Closure of the Proto-Tethys Ocean and Early Paleozoic amalgamation of microcontinental blocks in East Asia
Closure of the Proto-Tethys Ocean and Early Paleozoic amalgamation of microcontinental blocks in East Asia
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DOI：
10.1016/j.earscirev.2017.01.011
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发表时间：
2017-01
影响因子：
12.1
通讯作者：
San-zhong Li;Shujuan Zhao;Xin Liu;Huawen Cao;Shan Yu;Xiyao Li;I. Somerville;Sheng‐yao Yu;
中科院分区：
文献类型：
--
作者：
San-zhong Li;Shujuan Zhao;Xin Liu;Huawen Cao;Shan Yu;Xiyao Li;I. Somerville;Sheng‐yao Yu;
原特提斯洋是位于塔里木-华北和四布马苏/宝山地块之间的一个复杂的古海洋，它是在罗迪尼亚超大陆裂陷后打开的，主要闭合于早古生代末期。已知的研究表明，在原特提斯海洋中有许多大陆和/或微大陆。在原特提斯洋闭合和这些大陆/微大陆组合期间，东亚发育了一些与冈瓦纳早古生代造山带相似的早古生代蛇绿岩和HP-UHP变质岩。然而，对于原特提斯洋的边界以及这些大陆/微大陆与北方的塔里木-华北大陆的性质、关系和组合过程，学界仍存在一些争论。这些问题对于揭示和重建原特提斯洋闭合前的构造过程和超大陆盘古大陆的初始组合具有重要意义。毫不奇怪，原特提斯构造域以复杂的海陆构造、大陆的组合和分散为特征，从罗迪尼亚超大陆的裂谷和漂移到泛大陆超大陆的组合。因此，本文主要从野外地质、构造地质、岩浆作用、沉积地层、地球化学记录、年代学和层析成像等方面对原特提斯构造域北部进行总结和探讨，以期揭示三个关键方面：1)确定原特提斯洋南北边界；2)在原特提斯洋及其洋陆格局中建立大陆/微大陆的亲缘关系；3)厘清了微大陆组合的时间序列和样式以及原特提斯洋的闭合。综合分析结果表明，该区北部以古罗南-栾川缝合带（或宽平缝合带）及其向西昆仑的延伸为界；南界以龙木-双湖-长宁-孟连缝合带为界。原特提斯洋以北的塔里木-阿拉斯加州-华北地块具有向南俯冲的极性，在早泥盆世与冈瓦纳板块北缘发生碰撞。原特提斯洋的南支可能关闭，使得包括羌塘北部、若尔盖、扬子和华夏、布里亚-佳木斯和印度支那地块在内的大华南地块在早泥盆世向南俯冲并增生到冈瓦纳北缘。华北地块与冈瓦纳没有明显的亲缘关系，而其他陆块/微陆块如扬子、华夏、塔里木、柴达木、阿拉克斯、北秦岭、祁连、欧龙布鲁克、南羌塘、拉萨、兰坪-思茅和印度支那在早古生代早期均与冈瓦纳有亲缘关系。在480-400 Ma间断期，这些大陆块体/微大陆块体逐渐向南俯冲并增生到冈瓦纳大陆北缘东段，导致原特提斯洋的关闭和原泛大陆的形成。380 Ma以来，大华南地块和塔里木—华北地块从原盘古大陆的大冈瓦纳板块分离漂移，形成了古特提斯洋壳和绵略洋壳。经过这次小的调整，直到240-220 Ma，他们逐渐向北聚集，形成了月桂岛。
As a complex paleo-ocean located between the Tarim-North China and the Sibumasu/Baoshan blocks, the Proto-Tethys Ocean was opened from the rifting of the Supercontinent Rodinia and mainly closed at the end of the Early Paleozoic. The known studies suggest that there were many continents and/or micro-continents in the Proto-Tethys Ocean. During closure of the Proto-Tethys Ocean and assembly of these continents/micro-continents, some Early Paleozoic ophiolites and HP-UHP metamorphic rocks developed in East Asia similar to those Early Paleozoic orogens in Gondwana. However, some academic debates still remain on the boundaries of the Proto-Tethys Ocean and the nature, relationships and assembly processes of these continents/micro-continents to the Tarim-North China Continent to the north. These problems are important for revealing and reconstructing tectonic processes before the closure of the Proto-Tethys Ocean and the initial assembly of the Supercontinent Pangea. Not surprisingly, the Proto-Tethys tectonic domain is characterized by complex ocean-continent configurations, assemblies and dispersals of continents, from the rifting and drifting of the Supercontinent Rodinia to the assembly of the Supercontinent Pangea. Therefore, this paper mainly focuses on summarizing and discussing the northern part of the Proto-Tethys tectonic domain based on field geology, structural geology, magmatism, sedimentary formations, geochemical records, geochronology and tomography, in order to reveal three key aspects: 1) identifying the southern and northern boundaries of the Proto-Tethys Ocean; 2) establishing affinities of continents/micro-continents within the Proto-Tethys Ocean and its ocean-continent configuration; and 3) clarifying the temporal sequence and styles of micro-continental assembly and the closure of the Proto-Tethys Ocean. Integrated analysis results show that to the north the region is bounded by the paleo-Luonan-Luanchuan Suture (or Kuanping Suture) and its extension to West Kunlun; the southern boundary is marked by the Longmu Co-Shuanghu-Changning-Menglian Suture. The Tarim-Alax-North China Block to the north of the Proto-Tethys Ocean had a southward subduction polarity and collided with Gondwana along the northern margin of Gondwana in the Early Devonian. The southern branch of the Proto-Tethys Ocean may be closed, making the Greater South China Block, including the northern Qiangtang, Ruoergai, Yangtze and Cathaysia, Bureya-Jiamusi and Indochina blocks, southward subduction and accretion to the northern margin of Gondwana in the Early Devonian. The results also show that the North China Block had no clear affinity to Gondwana, whereas the other continental/micro-continental blocks, such as the Yangtze, Cathaysia, Tarim, Qaidam, Alax, North Qinling, Qilian, Oulongbuluke, South Qiangtang, Lhasa, Lanping-Simao and Indochina all have an affinity to Gondwana in the earlier part of the Early Paleozoic. During the interval 480–400 Ma these series of continental blocks/micro-continental blocks experienced gradual southward subduction and accretion to the eastern segment of the northern margin of Gondwana, resulting in the closure of the Proto-Tethys Ocean and formation of the supercontinent called Proto-Pangea. The Greater South China Block and the Tarim-North China Block separated and drifted from Greater Gondwana of the Supercontinent Proto-Pangea since 380 Ma, resulting in the formation of the Paleo-Tethys and the Mianlue oceanic crusts. After this minor adjustment and until 240–220 Ma, they assembled northward gradually to develop Laurasia, which in …