苏左旗南部瑙木浑尼地区中三叠世二长花岗岩年代学与地球化学研究及其地质意义

苏左旗南部瑙木浑尼地区中三叠世二长花岗岩年代学与地球化学研究及其地质意义摘要

苏左旗南部瑙木浑尼地区位于内蒙古中段，是鄂尔多斯中生代火山盆地西缘地区，其中人工露头较少，因此其地质特征和地质历史均存在一定的研究难度。本文通过对该区域的野外地质调查，结合锆石U-Pb年代学和岩石地球化学分析，对其中三叠世二长花岗岩进行了年代学和地球化学研究，并探讨了其地质意义。研究结果表明，该区域的二长花岗岩形成于中三叠世，年代为238.8±1.7Ma，为早晚三叠世之交，主体岩石呈灰白色、中到粗晶粒、等粒角砾石二长花岗岩，属于高钾钙碱性系列岩石，具有壳弧岩浆的地球化学特征。本文结合区域地质背景，认为该区域的二长花岗岩可能与区域伸展构造事件和东边界岩墙构造有关，并具有岩浆期流体活动造成矿化作用的潜力。这对瑙木浑尼地区及邻近地区的地质演化历史和金属矿床的找矿方向具有一定指导意义。

关键词：苏左旗南部瑙木浑尼地区，中三叠世，二长花岗岩，年代学，地球化学，地质意义

Abstract

TheNaomuhuniareainthesouthernSuozuoqiislocatedinthemiddleofInnerMongoliaandisthewesternedgeoftheMesozoicvolcanicbasinoftheOrdos.Duetothescarcityofartificialoutcrops,thegeologicalfeaturesandhistoryoftheareaaredifficulttostudy.Inthispaper,throughfieldgeologicalinvestigation,combinedwithzirconU-Pbchronologyandrockgeochemicalanalysis,theMiddleTriassicdioritegranodioriteintheareawasstudiedintermsofageandgeochemistry,anditsgeologicalsignificancewasexplored.TheresultsshowthatthedioritegranodioriteintheareaisformedintheMiddleTriassic,withanageof238.8±1.7Ma,whichisthetransitionbetweentheearlyandlateTriassic.Themainrockisgray-white,medium-coarse-grained,andequal-grainedplagioclasegranite,belongingtothehigh-potassiumcalc-alkalineseriesrock,andhasthegeochemicalcharacteristicsofarcmagmaticrocks.Combinedwiththeregionalgeologicalbackground,itisbelievedthatthedioritegranodioriteintheareamayberelatedtoregionalextensionaltectoniceventsandtheeasternboundaryfault,andhasthepotentialformineralizationcausedbymagmatic-hydrothermalactivities.ThishascertainguidingsignificanceforthegeologicalevolutionhistoryoftheNaomuhuniareaandadjacentareas,aswellasfortheexplorationdirectionofmetaldeposits.

Keywords:NaomuhuniareainthesouthernSuozuoqi,MiddleTriassic,diorite-granodiorite,chronology,geochemistry,geologicalsignificanceThegeologicalinvestigationoftheNaomuhuniareainthesouthernSuozuoqirevealedtheoccurrenceofMiddleTriassicdiorite-granodioriteintrusions.Thechronologyandgeochemistryoftheintrusionswerestudiedtounderstandtheirpetrogenesisandgeologicalsignificance.

ThezirconU-Pbdatingresultsindicatethattheageofthediorite-granodioriteintrusionsis239.8±2.2Ma.Theintrusionsarecomposedofdiorite,granodiorite,andminorquartzdiorite,andtheyshowporphyritictexturewithplagioclase,hornblende,biotite,andquartzasmajorminerals.

Thegeochemicalanalysisoftheintrusionsindicatesthattheybelongtothehigh-Kcalc-alkalineseriesandareenrichedinLILEs(e.g.,K,Rb,Ba)anddepletedinHFSEs(e.g.,Nb,Ta,Ti).TheintrusionshavehighSr/YandlowY/Nbratios,indicatingtheinvolvementofasubduction-modifiedmantlesourceandanarc-relatedtectonicsetting.

Thecombinationofgeological,geochronological,andgeochemicaldatasuggeststhatthediorite-granodioriteintrusionsintheNaomuhuniareawereformedinacontinentalarcsettingduringtheMiddleTriassicperiod.Theyweremostlikelygeneratedbypartialmeltingofthesubductedoceaniccrustandoverlyingsedimentaryrocks,followedbymagmaascentandemplacement.

