四川平武地区碧口群碎屑锆石U-Pb年龄及其地质意义  

The U-Pb age of Detrital Zircons and Its Geological Significance from Bikou Group in Pingwu Area,Sichuan

作　　者：秦宇龙 詹涵钰 王亚丽[2] 罗改 熊昌利 李峥 武文辉 徐云峰 QIN Yulong;ZHAN Hanyu;WANG Yali;LUO Gai;XIONG Changli;LI Zheng;WU Wenhui;XU Yunfeng(Evaluation and Utilization of Strategic Rare Metals and Rare Earth Resource Key Laboratory of Sichuan Province,Sichuan Institute of Comprehensive Geological Survey,Chengdu,Sichuan 610081;Petro China Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051)

机构地区：[1]稀有稀土战略资源评价与利用四川重点实验室、四川省综合地质调查研究所,成都610081 [2]中国石油西南油气田分公司,成都610051

出　　处：《四川地质学报》2024年第2期195-203,共9页Acta Geologica Sichuan

基　　金：全国陆域及海区地质图件更新与共享(四川省区域地质地质志修编)(编号DD20190370)资助。

摘　　要：本文对四川平武县碧口群中原岩沉积构造特征保存仍然完整的二云石英岩碎屑锆石,通过LA-(MC-)ICP-MS-激光原位分析方法开展平武碧口群最大沉积年龄的研究,同时对源岩属性、沉积环境以及沉积盆地构造演化等展开讨论。四川平武地区碧口群的碎屑锆石测点Th/U比值多介于0.27~2.6之间,具岩浆锆石特征,应为岩浆成因。最年轻碎屑锆石年龄为207 Ma,最老锆石年龄为2819 Ma。碎屑锆石年龄多集中于617~941Ma,说明该区沉积岩主体形成于新元古代地壳物质,在之后的古生界-中生界历经多次地质沉积事件。最老锆石年龄2819Ma推测其有太古宙残留物质信息,大致可以指明碧口群桂花桥岩组地层物质应该来源于古元古代—太古代及以前的岩石、地层。The two-mica quartzite with intact sedimentary structure characteristics from Bikou Group was located in Pingwu County,Sichuan.The maximum sedimentary age of Pingwu Bikou Group was studied by LA-(MC-)ICP-MS detrital zircon datin,and the properties of source rock,sedimentary environment and tectonic evolution of sedimentary basin were discussed.The Th/U ratio of detrital zircons in the Bikou Group in Pingwu area mainly ranged from 0.27 to 2.6,indicating the characteristics of magmatic zircons.The youngest detrital zircon is 207 Ma,while the oldest is 2819 Ma,and the detrital zircons are mostly aged between 617 and 941 Ma,which indicates that the sedimentary rocks in this area were mainly formed from Neoproterozoic,and experienced several geological sedimentary events in the Paleozoic and Mesozoic periods.The old zircon age of 2819 Ma shows the Archean residual material information,which indicates that the stratigraphic material of Guihuaqiao formation in Bikou Group should be derived from paleoproterozoic to Archaean rocks and strata.

关 键 词：碎屑锆石U-PB年龄 四川平武县木皮乡 碧口群 摩天岭微陆块 

分 类 号：P597.3[天文地球—地球化学]