Morphology,ChemistryandU-PbGeochronologyofZirconGrainsInQuartzMonzodioritefromtheSunzhuangArea,FanshiCounty,ShanxiProvince

Themorphology,REEgeochemistryandU-PbgeochronologyofzirconsfromquartzmonzodioriteintheSunzhuangarea,FanshiCounty,ShanxiProvincearepresentedinthisstudy.Thezirconcrystalscanbeclassifiedintofourmaintypesas:AB,L,SandP,and24subtypessuchasAB4,AB5,L5,andS3.Themaximumcrystallizationtemperatureofzirconwasestimatedas850°C,withtheminimumof550°C.Thepeaktemperaturesofthezirconcrystallizationrangefrom650°Cto700°C.TheabundancesofThandUinthezircongrainsshowlargevariationwiththeTh/Uvalues>0.4.TheThandUvaluesalsoshowapositivecorrelationinmostzircons.TheREEabundanceofzirconinthequartzmonzodioriterangesfrom280.4ppmto2143ppmwithanaverageof856.4ppm.ThechondritenormalizedzirconREEpatternsshowtwotypes,oneischaracterizedbyHREEenrichmentandLREEdepletionwithpositiveCe-anomalyandnegativeEu-anomalywhereastheotherisHREEenrichedandLREEdepletedwithnegativeEu-anomalybutwithoutpositiveCe-anomaly,andrelativelyflatpatterns.TheLA-ICP-MSU-Pbgeochronologyonthezirconsyieldsameanageof133±0.87Ma.Ourdataonzirconmorphology,compositionandU-PbgeochronologyrevealthattheparentmagmaofthequartzmonzodioritewhichwasemplacedduringlateYanshanianhadamixedcrust-mantlesource,withcrustalcomponentsdominating.Themagmaisinferredtohavebeenwaterrichandalkalinewithinitialhighoxygenfugacity.Post-magmatichydrothermalactivityoccurredunderrelativelyreducingconditionswhichwasconductiveforgoldprecipitationintheYixingzhaigolddeposit.