摘要
鲜水河断裂作为协调藏东地区高原物质挤出的边界断裂,在青藏高原构造演化中起着很重要的作用。近年来对其几何学运动学的研究表明断裂在南缘发生构造转换,形成小江地区的盆岭地貌;在西北端可能与风火山逆冲推覆构造相连。断裂具有分散变形和围绕东构造结旋转的特征。其年代学研究揭示断裂可能有两期活动,(15~13)Ma左右断裂开始做左旋走滑活动,但其活动范围可能局限在龙门山逆冲推覆构造带后缘;在5Ma左右,断裂重新活动并切穿了龙门山断裂延伸到小江断裂带。造成断裂分期活动的原因是藏东地区下地壳流体的存在。断裂形成的机制可能是由于晚中新世以来下地壳流体向藏东地区扩散,引起藏东地区地壳的增厚和高原的隆升,当高原隆升到一定高度,周缘块体无法继续承担高原隆升造成的压力时,高原物质向周缘挤出时产生的。
The Xianshuihe fracture zone plays an important role in the evolutionary history of the Qinghai-Tibet Plateau.The recent study indicates that structural transposition at the southern end of the fracture zone resulted in basin and range landform,while the northwest end of the fracture zone linked up with the Fenghuoshan thrust structure.The faulting might take place during about 13-15 Ma ago when the faulting was characterized by left-lateral strike-slip and during about 5 Ma when the faulting cut off the Longmenshan fracture zone and extended to the Xiaojiang fracture zone.The faulting might be attributed to the ascending lower crust-derived fluids after the Late Miocene epoch.
出处
《四川地质学报》
2009年第S2期65-69,共5页
Acta Geologica Sichuan
关键词
鲜水河断裂
藏东高原
构造演化
下地壳流体
Xianshuihe fracture zone
east Tibet Plateau
tectonic evolution
lower crust-derived fluids
