简介:ThedistributionofmonthlymeanerrorofNMCmodelforecastsanditsseasonalvariationareinvesti-gated.Theratioofmonthlymeanerrortostandarddeviationisusedheretofindoutthattheregionwhereacorrectionofsystematicerrorisneededandappropriateismainlyinlowlatitudes.Theimprovement,afterthemodel’sverticalresolutionandsomephysicalparameterswerechangedfromApril1985,isinvestigated,andtheNMCoperationalmodelforecastshavealsocomparedwiththoseofECMWF.
简介:ThispaperpresentsthefirstspecificstudyoftheTh-andU-bearingminerals,whichwererecentlyfoundintheSEMediterraneanmarginofSpain(ElHoyazoarea,Almeriaprovince).ThesemineralsareREEphosphates(mainlymonazite)whichoccurasamoeboidal-to-elongateinclusions,fromaround10120μmto120μm,hostedinsinglegarnetcrystalsfromdacitelavasandmetamorphicrocksfromtheElHoyazoVolcanicComplex.ThandUcontentsarehigherthan1wt%,with3.04to5.62wt%forTh02,and0.7to1.75wt%forUO2.Bothelementsarealsofoundinxenotime(ThO2:0.24,UO2:0.27wt%).Giventhattheerosionofthevolcanicsourcerockshasgenerateda“placer-type”depositofmonazitesandsandthatgarnets(maincarriersofmonazite)arebeingcommercialised,anenvironmentalmonitoringandmanagementplanshouldbeurgentlyexecutedinthearea.
简介:MarbleisassociatedwithultrahighpressureeclogiteintheDabieMountains.EastChina.U-Pbisotopedataforthemarbledefinea238U-206Pbisochronageof435±45awithaninitial206Pb/204Pbvalueof18.075±0.006,Theageof-435MaisinterpretedtorepresentthetimeoflimestonediagensisratherthanthetimeofmetarmorphicresettingaccompaniedbytheformationoftheultrahighpressureeclogitesatTriassic.ThepaleontologicandstratigraphicstudiesalsofavoralocalexcursioninthecarbonisotopiccompositionofthelatestordovicianwaterwithinasedimentarybasinbetweentheSino-KoreanandYangtzecratos.Becasusethelatestordovicianlimestonewasinvolvedintheeclogiteformation,thecontinentalcollisionbetweentheYangtzeandSino-KoreanPlateswouldpostdateordovican.
简介:Calculations,accordingtosomeopen-systemmodels,pointoutthatwhileastatisticallysignificantdiscrepancybetweentheresultsoftwoU-seriesmethods,^230Th/^234Uand^227Th/^220Th(or^231Pa/^235U),attestsarelativelyrecentandimportanturaniummigration,concordantdatescannotguaranteecloses-systembehaviorofsample.Theresultsof20fossilbonesfrom10Chinesesites,19ofwhicharedeterminedbytwoU-seriesmethods,aregiven,Judgingfromindependentagecontrols,8outofthe11concordantagesetsareunacceptable,Theresultsinthispapersuggestthaturaniummaycycleintooroutoffossilbones,suchgeochemicaleventsmaytakeplaceatanytimeandnoknownpreservingconditionmaysecurelyprotectthemfrombeingaffected.Soforthesitewwehavestudied,theU-seriesdatingoffossilbonesisoflimitedreliability.
简介:FollowingtherecommendationoftheInternationalCommissiononStratigraphy(16votesYes[94%],1abstention,2votesnotreceived),theGlobalboundaryStratotypeSectionandPoint(GSSP)forthebaseoftheTuronianStageoftheCretaceousSystemisdefinedasthebaseofbed86oftheBridgeCreekLimestoneMemberoftheGreenhornLimestoneFormationatthewesternendoftheDenverandRioGrandeRailroadcutnearthenorthboundaryofthePuebloReservoirStateParkRecreationArea,westofPueblo,Colorado,USA.ThisGSSPhorizonisalsoexposedandprotectedintheadjacentstaterecreationarea.ItcoincideswiththefirstoccurrenceoftheammoniteWatinocerasdevonense,isinthemiddleofaglobalpositiveexcursioninCarbon-13isotopes,andisbracketedbywidespreadbentonitesthathaveyieldedagesof93to93.5Ma.
