2015年9月，第21卷，第3期，519-528页 September 2015,Vol.21，No.3，pp.519528
D0I: 10.16108/j.issn10067493.2015035
高校地质学报
Geological Journal of China Universities
内蒙古固阳地区早石炭世花岗岩的发现：来自SHRIMP锆石U-Pb年代学的证据
刘超，孙蓓蕾，吴婧，曾凡桂* 太原理工大学地球科学与工程系，太原030024
摘要：内蒙古固阳地区位于华北克拉通北缘，区内出露大规模晚古生代早石炭世花岗岩，花岗闪长岩呈脉状侵人于主体花闵申，同时脉状侵入岩申还有闪长岩包体存在。对这三类岩石分别进行岩石地球化学分析和SHRIMP错石U-Pb同位系测定，结果表明3个样品均富集LILE和LREEs，且具有REE轻度分留，Nb、Ta与Ti负异常，Rh、Th和K正异需的特征，为钙碱性系列。花岗岩、花岗闪长岩和闪长岩三个岩体的SHRIMP锆石U-Pb定年结果分别为：330.8Ma、324.7Ma、329.2Ma，属于早石炭世。早石炭世华北克拉通与西伯利亚板块尚未发生碰撞，固阳地区北部的早石炭世岩体应为古业洲洋向华北板
块俯冲的结果。花岗岩主要源于陆壳物质的重熔，花岗闪长岩可能来源于花岗质岩浆和闪长质岩案的混合作用。关键词：固阳北部；SHRIMP锆石U-Pb年龄；早石炭世；岩浆混合
中图分类号：P518.12
文献标识码：A
文章编号：10067493（2015）030519-10
DiscoveryoftheEarlyCarboniferousGraniteinGuyang,Inner
Mongolia：EvidencefromZirconSHRIMPU-PbDating
LIU Chao, SUN Beilei, wU Jing, ZENG Fangui
Department of Earth Science & Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Abstract: Guyang area is located in the northern margin of the North China Craton, and Neopaleozoic granites are widespread there. In these: granitic intrusions, granodiorite oceurs as late intrusive veins, and diorite enclaves ean be found in the granodioritic veins. For these: three kinds of rxks, major and trace elements are measured to constrain their geochemical characteristics, while zircons are measured by SHRIMP to provide UPh ages. AIl these samples are calc-alkaline series, and enriched in LILE and LREEs, and show a mild fractionated REE. On a primitivemantle normalized spidergram, these rocks show distinctly negative Nh, Ta, Ti anomalies and positive Rh, Th, K anomalies. UPh dating of ziroon yielded erystallization ages of 330.8Ma, 324.7Ma, and 329.2Ma for the granite, the granodiorite and the diorite, respectively, which belong to the early earboniferous.The early Carboniferous magmatic rocks in northern margin of North China Craton should be associated to the subxlucting of Paleo-Asian Ocean to the North China plate, since this occurred hefore the convergence of the Siheria Craton and the North China Craton. Granites should be generated from remelting of continental crust, and granodiorite probably produced by mixing granitic magma and dioritic magma.
Key words: North Guyang, SHRIMP Zircon UPb dating, Early Carboniferous, magma mixing Corresponding author: ZENG Fangui, Professor; E-mail: zengfangui@tyut.edu.cn
收稿日期：20150303；修回日期：20150526 基金项目：国家自然科学基金（41372165）资助
作者筒介：刘超，女，1989年生，博士研究生，主要研究方向为地年代孚；E-mail；447270720@q-com
*通讯作者：曾凡桂，男，1965年生，教授，从事地分析，地质年代研究；E-mail:xengfangui@tyut.eduer