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)。