陕西勉县地区关帝坪闪长岩体的LA-ICP-MS锆石U-Pb年龄及其地质意义  

Zircon LA-ICP-MS U-Pb Dating of the Guandiping Diorite Pluton from Mianxian,South Qinling,Central China

作　　者：吴美玲[1] 郭永峰[1] 李学军[1] 

机构地区：[1]西北大学地质学系,西北大学大陆动力学国家重点实验室,陕西西安710069

出　　处：《西北地质》2009年第1期73-78,共6页Northwestern Geology

基　　金：国家自然科学基金面上项目(批准号40872060);西北大学地质学系国家基础科学人才培养基金地质学科学研究培训项目(XDCX07-02);国家自然科学基金委项目地质学人才培养基地建设(批准号J0630537)联合资助

摘　　要：秦岭造山带印支期花岗岩的成因研究是当前秦岭造山带研究的热点问题。通过对出露于陕西勉县地区勉略缝合带中光头山岩体西端的关帝坪黑云母闪长岩锆石LA-ICP MS U-Pb年代学研究,探讨其地质意义。岩石主要由斜长石、角闪石和黑云母组成,蚀变较轻。LA-ICP-MS锆石U-Pb测年得到的加权平均年龄为220.5±3.1Ma(MSWD=0.66,2σ),代表该闪长岩体的结晶年龄。该年龄与附近的光头山黑云母斜长花岗岩的年龄216±2Ma很接近,由此推断两者应产出于相同的构造背景。结合前人研究结果,推断该黑云母闪长岩体可能为勉略洋闭合后的碰撞后期产物。The Guandiping biotite diorite outcrops in the Mianlue suture zone, located in the western part of the Guangtoushan granite pluton. The biotite diorite is mainly consisted by plagioclase, bhrnblende and biotite, with slight alteration. LA-ICP-MS dating of zircon U-Pb yeilds a weighted mean age of 220.5Ma± 1Ma（MSWD）= 0.66, 2a）, which is considered representing the crystallizing age of the Guandiping diorite pluton. This age is similar with the emplacement age of the biotite-plagioclase granite （216Ma ± 2Ma） from the Guangtoushan Pluton in the surroundings,it can be inferred that the Guandiping biotite diorite pluton was formed in post-collisional setting.

关 键 词：勉略带 闪长岩 关帝坪闪长岩体 LA—ICP—MS锆石U—Pb定年 

分 类 号：P588.1[天文地球—岩石学] P588.122[天文地球—地质学]