3-3-Sampling-Mantle-Heterogeneity-through-Oceanic-Basalts-Isotopes-and-Trace-Elements_2014_Reference-Module-in-Earth-Systems-and-Environmental-Science

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1、3.3SamplingMantleHeterogeneitythroughOceanicBasalts:IsotopesandTraceElementsAWHofmann,Max-Planck-institutfu¨rChemie,Mainz,Germany;Lamont-DohertyEarthObservatory,Palisades,NY,USAã2014ElsevierLtd.Allrightsreserved.Thisarticleisreproducedfromthepreviousonlineupdate,volume2,pp.1–4

2、4,©2007,ElsevierLtd.3.3.1Introduction673.3.1.1EarlyHistoryofMantleGeochemistry673.3.1.2TheBasics683.3.1.2.1Majorandtraceelements:incompatibleandcompatiblebehavior683.3.1.2.2Radiogenicisotopes693.3.2LocalandRegionalEquilibriumRevisited693.3.2.1MineralGrainScale693.3.2.2Mesoscal

3、eHeterogeneities703.3.3Crust–MantleDifferentiation713.3.3.1EnrichmentandDepletionPatterns713.3.3.2MassFractionsofDepletedandPrimitiveMantleReservoirs733.3.4Mid-OceanRidgeBasalts:SamplesoftheDepletedMantle753.3.4.1IsotopeRatiosofStrontium,Neodymium,Hafnium,andLead753.3.4.2Osmiu

4、mIsotopes793.3.4.3TraceElements803.3.4.4N-MORB,E-MORB,T-MORB,andMORBNormalizations833.3.4.5SummaryofMORBandMORB-SourceCompositions843.3.5OceanIsland,Plateau,andSeamountBasalts853.3.5.1IsotopeRatiosofStrontium,Neodymium,Hafnium,andLeadandtheSpeciesoftheMantleZoo853.3.5.2TraceEl

5、ementsinOIB893.3.5.2.1‘Uniform’trace-elementratios903.3.5.2.2Normalizedabundancediagrams(spidergrams)923.3.6TheLeadParadox933.3.6.1TheFirstLeadParadox933.3.6.2TheSecondLeadParadox953.3.7GeochemicalMantleModels96Acknowledgments97References983.3.1IntroductionThroughthestudyofoce

6、anicbasalts,itwasfoundthatthemantleiscompositionallyjustasheterogeneousasthecrust.3.3.1.1EarlyHistoryofMantleGeochemistryThus,geochemistry,atermthatseemsmoreappropriatethanUntilthearrivalofthetheoriesofplatetectonicsandseafloorthemorepopular‘chemicalgeodynamics,’becameamajorsp

7、readinginthe1960s,theEarth’smantlewasgenerallytooltodecipherthegeologyofthemantle.believedtoconsistofperidotitesofuniformcomposition.ThepioneersofthiseffortwereGast,Tilton,Hedge,Thisviewwassharedbygeophysicists,petrologists,andgeo-Tatsumoto,andHart(HedgeandWalthall,1963;Gastet

8、al.,chemistsalike,anditservedtocharacterizethecompositions196