简介:TheJamesM.HarrisonAwardforOutstandingAchievementwasestablishedbytheIUGSExecutiveCommitteein2004tohonorindividualswhohaveservedtheUnioninanextraordinaryfashionforalongperiodoftime,andwhohavenorecognizedpositionasanofficeroftheUnion.TheawardisnamedforthelateJamesM.Harrison,aninternationallyknownanduniversallyrespectedCanadiangeologist(GeologicalSurveyofCanada)whowasoneofthefoundingfathersoftheIUGSanditsfirstPresident(1961-1964).
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简介:EO-1Hyperion高光谱遥感影像在实际应用中,需对图像进行大气纠正及补偿等预处理,以便获得较好质量的图像。为进一步分析和应用提供保障.笔者运用FLAASH大气校正模型对中国云南香格里拉地区的Hyperion卫星影像进行大气校正,利用图像MNF转换法对光谱曲线进行去噪平滑优化,再对校正前后影像进行遥感影像和典型地物光谱曲线对比分析.结果表明,影像经FLAASH大气校正和MNF平滑后,较好地消除了大气影响和Hyperion高光谱遥感图像的光谱噪声.
简介:Thereisageneralconsensusthatmostophiolitesformedabovesubductionzones(Pearce,2003),particularlyduringforearcextensionatsubductioninitiation(Shervais,2001;Stern,2004;WhattamandStern,2011).'Supra-Subductionzone'(SSZ)ophiolitessuchasthewell-studiedTethyanophiolites,generallydisplayacharacteristicsequentialevolutionfrommid-oceanicridgebasalts(MORBs)toislandarctholeiities(IATs)orbonites(BONs)(Pearce,2003;DilekandFurnes,2009,2011),whichweregeneratedinsequencefromthedecompressionmeltingofasthenosphericmantleandpartialmeltingofsubduction-metasomatizeddepletedmantle(SternandBloomer,1992;DilekandFurnes,2009;WhattamandStern,2011).However,ophioliteswithMORBand/oroceanic-islandbasalt(OIB)affinitiesarerare,andtheiroriginandtectonicnaturearepoorlyunderstood(Boedoetal.,2013;Saccanietal.,2013).ItisinterestingthatthecompositionoftheseophiolitesfromthecentralTibetanPlateau(CTP)isdominatedbyMORBsandminorOIBsandadistinctlackofIATsandBONs,whichisinconsistentwithmostophiolitesworldwide(RobinsonandZhou,2008;Zhangetal.,2008).Butthegenerationandtectonicnatureoftheseophiolitesarestillcontroversial.*Inthisstudy,wepresentnewgeochronological,mineralogicalandSr-NdisotopicdatafortheChayongandXiewumaficcomplexesinthewesternGarzê-Litangsuturezone(GLS),atypicalPaleo-TethyansuturecrossingtheCTP(Fig.1).TheTriassicophioliteinthewesternGLShasbeendescribedbyLietal.(2009),whofoundthatitmainlyconsistsofgabbros,diabases,pillowbasaltsandafewmetamorphicperidotites.TheophiolitehasbeentectonicallydismemberedandcropsoutinTriassicclasticrocksandlimestonesastectonicblocks.TheChayongandXiewumaficcomplexesaregenerallyregardedasimportantfragmentsoftheTriassicophiolites(e.g.,Jin,2006;Lietal.,2009).ZirconLA-ICP-MSU-Pbagesof234±3Maand236±2MacanbeinterpretedasformationtimesoftheChayongandXiewumaficcomplexes,respectively.Thebasalts
