东昆仑肯德可克铁矿区二长花岗岩组成、年龄及地质意义

The Geological Significances,Composition and Age of the Monzonitic Granite in Kendekeke Iron Mine

东昆仑地区华力西—印支造山旋回在三叠世中—晚期进入造山后伸展阶段,且伴生大量中酸性岩浆作用,其中肯德可克铁矿区发育的二长花岗岩是本区矽卡岩型铁矿的成矿母岩。地球化学数据表明:该二长花岗岩具有偏铝质—弱过铝质A型花岗岩的特征,形成于造山后期的伸展环境;LA-ICPM S锆石U-Pb测年得到其谐和年龄为(230.5±4.2)M a(n=7,M SW D=1.4),代表了岩体的形成年龄,并且其形成很可能与造山后岩石圈伸展,玄武质岩浆底侵提供热源引起下地壳物质深融作用有关,是印支末期岩浆活动的产物。

Hercynian-Indosinian orogenic cycle of East Kunlun underwent the post orogenic extending stage in the middle-late Triassic Epoch and was associated with large intermediate-acidity magmation,in which the monzonitic granite in Kendekeke iron mine is the host rock of the skarn-type iron ores.Geochemical analyses indicate that the monzonitic granite has the characteristics of metaluminous-weak peraluminous A-type granite,that formed in post orogenic extending environment;LA-ICPMS zircon U-Pb dated a concordant age of（230.5±4.2）Ma（n=7,MSWD=1.4）,represented the rock formation age,and it is likely to be the product of lower-crust suffered anatectic melting,which was caused by the heat source of basaltic magma underplating during the apotectonic lithosphere extension,and it is the product of late Indosinian magmatic activity.