榴辉岩相峰期流体活动来自东昆仑榴辉岩石英脉的证据.PDF
文本预览下载声明
10000569/2014/030(08)233950 ActaPetrologicaSinica 岩石学报
榴辉岩相峰期流体活动:来自东昆仑榴辉岩石英脉的
证据
1,2 2 1,2
贾丽辉 孟繁聪 冯惠彬
1,2 2 1,2
JIALiHui ,MENGFanCong andFENGHuiBin
1中国地质大学,北京 100083
2中国地质科学院地质研究所,大陆构造与动力学国家重点实验室,北京 100037
1ChinaUniversityofGeosciences,Beijing100083,China
2StateKeyLaboratoryforContinentalTectonicsandDynamics,InstituteofGeology,ChineseAcademyofGeologicalSciences,Beijing100037,China
20140210收稿,20140512改回
JiaLH,MengFCandFengHB2014Fluidactivityduringeclogitefaciespeakmetamorphism:Evidencefromaquartz
veinineclogiteintheEastKunlun,NW ChinaActaPetrologicaSinica,30(8):2339-2350
Abstract ThispaperreportsaquartzveinineclogitefromWenquanareaintheEastKunlun,andthroughacomprehensive
researchinUPbageandLuHfisotope,whichprovidessomeevidenceaboutfluidactivityinpeakeclogitefaciesmetamorphicstage
ThezircongrainsinWenquanquartzveinhaveperfecteuhedralhabitandshowsectororweakzoning,whichprecludesthepossibility
thatthezirconcrystalswerephysicallyintroducedintothequartzveinfromthecountryrockZircongrainsfromquartzveinandeclogite
206 238
yieldweightedmean Pb/ Udateof450±2Maand451±2Ma,respectively,whichdescribesthattheformingageofzirconin
quartzveinandthepeakeclogitefaciesmetamorphicstageareconsistentThesimilarityofHfisotopecompositioninthetwostylesof
zirconprovestheaqueousfluid/meltthatformedveinsisinternalsource,whichmaybederivedfromthefusedquartzineclogite,but
wecannotprecludetheexsolusionofstructuralhydroxylinomphaciteandgarnetQuartzveinformedmorelikelyinaqueousfluid
ratherthanmeltbecauseofthelowU,ThcontentsandTh/Uratiosinzircons
Keywords Zircon;Quartzvein;Eclogite;UPb;LuHf;EastKunlun
摘 要 本文通过对东昆仑温泉地区榴辉岩中石英脉的锆石UPb定年和LuHf同位素的综合研究,为榴辉岩相峰期变质
阶段的流体活动提供了一定的证据。石英脉中的锆石晶型较好,具有振荡环带或弱分带,排除了从寄主榴辉岩中捕获锆石的
可能性。石英脉和寄主榴辉岩中锆石UPb年龄的加权平均值分别为450±2Ma和451±2Ma,说明石英脉中锆石的形成年龄
与榴辉岩相的峰期变质阶段一致。两种锆石Hf同位素组成的相似性说明形成石英脉的流体/熔体为内部来源,推测可能为榴
辉岩中石英发生溶解以及绿辉石和石榴石分子结构中羟基的出溶作用形成。锆石
显示全部