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2008年  19卷  第1期

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Sedimentation Geochemistry and Environmental Changes during the Late Pleistocene of Paleolake Qarhan in the Qaidam Basin
常凤琴, 张虎才, 陈玥, 杨明生, 牛洁, 樊红芳, 雷国良, 张文翔, 类延斌, 杨伦庆
2008, 10(1).
摘要:
OnthebasisoftheanalysesofTOC,CaCO3,δ13Corg,δ18O,andδ13CoftheshellbarsectionintheQaidambasin,andcomparedwithgrainsizedata,theenvironmentalchangehistoryofthehighwaterlevelofpaleolakeQarhanwasreconstructedanditcouldbedividedintofivestages.From39.7to35.8kaBPwasthedevelopmentperiodofhighpaleolakelevel.From35.8to33.6kaBPand33.6to27.2kaBP,TOCandCaCO3contentsandδ18Ovalueswerehigh,whereas,δ13Corgvaluesandmediansizecontentwerelow,reflectingawarm-humidclimateandhighlakelevel.During27.2–22.3kaBPand22.3–17.5kaBP,bothtemperatureandthelakelevelwerelowerthanthoseinthepreviousstages,buttheclimatewasstillwarmerandmorehumidthanthatoftoday.Thelakeleveldecreasedbetween32.4and32.2kaBP,30.4and29.8kaBP,and28.4and27.2kaBP.Generally,theclimatewaswarmandhumidinQaidambasinandthehighlakelevelsustainedbetween39.7and17.5kaBP.Thelakeretreatedabruptlyat17.5kaBP,withaverystrongincreaseinevaporation,whichresultedinsaltformationandtheextinctionofCorbicula.
Evolution of Carbon Isotope Composition in Potential Global Stratotype Section and Point at Luoyixi, South China, for the Base of the Unnamed Global Seventh Stage of Cambrian System
左景勋, 彭善池, 朱学剑, 祁玉平, 林焕令, 杨显峰
2008, 10(1).
摘要:
ThisworkdealswiththeevolutionofcarbonisotopecompositionintheLuoyixi(罗依溪)Section,acandidateoftheGlobalStandardStratotype-sectionandPoint(GSSP),definingthebaseoftheas-yet-undefinedseventhstageofCambrianSystematthefirstappearanceofthecosmopolitanagnostoidLejopygelaevigata.ThislevelisfavoredinavoteofInternationalSubcommissiononCambrianStratigraphy(ISCS)asthebiohorizonfordefiningthebaseofaglobalstage.Twohundredandsixty-foursamplesforcarbonandoxygenisotopeanalysishavebeencollectedfromthecarbonatesuccessionsatanintervalof0.25to0.5minthissection.Resultsofthecarbonisotopedataexhibitaremarkabledisciplinariantrend.ThepatternofthecarbonisotopeevolutionisgentlyundulantwitharelativelylongperiodduringtheunderlyingDrumianStage,andthenthevaluesofδ13Cfluctuatesharplywithashortperiodinprovisionalseventhstage.Theonsetofsharpfluctuationintheδ13CvaluesbeginsattheproposedGSSPlevel,definingthebaseoftheglobalseventhstage,whereδ13Cvalueschangefromagentletrendtoasharptrend.Distinctcovariant-relationshipsamongδ13C,δ18O,andsealevelfluctuationssuggestthatawarmingchangeinpaleoclimatetookplaceduringtheearlyglobalseventhstage,whichledtoapositiveshiftinδ13Cvalues.
Characteristics of Clay Minerals in the Northern South China Sea and Its Implications for Evolution of East Asian Monsoon since Miocene
万世明, 李安春, 胥可辉, 尹学明
2008, 10(1).