简介:TheHuashixiaareaintheMadoiCounty,QinghaiProvince,westernChinaisoneofthemostimportantareasforthestudiesoftheformationandevolutionoftheA’nyemaqenmélangezoneduetothewellexposed,relativelycompletetectonostratigraphicsuccessions.However,thetimingandevolutionaryprocessoftheA’nyemaqenpaleo-oceanhaslongbeenpoorlyunderstood.Recently,weobtainedabundantradiolariansfromthesiliceousrocksoftheMaerzhengFormationofthismélangezoneinHuashixia.Total19speciesin10radiolariangenerahavebeenidentified.TheybelongmainlytotheAlbaillellaria,Spumellaria,Entactinaria,andLatentifistularia.Fourradiolarianassemblagezonesareestablished,including:thePseudoalbaillellarhombothoracata,Pseudoalbaillellascalprata,Ruzhencevispongusuralicus,andFollicucullusbipartitus-Follicucullussp.cf.F.ventricosuszones.RadiolarianfaunalcorrelationssuggestalateArtinskian–earlyKungurianageandlateCapitanian–earlyWuchiapingianageforthefirsttwozonesfromthelowerpartandthelasttwozonesfromtheupperpartsoftheMaerzhengFormation,respectively.AllradiolariansaretypicalofdeepwaterelementslivingindeepoceansinlowlatitudesduringthePermian.Previously,theradiolariansofEarlyCarboniferoustoEarlyPermianageandfusulinidsofEarly–MiddlePermianagehavealsobeenreportedfromtheA’nyemaqenmélangesuccessions.ThecombinationofthenewlyfoundradiolarianswiththepreviouslyreportedfaunalandmicrofloralassemblagesaswellasradiometricagesobtainedfromthesamestratigraphicunitsindicatesthattheA’nyemaqenpaleo-oceanmayhaveopenedinitiallyduringtheEarlyCarboniferous,expandedfromtheEarly–MiddlePermian,reacheditsacmeintheearlyLatePermian,shrunkduringthelatestPermiantoEarlyTriassic,andeventuallywasclosedintheMiddleTriassic.
简介:OnOctober18,2018,theChinaGeologicalSurveylaunchedaprojectoftheNationalKeyResearchandDevelopmentProgramofChina,entitled"PredictionandDeepExplorationDemonstrationofGoldPolymetallicDepositsintheJiaodongandLiaodongAreaswithintheNorthChinaCraton".Forthisproject,WulongandBaiyun-XiaotongjiapuyiinJiaodong,aswellasthenorthernZhaopingbeltsofLiaodong,werechosenasoreprospectingdemonstrationareas(Fig.1).
简介:InordertoinvestigatetheevolutionofShiquanhe-Yongzhu-Jialiophioliticmélangebelt,thegabbrosfromnewdiscoveredZhongcangophioliticmélangearestudiedthroughpetrology,whole-rockgeochemistry,zirconU-PbdatingandLu-Hfisotope.Thegabbrosinvestigatedinthispapercontaincumulategabbroandgabbrodike,andtheyhaveundergonegreenschist-amphibolitefaciesmetamorphism.Thechondritenormalizedrareearthelement(REE)patternsofmostoftheserocksshowflattypeswithslightlylightREE(LREE)depletionandtheN-MORBnormalizedincompatibleelementsdiagramsindicatedepletioninhighfieldstrengthelements(HFSE)(Nb,Ta)andenrichmentinlargeionlithophileelements(LILE).Thesegabbroshaveislandarcandmid-oceanridgebasaltaffinities,suggestingthattheywereoriginatedinanoceanicbackarcbasin.WholerockgeochemistryandhighpositiveεNd(t)valuesshowthatthesegabbroswerederivedfrom~30%partialmeltingofaspinellherzolitemantle,whichwasenrichedbyinteractionwithslab-derivedfluidsandmeltsfromsediment.U-Pbanalysesofzirconsfromcumulategabbroyieldaweightedmeanageof114.3±1.4Ma.Basedonourdataandpreviousstudies,weproposethatanintra-oceanicsubductionsystemandbackarcbasinoperatedintheNeo-TethyOceanofcentralTibetduringMiddleJurassicandEarlyCretaceous,resemblingmodernactiveintra-oceanicsubductionsystemsinthewesternPacific.