| 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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| 引用本文：黄学猛,许志琴,张进江.2017.哀牢山—红河断裂带新生代构造转换及其动力学机制[J].地球学报,38(s1):7-10. |
| DOI：10.3975/cagsb.2017.s1.03 |
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| 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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| 中文摘要:哀牢山—红河断裂带位于青藏高原东南缘, 由青藏高原延入南海, 是一条分割华南地块与印支地块的构造分界线, 在地貌上也是一条醒目的分界线。纵向上由4个北西向的长条状变质带组成(雪龙山、点苍山、哀牢山和Day Nui Con Voi变质带), 长约1 200 km。横向上分高级变质带和低级变质带, 二者之间为倾向北东的哀牢山逆冲断裂带, 其中高级变质带主要由元古界高级片麻岩、混合岩、淡色花岗岩脉以及S-L型糜棱岩组成, 低级变质带主要由古生界云母片岩、板岩、千枚岩和S型初糜棱岩组成, 夹杂着条带状基性岩与超基性岩。断裂带整体往南东方向逐渐变宽。西北段面理近直立, 线理近水平, 发育近直立的紧闭褶皱, 南东段较宽, 面理变平缓, 发育宽缓褶皱, 靠近北东侧面理倾向北东, 倾角较陡。中生代时期, 该断裂带是印支地块与杨子地块俯冲碰撞边界线, 也称为金沙江—哀牢山—松马缝合带。新生代以来, 受印度板块与欧亚板块持续挤压汇聚的影响, 青藏高原东南缘发生多期逃逸, 该断裂是藏东南地块挤出逃逸的边界, 协调着印支地块与杨子地块的相对运动。新生代早期印支地块向南东逃逸, 该断裂带作为逃逸块体的北边界表现为左旋走滑; 随着印度地块的持续向北推进, 新生代晚期华南地块(川滇地块)往南东逃逸, 该断裂带作为其南边界断裂表现为右旋走滑, 兼具正断分量。哀牢山—红河断裂带新生代两期次运动与印度板块东构造结的运动轨迹、青藏高原的隆升、逃逸时序、南海的扩张皆具有密切关系。对该断裂带转换时间和机制进行研究, 不仅有利于认识该断裂的演化历史, 而且有利于认识青藏高原的隆升、南海新生代构造演化历史。此外, 对该断裂新生代构造转换的研究有利于对构造逃逸模式、均匀变形模式、旋转模式以及下地壳流模式的检验。 |
| 中文关键词:哀牢山—红河断裂带 构造转换 滇西北断陷盆地 东构造结 应力轨迹 |
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| Cenozoic Tectonic Transition and Dynamic Mechanism of the Ailao Shan–Red River Fault Zone |
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| Abstract: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. |
| keywords:Ailao Shan–Red River fault zone tectonic transition the northwestern Yunnan extensional basins system eastern Himalayan syntaxis stress trajectory |
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