简介:TheJamesM.HarrisonAwardforOutstandingAchievementwasestablishedbytheIUGSExecutiveCommitteein2004tohonorindividualswhohaveservedtheUnioninanextraordinaryfashionforalongperiodoftime,andwhohavenorecognizedpositionasanofficeroftheUnion.TheawardisnamedforthelateJamesM.Harrison,aninternationallyknownanduniversallyrespectedCanadiangeologist(GeologicalSurveyofCanada)whowasoneofthefoundingfathersoftheIUGSanditsfirstPresident(1961-1964).
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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.
简介:安徽省南部晚二叠世早期含煤地层,主要分布在扬子地层区的下扬子地层分区和江南地层分区之中。根据岩性、岩相古地理分布及生物面貌等不同特征,在下扬子地层分区中可进一步划分为巢湖—安庆地层小区和宿松—繁昌地层小区;江南地层分区中划分为广德~休宁地层小区。以往煤田地质系统将上述三个地层小区中的晚二叠世早期含煤岩石地层均称为龙潭组,而我省地矿系统则把龙潭组下部的砂页岩段划出,称为堰桥组或银屏组。本文根据多重地层划分原则,把巢湖~安庆地层小区和广德—休宁地层小区中一套含煤碎屑岩石地层含(银屏组/堰桥组)统称为龙潭组;宿松—繁昌地层小区则称为吴家坪组。