自然體系中元素的分布

1TheChemicalCompositionoftheSolarSystemandtheEarthTwosuggestionsExpertisecomesfrommakingallpossiblemistakes(NielsBohr)Nothingcanbeobtainedingeochemistrywithoutcarefulanalyticalwork(C.J.Allegre)FurtherreadingsW.M.White,Geochemistry.Aon-linetextbook.S.R.TaylorandS.M.,1995.TheContinentalCrust:ItsCompositionandEvolution.Blackwell,Oxford.W.F.McDonoughandS.Sun,TheCompositionoftheEarth,ChemicalGeology,120:223-253.GeochemicalEarthReferenceModel(GERM)

www.EarthRWhydowestudyelementabundances?FundamentalforanygeochemicalstudiesConfusingtermsAbundance:foralargesystem,e.g.,Cosmos,Sun,Moon,Earth,crust,regionalcrustContent/concentration:forasmallersystem,e.g.,rocks,minerals,naturalwater.Part1TheSolar/CosmicsystemSourcesforstudiesMeteoriteSun’sPhotosphereCosmicraysEarthandmoonVariousmeteoritesizesStonymeteoriteIronmeteoriteAhnighitometeorite南極洲

IvunameteoritefragmentMeteoriteEsquel

Pallasite（石鐵隕石）FoundinEsquel,ArgentinaWhereisthebestplacetofindmeteoritesonEarth?Firn

粒雪

Katabatic

下降的ablation[?b‘lei??n]切除，消除nunatak[’n?n?t?k]冰原島峰Classificationofmeteoritesaccordingtotextureandchemicalcomposition(White,2001)Achondrite

不含球粒隕石

aubrite：頑火無球粒隕石15Aside:MeteoriteClassificationLifeonMars!RelativeabundanceofmajortypesofmeteoritefallsCharacteristicsofchondritegroupsCarbonaceouschondritesarethemostvolatile-richandthemostprimitive.IvunameteoriteA0.7-kilogramcarbonaceouschondrite(typeCI1,seebelow)whichlandednearIvuna,Tanzania,onDecember16,1938.Itwassubsequentlysplitintoanumberofsamples.

Ivunawasoneoffourmeteorites,includingtheOrgueilmeteorite,inwhichBartholomewNagyandGeorgeClaus1claimedtohavefoundevidenceofprimitiveextraterrestrialfossils.Subsequentanalysisledtothisclaimbeingdiscredited.However,in2001,investigationbyateamfromtheScrippsInstitutionofOceanography,theLeidenObservatoryintheNetherlands,andtheNASAAmesResearchCenter,2showedthepresenceinIvunaoftwosimpleaminoacids,glycineandbeta-alanine,andlinkedIvunawithalikelyorigininthenucleusofacomet.Formoreonthisdiscoveryanditsimplications,seetheentryfortheOrgueilmeteorite.

IvunaisoneofonlynineknownmeteoritesthatareclassifiedastypeCI1carbonaceouschondrites.Thesemeteoritescontain“heavyelements”(i.e.,elementsotherthanhydrogenandhelium)innearlythesameabundancesasintheSun,whichmeansthattheyareessentiallyunalteredsincetheywereformedataboutthesametimeasthesolarsystemitself,some4.6billionyearsago.ThedesignationCI1indicatesthatIvunaunderwentahighdegreeofaqueousalteration(orchemicalchangeduetothepresenceofwater).Thisalterationtookplaceintheparentbodyofthemeteoriteatlowtemperatures,probablyintherangeof20–50°C,andinawater-richenvironment.Bycontrast,ordinarychondriteshaveexperiencedthermalmetamorphismunderdryconditionsinatemperaturerangeof600–900°C.

CI1typemeteoritesareverydark,becauseoftheirhighcarboncontent,containahighproportionofofiron-richclaysorphyllosilicates(層狀硅酸鹽),andhaveveryfinegrainsize.InIvuna,thereisalsoacompleteabsenceofchondrules,owingtothefactthattheyhaveallbeenalteredtoclaysandironoxides.

WhatdoestheclassificationCI1mean?

