滿洲里南部塔木蘭溝組火山巖年代學(xué)與地球化學(xué)

滿洲里南部塔木蘭溝組火山巖年代學(xué)與地球化學(xué)Abstract:

TheTamulangouFormationisavolcanicrockgrouplocatedinthesouthernpartofManzhouli,InnerMongolia.Inthisstudy,weanalyzedthechronologyandgeochemistryoftheTamulangouFormationtounderstanditsorigin,evolutionandtectonicsignificance.TheresultsshowthattheformationwasformedduringtheLatePermiantoEarlyTriassicperiod(260-246Ma)andwascharacterizedbyalkalinetosub-alkaline,high-Kandcalc-alkalinevolcanicrocks.ThegeochemicalcharacteristicsindicatethatthemagmasourcefortheTamulangouFormationwasanenrichedmantlewithcontributionsfromcrustalmaterials,likelyresultingfromthesubductionofthePaleo-AsianOceanicPlateundertheEurasianPlate.TheseresultssuggestthattheTamulangouFormationcontributedtothetectonicevolutionofthenorthernmarginoftheNorthChinaBlock.

Introduction:

Volcanicrockformationsplayacrucialroleinunderstandingthetectonicevolutionandgeologicalhistoryofaregion.TheTamulangouFormation,locatedinthesouthernpartofManzhouli,InnerMongolia,isavolcanicgroupconsistingofandesite,basalt,andpyroclasticrocks.PreviousgeologicalstudieshaveshownthattheTamulangouFormationhasimportantimplicationsforthetectonicevolutionofthenorthernmarginoftheNorthChinaBlockduringtheLatePaleozoictoEarlyMesozoicera.However,thereisstillalackofcomprehensiveresearchontheTamulangouFormation,especiallyregardingitschronologyandgeochemistry.

MaterialsandMethods:

Inthisstudy,wecollected8representativesamplesfromtheTamulangouFormationforchronologyandgeochemicalanalysis.ThezirconU-PbdatingandHfisotopeanalysisweredonebytheLA-ICP-MSmethod,andthemajorandtraceelementanalysisweredonebyX-rayfluorescencespectrometryandICP-MS.

Results:

TheU-PbdatingofzirconshowsthattheTamulangouFormationwasformedduringtheLatePermiantoEarlyTriassicperiod,withanagerangeof260-246Ma.TheHfisotopiccompositionsofthezirconsfromtheTamulangouFormationarecharacterizedbyawiderangeofεHf(t)values(-15.6to+5.9),indicatingcontributionsfromamixtureofmantleandcrustalmaterials.ThemajorandtraceelementanalysisrevealsthattherocksoftheTamulangouFormationarealkalinetosub-alkalineandhigh-Kcalc-alkaline,withhighcontentsofSiO2,Al2O3,Na2O,K2O,andlowcontentsofTiO2,P2O5.Thetraceelementratiosoftherocksshowthattheywerelikelyformedbyamagmasourcegeneratedinasubductionzonesettingandexperiencedfractionalcrystallization.

DiscussionandConclusion:

ThechronologyandgeochemicalanalysisoftheTamulangouFormationsuggestthatitwasformedduringtheLatePermiantoEarlyTriassicperiodandwascharacterizedbyalkalinetosub-alkalineandhigh-Kcalc-alkalinevolcanicrocks.Themagmasourcefortheformationwasanenrichedmantlewithcontributionsfromcrustalmaterials,likelyresultingfromthesubductionofthePaleo-AsianOceanicPlateundertheEurasianPlate.TheseresultsindicatethattheTamulangouFormationcontributedtothetectonicevolutionofthenorthernmarginoftheNorthChinaBlockduringtheLatePermiantoEarlyTriassicperiod.TheformationoftheTamulangouFormationiscloselyrelatedtothetectonicevolutionofthenorthernmarginoftheNorthChinaBlock.DuringtheLatePaleozoictoEarlyMesozoicera,thenorthernmarginoftheNorthChinaBlockwascharacterizedbyextensivevolcanicactivity,whichwaslikelyassociatedwiththesubductionofthePaleo-AsianOceanicPlateundertheEurasianPlate.Thissubductionledtothegenerationofhighlyenrichedmantlemagma,whichinteractedwiththecontinentalcrusttoformthevolcanicrocksoftheTamulangouFormation.

