简介:包括锆石U-Pb年龄,Hf同位素的作文,学生和踪迹与数据集在西方Tianshan为Nalati山区域(NMR)包含数据的合成古生代的侵入的元素被介绍改进地区性的geodynamic的理解进化。在NMR的古生代的恼人的岩石能基于按年代先后、geo化学的数据被分类进四个范畴:480
简介:Eclogiticgarnet-amphibolerocksarescatteredaroundtheSongshugouultramaficbodiesinQinlingMountains.Threemetamorphicstagesarerecognizedintermsofpetrography,mineralchemistryandgeothermobarometry.Thefirstalbite-amphibolestagewasofgreenschistfaciesmetamorphismwithtypicalmineralassemblageofactinolite+epidote+chlorite+albite;thepressureandtemperatureconditionswereequaltoorlowerthan500MPaandabout400℃.Thesecondprogradeeclogiticgarnet-amphibolestagewasofamphibole-eclogitefaciesmetamorphismwithtypicalmineralassemblageofgarnet+hornblende±clinopyroxene+rutilewithoutphagioclase,thepressureconditionwasatleast1000-1200MPaandthetemper-atureabout600℃.Thethirdretrogradeepidote-amphibolestagewasofepidote-amphibolitefacieswithassemblageofplagoclase+hornblende+epidote+ilmenite/titanite,thetemperaturewas500-600℃andthepressurefrom800MPadownto500MPa.AllthreestagestookplaceinonesingletectonothermaleventcalledJimingianmovementa
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简介:Thiscontributionanalyzesthesimilaritiesanddifferencesbetweenthemeasuredactivitiesof137Csandexcess210Pb(210Pbex)inthecultivatedbrownandcinnamonsoilsoftheYimengMountainarea,discussestheinfluenceofsoiltextureonthemeasurementof210Pbex,andpresentsdifferencesbetweenthetwotypesofsoils.FieldsAandBwereselectedtorepresentthefieldsthatcontaincultivatedbrownandcinnamonsoils,respectively.Fromeitherstudyfield,onesiteofsectionedcoreandsixbulkcoreswerecollectedtomeasure137Cslevels,210Pbexlevels,andtheparticle-sizecompositionofsoilsamples.Threeundisturbedsoilsampleswerecollectedtomeasurecapillaryandaerationporosities.The137Csinventoriesforthetwostudyfieldsareverysimilar.The137Csisaman-maderadionuclide,whichmeansthatitsmeasuredlevelsforsoilsareunaffectedbysoiltexture.Incontrast,levelsofthenaturallyoccurring210PbexofsoilsfromFieldAwerelowerthanthoseofFieldBbyabout50%.Incontrasttoaquaticsediments,levelsof210Pbexinterrestrialsurfacesoilsareaffectedbytheemanationof222Rnfromthesoils.Itcanbeassumedthatthecoarserthesoils,thegreatertheemanationof222Rn;inaddition,thelowerthemeasured210Pbex,thegreatertheunderestimateofthisvalue.ThecultivatedbrownsoilsinFieldAarecoarserthanthecultivatedcinnamonsoilsinFieldB.Asaresult,222RninFieldAwilldiffusemoreeasilyintotheatmospherethanthatinFieldB.Asaconsequence,themeasured210PbexinsoilsfromFieldAismuchlowerthantheactualvalue,whereasthevaluemeasuredforFieldBismuchclosertotheactualvalue.
简介:Thebasin-rangecouplingrelationisaleadingsubjectofthemoderngeology.Ingeometry,relationsofthistypeincludecouplingsbetweenstretchedorogenicbeltanddown-faultedbasin,compressionalorogenicbeltandforelandbasin,strike-sliporogenicbeltandstrike-slipbasinandsoon.Faultchainsarethekeyforthesecouplingsandtherearetypicalexamplesforallthesecases.TheNorthChinadown-faultedbasiniscoupledwestwiththeTathanguplift,eastwiththeJiao-LiaoMountains,northwiththeYanshanorogenicbeltandsouthwiththeDabieorogenicbelt,thatistosay,thecentraldown-faultedbasinandthesurroundingorogenicbeltsbearacouplingrelationwithinauniformdynamisticsystem.Studyshowsthatthecentraldown-faultedbasinandtheNorthChinamantlesub-plumestructurehaveacloserelationduringtheirformation.Owingtointensivemantlesub-plumeuplifting,thebottomofthelithospheresufferedfromresistance,whichcausedthelithosphereoftheeasternNorthChinatobeheated,thinnedandfault-depressed.Meanwhile,mantlerocksthatweredetachedoutwardsintheshapeofmushroomwasdissectedbysurroundingductileshearingzones,whichleadtodecompressionandunloadingtogeneratehypomagmas,andaseriesofmantle-branchstructureswereformedaroundthedown-faultedbasin.Thereisanobviouscomparabilityamongthesemantlebranchstructures(orogenicbelts),andtheyhavebasin-rangecouplingrelationswiththecentraldown-faultedbasins.
简介:TheQilianMountainactivesourcenetworkdatawasprocessedusingthemethodsofstacking,cross-correlationandinterpolation,andtheairguntraveltimevariationcharacteristicsofPandSwavesaroundtheJanuary21,2016MS6.4Menyua,Qinghaiearthquake.Theresultsshowthatabout6monthsbeforetheearthquake,therelativetraveltimeofthreestationsneartheepicentershowedadeclinedchange(traveltimedecrease),andsuchachangeoflowvalueanomalywasrecoveredabout3monthsbeforetheearthquake.Thetraveltimedecreasethenappearedagain,andtheearthquakeoccurredduringtherecoveryprocess.ThemaximumdecreaseoftheS-wavetraveltimewas18ms,andthechangeintraveltimereturnedtonormalaftertheearthquake.Thevariationtrendofthe3stationsisconsistent,includingtheS-wavetraveltimechangeofstationZDY38,whichisnearesttotheepicenterandchangedobviously,andthevariationrangeofthetraveltimeissmalleratthestationsafar.Thisvariationpatternisrelatedtothepositionoftheseismicsource.Theshortertraveltimemeansthevelocityincrease,whichmayberelatedtotheregionalstressaccumulation.
简介:TheYushugouterrainofhigh-pressuregranulitefaciesinsouthernTianshanMountainiscomposedmainlyofanophiolitesuite.Mostselectedziroconsareroundorellipticalinshape,andsomeareoftetragonalprismwithroundedges.Thegranulometricanalysesshowthattheyarewellsortedinsedimentation.ZrO2/HfO2ratiosinzirconsrangefrom45to57.thesecharacters,togetherwiththepetrologicandgeochemicalcharactersofplagioclase-garnet-orthopyroxenitebearingzircons,indicatethattheprotolithofplagioclase-garnet-orthopyroxenitemaybederivedmainlyfromvolcanicbasesurgesedimentarydebrisinoceanicislandsandfromclaysformedbyseafloorweathering.Zirconsaresimplyofpyroclasticdebris.Theophioliteformationageof(440±18)Maandthefirst-stagemetamorphicage(amphiboliteorgranulitefacies)of(364±5)Mawereobtainedwithamethodofmultiplegrainsindifferentgroupsandamethodofconcordiaplot.TheseagesprovideimportantinformationonthetemporalandspatialoccurrenceofsouthernPaleoxoicTianshanOcean,Thesubductionrateoftheoceaniccrustandtheformationmechanismofophioliteofgranulitefacies.