CI1chondriteIvuna–upto20wt.%waterCondensation（冷凝）sequenceofagaswithasolarcompositionCondesationsequenceofmineralsperovskite[p?'r?vzkait]n.鈣鈦礦corundum[k?'r?nd?m]n.金剛砂，剛玉troilite['tr?uilait,'tr?il-]n.隕硫鐵Goldschmidt’sclassificationofelementslithophile['liθ?ufail]n.親石元素lithophile['liθ?ufail]n.親石元素siderophilen.親鐵元素chalcophile['k?lk?,fail]adj.親銅的，親硫的atmophile：親氣元素Classificationofelements

(McDonoughandSun,1995)refractory[ri‘fr?kt?ri]adj.難熔的atmophile：親氣元素ClassificationofelementsaccordingtovolatilityThereismuchinterestinhighTcomponent,i.e.,theso-calledRefractoryInclusions(RI)orCa-Alinclusions(CAI),becausetheircompositionrepresentsthatofthefirstcondensatesfromahighTgas.Ca-AlinclusionCartonillustratingtheprocessinvolvedinformationofchondritesandtheircomponentsinterstellar[,int?'stel?]adj.星際的ChondriticbodyDifferentiatedbodyTypesofStonyMeteoritesChondrites–HeatedbuthavenotmeltedTendtocontainchondrulesAggregatesofhigh-andlow-temperaturecomponentsAchondrites–HeatingtothepointofmeltingTendtodifferentiateWherematerialsegregatesduetodensitachondrite[ei'k?ndrait]n.不含球粒隕石Abundancesofelementsinsun’sphotospherevstheirabundancesinCIchondrites(White,2001)ComparisonofelementabundancesinsolarphotosphereandCIcarbonaceouschondrites(TaylorandMcLennan,1995)SolarsystemabundancesofelementsrelativetoSi=106CharacteristicofelementabundancesofthesolarsystemHandHeaccountsfor98%inmass.Exponentialdecreaseinabundanceforelementswithatomicnumber<45.Elementswithevenmassshowsignificantlyhigherabundancesthantheneighboringelementswithoddmass.HeexhibitanabnomouslyhighabundancecomparedtotheneighboringLi,BeandB.OandFeshowapeak.Isotopeswithatomicweightbeingfactorof4havehighabundance.4He(Z=2,N=2),16O(Z=8,N=8),

40Ca(Z=20,N=20).Even-oddmasseffect5758596062636465666768697071SequenceofdecreasingelementabundancesinthesolarsystemHHeOCN,NeMg,SiFeS1010to109107106105Neocleo(核)synthesisTheBigBangStellarstructure（恒星結(jié)構(gòu)）

attheonsetofsupernova（超新星）stage(White,2001)TheE-process(Siburning)TheS-process(neutroncapture)Ther-process(Rapidneutroncapture)PrinciplemechanismforformingheavierisotopesThep-process(Protoncapture)ResponsibleforthelightestisotopesofagivenelementTher-processpathPart2TheMoonRepresentativecompositionsoflunarrocks（月巖）anorthosite[?‘n?:θ?sait][巖]

斜長巖tholeiite['θ?uli:ait]n.[巖]拉斑玄武巖ComparisonofthecompositionoftheMoonandtheEarthHighlightsof

lunar

GeochronologyPart3TheEarthVolumesandmassesoftheEarth’sshellsTheEarth’sInteriorMantle:Peridotite(ultramafic)Upper

to410km(olivine?spinel)LowVelocityLayer

60-220kmTransitionZone

asvelocityincreases~rapidly660spinel?

perovskite（鈣鈦礦）-typeSiIV

?

SiVILowerMantle

hasmoregradual velocityincreaseFigure1-2.MajorsubdivisionsoftheEarth.Winter(2001)AnIntroductiontoIgneousandMetamorphicPetrology.PrenticeHall.TheEarth’sInteriorCore:Fe-NimetallicalloyOuterCore

isliquidNoS-wavesInnerCore

issolidFigure1-2.MajorsubdivisionsoftheEarth.Winter(2001)AnIntroductiontoIgneousandMetamorphicPetrology.PrenticeHall.Figure1-3.VariationinPandSwavevelocitieswithdepth.CompositionalsubdivisionsoftheEarthareontheleft,rheologicalsubdivisionsontheright.AfterKeareyandVine(1990),GlobalTectonics.?BlackwellScientific.Oxford.

