秦岭西坝花岗岩LA-ICP-MS锆石U-Pb年代学及其地质意义  

LA-ICP-MS Zircon U-Pb Geochronology and Geological Significance of Xiba Granitoids from Qinling,Central China

作　　者：张帆[1] 刘树文[1] 李秋根[1] 王宗起[2] 韩以贵[3] 杨恺[1] 吴峰辉[1] 

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室,北京100871 [2]中国地质科学院地质研究所,北京100037 [3]中国地质大学(北京)地学实验中心,北京100083

出　　处：《北京大学学报（自然科学版）》2009年第5期833-840,共8页Acta Scientiarum Naturalium Universitatis Pekinensis

基　　金："十一五"国家支撑计划课题(2006BAB01A11)资助

摘　　要：西坝花岗岩位于南秦岭构造带陕西境内,主要由花岗闪长岩、二长花岗岩和英云闪长岩组成。LA-ICP-MS锆石U-Pb原位同位素定年结果表明,西坝岩体侵位于印支期,由二长花岗岩样品(XB01-2)得到了219±1 Ma的年龄,花岗闪长岩样品(XB06-1)给出的年龄是218±1 Ma,二者在误差范围内一致,约218 Ma代表了西坝花岗岩体的成岩时代。西坝岩体的年龄结合区域构造背景以及前人研究的地球化学特征,说明它可能是秦岭主造山期岩浆活动的产物。Xiba granitoids are located in the South Qinling tectonic belt, Shaanxi province, which consist of granodiorite, monzogranite and tonalite. LA-ICP-MS zircon U-Pb dating yields two concordant ages, 219 ± 1 Ma for monzogranite sample XB01- 2, and 218 ±1 Ma for granodiorite sample XB06-1. The ages for two samples are uniform in test errors, indicating a crystallization age of - 218 Ma. This result, together with the previous studies concerning regional tectonic setting and geochemical characteristics of Xiba granitoids, show that they are produced in the magmatism event of the main orogenic stage of the Qinling orogenic belt.

关 键 词：西坝岩体 花岗岩 LA-ICP-MS 锆石U-PB 秦岭造山带 

分 类 号：P597.3[天文地球—地球化学]