简介：蚌埠地区广泛出露早前寒武纪变质基底,包括新太古代-古元古代五河岩群、凤阳群以及少量的钾长花岗(片麻)岩。五河岩群上、下亚群的形成时间、沉积时限等问题一直存在争议。本文通过对五河岩群上亚群殷家涧岩组内变晶屑凝灰岩夹层进行锆石U-Pb年代学研究,获得成岩年龄为2140±17Ma,表明五河岩群上亚群形成于古元古代中期。结合区域年代学研究成果,认为在蚌埠地区存在~2.1Ga的构造-岩浆-热事件。

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简介：天山东段古生代火山-沉积地层时代特别是变质事件的厘定对探讨天山古生代洋盆演化具有重要意义。本文首次对出露于哈密沁城地区的红柳沟组中的流纹岩进行了LA-ICP-MS锆石U-Pb测年,获得了锆石（U-Pb）年龄为（426±12）Ma（MSWD=0.31）,该年龄可以代表红柳沟组的沉积年龄。同时,获得变质锆石的加权平均年龄为（372±28）Ma（MSWD=0.021）,该期变质事件在天山普遍发育,可能与天山古生代洋盆碰撞有关。

简介：WeperformedasystematictraceandrareearthelementanalysisforthebeddedFe-MncarbonaterocksrelatedtothestratiformAg-Pb-ZnmineralizationintheLengshuikengoredistrict,JiangxiProvince,SouthChina.ThreetypesofFe-Mncarbonatesaredistinguished,namely,themassive,breccia,andveintypes.Bothcarbonateandsilicatefractionsinthesamplesareanalyzedfortheirtraceandrareearthelementconcentrationsusingastepacid-leachingtechnique.OurresultsshowthatthecarbonatefractionsinthemassivetypesampleshavethelowestREEconcentrationsbutpronouncedpositiveEuandYanomalieswithEu/Eu*valuefrom1.3to6.2andY/Hovaluefrom40.1to59.5,andsimilarcharacteristicsarealsoshownforthesilicatefractionsinthemassivetypesamples(Eu/Eu*=1.0–6.7,Y/Ho=20.7–55.1).TheseREEcharacteristicsaresimilartothoseofSedextypemassivesulfidedepositsworldwide,andwesuggestthatthemassivetypeFe-Mncarbonaterockswerelikelyformedfromanexhalativevolcanic-hydrothermalfluidfeedingthedepressionbasinofavolcaniclake.Thehighconcentrationsofredox-sensitiveelementsandratiossuchasU/Th,V/CrandV/(V+Ni)indicateadysoxicenvironmentfortheFe-Mncarbonatedeposition.Incontrast,thebrecciatypeandveintypeFe-Mncarbonatesamplesshowdifferenttraceandrareearthelementfeaturesfromthoseofmassivetypesamples,andtheyaremoresimilartothevolcanicrocksandmagmatic-hydrothermalfluidsintheLengshuikengoredistrictandmayreflectstrongoverprintingfromvolcanicandsub-volcanicmagmatismrelatedtotheporphyrytypemineralizationinthedistrict.

简介：TheShihugolddeposit,situatedintheTaihangMesozoicorogenoftheNorthChinaCraton(NCC),ishostedbyductile-brittlefaultswithinArcheanmetamorphiccorecomplex.Thedepositischaracterizedbygold-bearingquartz-polymetallicsulfidesveins.TheMapenggranitoidsstockandintermediate-basicdikesintrudedthemetamorphicbasementrocks,andarespatiallyrelatedtogoldmineralization.Detailedlaserablationinductivelycoupledplasmamassspectrometry(LAICP-MS)U-Pbzirconagesofthegraniticrocks,dykesandmineralizedquartzveinsinthestudiedarearevealitsmagmaticandmineralizedhistory.Themineralizedquartzveinscontaininheritedzirconswithagesofabout2.55Gaand1.84Ga,probablycomingfromthebasement.ThesetwoPrecambrianeventsarecoevalwiththoseinotherpartsoftheNCC.TheMapenggranitoidstock,thelargestintrusioninthearea,wasemplacedatca.130Ma,andiscoevalwithmagmaticzirconpopulationsfromdioritesandquartzdioritepophyritesinthesameregion.Theca.130MamagmatismandgoldmineralizationweremostlikelyrelatedtoanunderplatingeventthattookplaceintheTaihangorogenatLateMesozoic.Thetimingofgoldmineralizationwithrespecttofelsicmagmatismintheareaissimilartothoseobservedinothermajorgold-producingprovincesintheNCC.ThisepisodeissimultaneouswiththoseintheeasternmarginofNCC,indicativeofawidespreadlateYanshanianmetallogeniceventthatwasaresponsetotheEarlyCretaceouslithosphereintheeasternNCC,inwhichthemesothermalgolddepositswereformedfromsimilartectono-magmaticenvironments.