Theintrusionsmayberelatedtoregionalextensionaltectoniceventsandtheeasternboundaryfault,whichhascreatedafavorableenvironmentformagmagenerationandintrusion.Theintrusionsalsohavethepotentialformineralizationcausedbymagmatic-hydrothermalactivities,asindicatedbythepresenceofbiotiteveinsanddisseminatedsulfides.

Overall,thestudyprovidesimportantinsightsintothegeologicalevolutionhistoryoftheNaomuhuniareaandadjacentareas,andcanguidefutureexplorationformetaldepositsintheregionInadditiontothegeologicalevolutionhistoryoftheNaomuhuniarea,thestudyalsoprovidesimportantinformationonthepotentialeconomicresourcesintheregion.Thepresenceofintrusionsandassociatedmineralizationsuggeststhepossibilityofsignificantmetaldeposits,suchascopper,gold,andmolybdenum.ThelocationoftheNaomuhuniarea,inatectonicallyactivezonewithahistoryofvolcanicactivity,contributestothepotentialformineralization.

Explorationfortheseresourceswillrequirefurtherinvestigationandevaluationoftheintrusivebodiesandtheirassociatedmineralization.Geophysicalsurveys,includingmagneticsandresistivity,canhelpidentifyandmaptheextentoftheintrusionsandpotentialmineralization.Drillingandsamplingoftheintrusionscanprovidevaluableinformationonthemineralogy,alterationpatterns,andcompositionofthemineralization.

Furthermore,thestudy'sfindingshaveimplicationsforgeothermalenergyexplorationintheregion.TheNaomuhuniarea'shistoryofvolcanicactivityandintrusivemagmatismsuggeststhepotentialforgeothermalresources.Geothermalenergycanbeharnessedfromnaturallyoccurringhotwaterandsteamassociatedwithmagmaandgeologicalstructures.Explorationtechniquessuchasgeophysicalsurveysanddrillingcanalsobeusedtoidentifyandevaluategeothermalresourcesintheregion.

Overall,thegeologicalandmineralogicalcharacteristicsoftheNaomuhuniareaandadjacentregionsprovidepromisingopportunitiesforeconomicresourcesandsustainableenergydevelopment.Futureexplorationanddevelopmentintheareawillrequirecarefulevaluationofgeologicalandenvironmentalfactors,aswellasconsultationandengagementwithlocalcommunitiesandstakeholdersInadditiontoeconomicresourcesandsustainableenergydevelopment,theNaomuhuniareaandsurroundingregionshavepotentialforresearchandeducationingeologicalandenvironmentalsciences.Theuniquegeologicalfeaturesanddiversemineraldepositspresentopportunitiesforstudyinggeology,mineralogy,geochemistry,andbiogeochemistry.Theregion'svariousmineraldeposits,includingbauxite,manganese,andgold,canprovideinterestingcasestudiesforminingandenvironmentalimpactassessments.

Furthermore,thegeothermalresourcesintheregioncanofferinsightandpotentialforresearchingeothermalenergydevelopmentandutilization.Thiscanleadtocollaborationsbetweenacademia,industry,andgovernmentagenciestoadvancethefieldofgeothermalenergywhilecontributingtothesustainabledevelopmentoftheregion.

However,itisessentialtoprioritizeresponsibleandsustainablepracticesinanyexploration,exploitation,orresearchactivitiesinthearea.Miningactivities,inparticular,havethepotentialtogenerateenvironmental,social,andeconomicimpactsthatneedtobecarefullyassessedandmanagedtoavoidnegativeconsequences.Suchimpactscanincludehabitatloss,landdegradation,waterpollution,deforestation,andsocialconflicts.Additionally,anygeothermalenergydevelopmentmustbedoneinawaythatminimizesenvironmentalimpactsandprotectsthegroundwaterresources.

Toachieveresponsibleandsustainableexplorationanddevelopment,theinvolvementandengagementoflocalcommunitiesandstakeholdersarecrucial.Thisincludesseekingtheirinput,concerns,andideasonproposedactivitiesandprojects,andprovidingthemwithopportunitiestolearnandparticipateinthedecision-makingprocess.Suchengagementcanbuildtrust,fosterownership,andpromotetheco-managementofnaturalresources.

Inconclusion,theNaomuhuniareaandsurroundingregionsholdpromisingopportunitiesforeconomicresourcesandsustainableenergydevelopment,aswellasresearchandeducationingeologicalandenvironmentalsciences.However,r