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1、陕西华县八里坡钼矿床锆石U-Pb和辉钼矿Re-Os年龄及其地质意义*注:本文为国家自然科学基金项目(编号40534020,40702015)资助成果。收稿日期:2009-3-6;改回日期:2009-5-24。作者简介:焦建刚,男,1976年生。副教授,博士,从事矿床学及矿产勘查研究。Email:jiangang@chd.edu.cn。焦建刚1,2),袁海潮3),何克2),孙涛1),徐刚1),刘瑞平4)1)长安大学地球科学与资源学院,西安,710054;2)西部矿产资源与地质工程教育部重点实验室,西安,710054;3)西北有色地质勘查局712总队,陕西咸阳,712000;4)西安地质矿产研究所
2、,西安,710054内容提要:八里坡钼矿是在金堆城钼矿床外围找矿中新发现的斑岩型钼矿床,对其含矿斑岩和矿石进行了成岩成矿年龄精测。采用LA-ICP-MS方法对八里坡斑岩体进行单颗粒锆石U-Pb测年,获得成岩年为155.9±2.3Ma;采用ICP-MS法测定八里坡钼矿中辉钼矿Re-Os同位素年龄,获得模式年龄为156.3±2.2Ma;两种方法获得的年龄一致,表明成岩与成矿同时形成。八里坡斑岩体与东秦岭南泥湖、上房沟等斑岩体成岩年龄一致,早于金堆城钼矿床成矿年龄,表明八里坡斑岩体可能是新一期成岩成矿作用,形成于燕山运动的A幕,产出于东亚构造体制转变初期的地球动力学背景,具有重要成岩成矿意义。关键词
3、:锆石U-Pb年龄;Re-Os年龄;八里坡钼矿;东秦岭ZirconU-PbandMolybdeniteRe-OsDatingfortheBalipoPorphyryMoDepositinEastQinling,China,andItsGeologicalImplicationJIAOJiangang1,2),YUANHaichao3),HEKe2),SUNTao1),XUGang1),LIURuiping4)(1.SchoolofEarthScienceandResources,Chang’anUniversity,Xi’an,710054,Shaanxi,China;2.KeyLaborat
4、oryofWesternChina’sMineralResourcesandGeologicalEngineering,MinistryofEducationofP.R.C,Xi’an710054,China3.712TeamofNorthwesternGeologyExplorationBureauforNonferrousMetalResources,Xianyang,712000,Shaanxi,China;4.Xi’anInstituteofGeologyandMineralResources,Xi’an,710054,Shaanxi,China)Abstract:Locatedint
5、heeasternQinlingMolybdenumBelt,theBalipodepositisaporphyryModepositdiscoveredinrecentyears.Thisstudyprovidesthefirsthighlyprecisedatingofthemineralizationandrock-formingintheBalipoMolybdenumdeposit.ThedatingofzirconfromBalipograniticporphyrydeterminedbyLA-ICP-MSyieldsanageof155.9±2.3Ma.TheRe-Osmodel
6、agesofthedepositarebetween152.8±1.1Ma~157.8±2.2Ma,andRe-Osisochroneageis156.3±2.2Ma.ThezirconU-PbandmolybdeniteRe-Osisotopicagesarequiteclose.TheresultssuggestthattheBalipoMolybdenumdepositwasformedatleast10MaearlierthantheJinduicheng,Nannihu,ShangfanggouandLeimengouporphyrymolybdenumdepositsinthesa
7、memolybdenumbelt.Onthebasisoftheaccuratelyconfirmedagesofthemineralizationandrock-forming,thegeodynamicevolutionandformingmechanismarefurtherdiscussed.TheBalipoMolybdenumdepositformedduringEpisodeAoft