简介：西准噶尔东部哈拉阿拉特山南麓乌尔禾地区新发现大量中基性岩墙群。岩墙群侵位于下二叠统佳木河组磨拉石建造中,展布方向与达尔布特大断裂延伸方向一致。岩墙群中采集的3个锆石U-Pb年龄样品测年结果分别为（286.3±4）Ma（n=18,MSWD=0.32,95%置信度）,（286.5±5.6）Ma（n=10,MSWD=0.3,95%置信度）和（283.6±2）Ma（n=6,MSWD=0.57,95%置信度）,误差范围内基本一致,据此确定该岩墙群形成于早二叠乌拉尔世（Cisuralian）亚丁斯克期（Artinskian）。中基性岩墙群具鲜明的与岛弧俯冲作用有关的地化特征,做为西准东部俯冲造山的地质记录,测年结果表明,西准东部的俯冲造山作用明显滞后于西部,整个西准地区俯冲造山作用结束的最终时限为早二叠世晚期。

简介：Themulti-stageintrusionsofintermediate-acidmagmaoccurintheBangpuminingdistrict,thepetrogenicagesofwhichhavebeenidentified.Thetimesandsequencesoftheiremplacementhavebeencollatedandstipulatedindetailinthispaperbyusingthelaserablation-inductivelycoupledplasma-massspectrometry(LA-ICP-MS)zirconU-Pbdatingmethod.Theagesofbiotitemonzogranitethatwereformedbeforemineralizationinthesouthwestofthisminingdistrictare70±1Ma(meansquareofweighteddeviates(MSWD)=9.5,n=8)and60.60±0.31Ma(MSWD=3.8,n=16),whichbelongtothelateCretaceous-earlyPaleoceneinage.Thatmeans,theyareproductsofanearlytectonicmagmaticeventofthecollisionbetweentheIndianandAsiancontinentals.Theagesofore-bearingmonzograniteporphyryandore-bearingdioriteporphyriteare16.23±0.19Ma(MSWD=2.0,n=26)and15.16±0.09Ma(MSWD=3.9,n=5)separately,whichbelongtothemiddleMioceneinage;namely,theyareproductsoftheGangdesepost-collisionextensionalstagewhencrust-mantlematerialsmeltedandmixedaswellasmagmaticintrusionsimultaneouslyoccurred.Somezirconswithagesof203.6±2.2Ma(MSWD=1.18,n=7)werecapturedintheore-bearingdioriteporphyrite,whichshowsthattherehadbeentectono-magmaticeventsinthelateTriassic-earlyJurassic.Molybdenum(copper)ore-bodiesproducedinthemonzograniteporphyryandcopper(molybdenum)ore-bodiesproducedinthedioriteporphyritearethemainoretypesinthisoredeposit.ThemodelagesofRe-Osisotopicdatingforthe11molybdeniteare13.97-15.84Ma,whileisochronagesare14.09±0.49Ma(MSWD=26).Theisochronagesofsevenmolybdenitefrommolybdenum(copper)orewithmonzograniteporphyrytypeare14.11±0.31Ma(MSWD=5.2).Thereisgreaterrorintheisochronagesoffourmolybdenitefromcopper(molybdenum)orewithdioriteporphyritetype,andtheirweightedaveragemodelagesof14.6±1.2Ma(MSWD=41),whichgenerallyrepresentthemineralizationage.TheresultsabouttheR

