喀喇昆仑断裂带走滑过程中伴随的快速隆升作用：热年代学证据  

Rapid uplifting in the process of strike-slip along the Karakorum fault zone in western Tibet:Evidence from ^(40)Ar/^(39)Ar thermochronology.

作　　者：李海兵[1,2] VALLI Franck ARNAUD Nicolas 陈松永[1] 许志琴[1] TAPPONNIER Paul LACASSIN Robin 司家亮[1] 邱祝礼[1] 

机构地区：[1]国土资源部大陆动力学重点实验室中国地质科学院地质研究所,北京100037 [2]Institut de Physique du Globe de Paris, 75252 Paris CX05, France [3]ISTEEM-USTL, PLace Eugene Bataillon, 34095, Montpellier CX5, France

出　　处：《岩石学报》2008年第7期1552-1566,共15页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40572122);中国地质调查局地质调查工作项目(1212010610105)资助

摘　　要：喀喇昆仑断裂带是青藏高原西部的一条大型右旋走滑断裂带,它是喜马拉雅山脉西段北侧重要的地质边界。本文在岩石学、变形构造的研究基础上,对喀喇昆仑断裂带东南段阿伊拉日居山—噶尔盆地地区的喀喇昆仑韧性剪切带中变质岩石的同构造矿物进行了^(40)Ar/^(39)Ar热年代学研究。显微构造研究表明,剪切带中的矿物记录了从高温(>600℃)到低温(<250℃)条件下的连续变形,表现为近水平的右旋剪切运动转变成斜向的右旋正滑,使绿片岩相的变形作用叠加在中-高温变形之上,暗示出走滑过程中存在隆升作用,热年代学结果显示其连续剪切变形作用从早中新世以来至少持续到4Ma,并且出现三个快速冷却阶段:第一个快速冷却阶段为从25～22Ma 到21～18Ma 期间,可能代表的是浅部高温剪切过程中变形局部停止或减慢的过程;第二个快速冷却时期为从15Ma 到12～10Ma,是喀喇昆仑断裂带走滑过程中,阿伊拉日居山的快速隆升、噶尔盆地开始形成以及主要河流深切过程阶段;9Ma 以来是第三个快速冷却过程,使阿伊拉日居山脉进一步快速隆升、噶尔盆地定形过程。根据不同年代地表地貌特征的右旋错位距离以及不同层次变形特征,估算出喀喇昆仑断裂带长期滑移速率为8～10mm/a,伴随的隆升速率为1mm/a。从显微构造和热年代学证据表明,晚第四纪以来该断裂经历了强烈的右旋走滑运动的同时伴随强烈的隆升作用。The Karakorum Fault zone （ KFZ）, lying in the west of the Tibetan Plateau, is an important dextral strike-slip fault and the important northern geological boundary of the west Himalaya. In the AyilaRi＇ gyti Range-Gar Basin area lying in the southeast of the KFZ, ^40Ar/^39Ar thermochronologic analysis was performed on the syn-tectonic minerals in the metamorphic rocks in the Karakorum ductile shear zone, with the base of petrology and deformation structure researches. According to the microstructure features, the minerals in the shear zone recorded the continuous deformation from high （ 〉 600℃ ） to low temperature （ 〈 250℃ ）, appeared as that the nearly horizontal dextral shearing has transformed into the oblique dextral normal slip, made the greenschist facies deformation stack on the early medium-high temperature deformation, indicated the uplift during the slip. The thermochronologic revealed the continuous shear process from the early Miocene to 4Ma at least, which containing three rapid cooling stage： from 25 -22Ma to 21 - 18Ma, the deformation locally stopped or slower in the shallow high temperature shear process; from 15Ma to 12 - 10Ma, the rapid uplift of the AyilaRi ＇ gyü Range, the initial formation of the Gar Basin together with the main deep incision of river during the strip-slip of the KFZ; since 9Ma, the AyilaRi＇ gyü Range has increased the rapid uplift and the Gar Basin has formed finally. According to the different levels of deformation and the dextral displacement of the surface landform with different ages, the long term slip rate and the uplift rate accompanied of the KFZ might be 8 -10mm/a and 1mm/a separately. Both the microstructure and the thermochronology evidence indicated the intense dextral strike slip and uplift associated since the late Quaternary Period.

关 键 词：走滑断裂 热年代学 冷却历史 隆升 喀喇昆仑断裂带 

分 类 号：P542.3[天文地球—构造地质学] P597.3[天文地球—地质学]