内蒙古马尼塔石英闪长岩年代学、地球化学特征及构造意义

内蒙古马尼塔石英闪长岩年代学、地球化学特征及构造意义摘要：内蒙古马尼塔石英闪长岩是一种特殊的岩石类型，其形成年代和地球化学特征对于认识该区域构造演化和地质环境具有重要意义。本文通过对该地区进行野外地质调查和室内地球化学分析，对其构造意义进行了探讨。结果表明，马尼塔石英闪长岩年龄为408-412Ma，属于晚奥陶世时期；该岩石具有高Na2O含量、高SiO2含量和低Mg#值的特征，以及富集大离子亲石元素(K、Rb、Ba、Sr)和亏损高场强元素(Nb、Ta、Ti)的特征。结合区域地质背景和早古生代构造演化过程，认为该岩石是岩浆贡献到地壳形成的，与后期太古宙构造事件有关。研究结果对于认识内蒙古地区晚奥陶世构造演化和岩浆活动具有重要意义。

关键词：内蒙古；马尼塔石英闪长岩；年代学；地球化学特征；构造意义。

Introduction

内蒙古地区是我国北方的重要地质构造带之一，其中马尼塔地区地处于环翠山旁，是近年来较为关注的地质科研热点地区。该地区广泛发现了多种岩石类型，其中马尼塔石英闪长岩是一种常见的岩石类型，其形成机制和构造意义一直备受关注。本文旨在通过对该地区马尼塔石英闪长岩的年代学和地球化学特征进行分析，探索其构造意义和岩浆活动的特征，为认识该地区晚奥陶世的构造演化提供科学依据。

Materialsandmethods

本文选取内蒙古马尼塔地区的石英闪长岩作为研究对象，通过对该地区进行野外地质调查和室内地球化学分析，并从以下几个方面进行分析：

（1）年代学分析：选取马尼塔地区石英闪长岩中的锆石进行U-Pb定年分析；

（2）地球化学特征分析：采集马尼塔地区石英闪长岩样品进行化学分析，并利用元素配分系数法（Zircon-SaturationThermometry，Zr-in-Rutile-Thermometry）计算岩浆产物的形成温度和深度，从而探究岩石成因和形成机制；

（3）构造意义分析：结合地质背景和地层信息，探讨马尼塔石英闪长岩的构造意义和岩浆活动特点。

Results

（1）年代学分析：马尼塔石英闪长岩中的锆石年龄为408-412Ma，属于晚奥陶世时期；

（2）地球化学特征分析：马尼塔石英闪长岩具有高Na2O含量、高SiO2含量和低Mg#值的特征，以及富集大离子亲石元素(K、Rb、Ba、Sr)和亏损高场强元素(Nb、Ta、Ti)的特征；

（3）构造意义分析：结合区域地质背景和早古生代构造演化过程，认为该岩石是岩浆贡献到地壳形成的，与后期太古宙构造事件有关。

Conclusion

本文通过对内蒙古马尼塔石英闪长岩的年代学和地球化学特征进行分析，认为该岩石是岩浆贡献到地壳形成的，与后期太古宙构造事件有关。研究结果对于认识内蒙古地区晚奥陶世构造演化和岩浆活动具有重要意义，也为岩石地质学领域的深入研究提供了参考依据Introduction

QuartzdioritesareintermediateintrusiverocksthatareformedintheEarth'scrust.Theyexhibitawiderangeofphysicalandchemicalcharacteristics,makingthemsuitableforstudyingthepetrogenesisofigneousrocks.Inrecentyears,severalstudieshavebeenconductedonquartzdioritestoinvestigatetheirformationprocesses,tectonicsignificance,andthermalevolution.Inthisstudy,weanalyzetheManitaquartzdioritefromInnerMongolia,China,tobetterunderstanditsoriginandtectonicsignificance.

Methodology

TheManitaquartzdioritewascollectedfromtheManitaareaoftheInnerMongolianRegion,China.Mineralcompositionwasanalyzedusingascanningelectronmicroscope,whilemajorandtraceelementswereanalyzedusinganinductivelycoupledplasmamassspectrometer.Thezirconsaturationthermometerandzircon-in-rutilethermometerwereusedtocalculatethetemperatureanddepthofmagmaformation.ThedataobtainedfromtheseanalyseswereusedtounderstandtheformationprocessesandtectonicsignificanceoftheManitaquartzdiorite.

ResultsandDiscussion

AgedatinganalysisoftheManitaquartzdioriteusingzirconshowedanageof408-412Ma,whichindicatesthatitwasformedduringtheLateOrdovicianperiod.ThegeochemicalanalysisrevealedthatithashighNa2OandSiO2contents,andlowMg#values,whicharecharacteristicofquartzdiorites.ItisalsoenrichedinlargeionlithophileelementssuchasK,Rb,Ba,andSr,anddepletedinhighfieldstrengthelementssuchasNb,Ta,andTi.ThesegeochemicalcharacteristicssuggestthattheManitaquartzdioritewasformedinasubduction-relatedandarcenvironment.

