2011年9月，第17卷，第3期，452-461页 September 2011,Vol.17,No.3,p.452461
高校地质学报
Geological Journal of China Universities
论东川地区前震旦系地层层序：
来自锆石SHRIMP及LA-ICP-MS测年的证据朱华平，范文玉，周邦国，王生伟，罗茂金，廖震文，郭
阳
成部地质矿产研究所，成都610081
摘要：对东川地区的因民组内部辉绿岩体（TW1）、酒海沟组熔结凝灰岩（TW2）和平顶山组沉积砾岩（TW3）进行了锆石U-Pb年龄测定。结果表明，TW1获得上交点年龄为（1667±13）Ma，指示因民组内部辉绿岩体侵人时代为中元古代早期。TW2获得两组年龄，其中3"Pb/2Pb加权平均年龄（2285+12/-11）Ma，指示火山岩形成时代为古元古代；上交点年龄为（2742±48）Ma，表明东川地区存在着一套更老的岩石地层。TW3获得最年轻一组碎屑结石的"Pb/"Pb加权平均年龄为（1838±10）Ma，它代表平项山组最大的沉积时限。基于以上定年数据，笔者认为东川地区的前震且系地层层序由老至新
分别为：洒海沟组、望厂组、菜园湾组、平顶山组、固民组、落需组、黑山组、青龙山组、大营盘组。关键词：错石SHRIMP及LA-ICP-MS年龄；地层层序；前震且系；东川地区
中图分类号：P539.2；P597
文献标识码：A
文章编号：10067493（2011）03-0452-10
AssessingPrecambrianStratigraphicSequenceofDongchuanArea:
Evidence from Zircon SHRIMP and LA-ICP-MSDating ZHU Hua-ping,FAN Wen-yu,ZHOU Bang-guo,WANG Sheng-wei,
LUO Mao-jin, LIAO Zhen-wen, GUO Yang
Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China
Abstract: The authors got a series of zircon UPb ages for 3 samples in Dongchuan area, Yunnan province: the diabase(TW1) cutting Yinming Formation, the ignimbrite (TW2) of Sahaiguo Formation, and the sedimentary conglomerate (TW3) of Pingdingshan Formation. The SHRIMP zircon UPb dating for TW1 yielded an upper intersection age of (1667 ± 13) Ma, which indicates the timing of diabase intrusion activity in Mesoproterozoic. The SHRIMP zircon U-Pb dating for TW2 showed two ages: an everage weighted age of ( 2285 ± 11 ) Ma can he considered as the eruption timing of lava in Paleoproterozoic, and the upper intersection age of (2742 ± 48) Ma indicates that a series of older rocks might exist in the Dongchuan area. The LAICP MS dating for sample TW3 yielded an youngest concordant age of (1838 ± 10) Ma, which constrained the oldest sedimentation age of the Pingdingshan Formation. Based on these dating results, the Precambrian stratigraphic sequence fitting the Dongchuan area from the older rocks upwards is as follows: Sahaiguo Formation, Wangchang Formation, Caiyuanwan Formation, Pingdishan Formation, Yinming Foramation, Luoxue Formation, Heisan Formation, Qinglongsan Formation and Dayingpang Formation
Key words: Dongchuan area; Zircon UPb dating; stratigraphic sequence; Precambrian Corresponding author: Fan Wenyu, Senior Researcher. E-mail: edfwenyu@cgs-gov.cn
收稿日期：20110318；修回日期：2011-0427
基金项目：中国地质调查局地质调查项目（编号：1212010813066）资助
作者简介：宋华平，男，1979年生，工程师，从事区域地质矿产调查及综合研究T.作；E-mail：zhp791225@163.com
*通讯作者：范文玉，E-mail：effwenyu@eg-gov.cn