简介:Henglingguan和Beiyu变形granitoids,在Zhongtiaoshan前寒武纪的建筑群的西北分布式,包括trondhjemites和计算碱的monzogranites,与太古代的ZhaiziTTG片麻岩显示恼人的接触。并且Beiyumetamorphicgranitoids主要由trondhjemites组成,在Hujiayu背斜褶层的核心分布式。分别地,标明日期加权平均值~(207)Pb/~(206)Pb变老的数据表演的新虾锆石U-Pb是为Henglingguan变形计算碱的monzogranites和Beiyumetamorphictrondhjemites的2435.9Maand2477妈并且揭示600妈继承了的~2在magmatic锆石的核心。Whole-rockgeochemical数据显示那所有Henglingguan和Beiyu变形trondhjemitesandcalc碱的monzogranites属于遇见了铝土的中等钾、高钾的calc-alkalineseries。这些岩石被相对高的全部的碱内容描绘(Na_2O+K_2O,在to9.08%上面),弄空的Nb,Ta,P和Ti,和衰退权利的REE模式与对高LREEs/HREEsfractionation中等(吝啬的比率(La/Yb)_n=25)。在多元素蜘蛛图的Henglingguan和Beiyumetamorphictrondhjemites显示negativeRb,Th和K异例由原始披风使正常化。Sm-Nd同位素的数据表明这些granitoids有起始的ε_(Nd)到+2.4和Nd的(t)=-1.2弄空T_(MD)=的披风模型年龄2622马马。所有thesegeochemical特征显示这些granitoids在一条大陆边缘的弧被形成,并且trondhjemites主要从少年的部分融化发源玄武岩的材料并且然而,Henglingguan变形计算碱的monzogranites源于在一条大陆边缘的弧下面在古老的外壳中材料再循环。花岗石的岩浆在他们的形成期间经历了污染和分离结晶。
简介:TheYangshangolddepositisasuper-largefine-graineddisseminatedgolddepositlocatedinsouthernGansuProvince.ItsmetallogenicagehasbeendeterminedbyusingthecathodoluminescenceimageandionprobeU-Pbdatingtechniques.Itisfoundthatzirconsfromquartzveinletofthefine-graineddisseminatedgoldoreshowcharactersofmagmaticoriginwithprismidiomorphism,oscillatoryzoninganddominantTh/Uratiosof0.5-1.5.Threemainpopulationsofzirconsareobtained,givingaverage206pb/238Uagesof197.6±1.7Ma,126.9±3.2Maand51.2±l.3Marespectively.ThefirstagecorrespondstotheK-Arageoftheplagiogranitedike,whilethelattertwoagesindicatethatburiedCretaceousandTertiaryintrusivesexistintheorefield,suggestingthattheYangshangolddepositwasgeneticallyrelatedtothethreemagmatichydrothermalactivities.Bycontrast,zirconsfromcoarsegold-bearingquartzveinintheminingareaaremucholderthanthehostrock,indicatingthattheveinwasformedearlierandwasnotcontaminatedbylatermagmaticfluids.ItisconcludedthatthecouplingofmultiperiodichydrothermalactivitiesintheminingareahascontributedalottomineralizationoftheYangshangolddeposit.
简介:ThereportednewU-Pbagebysensitivehigh-resolutionionmicroprobe(SHRIMPⅡ)onzirconwasobtainedfromatuffsampleatthebasalDoushantuoFormationintheJiuqunaosection,whichsituatedatthewesternlimboftheHuanglinganticlineintheYangtzeGorgesinZigui,Hubei,SouthChina.Eighteenspotsofzirconswereanalyzedandtheyformtwoclusters:oneincludesthreespots,withaninheritedageof784+15Ma(MSWD=0.05);theotherconsistsof15spotsandgivesaweightedmean^206pb/^238Uageof628.3±5.8Ma(MSWD=0.86).ItisthefirstSHRIMPU-PbzirconageobtainednearlythebaseoftheDoushantuoFormationofEdiacaranandrepresentsamaximumageoftheDoushantuoFormationItalsoformsanageconstraintontheupperlimitageoftheNantuo(Marinoantype)glaciation.