摘要:
Claymineralassemblages,crystallinity,chemistry,andmicromorphologyofclayparticlesinsedimentsfromODPSite1146inthenorthernSouthChinaSea(SCS)wereanalyzed,andusedtotracesedimentsourcesandobtainproxyrecordsofthepastchangesintheEastAsianmonsoonclimatesincetheMiocene,basedonamulti-approach,includingX-raydiffraction(XRD)andscanningelectronmicroscopycombinedwithenergydispersiveX-rayspectrometry(SEM-EDS).Claymineralsconsistmainlyofilliteandsmectite,withassociatedchloriteandkaolinite.TheilliteatODPSite1146hasverywell-to-wellcrystallinity,andsmectitehasmoderate-to-poorcrystallinity.InSEMthesmectiteparticlesatODPSite1146oftenappearcauliflower-like,atypicalmicromorphologyofvolcanicsmecites.ThesmectiteatODPSite1146isrelativelyrichinSielement,butpoorinFe,verysimilartothesmectitefromtheWestPhilippineSea.Incontrast,thechemicalcompositionofilliteatODPSite1146hasnoobviousdifferencesfromthoseoftheLoessplateau,YellowRiver,YangtzeRiver,andPearlRiver.AfurtherstudyonsedimentsourceindicatesthatsmectiteoriginatesmainlyfromLuzon,kaolinitefromthePearlRiver,andilliteandchloritefromthePearlRiver,Taiwanand/ortheYangtzeRiver.TheclaymineralassemblagesatODPSite1146werenotonlycontrolledbycontinentaleatheringregimessurroundingtheSCS,butalsobythechangingstrengthofthetransportprocesses.Theratiosof(illite+chlorite)/smectiteatODPSite1146wereadoptedasproxiesfortheEastAsianmonsoonevolution.Relativelyhigherratiosreflectstronglyintensifiedwintermonsoonrelativeto summermonsoon,incontrast,lowerratiosindicateastrengthenedsummermonsoonrelativetowintermonsoon.TheconsistentvariationofthisclayproxyfromthoseofLoessplateau,eoliandepositionintheNorthPacific,planktonic,benthicforaminifera,andblackcarbonintheSCSsince20MashowsthatthreeprofoundshiftsoftheEastAsianwintermonsoonintensity,andaridityintheAsianinlandandtheintensityofwintermonsoonrelativetosummermonsoon,occurredatabout15Ma,8Ma,andtheyoungeratabout3Ma.Thephaseduplift&nb
Morphological Characteristics of (K, Na)-Rectorite from Zhongxiang Rectorite Deposit, Hubei, Central China
Hong Hanlie* (洪汉烈), Zhang Xiaoling (张晓玲), Wan Miao (万淼), Hou Yijun (侯一俊), Du Dengwen (杜登文)
2008, 10(1).
摘要:
The morphological characteristics of the Zhongxiang (钟祥) rectorite have been studied using X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), scanning electron microscopy (SEM), atomic force microscope (AFM), and high-resolution transmission electron microscopy (HRTEM).The structural formula of the Zhongxiang rectorite is: (Na0.45K0.32Ca0.37Mg0.08)(Al3.78Fe0.11Ti0.10)[(Si6.22Al1.78)O20](OH)4?nH2O. It should be confined to a regular interstratification of (K, Na)-mica and Ca-montmorillonite. SEM observations show that Zhongxiang rectorite occurs as platy and fold-shaped crystals, and mainly as extremely thin plates with thickness ranging from 0.4 to 0.05 μm and a smooth (001) surface. There are well-developed polygonal steps on the surfaces of some thick crystals, suggesting a layer-by-layer growth mechanism. AFM observations show a series of steps with a height of 2 nm on the platy particles, suggesting the stacking of 20 nm fundamental particles. Club-like or fiber-shaped halloysite is included in the platy crystals with their elongated dimension paralleling (001) of the platy crystals or crossing the (001) surface of the platy rectorite, indicating multi-stage crystallization and involvement of hydrothermal fluids. The Zhongxiang rectorite was generated by both layer-by-layer growth mechanism and dissolution and crystallization growth mechanism with multistages.
Zircon LA-ICP MS U-Pb Dating of the Longkang Andesitic Ignimbrites from Jiuzhaigou: Evidence of the Mianlue Suture Westward Extension
Qin Jiangfeng (秦江锋), Lai Shaocong* (赖绍聪), Zhang Guowei (张国伟), Diwu Chunrong (第五春荣), Li Yongfei (李永飞)
2008, 10(1).