简介：Post-collisionalvolcanicrocksofMesozoicageoccurintheregionsadjacenttoGerze,partofthesouthernQiangtangTerraneofnorthernTibet,China.Geochronological,geochemical,andwholerockSr-Ndisotopicanalyseswereperformedonthevolcanicrockstobettercharacterizetheiremplacementageandmodelsfortheirorigin.Laserablation-inductivelycoupledplasma-massspectrometry(LA-ICP-MS)U-Pbzirconanalysesyieldedconsistentagesrangingfrom123.1±0.94Mato124.5±0.89Maforsixvolcanicrocksfromthestudyarea.Theintermediatevolcanicrocksbelongtothealkalineandsub-alkalinemagmaseriesintermsofK2O+Na2Ocontents(5.9%–9.0%),andtotheshoshoniticandcalc-alkalineseriesonthebasisoftheirhighK2Ocontents(1.4%–3.3%).TheGerzevolcanicrocksarecharacterizedbytheenrichmentoflightrareearthelements[(La/Yb)N=34.9–49.5]andlarge–ionlithophileelements(e.g.,Rb,Ba,Th,U,K,Pb,andSr),slightlynegativeEuanomalies(Eu/Eu*=0.19–0.24),andnegativeanomaliesinhighfieldstrengthelements(e.g.,Nb,Ta,HfandTi),relativetoprimitivemantle.Thesamplesshowslightlyelevated(87Sr/86Sr)ivaluesthatrangefrom0.7049to0.7057,andlowεNd(t)valuesfrom-0.89to-2.89.Theseresultssuggestthatthevolcanicrocksstudiedderivedfromacompositionallyheterogeneousmantlesourceandthattheirparentmagmaswerebasaltic.Themoremafic,parentalmagmastotheGerzevolcanicrockslikelyunderwentfractionalcrystallizationofclinopyroxene,hornblende,biotite,andpotassiumfeldspar,duringascent,withlittletonocrustalcontamination,priortotheireruption/emplacement.Whilethesevolcanicrocksexhibitgeochemicalsignaturestypicalofmagmasformedinadestructiveplate-marginsetting,itisplausiblethattheirmantlesourcemightalsohaveacquiredsuchcharacteristicsinanearlierepisodeofsubduction.

简介：安徽北淮阳构造带鲜花岭找矿远景区发育中酸性侵入岩相关的铜铅锌矿化,本次研究选取铜铅锌矿化相关的鲍冲二长岩开展锆石LA-ICP-MSU-Pb年代学及LA-MC-ICP-MS锆石Lu-Hf同位素分析。结果显示锆石Th/U比值为0.54-1.33,属于典型岩浆成因锆石。鲍冲二长岩锆石U-Pb年龄加权平均值为(124±2)Ma(n=10,MSWD=3.2);结合锆石自形、发育岩浆环带等特点,该年龄是鲍冲二长岩的结晶年龄。这一形成年龄对应于大别造山带构造垮塌事件,因此,北淮阳构造带鲜花岭地区铜铅锌矿化可能形成于早白垩世后岩石圈减薄环境。原位锆石Lu-Hf同位素研究显示,鲍冲二长岩的εHf(t)在-15.7~-10.2之间,两阶段锆石Hf模式年龄为1.82~2.17Ga,指示岩浆源区为古元古代的基底。结合前人资料,安徽北淮阳构造带成矿作用可以划分为三期:第一期晓天盆地的火山热液型金矿化(130Ma),第二期鲍冲岩体有关的铜铅锌矿化(124Ma)和第三期的斑岩型钼矿化(114Ma)。

简介：色勒特果勒矽卡岩型铜钼多金属矿床与侵位于上石炭统东图津河组花岗闪长斑岩关系密切。对花岗闪长斑岩的锆石SHRIMPU-Pb测年结果表明,花岗闪长斑岩的形成年龄为（302±3）Ma,MSWD=2.1,指示其形成于晚石炭世。岩石地球化学特征表明,斑岩体为准铝-弱过铝的I型花岗岩,属钙碱性系列,富集K,Rb和Th等LILE元素和相对亏损Nb,Ta,Hf,Y,Yb等HFSE元素,出现了较明显的Nb,Ta负异常,暗示其源区为大陆弧环境。本区斑岩具高的LREE/HREE和LILE/HFSE比值,较低的Ba/Th比值,暗示斑岩的岩浆受俯冲带熔体显著改造。结合邻区岩浆岩特征及时代,花岗闪长斑岩形成于后碰撞阶段,其形成可能与晚泥盆—早石炭世俯冲的洋壳形成的新生大陆地壳在晚石炭世造山后伸展体制下部分熔融有关。