简介:Delaminationoccursmainlyinthelithosphericmantle,involvinginteractionwiththeasthenosphere,theprocessofwhichishardtoobservedirectly.ourresearchongranitoidsinthewesternkunlunorogenicbelt,China,indicatesthathighconterntsoftheheat-producingelementsThandUmayfurnishlithosphericdelaminationwithnewevidence,Atthesametime,wehaveestablishedtheTh-SiOandU-SiO2diagramstodiscriminatedelamination.
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.
简介:1一个科学家小组一直在把钻孔打入格陵兰冰原深处,以期发现世界过去的气候记录。该记录是年际冰层之间形成的小空气泡。气泡中的空气含有两种不同氧的同位素。它们随温度而变化,因而有可能用图表示出数十年、百年或上千年以前的冷暖年份。在过去几十年中,科学家们在南极和北极钻取冰核,从而获取了上一个冰川期的气候情况。结果发现气候变化很大,并在相对温暖期和相对凉爽期之间摇曳不定。从格陵兰冰原中部采到的新冰核提供了一间冰期的详细记录。从2780m到2870m深处提取的冰核表明间冰期的气候在三种状态之间振荡,而不是人类有记载以来的一种状态。其中间的状态接近于我们现在的气候,其余两种是冷得多或热得多。
简介:与在中间的最好、古典的剖面图Trans北方ChinaOrogen分割的邻近的Fuping和HengshanComplexesrepresents联系的Wutai建筑群,通常划分了成东方、西方的块。UnconformablyoverlyingWutaiandFuping建筑群Hutuo组在这个区域被看作最年轻的岩石地层单位并且为解释前寒武纪的历史以及theTrans北方中国造山带的全面进化重要。在这个组的沉积岩的起源的知识的缺乏妨碍了depositional和构造意义的理解。LA-ICP-MS被使用为花岗石的卵石获得U-Pb锆石年龄,Hutuo组的最低岩石层位学的岩石,它,与结合了以前的岩石层位学,geochronological,结构、变形的数据,在沉积起源和这个区域的构造进化上提供新限制。Hutuo的顺序从更低的底砾岩andvolcaniclastic岩石(Doucun亚群)向上组织范围,通过碎屑沉积物,板岩,白云石和云石(Dongye亚群),到在顶(Guojiazhai亚群)的沙岩和集团企业。从在Doucun亚群底砾岩保存的花岗石的卵石的锆石给加权的mean~(207)在2517妈和2566妈之间的Pb/~(206)Pb年龄,它与为迟了的ArcheanWutaiGranitoids的那些一样,显示卵石从Wutai花岗石的侵入(2566-2515妈)被导出。基于新数据和以前的研究,与在Hutuo组为volcanics获得的2087±9妈的火的锆石结晶化年龄结合了,Hutuo组在在东方块的西方的边缘下面在西方的块的东方指导俯冲期间在theWutai弧后面发展了的subduction相关的制动火箭弧低岬盆环境被扔。这盆经历了长寿沉积并且最后在~1期间关上了导致了北方中国古地台的最后的合并的850妈collisional事件。
简介:典型地,Indosiniangraniticplutons产出的三的LA-ICPMS锆石U-Pb地球年代学为从在湖南的Xiema和Xiangzikouplutons的黑云母monzomitic花岗石的214.1+-5.9妈和210.3+-4.7妈的加权平均值~(206)Pb/~(238)U年龄省,并且为从Napengpluton的黑云母花岗石的205.3+-1.6Ma,,西方的Guandong省分别地,显示出结晶化的类似的迟了的Indosinian年龄。在有在华南块(SCB)以内的另外的geochronological数据fromIndosinian花岗石的联合,有约210妈和早Indosinian花岗石(230-245妈)的年龄的那些迟了的Indosiniangranites在相同构造背景有类似的岩石成因论,这被建议。在SCB以内的Indosinian花岗石可能是在压缩政体的变厚的外壳的深溶酌的产品。这些数据为Indosinian花岗石的时间、空间的分发和SCB的动态进化提供进一步的理解。