东帕米尔变质核杂岩构造的厘定

DETERMINATION OF METAMORPHIC CORE COMPLEX IN EAST PAMIR

卡拉库鲁木变质核杂岩是慕士塔格岩体的南缘部分,由长城系片麻岩以及燕山期花岗岩组成,其中长城系片麻岩为一套低角闪岩相的变质侵入岩,主要岩性为(石榴石)黑云二长片麻岩、(石榴石)黑云斜长片麻岩;根据变形程度,将其划分为内带、中带及外带,其中在内带见有燕山期花岗岩.剥离断层沿变质核杂岩边缘呈向南凸出的弧形展布.剥离断层上盘滑脱体由长城系赛图拉岩群高绿片岩一低角闪岩相的变质岩系构成.变质核杂岩构造的形成时代为早一中侏罗世.

Karakum metamorphic core complex is located at the southern margin of Muztag complex, and composed of gneisses of Changchen System and Yashanian granitoids. The gneisses of Changchen system are a suite of low-amphibolite facies meta-intrusive rocks, dominated by (garnet) biotite monzonitic gneisses and (garnet) biotite plagio-gneisses. Inner zone, medium zone and outer zone are subdivided according to different degree of deformation. Yanshanian granitoids are present within the inner zone. The detachment fault occurs along the margin of the core complex as a south-facing arc-shaped line. The hanging wall of the detachment fault consists of high-greenschist-facies to low-amphibolite-facies metamorphic rocks of Saitulayan group. The formation of core complex structure is constrained to be early-middle Jurassic.