四川九龙新火山花岗岩体单颗粒锆石LA-ICP-MSU-Pb定年及其地质意义  

LA-ICP-MS zircon U-Pb dating and geological implications for the Xinhuoshan granites in Jiulong,Western Sichuan

作　　者：马国桃[1] 姚鹏[1] 马东方[1] 高大发[1] 汪名杰[1] 李建忠[1] 张慧华[1] 陈敏华[1] 梁鲸[2] 

机构地区：[1]成都地质矿产研究所,四川成都610081 [2]四川里伍铜业股份有限公司,四川九龙626200

出　　处：《沉积与特提斯地质》2012年第4期70-75,共6页Sedimentary Geology and Tethyan Geology

基　　金：四川李伍铜矿;泸沽铁矿床成矿规律总结研究项目(编号:20089952);四川省九龙县黑牛洞铜矿详查项目资助的成果

摘　　要：本文对四川九龙新火山花岗岩岩体中的锆石进行了详细的LA-ICP-MS U-Pb同位素年龄测定。该岩体中的锆石发育较好的环带结构,Th/U值较高(大于0.13),具有岩浆成因锆石的特征。研究结果表明,新火山岩体中锆石的206Pb/238U加权平均年龄为181.2±1.4Ma(MSWD=3.3),代表了新火山花岗岩的结晶年龄,为早侏罗世,反映了松潘-甘孜造山带燕山期岩浆活动的一个重要阶段,为进一步理解松潘-甘孜燕山期花岗质岩浆活动及其动力学背景等提供了有力的证据。The LA-ICP-MS zircon U-Pb dating is made for the Xinhuoshan granites in Jiulong, Western Siehuan. The selected zircon grains from the granites display well-defined girdle structures in the eathodolumineseence images and higher Th-U ratios （more than 0. 13） characteristic of magmatie origin. The ^206pb/^238pb weighted average age of 181. 2±1. 4 Ma （ Early Jurassic） for the Xinhuoshan granites （ MSWD = 3. 3） represents the age of crystallinization of the Xinhuoshan granites, and an important phase of the Yanshanian magmatism in the Songpan- Garze orogenic zone. The findings in this study may serve as the circumstantial evidence for better understanding of the granitic magmatism and dynamic settings in the Songpan-Garze orogenic zone druing the Yanshanian.

关 键 词：锆石LA—ICP—MS U—Pb定年 燕山期花岗岩 九龙 

分 类 号：P588.121[天文地球—岩石学]