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时间:2020-03-26
《皖南及邻区燕山期两个类型花岗岩地球化学对比与岩石成因.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、矿物岩石地球化学通报·研究成果·BulletinofMineralogy,PetrologyandGeochemistryVoI_3ONo.4.Oct.2011皖南及邻区燕山期两个类型花岗岩地球化学对比与岩石成因翁望飞,支利庚,蔡连友,徐生发,王邦民安徽省地质矿产勘查局332队地调院,安徽黄山245000摘要:皖南周边分布着4O余处大小不等的燕山期花岗岩体,依据岩石年龄可划分出2个幕次:一是130~170Ma,平均145Ma,为晚侏罗世~早白垩世早期(J。一K}),以花岗闪长(斑)岩为主;二是10
2、9~132.2Ma,平均123.5Ma,为早白垩世中、晚期(K}),岩性为花岗岩。研究表明,J3-Ki花岗闪长岩为c型、高钾钙碱性埃达克岩,发育于造山后构造,应力由挤压转变为伸展的转折期,源自印支期加厚地壳部分熔融。而K{幕花岗岩为A型花岗岩,产生于造山后的构造伸展环境,源自正常安山质地壳在印支期加厚地壳熔融结束之后继续受地幔物质底侵部分熔融。埃达克岩与斑岩铜矿及金、银等矿床成因上密切相关,A型花岗岩富集稀土元素及w、Zr、Nb、Ta、U等。因此加强皖南及邻区埃达克岩和A型花岗岩的研究,可为该地区
3、寻找斑岩铜矿床及稀土、稀有金属等矿床提供一个新的思路和方向。关键词:地球化学特征;埃达克岩;A型花岗岩;岩石成因;构造环境;燕山期;皖南中图分类号:P581;P588;P591文献标识码:A文章编号:1007—2802(2011)04—0433—16PetrogenesisandGeochemicalComparisonofTwoTypesofYanshanianGraniteinSouthAnhuianditsSurroundingAreaWENGWang—fei,ZHILi—geng,CAIL
4、ian~you,XUSheng—fa,WANGBang~ming332GeologicalTeamofAnhuiBureauofGeologyandMineralExploration,Huanghshan245000,ChinaAbstract:Morethan40YanshaniangranitesaredistributedinsouthAnhuiandsurroundingarea,andagesofthesegranitescanbeclassifiedintotwostages:the
5、firststagebelongstoJ3-K,13O~170Mawithanaverageageof145Ma,andthesecondstagebelongstoK,109~132.2Mawithanaverageageof123.5Ma.Theanalysisofpetro—logicalandgeochemicalcharacteristicsshowsthatthegranodioritesofJ3-KinsouthAnhuiandvicinitiesareCtype,high-Kcal
6、c—alkalineadakite(HKCAA),formedfrompartialmeltingofthethickenedlowercrustbydelami—nationinMesozoicineasternChina.TheanalysisofgeochemicalcharacteristicsofthegranitesinKshowsthattheyareA2一typegranites,formedinextensionalenvironmentafterorogeny,resultin
7、gfrompartialmeltingofande—siticcrustaftertheformationofadakite.Inaddition,acloserelationshipexistsamongadakite,porphyrycopperandmulti—metaldeposits,andA-typegraniteplaysaimportantroleintheenrichmentofrareearthelements,suchas,W,Zr,Nb,Ta,Uandsoon.Theref
8、ore,thoroughresearchesonadakiteandA-typegraniteinsouthAnhuiandvicinitieswillprovidenewideasanddirectionsfortheexplorationofporphyrycopper,rareearthelementandraremetaldeposits.Keywords:geochemicalcharacteristic;adakite;A—typegranite;petrogenesi
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