma），部分活动边缘从阿拉善陆块分裂出来，安第斯型活动边缘演化为约490~445 Ma弧后盆地环境中形成的MORB状地壳（即SSZ型蛇绿岩带）为代表的西太平洋型海沟-弧-弧后体系。在此期间，俯冲大洋岩石圈沿着约6-7℃/km的冷地温发生低温-高压变质作用。祁连洋在奥陶纪末（约445Ma）闭合。大陆块体开始碰撞，在大约 435-420 Ma 时，祁连-柴达木块体的北缘被下降的海洋岩石圈推挤/拖拽到阿拉善地块下方，深度约为 100-200 公里。志留世晚期和泥盆纪早期，由于俯冲地壳物质的折返，发生了强烈的造山活动。简而言之，祁连造山带在概念上是板块构造作用的典型例子，从大陆裂解到洋盆的发展和演化，到大洋俯冲的开始和弧和弧后系统的形成，再到最终的大陆碰撞/俯冲和折返。 (C) 2012 年国际冈瓦纳研究协会。由 Elsevier B.V. 出版。保留所有权利。
The Qilian Orogen at the northern margin of the Tibetan Plateau is a type suture zone that recorded a complete history from continental breakup to ocean basin evolution, and to the ultimate continental collision in the time period from the Neoproterozoic to the Paleozoic. The Qilian Ocean, often interpreted as representing the "Proto-Tethyan Ocean", may actually be an eastern branch of the worldwide "Iapetus Ocean" between the two continents of Baltica and Laurentia, opened at >= 710 Ma as a consequence of breakup of supercontinent Rodinia.Initiation of the subduction in the Qilian Ocean probably occurred at similar to 520 Ma with the development of an Andean-type active continental margin represented by infant arc magmatism of similar to 517-490 Ma. In the beginning of Ordovician (similar to 490 Ma), part of the active margin was split from the continental Alashan block and the Andean-type active margin had thus evolved to western Pacific-type trench-arc-back-arc system represented by the MORB-like crust (i.e., SSZ-type ophiolite belt) formed in a back-arc basin setting in the time period of similar to 490-445 Ma. During this time, the subducting oceanic lithosphere underwent LT-HP metamorphism along a cold geotherm of similar to 6-7 degrees C/km.The Qilian Ocean was closed at the end of the Ordovician (similar to 445 Ma). Continental blocks started to collide and the northern edge of the Qilian-Qaidam block was underthrust/dragged beneath the Alashan block by the downgoing oceanic lithosphere to depths of similar to 100-200 km at about 435-420 Ma. Intensive orogenic activities occurred in the late Silurian and early Devonian in response to the exhumation of the subducted crustal materials.Briefly, the Qilian Orogen is conceptually a type example of the workings of plate tectonics from continental breakup to the development and evolution of an ocean basin, to the initiation of oceanic subduction and formation of arc and back-arc system, and to the final continental collision/subduction and exhumation. (C) 2012 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.