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1、礦物巖石地球化學(xué)通報(bào)·研究成果·BulletinofMineralogy,PelrologyandGeochemistryVo1.29No.4,Oct.2010貴東巖體黑云母成分特征及其對(duì)鈾成礦的制約陳佑緯,畢獻(xiàn)武,胡瑞忠,朱維光,胥磊落,董少花1.巾國(guó)科學(xué)院地球化學(xué)研究所礦床地球化學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室,貴陽(yáng)5500022.中國(guó)科學(xué)院研究生院,北京100049摘要:魯溪巖體和下莊巖體為粵北貴東復(fù)式巖體的重要組成部分,兩巖體構(gòu)造背景相同,空間上緊密共生,時(shí)間上近乎同時(shí)生成,但魯溪巖體不成礦,而下莊巖體賦存著大量鈾礦床。這種差異的原因探究對(duì)深刻揭示花崗巖型鈾礦床成礦機(jī)制具有重要的意義。對(duì)
2、魯溪巖體和下莊巖體中黑云母的電子探針、穆斯鮑爾譜和ICPMS分析表明,兩巖體黑云母的主量元素具有富鐵貧揮發(fā)分的特點(diǎn);微量元素特征類似,具明顯的負(fù)銪異常;相對(duì)于魯溪巖體,下莊巖體的演化程度和揮發(fā)性組分F含量較高,而溫度和氧逸度較低。從魯溪巖體到下莊巖體,由于演化程度升高,F(xiàn)含量增高,溫度和氧逸度降低,使鈾在花崗巖中的豐度升高,賦存方式由不利于成礦的類質(zhì)同像替換演變?yōu)橛欣诔傻V的品質(zhì)鈾礦形式存在,這是魯溪巖體不成礦而下莊巖體有大量鈾礦床的主要原因。關(guān)鍵詞:黑云母;礦物化學(xué);鈾豐度;鈾賦存形式中圖分類號(hào):P618.14文獻(xiàn)標(biāo)識(shí)碼:A文章編號(hào):l0072802(20l0)040355-0
3、9TheGeochemicalCharacteristicsofBiotitesandtheirConstraintsonUraniumMineralizationinGuidongPlutonCHENYou—wet一,BIXian—WU,HURut—zhong,ZHUWei—guang.XULetluo~.DONGShaohua’1.StateKeyLaboratoryofOreDepositGeochemistry,Institute0.,Geochemistry,ChineseAcademyofSciences,Guiyang550002,China;2.GraduateU
4、niversityofChineseAcademyofSciences,Beijing100049,ChinaAbstract:TheLuxigraniteandtheXiazhuanggraniteareimportantpartsoftheGut~dongcompositeplutoninthenorthernGuangdongprovice.Theyhavethesametectonicsetting,similarspatialassociationandsimilarage.However.manyuraniumdepostitesareformedinXiazhuan
5、ggranitewhilenoneisfoundintheIuxigranite.Ade—tailstudyonthisdifferenceissignificantforunderstandingthemetallogenicmechanismofgranite——typeuraniumde—posit.Biotitecontainsalotofgeochemicalinformationaboutthemagmaticcrystallization.Theresultsoftheelec—trionmicroprobe,MOssbauerspectroscopyandICP—
6、MSanalysesofbiotitescollectedfromI.uxiandXiazhuanggranitesindicatedthatthesebiotiteshavesimilarmajorelementcontents,richinFebutpoorinvolatileconsi—tutents,andhavesimilartraceelementcontents,strongnegativeEuanomalies.ThebiotitesofXiazhuanggranitearedistinguishedfromthoseoftheLuxigranitebyhighe
7、revolutiondegree,moreFcontent,lowertemperatureandloweroxygenfugacity.TheevolutiondegreeandFcontentincreaseandthetemperatureandoxygenfugacityde—creasefromLuxigranitetoXiazhuanggranitemaycausethattheuraniumcontentincreasesandthattheexistingstat