摘要:
Genesisofmetasedimentary-volcanicsoutcropedinKangxian-Pipasi-Nanping(康县-琵琶寺-南坪)tectoniczoneiscloselyrelatedwithtectonicevolutionoftheMianlue(勉略)Ocean.InthewestendofKangxian-Pipasi-Nanpingtectoniczone,therearehundredmetersofandesiticignimbritesandtuffites.ZirconU-Pbdatingonthesevolcanicshasgreatsignificancetothetectonicimplicationofthevolcanicrocks.Zirconsfromanignimbritesample(JZG-L)havebeencollectedfromYazhagou(牙扎沟)intheeastendoftheTazang-Longkang(塔藏-隆康)SectionforLA-ICPMSU-Pbdating.ThezirconsfromLongkangandesiticignimbritesaremagmaticgenesiswithoscillatoryzoningandhighU((35–750)ppm),Th((311–717)ppm)contentswithhighTh/U(0.44–1.30)ratios.Themeasured206Pb/238Uratiosareingoodanalyticalprecision,yieldingaweightedmeanageof(246±3)Ma(MSWD=2.6,n=12,2σ).Somedetritalzirconshavealsobeenobserved,theyhavemaximalconcordiaageof(2481±33)Ma,whichindicatestheexistenceofPrecambrianmaterialintheJiuzhaigou(九寨沟)area.Combinedwithregionalgeologyandthevolcanicrocksinthestudiedarea,the(246±3)MazirconU-PbagesuggestsaLatePermianorogenicvolcanismandprovidesimportantgeochronologyevidencefortheMianluesuturewestwardextension.
Sequence Stratigraphic Delineation and Correlation of the Dongying Formation in the Nearshore and Adjacent Sea Areas,
朱红涛, 杜远生, 颜佳新, 徐亚军, 杨萍, 刘新宇
2008, 10(1).
摘要:
Basedontheanalysisofwelllogs,seismicdata,corestudies,theDongying(东营)Formationalongthenearshoreandadjacentseaareas,Bohai(渤海)Baybasinhasbeensubdividedintothreethird-ordersequencesfrombasetotop:namely,sequencesSQ1,SQ2andSQ3.Thethreesequenceshavedifferentwireline(SP)logresponses,showingtriple-sectioncharacteristicswithSQ1beingcharacterizedbyprimarilyflatbaselinewithintercalationofrelativelylowspontaneouspotential,SQ2generallyexhibitingweakormoderateamplitudespontaneouspotentialwithfinger-shapedpeaks,andSQ3havingrelativelyhighspontaneouspotentialwithfunnel-shapedlogcurves.Onthebasisofthetriple-sectioncharacteristics,thestratigraphicsequencescanbecorrelatedconsistentlythroughouttheentirestudyarea.AstratigraphicandsedimentarymodelforsequencesSQ1toSQ3oftheDongyingFormationinthestudyareahasbeenproposed.Theaccommodationspacechangeinthetwosidesoftheasymmetricalbasinwasexaminedandtheasymmetricalbasinhasthefeatureoftheasymmetricalaccommodationspacechange.Theasymmetricalphysiographyisavitalfactortoinfluencetheaccommodationchangesinadditionaltothelakelevelchange,tectonismandsedimentsupply.ThismayhaveimportantimplicationstosimilarbasinsinotherpartsofChinaorelsewhere.
Simplicial Indicator Kriging
R Tolosana-Delgado, V Pawlowsky-Glahn, J J
2008, 10(1).
摘要:
Indicatorkriging(IK)isaspatialinterpolationtechniquedevisedforestimatingaconditionalcumulativedistributionfunctionatanunsampledlocation.Theresultisadiscreteapproximation,anditscorrespondingestimatedprobabilitydensityfunctioncanbeviewedasacompositioninthesimplex.ThisfactsuggestedacompositionalapproachtoIKwhich,byconstruction,avoidsallitsstandarddrawbacks(negativepredictions,not-orderedorlargerthanone).Here,asimplealgorithmtodeveloptheprocedureispresented.
