桂西北地区石英斑岩特征与其与金矿成矿的关系

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1、AbstractTheCarlin-typegolddepositsinnorthwestofGuangxiprovinceisconsideredasanimportantofCarlin-typegolddepositconcentrationareaof“Dian-Qian-Gui”.NorthwestGuangxidistributedseveralquartzporphyryveinssuchasBama,LingyunandFengshan.IsotopicgeochronologystudyindicatesthattheLateYanshanianperiod

2、duringwhichthequartzporphyryformedmatchestheOreformingageofCarlintypegolddeposits.Buttherelationshipbetweengoldmineralizationandquartzporphyryremainscontroversial.Inthispaper,weobtainedthefollowingmainachievementsandunderstandings,basedonthestudiesofbodymorphology,occurrenceandcharacteristi

3、csofthequartzporphyrywhichwerecollectedfromdifferentareas,aswellasmajorelement,traceelement,rareearthelementandleadisotopegeochemistrydataanalysis.TherearefrequentmagmaticactivitiesandlargeamountofmagmaticrocksinthenorthwestofGuangxi.Thevolcaniczoneischieflycomposedofintermediate-basicvolca

4、nicrocksandbasicvolcanicrocks.AcidicmagmaeruptedandoverflowedatearlyTriassic,middleTriassic,formingverythickacidicvolcanorock.AfterLatePaleozoiccrustextensionandfaultdepression,basicmagmaraisedthroughthecrackofmantle.Thisprocessisthekeyfeatureofmagmaactivity.TheLateYanshanianquartzporphyrie

5、sappearinLongtian,Lingyun,Bama,LongchuanandMountFengupliftintheformofsmallrockbodyanddike.ItstectoniccompressionenhancedinYanshanperiod.Thecontinententeredintothestageofcontinentalmargin.AcidicintrusiverocksappearedasaresultoftheintensiveYanshantectonicacitivity.Theinvasionofacidicmagmaprov

6、idedfavorabletectonicbackgroundanddeepstructuralconditionstotheformationofthegolddeposit.ThestudyareawhichislocatedintheancientTethystectonicbelt,belongingtoYoujiangriftbelt,hasthefeatureofplateboundaryfaultzoneandthecontinentalmarginbasin.Thespecialtectonicconditionofcontinentalislandarcan

7、dorogenicbeltisthefavorabletectonicbackgroundfortheformationofgolddeposit.ThequartzporphyrywithhighcontentsofSiO2areacidicrocks;Na2Olevelsarelow,theaveragecontentis0.06%.ThecontentsofK2O(theaverageis3.27%)andAl2O3(theaverageis13.54%)arehigh,therocksbelon