摘要
EarlyPaleozoicgranodioritehasbeenidentifiedonthenorthernmarginoftheNorthChinacratonintheeastsectionofthecentral-Asianorogenicbelt,whichwaspreviouslyknownasearlyIndosinianinage.ByusingtheLA-ICP-MSmethod,theobtainedzirconU-Pbageis445.62.7Ma,whichrepresentsthecrystallizationageofthegranodiorite.Thegranodioriteneartheeastofthelarge-sizedBilihegolddepositisofthetholeiiteserieswithlowpotassium.Itisquasi-aluminousI-typegranite,enrichedinsodium(Na2O/K2O=7.299.77)andmagnesium(Mg#=0.510.67).TheΣREEvalueisrelativelylow,obviousdifferentiationisshownbetweenLREEandHREEandwithinLREE,andtheEuanomalyislowandnegative(δEu=0.740.91).Intheprimitive-mantlenormalizedspiderdiagramsoftraceelements,thegranodioriteisrelativelyrichinLREEandLILE(Ba,Sr,Th),andstronglydepletedinHFSE(Nb,Ta,TiandP),whichshowsfeaturesofsubductionzonecomponents(SZC).InthediscriminationdiagramsoftectonicsettingsofgraniteforRbvs.(Nb+Y),Rbvs.(Ya+Ta),La/Nbvs.Ba/NbandTh/Nbvs.Ba/Nb,thegranodioriteexhibitstypicalfeaturesofislandarcgranite.ThenormalizedvaluesofKandRbareextremelylow,whilethevaluesofSrandEuareveryhigh,whicharesimilartothoseofislandarcmagmathathasundergonemetasomatismoffluidfromtheoceaniccrust.ThegranodioriteisrelativelydepletedinεHf(t)(5.17.1)andlowinεHf(t)modelages(1089921Ma).IntheεHf(t)vs.age(T)diagram,thedistributionareaofthegranodioriteisaccordantwiththefieldoftheXing'anling-Mongoliaorogenicbelt,whichindicatesthatthemagmaticsourcesaremainlythemixtureofpartialmeltingofwedgedmantlesubjectedtometasomatismoffluidfromtheoceaniccrustandyoungsubstancefromthecrust.ThegranodioriteissimilartothefelsicarcmagmaintheDamaoBanner,BateObon,BoinSumandOrdorSumregions,andtheyaltogetherconstituteanearlyPaleozoicaccretionaryislandarcma
出版日期
2012年05月15日（中国期刊网平台首次上网日期，不代表论文的发表时间）