Euler Deconvolution with Improved Accuracy and Multiple Different Structural Indices
G R J Cooper*
2008, 10(1).
摘要:
Eulerdeconvolutionisasemi-automaticinterpretationmethodthatisfrequentlyusedwithmagneticandgravitydata.Foragivensourcetype,whichisspecifiedbyitsstructuralindex(SI),itprovidesanestimateofthesourcelocation.Itisdemonstratedherethatbycomputingthesolutionspaceofindividualdatapointsandselectingcommonsourcelocationstheaccuracyoftheresultcanbeimproved.Furthermore,onlyaslightmodificationofthemethodisnecessarytoallowsolutionsforanynumberofdifferentSIstobeobtainedsimultaneously.Themethodisapplicabletobothevenlyandunevenlysampledgeophysicaldataandisdemonstratedongravityandmagneticdata.Sourcecode(inMatlabformat)isavailablefromwww.iamg.org.
Fractal Modeling of Sphalerite Banding in Jinding Pb-Zn Deposit, Yunnan, Southwestern China
Wang Zhijing* (王志敬), Cheng Qiuming (成秋明), Xu Deyi (徐德义), Dong Yaosong (董耀松)
2008, 10(1).
摘要:
SphaleritebandingisacommontextureinJinding(金顶)Pb-Zndeposit,Yunnan(云南),southwesternChina.Thefrequencydistributionandirregularityofsphaleritegrainsobservedinthebandingsarecharacterizedquantitativelybyfractalmodels.Fractaldimensionscalculatedbyseveralfractalmodelsincludingbox-countingmodel,perimeter-area(P-A)model,andnumber-area(N-A)modelshowthegradualchangefromouterbandingtoinnerbanding,indicatingadecreaseinareapercentage,inirregularity,inshapeandingrainsize,andanincreaseinthenumbersofgrains.Theseresultsmayimplyaninwardgrowthofsphaleriteduringmineralization,andself-organizationpropertiesareinvolvedinthenonlinearprocessofmineralization.
Effect of Multipoint Heterogeneity on Nonlinear Transformations for Geological Modeling: Porosity-Permeability Relations Revisited
J A Vargas-Guzmán*
2008, 10(1).
摘要:
Ananalysisofstatisticalexpectedvaluesfortransformationsisperformedinthisstudytoquantifytheeffectofheterogeneityonspatialgeologicalmodelingandevaluations.Algebraictransformationsarefrequentlyappliedtodatafromloggingtoallowforthemodelingofgeologicalproperties.Transformationsmaybepowers,products,andexponentialoperationswhicharecommonlyusedinwell-knownrelations(e.g.,porosity-permeabilitytransforms).Theresultsofthisstudyshowthatcorrectcomputationsmustaccountforresidualtransformationtermswhichariseduetolackofindependenceamongheterogeneousgeologicalproperties.Inthecaseofanexponentialporosity-permeabilitytransform,thevaluesmaybepositive.Thisprovesthatasimpleexponentialmodelback-transformedfromlinearregressionunderestimatespermeability.Inthecaseoftransformationsinvolvingtwoormoreproperties,residualtermsmayrepresentthecontributionofheterogeneouscomponentswhichoccurwhenpropertiesvarytogether,regardlessofapair-wiselinearindependence.Aconsequenceofpower-andproduct-transformmodelsisthatregressionequationswithinthosetransformationsneedcorrectionsviaresidualcumulants.Ageneralizationofthisresultisthattransformationsofmultivariatespatialattributesrequiremultiple-pointrandomvariablerelations.Thisanalysisprovidespracticalsolutionsleadingtoamethodologyfornonlinearmodelingusingcorrectbacktransformationsingeology.
Monotone Regression and Correction for Order
韩燕, 杨毅恒
2008, 10(1).
摘要:
The indicator kriging (IK) is one of the most efficient nonparametric methods in geo-statistics. The order relation problem in the conditional cumulative distribution values obtained by IK is the most severe drawback of it. The correction of order relation deviations is an essential and important part of IK approach. A monotone regression was proposed as a new correction method which could minimize the deviation from original quintiles value, although, ensuring all order relations.