康西瓦断裂带晚新生代构造地貌特征及其构造意义

文章详细调查了康西瓦断裂带发育的断层崖、断层陡坎、地震破裂带、错断山脊、拉分盆地、挤压脊、偏心洪积扇、错断水系等新构造运动形迹，这些新构造运动形迹表明了康西瓦断裂带在晚新生代以来发生了强烈的左旋走滑运动，并兼有正滑运动分量。数字地形高程模型(DEM)分析表明康西瓦断裂西端终止于塔什库尔干谷地东部的瓦恰河谷内，东端与著名的阿尔金断裂带相连。如果以喀拉喀什河和玉龙喀什河为参照系，康西瓦断裂晚新生代以来的左旋走滑累积位移量可达 80～85km，根据断裂带 8～12mm/a的长期走滑速率，推测康西瓦断裂带新生代以来的左旋走滑运动开始于约10Ma。结合我们获得的断裂带两侧岩浆岩的年龄，表明康西瓦断裂带左旋走滑运动的开始时代为晚中新世，现今康西瓦地区的构造地貌格局很可能是中新世晚期以来强烈的左旋走滑运动形成的。

LATE CENOZOIC TECTONO­GEOMORPHIC FEATURES OF THE KANGXIWAR FAULT ZONE|NORTHWESTERN TIBETAN PLATEAU|AND ITS ECTONIC IMPLICATION

The Kangxiwar(Karakax)Fault Zone，extending over 700kms on the northwestern margin of the Tibetan Plateau，is a boundary fault that separated Tianshuihai terrane and West Kunlun terrane. Previous studies show that the Kangxiwar Fault Zone is a fault with an active history from Late Cenozoic. In this paper we reported our systematical investigation of fault scarp，shutter ridge，pull­apart basin and pressure ridge，eccentric alluvial and diluvial fan，systematic offset streams and surface rupture Zone produced by neotectonic movements along the Kangxiwar Fault Zone. These neotectono­geomorphic features demonstrate left­lateral strike­slip movements with normal slip component of this fault occurred since Late Cenozoic. We estimate that the Kangxiwar Fault probably began left­lateral faulting at ca.10Ma based on a total minimum displacement of 80～85km，and assuming a constant long­term slip rate of ca.10mm/a in the past several millions years. Previous isotopic age of magmatic activity along this fault indicated an extensive movement initiated at 8～10Ma，and there is close relationship between the formation of tectono­geomorphic pattern and the left­lateral movement of the Kangxiwar Fault Zone since Late Miocene. In addition，according to Digital Elevation Model(DEM)of the Northern Tibetan Plateau，we suggest that the Kangxiwar Fault Zone terminated at Wuqa Valley near Tashkorgan Basin in the west end and connected to the Altyn Tagh Fault Zone in the east end.