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《西秦嶺天水地區(qū)太白花崗巖體LA-ICP-MS鋯石U-Pb年齡、地球化學(xué)特征及其地質(zhì)意義.pdf》由會(huì)員上傳分享,免費(fèi)在線閱讀,更多相關(guān)內(nèi)容在行業(yè)資料-天天文庫(kù)。
1、第33卷第7期地質(zhì)通報(bào)Vo1.33.No.72014年7月GEoLoGICALBULLETINOFCHINAJu1.,2014西秦嶺天水地區(qū)太白花崗巖體LA—ICP—MS鋯石u—Pb年齡、地球化學(xué)特征及其地質(zhì)意義任厚州,裴先治1,2,劉成軍,李佐臣L,李瑞保L,魏博,陳偉男,王元元,胥曉春,劉圖杰,陳有斷KENHou—zhou,PEIXian—zhi,LIUCheng—jun,LIZuo—chen,LIILui—bao,WEIBo,CHENWei—nan,WANGYuan—yuan,XUXiao—chun,LIUT
2、u-jie,CHENYou—xin1.長(zhǎng)安大學(xué)地球科學(xué)與資源學(xué)院,陜西西安710054;2.長(zhǎng)安大學(xué)西部礦產(chǎn)資源與地質(zhì)工程教育部重點(diǎn)實(shí)驗(yàn)室,陜西西安7100541.SchoolofEarthScienceandResource,Chang"anUniversity,XUan710054,Shaanxi,China;2.KeyLaboratoryofWesternMineralResourcesandGeologicalEngineering0廠n£ofEducation,Chang~nUniversity,Xi"a
3、n710054,Shaanxi,China摘要:秦嶺造山帶南緣勉略構(gòu)造帶北側(cè)發(fā)育有近東西向展布的印支期花崗巖帶,位于甘肅徽縣地區(qū)的太白巖體是該花崗巖類的一部分。LA—ICP-MS鋯石u—Pb同位素年齡表明,太白巖體的形成時(shí)代為221.8Ma_+1.5Ma,屬于印支期晚期。主要巖石類型為灰白色一肉紅色中細(xì)粒二長(zhǎng)花崗巖和花崗閃長(zhǎng)巖。地球化學(xué)特征表明,太白巖體屬于準(zhǔn)鋁質(zhì)一弱過(guò)鋁質(zhì)的高鉀鈣堿性系列;稀土元素總量∑REE為79.O×10~194x10~,稀土元素配分模式呈輕稀土元素強(qiáng)烈富集、重稀土元素相對(duì)虧損的右傾型,Eu負(fù)
4、異常明顯;高場(chǎng)強(qiáng)元素(HFSE)Nb、P、Ti、Y、Yb和大離子親石元素Ba、sr強(qiáng)烈虧損。太白巖體是以中基性巖石為主的殼源物質(zhì)部分熔融形成的巖漿上升侵位形成的,且處于同碰撞(擠壓環(huán)境)向后碰撞(伸展環(huán)境)轉(zhuǎn)化階段,為后造山期花崗巖,是揚(yáng)子板塊和華北板塊全面碰撞導(dǎo)致增厚下地殼物質(zhì)部分熔融的產(chǎn)物。關(guān)鍵詞:西秦嶺;太白巖體;二長(zhǎng)花崗巖;LA—ICP—MS鋯石u—Pb年齡;后碰撞中圖分類號(hào):P588.121;P597~.3文獻(xiàn)標(biāo)志碼:A文章編號(hào):1671—2552(2014)07—1041—14RenHZ,PeiXZ,L
5、iuCJ,LiZC,LiRB,WeiB,ChenWN,WangYY,XuXC,LiuTJ,ChenYX.LA—ICP—MSzirconU-·PbdatingandgeochemistryoftheTaibaiintrusioninTianshuiareasofwesternQinlingMountainsandtheirgeologicalsignificance.GeologicalBufleanofChina,2014,33(7):1041—1054Abstract:AnEW——trendingIndosini
6、angranitoidebeltextendsnearnorthernMianluesuturezoneonthesouthmarginofQiNingorogenicbelt.TheTaibaiintrusionisapartoftheIndosiniangranitoidslocatedintheHuixianCountyofGansuProvince.LA—ICP—MSzirconU—PbdatingoftheTaibaiintrusionindicatesthattheemplacementageofthe
7、Taibaiintrusionis221.8Ma+1.5Ma,sug-gestingLateIndosinian.TheTaibaiintrusionismainlycomposedofgray—palered,mediumtofinegr~nedmonzoniticgraniteandgranodiorite.Accordingtothegeochemicalcharacteristics,itissuggestedthatTaibaiintrusionbelongstothemetaluminoustoweak
8、lyperaluminoushigh—potassiccalc—alkalineseriesandischaracterizedbystrongdepletionofhighfieldstrengthelements(HFSE)Nb,Ti,PY,YbandlargeionelementsBa,SrwithobviousnegativeEuanomalies.