投稿时间：2012-08-04
修订日期：2013-04-24
中文摘要:边家大院铅锌银矿床位于大兴安岭南段,西拉沐伦河深大断裂北缘。矿区侵入岩有早期的辉石闪长岩、晚期的花岗闪长岩和花岗斑岩,矿化与晚期花岗闪长岩密切相关。矿化有脉状和隐爆角砾岩型2种,脉状矿体赋存于花岗闪长岩内部或与围岩的接触带上,隐爆角砾岩筒发育于花岗闪长岩体上部。花岗闪长岩LA-ICP-MS锆石U-Pb年龄为(143.2±1.5) Ma,指示矿化是晚侏罗世构造应力场由挤压环境转变为伸展环境条件下构造-岩浆-热液作用的产物。206Pb/204Pb、207Pb/204Pb和208Pb/204Pb范围分别集中在18.1605~18.1832、15.5502~15.5534和38.2013~38.2171,平均值分别为18.1705、15.5519、38.2102。铅同位素分布集中,成矿物质来自于深源岩浆,且来源比较单一。δD值分布在-101‰~-110‰,δ18O值介于3.45‰~3.75‰,成矿流体主要为岩浆热液。综合矿床地质特征和测试分析认为边家大院是一中温岩浆热液矿床。
Abstract:The Bianjiadayuan Pb-Zn-Ag Deposit is located in southern Da Hinggan Mountains and at the northern edge of Xar Moron deep fault. The main styles of mineralization are veins and crypto-explosive breccia. The ore veins are mainly developed in the contact zone between granodiorite and wall rock. Crypto-explosive breccia occurs in the upper part of the granodiorite. The pyroxene diorite intruded first, followed by granodiorite and quartz porphyry. LA-ICP-MS zircon U-Pb dating indicates that the mineralization-related granodiorite was emplaced at (143.2±1.5) Ma. The mineralization resulted from the tectonic-magmatic-hydrothermal activity during the transformation of the tectonic stress field from extrusion to extension in the late Jurassic period. Lead isotope ratios in sulfides vary from 18.1605 to 18.1832 for 206Pb/204Pb, 15.5502 to 15.5534 for 207Pb/204Pb, and 38.2013 to 38.2171 for 208Pb/204Pb. Their mean values are 18.1705, 15.5519 and 38.2102, respectively. The lead isotope ratios are concentratedly distributed, suggesting that the lead are dominated by deep magma from a single source. δD and δ18O values range from -101‰ to -110‰ and 3.45‰ to 3.75‰, respectively, and the ore-forming fluids dominantly originated from magmatic hydrothermal solution. Based on the geological characteristics and an analysis of the testing data, the authors hold that the Bianjiadayuan Pb-Zn-Ag deposit is a mesothermal magmatismc-hydrothermal deposit.
keywords:geochemistry U-Pb dating of zircon multi-isotope deposit genesis Pb-Zn-Ag deposit Bianjiadayuan
文章编号：
中图分类号：P618.42;P618.43;P618.52
文献标志码：
基金项目:本文得到国家科技支撑计划重点项目(编号:2007BA25B04、2011BAB06B04-05)和内蒙古矿调项目(编号:NMKD2010-3)的联合资助
引用文本：
阮班晓,吕新彪,刘申态,杨梧.2013.内蒙古边家大院铅锌银矿床成因——来自锆石U-Pb年龄和多元同位素的制约[J].矿床地质,32(3):501~514RUAN BanXiao,LÜ XinBiao,LIU ShenTai,YANG Wu.2013.Genesis of Bianjiadayuan Pb-Zn-Ag deposit in Inner Mongolia：Constraints from U-Pb dating of zircon and multi-isotope geochemistry[J].Mineral Deposits32(3):501~514
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