阿尔金北缘大平沟韧-脆性变形带特征  

Study on the Dapinggou ductile-brittle deformation belt in northern Altum margin area,NW China.

作　　者：陈柏林[1] 王世新 祁万修 陈正乐[1] 刘荣 杨风 蒋荣宝[1] 李丽[1] 杨屹 李学智 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]新疆地质调查院第一地质调查所,乌鲁木齐830011

出　　处：《岩石学报》2008年第4期637-644,共8页Acta Petrologica Sinica

基　　金：“十一五”国家重点基础研究发展计划“973”项目(编号:2007CB411305);国家科技支撑计划重点项目(编号:2006BAB07B02-04)的资助成果。

摘　　要：大平沟韧-脆性变形带出露于紧邻阿尔金北缘断裂北侧的新太古界达格拉格布拉克群钾长片麻岩中,与阿尔金走滑断裂索尔库里段相距约50km。总体呈东西向展布,高角度向南倾斜,倾角65～85°。次级变形带呈北西西向-东西向波状起伏延伸。单个次级变形带规模一般长数百米,宽数十米。变形带内岩石的线理、面理构造发育,石英、钾长石矿物粒内变形效应明显,同构造变形的新生矿物绢云母比较发育。变形性质为韧-脆性压扭性构造变形,发育糜棱岩系列岩石,特别是含钾长石残斑的绢云母石英质糜棱岩最为常见。变形岩石组构显示石英以底面和近于底面滑移的方式发生变形,反映出是中-低温条件(250～350℃);有限应变测量显示岩石变形强度中等,应变椭球轴比为2.9～4.8;变形运动学特点为右行逆冲,变形主压应力方向为北北西向,最大差应力为59～61MPa。结合区域构造演化,作者认为该韧-脆性变形带是发生于早古生代板块碰撞的大地构造背景条件下,并反映了板块碰撞过程中基底岩块的变形特点。The Dapinggou ductile-brittle deformation belt outcrops among the brown-red K-feldspar gneiss of the Late Archaeozoic Dagelabulake Group, being nearby the northern side of the northern Ahun fault and about 50km far away from Xorkol part of the Ahun strike-slip fault. The belt dips to Southern at a high-angle of 65 -85° with an EW-trending. Each second-order ductile-brittle deformation belt trends EW to NWW trending wavy, with a hundreds meter length and tens meter width. There develops lineation and foliation in the belt and an obvious intragranular deformation of minerals, such as quartz and K-feldspar. Synkinematic recrystallized sericite well develops inner deformed rocks. The mechanical property of the belt is ductile-brittle shear-compressional deformation. There developed kinds of mylonite, specially, the K-feldspar porphyroid - bearing sericite quartz mylonite is common sight in the belt. Analysis of petro-fabrics shows that the quartz is mainly deformed along its basal or basal-near glide system, witch indicates that the deformation temperature is about 250 -350℃. Finite strain measurement Shows that the strain ellipsoid axis ratio （Rxz） is 2.9 -4.8. The differential stress value is measured about 59 -61MPa and the sense of movement is right-lateral thrusting with a NNW-trending maximum compressive stress. Combining to the geotectonic evolution, the authors consider that the Dapinggou ductile-brittle deformation belt developed under the geotectonic setting of collision of plates in the early Paleozoic, indicated the deformation feature of basement rock under the collision process.

关 键 词：韧-脆性变形带 压扭性 大平沟 阿尔金北缘 

分 类 号：P542.3[天文地球—构造地质学]