内蒙古黄花滩铜镍矿区辉长岩LA-ICP-MS锆石U-Pb定年及地球化学特征  

LA-ICP-MS Zircon U-Pb Age and Geochemistry of Gabbros from the Huanghuatan Copper-Nickel Deposit,Inner Mongolia

作　　者：赵泽霖[1,2] 李俊建[2] 党智财 付超[2] 唐文龙[2] 王守光[3] 刘利双 赵丽君[2] 

机构地区：[1]中国地质科学院研究生部,北京100037 [2]中国地质调查局天津地质矿产研究所,天津300170 [3]内蒙古自治区地质调查院,内蒙古呼和浩特010020 [4]中国地质科学院地质研究所,北京100037

出　　处：《岩矿测试》2016年第2期208-216,共9页Rock and Mineral Analysis

基　　金：国家国际科技合作项目(2012DFB20220);中国地质调查局项目(1212010561510,1212010811061)

摘　　要：在乌拉特后旗—达茂旗—四子王旗一带的内蒙古中部地区分布着超基性-酸性连续岩浆系列,开展其岩体年代学、地球化学研究可为内蒙古中部地区与超基性-基性岩有关的铜镍矿成矿规律研究提供基础地质资料,还可以推断岩浆侵位时期的区域大地构造背景。本文以达茂旗黄花滩铜镍矿区出露的辉长岩为研究对象,采用LA-ICP-MS仪器对无裂隙、高透明度、阴极发光均匀、环带清晰的锆石进行U-Pb定年,获得岩体加权平均年龄为262.4±1.1 Ma,并利用XRF和ICP-MS进行岩石地球化学分析显示黄花滩辉长岩具有后碰撞拉伸环境下的岩浆特征。综合前人相关研究认为,内蒙古中部地区于中二叠世晚期（255~275 Ma）已经进入后碰撞构造阶段,而古亚洲洋在该区域的闭合应发生在晚二叠世前（~285 Ma）,此结论丰富了古亚洲洋闭合时间上限及中晚二叠世期间内蒙古中部地区构造背景方面的证据。A series of ultrabasic-acid igneous rocks are distributed in the belt of Urad houqi-Damaoqi-Siziwangqi, in middle Inner Mongolia. The formation age and geochemistry of these rocks can provide basic geological information for the metallogenic regularities of Cu-Ni deposits related to ultrabasic-basic rocks. The age and geochemistry can also be used to infer the tectonic setting during magma emplacement. The Huanghuatan copper- nickel deposit in Damaoqi was selected for this research. Because of less fractures, high transparency, uniform cathodoluminescence and clear oscillatory zonings, zircon U-Pb dating is prior to be tested on LA-ICP-MS. The result yielded a weighted age of 262. 4 ±1. 1 Ma. The geochemical characteristics investigated by X-ray Fluorescence Spectrometry （XRF） and Inductively Coupled Plasma-Mass Spectrometry （ICP-MS） indicate that Huanghuatan gabbros may have formed in a post-collision tensional environment. Combining with previous studies, it is suggested that the central region of Inner Mongolia had entered into the post-collision stage during the late Permian （255 -275 Ma）, whereas the close of Paleo-Asian Ocean in this limited area occurred before late Permian （ about 285 Ma）. This conclusion provides the upper time limit for the close of Paleo-Asian Ocean and the tectonic setting of the central part of Inner Mongolia during middle-late Permian.

关 键 词：内蒙古黄花滩铜镍矿区 辉长岩 LA-ICP-MS锆石U-PB定年 地球化学特征 后碰撞 

分 类 号：P588.124[天文地球—岩石学] O657.63[天文地球—地质学]