不同类型热液金矿系统的流体包裹体特征

1000-0569/2007/023(09)-2085-08ActaPetrologicaSinica岩石学报不同类型热液金矿系统的流体包裹体特征陈衍景1，2倪培3范宏瑞4FPirajno1，5赖勇2苏文超6张辉6CHENYanJing,NIPei，FANHongRui,FPirajno,LAIYong,SUWenChaoandZHANGHui1.中国科学院广州地球化学研究所成矿动力学重点实验室，广州5106402.北京大学造山带与地壳演化重点实验室，北京1008713.南京大学壳慢演化与成矿国家重点实验室.南京2100934.中国科学院地质与地球物理研究所岩石圈演化重点实验室，北京1000295.GeologySurveyofWestAustralia,100PlanStreet,Perth,WA6004，Australia6.中国科学院地球化学研究所，贵阳5500021.KLMD,GuangzhouInstituteofGeochemistry认ChineseAcademyofSciences,Guangzhou510640，China2.LaboratoryofOrogenandCrustEvolution,PekingUniversity,Beijing100871，China3.KeyLaboratoryofCrust-MantleEvolutionand}ineralization,NanjingUniversity,Nanjing210093，China4.KeyLaboratoryofLithosphereEvolution,InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Beijing100029,China5.GeologySurveyofWestAustralia,100PlainStreet,Perth,WA6004，Australia6.InstituteofGeochemistry，ChineseAcademyofSciences,Guiyang550002，China2006-12-30收稿，2007-06-22改回.ChenYJ,NiP,FanHR,PirajnoF,LaiY,SuWCandZhangH.2007.Diagnosticfluidinclusionsofdifferenttypeshydrothermalgolddeposits.ActaPetrologicaSinica.23(9);2085一2108AbstractThispaper,usinggolddepositsasexample,attemptstosetupascientificlinkagebetweenoregeologyandfluidinclusions，consideringthatinpreviouspublishedworks,observationsandmeasurementsofthefluidinclusionscommonlywerenotwellinterpreted.Insomecases,geologicaldatadidnotagreewiththeresultsobtainedfromfluidinclusionstudies.Inthispaper,wefirstreviewpreviousclassificationsofgolddeposits，andthen，subdividegolddepositsintofiveclasses，basedonthedominantore-formingprocesses:1)intrusion-relatedhypothermalsystems，suchasporphyry-systems,breccia-pipes,IOCGandskarns;2)orogenic-ormetamorphichydrothermaltype;3)epithermal-type,i.c.reworkinghydrothermaldepositshostedincontinental-faciesvolcanic-subvolcanicrocks;4)fine-graindisseminatedtype(Carlin-typeand/orCarlin-style)，i.e.reworkinghydrothermaldepositshostedsediments;and5)hydrothermalmetalliferoussedimentsrelatedtosubmarineventing,suchasVMSandSEDEXstyles.Inthisworkweselectdiagnosticgeologicalandfluid-inclusioncharacteristicsofthesefiveclassesofore-systems，andclarifytheirkeydifferencesthatcanbeusedasgeneticmarkers.Ore-fluidsareclassifiedintothreeend-members，namelyreworking,metamorphicandmagmaticfluids.Manyore-systemsareknowntoformasaresultofmultiplefluidsduringmulti-stageevents;andtheirlate-stageofmineralizationalwaysbeingcausedbyfluidswithahigh-proportionofreworkingoftheoriginaloresystemsorbyrenewedfluidflow.Therefore，thefeaturesoflate-stagefluids，alterationandmineralizationcannotbeusedtoidentifytheoriginandgenetictypeofanore-system.Instead，wesuggestthatonlytheearly-stagesignaturescanbeemployedtodeterminetheoriginandtypeofanore-system.Reworkingfluidsarecharacterizedbylow-temperature(3000C)，low-salinityandlow-contentofCOZ，andsourcedfrommeteoricand/orseawater;metamorphicfluidsbymoderate-temperature,low-salinityandhigh-contentofCOZ;andmagmaticfluidsbyhigh-本文受国家973项目(2006CB403500)和I_I家自然科学基金项目(编号为40425006,40730421)的资助。第一作者简介:陈衍景，男，1962年生，中国科学院广州地球化学研究所成矿动力学重点实验室研究员，北京大学地质学系教授从事矿床地质研究，E-mail:[e-mail];[e-mail]2086ActaPetrologicaSinica岩石学报2007,23(9)temperature，high-salinityandhigh-contentofCOZ.Magmatichydrothermalore-systemscontainmulti-daughter-crystal-bearingandhigh-salinity,C02-richfluidinclusions;metamorphicore-systemscontainlow-salinity,C02-richfluidinclusions;andthereworkinghydrothermalore-systemscontainneitherdaughter-crystal-bearingnorC02-rich/bearingfluidinclusions，butarepopulatedbyaqueouswater-solutionfluidinclusions.Finally,wediscussthetectonicsettingsoftheore-systemsofthevariousclasses.Forexamples,theorogenic-typeformedduringprocessesofcrustalcompression,orogenesis，metamorphismanduplift;submarinemetalliferoussedimentsdevelopedinthesettingofriftbasins;Paleozoicorearlierepithermal-typeore-systemscanbepreservedinaccretionaryorogens.Itissuggestedthattheore-systemsandtheirfluidinclusionscanbeusedasanidealprobetotracegeodynamicevolutionofcontinents.KeywordsGoldore-system,Fluidinclusion，Oregeology,Probe,Continentaldynamics摘要为使流体包裹体研究结果得到较好的解释，避免矿床地质描述与流体包裹体研究结果发生矛盾，本文试图以金矿床为例，建立科学而简便易行的矿床地质与包裹体特征之间的链接。为此，本文简单评述了现有金矿床成因分类方案，建议以主导成矿系统发育的地质作用特征划分5种类型:①装控高温热液型，包括斑岩型、爆破角砾岩型、铁氧化物型、夕卡岩型等岩装热液型矿床;②造山型，即变质热液型;③浅成低温热液型—陆相火山岩一次火山岩中的改造热液型;④微细粒浸染型(卡林型或/类卡林型)—沉积岩容矿的改造热液型;⑤热水沉积型(VMS型和SEDEX型)—水下喷出地表的改造热液型。然后，分别介绍了5类成矿系统的标志性地质和流体包裹体特征，找出了它们之间具有成因标志意义的关键性差异;将成矿流体分为改造、变质和岩浆3个端元性成分，发现多数热展矿床具有多阶段多因复成的特点.晚阶段流体均为改造热液或有大量改造热液注入，因此指出，晚阶段的流体、蚀变和矿化特VIT不能用于判别矿床成因和类型，只有早阶段的特征才能准确指示矿床成因和类型。改造热液以低温、低盐度、低CO,含量为钱征，主要来自大气降水和/或海水;变质热液以中温、低盐度、动力学的理想探针。关键词金成矿系统;流体包裹体;矿床地质;探针;大陆动力学中图法分类号P618.511.引言除砂金和铜镍硫化物矿床中的伴生金以外，所有金矿床都属于热液金矿床。热液金矿床是成矿流体活动的产物，成矿流体活动记录在热液矿物及其流体包裹体中，这使得流体包裹体成为研究流体成矿作用的“化石”或“探针”。流体包裹体研究包括单个包裹体原位观测和群体包裹体分析两种途径，前者如冷热台观测，激光拉曼光谱分析，LA-ICPMS分析等技术;后者如爆裂温度记录，气相和液相色谱或质谱分析，碳、氢等同位素分析等。随着科学技术的进步，单个和群体包裹体测试手段都不断更新(详见卢焕章等，2004)，获得的数据和认识日趋准确、可信，且两种途径的结果相互补充，不但促进了流体包裹体地球化学的发展，而且强化了包裹体的“化石”或“探针一”功能。目前，“包裹体探针”已成为热液金矿床成矿作用研究中一项不可缺省的重要内容。然而，由于流体成矿系统的复杂性和人类掌握科学技术知识的局限性，大量包裹体研究资料未能被科学解释和运用，突出地表现在矿床地质与流体包裹体特征之间脱节，甚至出现包裹体研究结果与矿床地质特征描述自相矛盾的现象。例如，多数学者主张祁雨沟