| 中国西南特提斯构造演化—幔柱构造控制 |
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| 关键词:Tethys in southwestern China Tethys orogenic belt plume tectonics |
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| Tectonic Evolution of the Tethys in Southwestern China:Is Controlled by Plume Tectonics |
| our plate suture zones and five diverse blocks bounded by these suture zones have been recognized in the Tethys domain in Sanjiang, China. These suture zones are Ganzi-Litang, Jinshajiang-Ailaoshan, Lancangjiang and Yarlung Zangbo suture zones, while the blocks are Zhongza,Qamdo-Simao, Baoshan(Qiangtang)and Lhasa blocks, cross the Tethyan Region in S. W. China. The relics ophiolites, ophiolitic melanges, abyssal sediments and high-pressure metamorphic rocks developed along these suture zones. Volcano arc or/and magma arc usually coupled with suture zone, and constitute trench-arc-basin system. The new geological data in the paper indicate that paleo-Tethys Ocean opened in Devout an-Carboniferous period to form the Lancangjiang and Jinshajiang-Ailaoshan oceanic branches in both sides of Qamdo-Simao central continent, located between Gondwana and Lauasian Lands. The two ocean slabs became to subduct forward underneath Qamdo-Simao continent (block) since Late Permian, and resulted in formation of Tuobajinghong arc-basin system and Jiangda-Luchun arc-basin system developed along southern and northern margins of the central continent, respectively. Corresponding to the subductions and closure of the two oceanic branches, the meso-Tethys became to deveolp since Triassic period. the Ganzi-Litang oceanic basin opened during Late Permian-Late Triassic, and resulted in drifting of the Zhongza block from Yangtze continent. The Yarlung Zangbo ocean and Nujiang oceanic basin opened at the end of Late Triassic and the Lhasa and Qiangtang bolcks left from northern margin of Gondwana Land. Both the Litang and Yarlung Zangbo oceanic slabs subducted forward Qamdo-Simao central continent in Late Triassic and Jurassic-Cretaceous, respectively, corresponding to the closure of both the oceans. The Triassic Yidun island-arc and Gangdise magmatic arc developed in eastern side of the Jinshajiang suture zone and southern side of Lancangjiang suture, respectively.The lithosphere evolution of the Tethys in Southwestern China seems to be complained by the plume tectonics model. The model emphasis that a huge cold plume occurred underneath the Qamdo-Simao central continent since Early Permian and two hot plumes from deeper mantle appeared in northern margin of the Gondwana Land in Late Triassic(Renuion Plume)and southern Inargin of the Yangtze continent in Late Permian(Emei Plume). The Reunion Plume resulted in the development of the Deccan flood basalt probing and breakup of the Seychells block from mainland india in Late Cretaceous(Whit and McKenzie, 1989), and probably supplied a huge driving force for the opening of the Yarlung Zangbo ocean at end of Triassic. The Emei Plume resulted in formation of the Emeishan food basalt province in Late Permian(Lu, 1996) and opening of the Litang ocean in Triassic. The cold plume underneath QalndthSimao central continent occurred in Permian period probably is located in the Vietnam downwelling center (Iodine, 1989), based on available paleo-magnetic data and seismic tomograpy in Southwestern China and dating ages of colliding granites along northeastern side of the Lancangjiang suture zone. The cold plume resulted in Subduction in early paired of two branches of the paleo-Tethys Ocean forward underneath Qamdo-Simao continent and drifting of the blocks from the margins of the Gondwana Land and Yangtze continent to the Qamdo-Simao central continent. |
| HOU Zeng-qian,LU Ji-ren,LI Hong-yang,WANG Deng-hong,LÜ Qing-tian.1996.Tectonic Evolution of the Tethys in Southwestern China:Is Controlled by Plume Tectonics[J].Acta Geoscientica Sinica,17(4):439-453. |
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