西昆仑康西瓦断裂带西延特征及其构造意义

青藏高原西北部康西瓦走滑断裂带(Karakax fault)为一条经过长期演化且现今仍在活动的重要大型断裂带,该断裂对该地区形成演化起到至关重要的控制作用。目前大多学者们认为该断裂在东段沿喀拉喀什河谷大致呈东西走向延伸,后在其西段麻扎地区向北西方向延伸。然而,通过详细的野外地质调查在该断裂带西段的麻扎地区新发现了一条NEE-SWW向的断裂,将之命名为麻塔断裂。实测地质剖面和显微构造分析发现麻塔断裂与康西瓦断裂具有相似的几何学和运动学特征,同样经历了早期右旋逆冲的韧性走滑变形和后期左旋脆性走滑变形,理应划分为一条断裂,前者是后者自麻扎向西的延伸部分。麻塔-康西瓦断裂共同参与调节了自古生代以来板块碰撞拼合在青藏高原西北部的构造变形,现今西昆仑-帕米尔地区的构造地貌格局正是康西瓦和喀喇昆仑等大型断裂新生代活动而形成的。

The characteristics and tectonic implications of the western extension of the Karakax fault, West Kunlun

The Karakax strike-slip fault, located in the northwestern Tibet, is a long-lived evolution deformation belt, which is still active at present and plays an important role in controlling the evolution of this area. Most geologists suggest that the Karakax fault is generally east-west striking along the Karakax river valley, and northwest striking until to the Tashkorgan in the Mazar area. However, via the detailed field geological survey, an ENE-WSW fault, which named as the Matar fault, is identified at the Mazar area. Based on the measuring geological sections and analyzing microscopic structures, the similar geometry and kinematic characteristics were existed between the Karakax and Matar faults. Both the two faults have undergone the right-lateral and thrust ductile deformation in the early stage, and turned to left-lateral brittle deformation in the later stage. The Matar fault and the Karakax fault should belong to the same fault system, and the former is the westward extension of the latter. Both the two faults adjusted together the tectonic deformation of the northwestern Tibetan Plateau caused by the plate collision since Paleozoic, and the geomorphology characteristics of the West Kunlun-Pamir area were formed by the strong activity of the Karakax fault and the Karakarum fault and so on in Cenozoic.