| 哀牢山—红河断裂带新生代构造转换及其动力学机制 |
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| 关键词:Ailao Shan–Red River fault zone tectonic transition the northwestern Yunnan extensional basins system eastern Himalayan syntaxis stress trajectory |
| 基金项目:中央级公益性科研院所基本科研业务专项(编号: ZDJ2016-18) |
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| Cenozoic Tectonic Transition and Dynamic Mechanism of the Ailao Shan–Red River Fault Zone |
| The Ailao Shan–Red River fault zone (ASRRFZ) in southeastern Tibet, which extends from the Tibet plateau to the South China Sea, is a geological and geomorphic boundary between South China block and Indochina block. This fault zone, about 1 200 km long, is longitudinally divided into the Xuelong Shan, Di-ancang Shan, Ailao Shan, and Day Nui Con Voi metamorphic massifs. This fault zone is transversely divided into the higher metamorphic belt to the northeast, the lower metamorphic belt to the south-west and reverse Ailao Shan reverse fault in between. The higher metamorphic belt is composed by Pro-terozoic gneiss, migmatite, leucogranitic veins and S-L type mylonite, while the lower metamorphic belt is composed by the Paleozoic schist, slate, phyllite, S type protomylonite and ribbons of mafic and ultrama-fic rocks. The ASRRFZ widens towards the southeast. Sub-vertical foliations and tight folds are developed in the northwestern segment of the ASRRFZ. Gently dipping foliations and wide open folds are developed in the southeastern segment of the ASRRFZ. Sub-horizontal lineations and NE-dipping high-angle foliations developed all along the fault. In the Paleo-zoic, the ASRRFZ, which is also called as the Jinsha-jiang–Ailao Shan–Songma suture zone, is the subduc-tion-collisonal boundary between the Indochina and South China block. In the Cenozoic, due to continuous convergence between the Indian and Eurasia plate, polyphase extrusion occurred in southeastern Tibet and the ASRRFZ acted as a transform fault accom-modating the relative motion between the Indochina block and the South China block. The Indochina block was extruded to the southeast during early Cenozoic and the north boundary fault of the ASRRFZ activated as left-lateral motion. With the northward indentation of the Indian plate, the South China block (locally called as Chuandian block) extruded to the southeast during late Cenozoic time, and the southern boundary fault of the ASRRFZ slipped right-laterally with some normal component. The two phase motion of the ASRRFZ is in intimate relation with the movement trajectory of the eastern Himalayan Syntaxis, uplift of the Tibetan Plateau, extrusion sequence and the open-ing of the South China Sea. Studying the tectonic transition and dynamic mechanism of the ASRRFZ is not only beneficial to the recognition of the structural evolution of the ASRRFZ, but also beneficial to the recognition of the tectonic uplift of the Tibetan pla-teau and the Cenozoic tectonic evolution of the South China Sea. Additionally, studying the tectonic transi-tion of the ASRRFZ is of great significance to the verification of the different tectonic models, such as the tectonic extrusion, diffuse deformation, tectonic rotation and lower crustal flow models. |
| HUANG Xue-meng,XU Zhi-qin,ZHANG Jin-jiang.2017.Cenozoic Tectonic Transition and Dynamic Mechanism of the Ailao Shan–Red River Fault Zone[J].Acta Geoscientica Sinica,38(s1):7-10. |
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