嫩江科洛地区晚侏罗世深熔花岗岩对嫩江—黑河构造带的响应

Response of Late Jurassic anatectic granite to the Nenjiang-Heihe tectonic belt in Kolo area of Nenjiang

通过对嫩江—黑河构造带内的岩石建造研究,在嫩江科洛地区识别出一套深熔花岗岩体,岩石宏观上为一套具非典型花岗岩结构的深熔型侵入岩,具交代结构、斑杂状构造和眼球状构造。对深熔花岗岩进行了锆石LA-ICP-MS U-Pb年龄测试,获得了3组不谐和的U-Pb年龄:390 Ma、157~163 Ma和113 Ma。其中,113 Ma年龄代表了岩石遭受后期变质热事件年龄;157~163 Ma的年龄代表了原岩结晶年龄。综合分析深熔花岗岩成因,认为其主要与嫩江—黑河断裂深部韧性剪切热效应作用下发生的深熔有关,深熔花岗岩的划分和厘定为深入研究嫩江—黑河断裂带在中生代的活动提供了新的素材。

Through the petrography research of the Nenjiang-Heihe tectonic belt,the authors found a set of anatectic granite body in Kolo area of Nenjiang. From the point of macroscopic view,the rock is an anatectic intrusive body of atypical granite with metasomatic texture,taxitic structure,and augen structure. The authors tested the age of the anatectic granite using zircon LA-ICP-MS U-Pb dating,and obtained three groups of discordant U-Pb age,which were 390 Ma,157 ~ 163 Ma and 113 Ma. The age of 113 Ma represents late metamorphic thermal event age and the age of 157 ~ 163 Ma means the age of protolith crystallization. Througn comprehensive analysis of the anatectic granite formation,the authors supposed that it was mainly related to the anatexis under the thermal effect of the deep ductile shear in Nenjiang-Heihe fault. The division and determination of the anatectic granite provide new data for deeper study of the Mesozoic activity of Nenjiang-Heihe fault.