滇东者海上二叠统宣威组下部地层碎屑锆石U-Pb测年及其地质意义  

LA-ICP-MS U-Pb geochronology and its geological implications of the detrital zircons from the lower strata of Upper Permian Xuanwei formation in Zhehai town, eastern Yunnan Province

作　　者：何冰辉 刘少峰[2] 吴鹏[3] 

机构地区：[1]西藏阿里地区国土资源局,西藏阿里859000 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]太原理工大学地球科学与工程系,太原030000

出　　处：《地质调查与研究》2017年第2期126-133,146,共9页Geological Survey and Research

基　　金：国家重点基础研究发展计划项目"二叠纪地幔柱构造与地表系统演变-二叠纪大规模岩浆作用的地质和构造背景(2011CB808901)"

摘　　要：对滇东者海镇上二叠统宣威组下部砂岩样品进行了碎屑锆石LA-ICP-MS U-Pb测年,获得41个有效数据,年龄分布范围为252.4~2613.9 Ma.根据样品碎屑锆石晶体形态特征、Th/U值、稀土元素富集情况等,推测其物源区可能是川滇古陆。用样品中最年轻的碎屑锆石年龄来限定宣威组的最老沉积年龄,并约束峨眉山玄武岩喷发的结束时间为252.4±4.1 Ma,这为峨眉山大火成岩省活动过程的研究提供了重要信息。The detrital zircon LA-ICP-MS U-Pb dating of the sandstone from the lower sequences of Late Permian Xuanwei formation in Zhehai town, eastem Yunnan province shows that the age ranges is from 252.4 Ma to 2613.9 Ma, which means the detrital provenance may be from the West Sichuan-Central Yunnan oldland. It is more reasonable to use the minimum age of zircons in the sample to confine the oldest depositional age for Xuanwei formation, and confine the end time of the Emeishan basalt eruption with age of 252.44-4.1 Ma. It provides important information for study on the activity of the Emeishan large igneous province.

关 键 词：峨眉山大火成岩省 川滇古陆 碎屑锆石 LA-ICP-MSU-Pb测年 宣威组 物源 

分 类 号：P597.3[天文地球—地球化学]