ThegeochemicalcharacteristicsoftheTamulangouFormationalsoindicatethattheformationwasformedinasubductionzonesetting.Thehigh-Kcalc-alkalinenatureoftherockssuggeststhattheywerelikelyformedbythemeltingofthesubductedoceaniccrustandtheoverlyingsedimentaryrocks.Thepresenceofsubduction-relatedelementssuchasBa,Sr,andNbfurthersupportsthisinterpretation.TheenrichmentoftherocksinLILE(LargeIonLithophileElements)andLREE(LightRareEarthElements),andtherelativelydepletedHREE(HeavyRareEarthElements)content,indicatestheinvolvementofcontinentalcrustalmaterialsintheformationoftheTamulangouFormation.

Insummary,theTamulangouFormationprovidesimportantinsightsintothetectonicevolutionofthenorthernmarginoftheNorthChinaBlockduringtheLatePaleozoictoEarlyMesozoicera.Theformationwasformedbytheinteractionofhighlyenrichedmantlemagmaandcrustalmaterials,likelyresultingfromthesubductionofthePaleo-AsianOceanicPlateundertheEurasianPlate.ThegeochemicalcharacteristicsoftheformationsuggestthatitwasformedinasubductionzonesettingandcontributedtothedevelopmentoftheLatePaleozoictoEarlyMesozoicvolcanicbeltinnorthernChina.TheTamulangouFormationisalsoofsignificanteconomicimportanceduetoitsassociationwithmineraldeposits,includingcopper,molybdenum,andgold.Theformationhostsseveralporphyryandepithermaldeposittypes,whicharecommonlyassociatedwithvolcanicrocksinsubductionzones.Thesedepositsrepresentpotentialtargetsformineralexplorationanddevelopment,andhavecontributedtotheeconomicdevelopmentoftheregion.

Inadditiontoitseconomicimportance,theTamulangouFormationalsoprovidesimportantinsightsintotheenvironmentalandclimaticconditionsoftheLatePaleozoictoEarlyMesozoicera.Thevolcanicactivityassociatedwiththeformationlikelyhadasignificantimpactonthelocalandglobalenvironments,includingchangestoatmosphericcomposition,climate,andoceanchemistry.StudyingtheTamulangouFormationandtheassociatedvolcanicrockscanhelpshedlightontheimpactsofpastvolcanicactivityontheEarth'senvironmentandclimate.

Overall,theTamulangouFormationisasignificantgeologicalunitthatprovidesvaluableinformationaboutthetectonicevolution,mineralresources,andenvironmentalchangesofthenorthernmarginoftheNorthChinaBlockduringtheLatePaleozoictoEarlyMesozoicera.Itscontinuedstudyandexplorationcanhelpadvanceourunderstandingofthegeologicalhistoryandnaturalresourcesoftheregion,andmayhaveimportantimplicationsforeconomicdevelopmentandenvironmentalmanagement.Inadditiontomineraldeposits,theTamulangouFormationalsocontainsimportantfossilassemblagesthatprovideinsightintotheevolutionoflifeduringtheLatePaleozoictoEarlyMesozoicera.Fossilizedplantsandanimals,includingammonites,bivalves,andmarinereptiles,havebeendiscoveredintheformationandhelppiecetogetherthehistoryoflifeduringthistime.

TheTamulangouFormationisalsoanimportantreferenceforunderstandingthecomplextectonichistoryofthenorthernmarginoftheNorthChinaBlock.ThevolcanicactivityassociatedwiththeformationislikelyrelatedtothesubductionofthePaleo-AsianOceanbeneaththeNorthChinaBlock,whichhasbeenakeytectonicprocessintheregionforhundredsofmillionsofyears.Understandingthetectonicevolutionoftheregionisimportantforpredictingfuturetectonicactivityandnaturalhazards,andformanagingresourcesandinfrastructureintheregion.

Inrecentyears,scientificstudiesoftheTamulangouFormationhaveincreased,ashaveeffortstoexploreitspotentialmineralresources.Futurestudiescouldfocusonfurthercharacterizingthevolcanicactivitythatformedtheformation,aswellasinvestigatingthepotentialforadditionalmineraldepositsandfossildiscoveries.StudyingtheTamulangouFormationanditsassociatedgeologicalfeaturescanhelpresearchersgainabetterunderstandingoftheEarth'snaturalhistoryandhowithasshapedourplanetovertime.Additionally,theTamulangouFormationisanimportantareaofstudyforunderstandingclimatechangeduringtheLatePaleozoictoEarlyMesozoicera.Rocklayerswithintheformationholdevidenceofsea-levelchange,whichisakeyindicatorofpastclimateconditions.Byanalyzingthecompositionandstructureoftherocklayers,researcherscanreconstructpastclimatepatternsandbetterunderstandthefactorsthatcontributedtoclimatechangeduringthistimeperiod.

Furthermore,