西秦岭德乌鲁埃达克岩的发现及地质意义  

The Discovery and Geological Significance of the Dewulu Adakite rocks in Western Qinling

作　　者：冯小明[1] 李注苍[1] 张海峰[1] Feng Xiaoming;Li zhucang;Qi Jianhong;Zhang Haifeng;Yang Zhiyong(Third Institute Geological and Mineral Exploration of Gansu provincial Bureau of Geology and Mineral Resources,Lanzhou,Gansu,730000,China)

机构地区：[1]甘肃省地矿局第三地质矿产勘查院,甘肃兰州730000

出　　处：《新疆地质》2020年第3期293-297,共5页Xinjiang Geology

基　　金：甘肃省合作-美武一带1:5万矿产远景调查项目(甘财建(2010-254))资助。

摘　　要：德乌鲁岩株位于西秦岭夏河-合作大断裂和力士山-围当山断裂间的中秦岭褶皱带。岩性以花岗闪长岩为主,石英闪长岩和石英二长闪长岩次之,为一套中酸性侵入岩,SiO2含量58.6%~65.96%;Al2O3含量14.23%~14.86%;MgO含量3.24%~5.84%;Sr含量262.4×10-6~325×10-6,为喜马拉雅型花岗岩(Sr小于400×10-6);Y含量为15.86×10-6~17.07×10-6,与经典C型埃达克岩定义一致。该埃达克岩的确立,对深化西秦岭区域成矿构造和指导今后找矿具有借鉴意义。The Dewulu rock located in the central Qinling fold belt between in the Xiahe-Hezuo fault and Lishishan-Weidangshan fault in Western Qinling,which is a set of intermediate-acid intrusive rocks and the main lithology is granodiorite,the quartz diorite and quartz monzobiorite is secondary lithology.Its SiO2 content is 58.6%~65.96%>56%;Al2O3 content is 14.23%~14.86%<15%;MgO content is 3.24%~5.84%<6%;Sr content is 262.4×10-6~325×10-6<400×10-6,which is Himalayan type granite(Sr<400×10-6);Y content is 15.86×10-6~17.07×10-6<18×10-6,They have the same characteristics with the C-type adakite ones.The U-Pb isotope age of the Dewulu rock was 227.5±2.2 Ma and its formation time was early of the late Triassic.Therefore,in the early of the later Triassic,the Yangtze plate subducted and the North China plate happened to the continent-continent collision in the Qinling orogenic,the Yangtze plate subducted under the North China plate and this resulted in thickening of the earthcrust and increasing of the geothermic gradient.The metamorphic basalts in the lower crust were partially melted due to the temperature rising and formed a C-type adakite melt.The establish of adakite rocks have significant information to improve native metallogenic constrution and guide prospecting for the future in Western Qinling.

关 键 词：地球化学 埃达克质岩 地质意义 德乌鲁 西秦岭 

分 类 号：P588.14[天文地球—岩石学]