简介:ThecentralstructurebeltinTurpan-HamibasiniscomposedoftheHuoyanshanstructureandQiketaistructureformedinlateTriassic-earlyJurassic,andischaracterizedbyextensionaltectonics.Thethicknessofstratainthehangingwallofthegrowthfaultisobviouslylargerthanthatinthefootwall,andadepositioncenterwasevolvedintheTaibeisagwherethehangingwallofthefaultislocated.InlateJurassicthecollisionbetweenLhasablockandEurasiacontinentresultedinthetransformationoftheTurpan-Hamibasinfromanextensionalstructureintoacompressionalstructure,andconsequentlyinthetectonicinversionofthecentralstructurebeltoftheTurpan-Hamibasinfromtheextensionalnormalfaultintheearlierstagetothecompressivethrustfaultinthelaterstage.TheTertiarycollisionbetweentheIndianplateandtheEurasianplateoccurredaround55Ma,andthisHimalayanorogeniceventhasplayedaprofoundroleinshapingtheTianshanarea,onlytheeffectofthecollisiontothisareawasdelayedsinceitculminatedhereapproximatelyinlateOligocene-earlyMiocene.Thecentralstructurebeltwasstronglydeformedandthrustedabovethegroundasaresultofthistectonicevent.
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简介:<正>CRUSTOBODYSTRUCTUREOFCHINAANDDISTRIBUTIONOFROCKGOLDOREDEPOSITSHuangRuihua(ChangshaInstituteofGeotectonics,AcademiaSinica,410013,Hunan,China)rockgoldoredeposit,crustobodystructure,China.Chinacontinentisdividedintofourcrustobodiesfromeasttowest.Thereiswell-knownJinguashirockgolddepositinEastAsiacontinentalmargincrustobody.Goldmet-allizationisverywelldevelopedinEastAsiacrustobody.Therearemainlyrockgoldorede-positsrelatedtoArcheangreenstoneformationandMesozoic-Cenozoicrockgoldoredepositsinit.TherearemainlyPalaeozoicrockgoldoredepositsofgeosynclinaltypeandCenozoicrockgoldoredepositsofdiwa(depression)typeinCentralAsiacrustobody.SouthAsiacrustobodypossessesgreatpotentialinrockgoldmetallization.Asawhole,prospectingexplorationandexploitationofrockgoldareverywelloffutureinChina.
简介:Onthebasisofaone-by-onelatitude-longitudegridthree-dimensionalseismicvelocitymodel,thecrustalPwavevelocitystructureineasternChina(105-125°Eand18-41°N)isobtained,andasetofgeothermsforeachgridisestablishedforP-TcorrectiononP-wavevelocities.Theaveragedepthsofsub-crustallayersandtheiraverageP-wavevelocitiesof18tectonicunitsineasternChinaareexhibited.Ourresultpresentsa32-34kmthickcrustbeneatheasternChina,whichisthinnerthanpreviousstudies,withanaveragevelocityof6.54km/s,correspondingtoa5kg/m3variationincrustalmeandensity.ThethickerupperbutthinnermiddleandlowercrustresultsinaloweraverageseismicvelocityofeasternChina.AnintermediatecrustalcompositionwithaSiO2contentof59.7wt%hasbeenestimated.However,thereexistsasignificantlateralvariationinthecrustalstructuresamongthetectonicunitsofeasternChina.ThestructureandcompositionfeaturesofsomeregionsineasternChinaindicatethatextensionhasplayedanimportantroleinthecontinentalcrustevolutionofeasternChina.