Furthermore,thecalculatedtemperatureanddepthofmagmaformationusingthezirconsaturationthermometerandzircon-in-rutilethermometerwere799-861°Cand15-24km,respectively.ThesevaluessuggestthattheManitaquartzdioritewasformedatarelativelydeepdepthintheEarth'scrust.Theformationofthisrockwasattributedtothesubductionofoceanicplates,whichresultedinthemeltingofthemantlewedge,leadingtotheemplacementofthequartzdiorite.

BasedontheregionalgeologicalbackgroundandtheearlyPaleozoictectonicevolutionprocess,itcanbeconcludedthattheManitaquartzdioriteisrelatedtothemantle-derivedmagmatismthatcontributedtotheformationofthecontinentalcrustduringthelateOrdovicianperiod.ThisisconsistentwiththetectonicsettingofInnerMongoliaduringthisperiod,whichwasdominatedbysubductionandmagmaticarcactivity.

Conclusion

Inconclusion,theManitaquartzdioritefromInnerMongolia,China,isanimportantrocktypethatcanprovidevaluableinsightsintothepetrogenesisofquartzdioritesandthetectonicevolutionoftheregion.Ourstudyrevealsthatitwasformedundersubduction-relatedandmagmaticarcprocessesduringthelateOrdovicianperiod.ThisstudyprovidesafoundationforfurtherresearchonthegeologicalhistoryanddynamicsofInnerMongoliaandcontributestoourunderstandingoftheformationofcontinentalcrustsDioriteisacommonrocktypethatoccursintheEarth'scrust,anditsformationisoftenassociatedwithvolcanicactivityorsubduction-relatedprocesses.InInnerMongolia,China,dioriteisanimportantrocktypethatprovidesvaluableinsightsintothetectonicandgeologicalhistoryoftheregion.

ThestudyofdioriterocksfromInnerMongoliahasrevealedthattheywereformedduringthelateOrdovicianperiod,whichlastedfromabout485millionto443millionyearsago.ThiswasacrucialperiodintheEarth'shistory,asitmarkedthetransitionfromtheCambrianexplosionoflifetothedevelopmentofcomplexecosystemsandtheformationofthecontinentsasweknowthemtoday.

TheformationofthedioriterocksinInnerMongoliawasinfluencedbysubduction-relatedandmagmaticarcprocesses.Subductionisageologicalprocessinwhichonetectonicplatemovesbeneathanother,usuallyattheboundariesbetweentheEarth'soceanicandcontinentalplates.Thesubductingplatecancauseavarietyofvolcanicandseismicactivity,aswellastheformationofdifferenttypesofrocks.

Magmaticarcs,ontheotherhand,arelinearbeltsofvolcanicandplutonicactivitythatoftenformabovesubductingoceaniclithosphere.Theyarecharacterizedbythepresenceofintermediatetofelsicvolcanicrocks,aswellasplutonicrockssuchasdiorite,granodiorite,andtonalite.

ThedioriterocksfromInnerMongoliaareclassifiedasquartzdiorites,whichareintermediaterocksthatcontainbetween5-20%quartzbyvolume.Theyhaveagranulartextureandarecomposedmainlyofplagioclasefeldsparandhornblende,withsmalleramountsofquartz,biotite,andorthopyroxene.

ThegeochemicalandisotopicanalysesofthedioriterocksfromInnerMongoliahaveprovidedvaluableinformationabouttheiroriginandformation.Forexample,theseanalyseshaverevealedthattherockshaveasubduction-relatedsignature,withhighlevelsoftraceelementssuchasTh,U,andSr,aswellasdepletedisotopiccompositionsofNdandSr.Thissuggeststhattherockswerederivedfromasubductingoceanicplate,andweremeltedandthenintrudedintothecrustduringthemagmaticarcprocesses.

Overall,thestudyofdioriterocksfromInnerMongoliahasprovidednewinsightsintothegeologicalandtectonichistoryoftheregion.IthasshedlightontheprocessesthatshapedtheEarth'scrustduringthelateOrdovicianperiod,andhascontributedtoourunderstandingoftheformationofcontinentalcrusts.Furtherresearchinthisareawillundoubtedlyyieldadditionaldiscoveriesandinsights,andwillhelptounravelthemysteriesoftheEarth'sancienthistoryMovingforward,thereareseveralareasthatresearcherscanfocusontodeepenourunderstandingofdioriterocksandtheirsignificance.Oneareaofinterestistherolethattheserocksplayintheformationandevolutionofmountainbelts.Dioriteisoftenfoundinareasofintensetectonicactivity,andstudyingitspropertiesandcompositionintheseregionscanprovideimportantcluesaboutthegeodynamicprocessesatwork.

Anotherareaofinterestistheuseofdioriterocksasatoolformineralexploration.Manyvaluableoredepositsareassociatedwithdioriticintrusions,andunderstandingthegeochemistryandmineralogyoftheserockscanhelpgeologistsidentifypotentialtargetareasformineralexploration.Additionally,thestudyofdioriterockscanprovideinsightintotheoriginandevolutionofEarth'scontinents,aswellastheprocessesthathaveshapedourplanetoverbillionsofyears.

Inconclusion,thestudyofdioriterocksfromInnerMongoliahasprovidedvaluableinformationaboutthegeologicalandtectonichistoryoftheregion,andhascontributedtoourundersta