甘肃西秦岭舟曲憨班花岗岩体的单颗粒锆石U-Pb年龄及地质意义  

Single-grain zircon U-Pb ages and geological significance of the Hanban granite from Zhouqu(Gansu)in the west Qinling orogenic belt

作　　者：刘明强[1] 

机构地区：[1]甘肃省地质调查院,甘肃兰州730000

出　　处：《地质科学》2012年第3期899-907,共9页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：甘肃省国土资源厅1:25万武都幅区调及地壳稳定性评价项目资助

摘　　要：在1:25万武都幅区域地质调查中对西秦岭憨班花岗岩体进行了调查研究,通过高精度单颗粒锆石U-Pb同位素测年,获得^(206)Pb/^(238)U表面年龄统计权重平均值分别为:205±1 Ma和212±1.4 Ma,属印支晚期。岩石化学和地球化学特征表明,憨班岩体属高钾钙碱性系列,在Rb-Yb+Nb和Nb-Y图解中,样品均投在火山弧花岗岩+同碰撞花岗岩区。憨班岩体形成于陆陆碰撞造山阶段后期,可能形成于加厚地壳的部分熔融。Petrological and geochemical characteristics as well as formation ages of the Hanban granitic pluton has been investigated during the regional geological survey（ scale 1：250 000）in Wudu ,west Qinling Mountains. High-precision single-grain zircon U-Pb dating results yielded weighted average ages of 205 ± 1 Ma and 212±1.4 Ma for fine-to middle-grained granodiorite and porphyritic adamellite in the Hanbzm pluton, respectively, indicating that the pluton was formed in the late Indosinian. The Hanban granitic rocks are high-K calc-alkaline in major elements and are plotted in the field of volcanic arc and syn-collisional granite in the Rb-Yb＋ Nb and Nb-Y plots. It is proposed that the Hanban pluton was formed by partial melting thickened crust in the late stage of continent-continent collision.

关 键 词：西秦岭 憨班花岗岩 单颗粒锆石U—Pb年龄 印支期 

分 类 号：P588[天文地球—岩石学] P597[天文地球—地质学]