摘要
TheLateCretaceousMambagranodioritebelongstoapartoftheMesozoicGangdesecontinentalmagmaticbelt.Noquantitativemineralogicalstudyhasbeenmadehitherto,andhencethedepthatwhichitformedispoorlyconstrained.HerewepresentmineralogicaldatafortheMambapluton,includinghostrocksandtheirmaficmicrogranularenclaves(MMEs),toprovideinsightsintotheiroverallcrystallizationconditionsandinformationaboutmagmamixing.AllamphibolesintheMambaplutonarecalcic,with~B(Ca+Na)>1.5,andSi=6.81–7.42apfuforthehostrocksandSi=6.77–7.35apfufortheMMEs.Theparamountcationsubstitutionsinamphiboleincludeedenitetypeandtschermakitetype.BiotitesbothinthehostrocksandtheMMEscollectivelyhavehighMgO(13.19wt.%–13.03wt.%)contents,butdefineanarrowrangeofAlapfu(atomsperformulaunit)variations(2.44–2.57).TheoxygenfugacityestimatesarebasedonthebiotitecompositionsclusteraroundtheNNObuffer.Thecalculatedpressurerangesfrom1.2to2.1kbaraccordingtothealuminum-in-hornblendebarometer.Thecomputedpressurevariesfrom0.9to1.3kbarbasedonthealuminum-in-biotitebarometerwhichcorrespondstoanaveragedepthofca.3.9km.Besides,theestimatesofcrystallizationpressuresvaryfrom0.8to1.4kbarbasedontheamphibolebarometerproposedbyRidolfietal.(2010),whichcanbeequivalenttothedepthsrangingfrom3.1to5.2km.TheMMEshaveplagioclaseoscillatoryzoningsandquartzaggregates,probablyindicatingthepresenceofmagmamixing.Besides,core-to-rimelementvariations(Rb,Sr,Ba,andP)fortheK-feldsparmegacrystsserveasrobustevidencetosupportmagmamixingandcrystalfractionation.ThisindicatesthesignificanceofthemagmamixingthatcontributestotheformationofK-feldsparmegacrystzoningsintheMambapluton.
出版日期
2016年04月14日（中国期刊网平台首次上网日期，不代表论文的发表时间）
