ThePayangazucomplexinthecentralMyanmariscomposedmainlyofquartzdiorite,granodiorite,andsomesynplutonicmaficdikes.ThequartzdioriteandgranodioritehavezirconU-Pbagesof130.5±4.0(MSWD=3.5)and118.4±2.5Ma(MSWD=2.4),respectively.Rocksamplesofthequartzdioriteandgranodioritearemetaluminous,enrichedinlarge-ionlithophileelementslikeLREE,Rb,Th,andU,anddepletedinhighfield-strengthelementssuchasHREE,Nb,Ta,P,andTi,indicativeofarc-typemagmaticaffinities.WholerocksamplesofthequartzdioritehaveεHf(t)valueof+0.6,initial^87Sr/^86Srratiosof0.7086to0.7100,andεNd(t)valuesof-4.8to-4.9;whereasrocksofthegranodioritearerelativelyisotopicallyenriched,withεHf(t)valuesof-5.1to-7.2,initial^87Sr/^86Srratiosof0.7117to0.7118,andεNd(t)valuesof-8.7to-8.8.TheisotopicdatatogetherwiththehighMg#(boththequartzdioriteandgranodioritehaveMg#valuesof>40)suggestastronginvolvementofmantlematerialsinthegenesisoftheparentmagmas.Thepossiblepetrogeneticprocessmaybethattheascendingofmeltsfrompartialmeltingofmetasomatizedmantlewedgetriggeredbydehydrationofsubductedslabresultedinpartialmeltingofthelowercrustandmixedwiththelatter.TheseEarlyCretaceousintrusionsfromthecomplexareolderthanthosefoundintheeasternWuntho-PopaarcinwesternMyanmar,easternHimalaya,andwesternYunnanwhichareinterpretedtoberelatedtotheNeo-Tethyansubduction,andhaveεNd(t),εHf(t)valueslowerthanthelatter.Onthecontrary,theagesandgeochemicalcharacteristicsofthePayangazucomplexareconsistentwithsomeoftheintrusionsinthenorthernmagmaticbeltinTibet,easternHimalaya,andwesternYunnanwhicharebelievedtobeassociatedwiththesubductionoftheBangong-NujiangOceancrust.Thus,weproposethattheEarlyCretaceousintrusionsinthecentralMyanmararemostlikelyrelatedtothesouthwardsubductionofanoceanslabthatwaspossiblyanextensionoftheBangong-NujiangOcean.
