豫西夜长坪钼矿床辉钼矿铼_锇同位素年龄及地质意义_毛冰.pdf

2011年12月矿床地质第30卷第6期
December,2011MINERALDEPOSITSVol.30No.6

文章编号:0258-7106(2011)06-1069-06

豫西夜长坪钼矿床辉钼矿铼-锇同位素年龄
及地质意义

毛冰1,叶会寿2**,李超3,肖中军4,杨国强5
(1中国地质大学地球科学与资源学院,北京100083;2中国地质科学院矿产资源研究所,国土资源部成矿作用与资源
评价重点实验室,北京100037;3国家地质实验测试中心,北京100037;4河南省地质矿产勘查开发局第一地质
调查队,河南郑州450072;5中冶国际工程技术有限公司,北京100028)

摘要夜长坪钼矿床位于东秦岭-大别造山带,其赋矿围岩为中元古界官道口群龙家园组白云岩,辉钼矿化的
主要类型为细脉状、网脉状、浸染状和条带状,围岩蚀变有透辉石化、金云母化、滑石化、绿泥石化、蛇纹石化、硅化和
碳酸盐化,为斑岩-矽卡岩型钼矿床。选取5件辉钼矿样品进行了Re-Os同位素定年,获得模式年龄(145421)
Ma~(143624)Ma,等时线年龄(145344)Ma(2,MSWD=080),表明钼成矿作用发生于晚侏罗世早白
垩世。结合前人对东秦岭-大别造山带不同时期地球动力学背景的研究,笔者认为,夜长坪钼矿床形成于古太平洋板
块向欧亚大陆板块俯冲的弧后岩浆带。
关键词地球化学;Re-Os同位素定年;斑岩-矽卡岩型钼矿;夜长坪;豫西
中图分类号:P618.65文献标志码:A

MolybdeniteRe-OsisochronageofYechangpingModeposit
inwesternHenanProvinceanditsgeologicalimplications

MAOBing1,YEHuiShou2,LIChao3,XIAOZhongJun4andYANGGuoQiang5
(1ChinaUniversityofGeosciences,Beijing100083,China;2MRLKeyLaboratoryofMetallogenyandMineralAssessment,
InstituteofMineralResources,CAGS,Beijing100037,China;3NationalResearchCenterofGeoanalysis,Beijing100037,
China;4No.1GeologicalSurveyParty,HenanBureauofGeologyforExplorationandDevelopmentofMineralResources,
Zhengzhou450072,Henan,China;5MCCInternationalIncorporation,Beijing100028,China)

Abstract

TheYechangpingModepositisaporphyry-skarnModepositintheEastQinling-Dabieorogenicbelt.Its
ore-hostingwallrockischertbandeddolomitebelongingtoLongjiayuanFormationofMiddleProterozoicGuan-
daokouGroup,itsmainoretypesareveinlets,stockworks,disseminationsandbanding,anditsmajorwallrock
alterationsincludediopsidization,phlogopitization,talcization,chloritization,serpentinization,silicification,
potassicalterationandcarbonation.Fivemolybdenum-bearingsampleswereselectedforpreciseRe-Osdating,
whichyieldedmodelagesrangingfrom(145421)Mato(143.62.4)Maandanisochronageof(1453
44)Ma(2,MSWD=0.80),indicatingthatthemolybdenumdepositwasformedintheLateJurassic-Ear-
lyCretaceousperiod.Basedonastudyofgeodynamicsettingsofmolybdenumdepositsofdifferentagesinthe