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1、2012年6月巖礦測(cè)試Vo1.31.No.3June2012R0CKANDMINERALANALYSIS549~553文章編號(hào):0254—5357(2012)03—0549—05贛南興國(guó)楊村巖體鋯石u—Pb年齡測(cè)定及其地質(zhì)意義侯可軍,陳振宇,王登紅,陳鄭輝,趙正(國(guó)土資源部成礦作用與資源評(píng)價(jià)重點(diǎn)實(shí)驗(yàn)室,中國(guó)地質(zhì)科學(xué)院礦產(chǎn)資源研究所,北京100037)摘要:位于南嶺東段北部贛南地區(qū)興國(guó)縣境內(nèi)的楊村巖體,侵入于前寒武紀(jì)基底變質(zhì)巖中,其西側(cè)又與白堊系贛州組砂巖、礫巖斷層接觸,因而其地質(zhì)年代難以根據(jù)接觸關(guān)系準(zhǔn)確判斷,而巖體本身風(fēng)化程度比較高,難以利用K—Ar法和Rb—Sr等
2、時(shí)線等方法獲得可靠年齡,以往將該巖體歸屬于加里東期。文章采用激光剝蝕一多接收器電感耦合等離子體質(zhì)譜(LA—MC—ICPMS)鋯石U—Pb定年方法,獲得其鋯石嘶Pb/弼U加權(quán)平均年齡為(175.8±1.0)Ma,從而準(zhǔn)確地查明該巖體侵位于燕山早期第一階段與第二階段的過(guò)渡時(shí)期。這一階段在南嶺是鎢多金屬發(fā)生大規(guī)模成礦作用的開(kāi)始階段,因而楊村巖體地質(zhì)年代的確定為今后的地質(zhì)找礦提供了新的線索。關(guān)鍵詞:楊村巖體;LA—MC—ICPMS鋯石u—Pb定年;燕山早期;大規(guī)模成礦作用中圖分類號(hào):P59;P597.3;0657.63文獻(xiàn)標(biāo)識(shí)碼:AZirconU-PbAgeDatingfo
3、rtheYangcunGraniteMassesfromSouthJiangxiProvinceandItsGeologicalSignificanceHOUKeun,CHENZhen—yu,WANGDeng—hong,CHENZheng—hui,ZHAOZheng(KeyLaboratoryofMetallogenyandMineralResourceAssessment,MinistryofLandandResources,InstituteofMineralResources,ChineseAcademyofGeologicalSciences,Beijing
4、100037,China)Abstract:TheYangcungranitemassislocatednortheastofNanlingandXingguocountryoftheSouthJiangxiarea.ItintrudesintometamorphosedrocksofPrecambrianbasement,andisadjacenttoCretaceousSandstoneandconglomerateatitswestsidewithafault.Theformingtimeofthisgranitemassesisdificulttojudge
5、correctlybyitscontactrelations,anditwaspreviouslyassignedtotheCaledonianperiod.Inthispaper,wegiveaU—Pbageof(175.8-4-1.0)MaofzirconbyLaserAblation—MulticollectorInductivelyCoupledPlasma—MassSpectrometry(LA—MC—ICPMS)datingtechnology,thusascertainingthisgranitemassasanintrusionduringthepe
6、riodbetweenthefirstandsecondstageoftheearlyYanshanian,andthisperiodistheonsetperiodofextensivemineralizationoftungstenandmulti-metalsintheNanlingarea.Therefore,thedeterminationofthegeochronologyoftheYangcungranitemasseswillprovidenewinformationforprospectinginthefuture.Keywords:Yangcun
7、granitemasses;LA—MC—ICPMSzirconU—Pbdating;earlyYanshanian;extensivemineralizationperiod收稿日期:2011一l2—20;接受日期:2012—03—28基金項(xiàng)目:中國(guó)地質(zhì)大調(diào)查項(xiàng)目“南嶺地區(qū)巖漿巖成礦專屬性研究”(1212011120989);“我國(guó)重要礦產(chǎn)和區(qū)域成礦規(guī)律研究”課題(1212010633903);國(guó)家深部探測(cè)技術(shù)與實(shí)驗(yàn)研究專項(xiàng)“南嶺成礦帶地殼巖漿系統(tǒng)結(jié)構(gòu)探測(cè)實(shí)驗(yàn)”(SinoProbe0301);“南嶺于都一贛縣礦集區(qū)立體探測(cè)技術(shù)與深部成礦預(yù)測(cè)示范”課題(20101