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简介：AmarinestratigraphicsequenceacrossthePliocene/Pleistoceneboundaryhasbeenfoundinthenorth-erncontinentalshelfoftheSouthChinaSea.ThemarineQuaternarydepositsintheYinggehaiBasinmayex-ceed2,000minthickness,probablyprovidingthebestsectionforstudyingthelowerboundaryofthemarinePleistoceneinSouthChina.TheverticalsuccessionwithplanktonicforaminifersandnannofossilsrevealedinboreholesinthebasinhasbeenwellcorrelatedwiththatintheinternationalstratotypesectionofthePliocene/PleistoceneboundaryatVrica,Italy,resultingintheacquirementofabiostratigraphicboundaryat1.64Ma.Thisboundary,however,doesnotcoincidewithanyprominentlithologicalpalaeoenvironmentalchangesinthestudyareaandcanhardlybeusedingeologicalpractice.Thereare,incontrast,significantchangesatthelevelofLADofGloborotaliamulticameratasensulatolocatedbelowtheabove-mentionedboundary.Thepercentageofplanktonicforaminifersinthetotalpopulationandpreservationofforaminiferaltestsdisplaygreatchangesatthislevelcorrespondingtoaclearonlapontheseismicprofilesandindicatingadepositionalhiatusatca.2.0-2.5Ma.SincethelevelcanbewidelytracedinthePearlRiverMouthBasinandtheBeibuGulfBasinandwellcorrespondswiththemarkeddepositionalenvironmentalchangesrecordedinthewestPacificandotherregions,itisrecommendedthatthePlio/PleistoceneboundarybedrawnatthelevelofGr.multicameratasensulatoLAD,roughlyconcurrentwiththeGauss/Matuyamaturn.

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简介：MicromorphologicalcharacteristicsoffourpaleosollevelsoftheManonga-WemberedepositsinCentralTanzaniaindicateperiodsofwetterclimateinthePliocenethanatpresent.Thestratigraphyofthestudiedsectionshowsaseriesoflacustrinecalcareousclaysedimentsalternatingwithgravel,sandandsilt.ThesedimentsarebelievedtohavebeendepositedintheManonga-Wemberepaleolakeenvironment.Paleosolsintercalatethesesedimentsandwereformedwhenstablelandscapesdevelopedonformerlakebedsduringregressionperiods.MicromorphologicalfeaturesofthepaleosolsindicatestrongclayilluviationofredtoyellowtypicclaycoatingandsomeFe-Mnhydoxidehypocoatingsinvoidsandchannels.Thegroundmassconsistsofeitheranaccumulationofbioturbatedyellowtoredclaycoatingfragmentsoranargillicredtoyellowgroundmassofclaymass.Suchanilluviationanditsassociatedgroundmassiscomparabletointenseclayilluviationfrontsthatarefoundinpresent-daycalcareoussedimentsofwarmandwetclimates.ThepaleosollevelsthereforerepresentwetterclimaticconditionsthantodayintheareaduringtheLowerPliocene.

简介：Thisstudyisthefirsttoreporttheradiocarbonages,mineralogical,morphological,geochemicalandstableisotopecompositionsofcalcretesfromNeogenesedimentsaroundlakesEymirandMoganintheG?lba??BasinofCentralAnatolia.MorphologicallydifferentformsofcalcretesintheG?lba??Basinincludepowdery,nodular,fractureinfill,laminarandhardpantypes.Calciteisthedominantmineralofcalcretecompositions;thediagnosticfeaturesofdessicationcracks,randomfractures,MnOliningsanddensespariticinfillingsareobserved.Chemicalanalysesshowaridconditionswithmeanannualprecipitationof<50mm.δ13Ccompositionsofthecalcretesrangefrom-6.77‰to-9.32‰PDB,typicalformostpedogeniccalcretes,reflectingthedevelopmentunderseasonallyaridclimatesandC3-dominatedvegetationcover.δ18Ovaluesarebetween-5.57‰and-7.80‰PDB,indicatingtheformationfrommeteoricwaterinavadosezoneenvironment.TheresultssuggestthattheMiddlePleistocenewasariderandwarmer,favouringtheformationofpalygorskiteinassociationwiththedifferentformsofcalcreteoccurrences,whereastheLatePleistocenewasdryerandcooler,supportingthedevelopmentofcalcretes.