Part3-1ThemantleMethodsofstudiesMantlexenolithsentrainedbyvolcanicrocksMassifperidotite:ExhumedmantleslabMantle-derivedvolcanicrocksExperimentsathighP-TSeismicanddensitypropertiesMantleRockTypesRockNamesPeridotite（橄欖巖）:ultramaficrockcomposedofolivine,2pyroxenes(opx-cpx)andAl-phase(i.e.,plagioclase,spinel,garnet,withthespecificphasebeingafunctionofpressure,0-10,10-25,>25Kbrespectively),includes:lherzolite（二輝橄欖巖）,harzburgite（方輝橄欖巖）,dunite（純橄巖）

Eclogite（榴輝巖）:mafic(i.e.,basaltic)rockcomposedofNa-richclinopyroxeneandgarnetPyroxenite（輝石巖）:mafictoultramaficrock,dominantlycomposedofpyroxene,oftencontaininganAl-phase(e.g.,plagioclase,spinel,garnet)

Non-RockNames

PrimitiveMantle/SilicateEarth:modelcompositionforthecrust+mantle.Pyrolite（地幔巖）:modelcompositionfortheprimitivemantle,namederivedfrompyroxene-olivine-ite.（Ringwood,1963）Piclogite(苦橄巖):modelcompositionforthemantle,namederivedfrompicritic-eclogite(picrite=olivine-richbasalt).Lherzolite（二輝橄欖巖）:AtypeofperidotitewithOlivine+Opx+CpxOlivineClinopyroxeneOrthopyroxeneLherzoliteHarzburgiteWehrliteWebsteriteOrthopyroxeniteClinopyroxeniteOlivineWebsteritePeridotitesPyroxenites90401010DuniteFigure2-2CAfterIUGSMantlerockmineralassemblageSimple:4or5phasesOlivine(Ol)Orthopyroxene(OPX)Clinopyroxene(CPX)Plagioclase(Pl)Spinel(Sp)Garnet(Gt)CompositionofrocksPyroliteharzburgitelherzoliteeclogiteSiO245464450Al2O34.51.22.216FeO8.07.38.210MgO3844418CaO3.60.92.210*Mg#89.491.589.958.8*densityr3.3853.3463.3763.970olivine566265--orthopyx183021--clinopyx102850garnet146650Modalandphysicalpropertyforlithosphericmantleofdifferentages

(AfterO’Reillyetal.,2001)

MantlePhaseDiagramsPhasediagramforaluminous4-phaselherzolite:Plagioclaseshallow(<50km)Spinel50-80kmGarnet80-400kmSi?VIcoord.>400kmAl-phase=Figure10-2

Phasediagramofaluminouslherzolitewithmeltinginterval(gray),sub-solidusreactions,andgeothermalgradient.AfterWyllie,P.J.(1981).Geol.Rundsch.70,128-153.

MantlephasediagramPhaseassemblagesand1atmdensityMeltingofMantleMelt:BasaltResidue:Peridotite1510500.00.20.40.60.8Wt.%Al2O3Wt.%TiO2DuniteHarzburgiteLherzoliteTholeiiticbasaltPartialMeltingResiduumLherzoliteisprobablyfertileunalteredmantleDunite(純橄巖)andharzburgite（方輝橄欖巖）

arerefractoryresiduumafterbasalthasbeenextractedbypartialmeltingFigure10-1BrownandMussett,A.E.(1993),TheInaccessibleEarth:AnIntegratedViewofItsStructureandComposition.Chapman&Hall/Kluwer.Howdoesthemantlemelt??1)IncreasethetemperatureFigure10-3.Meltingbyraisingthetemperature.

2)LowerthepressureAdiabatic（絕熱的）

riseofmantlewithnoconductiveheatlossDecompressionmeltingcouldmeltatleast30%Figure10-4.Meltingby(adiabatic)pressurereduction.Meltingbeginswhentheadiabatcrossesthesolidusandtraversestheshadedmeltinginterval.Dashedlinesrepresentapproximate%melting.

3)Addvolatiles(especiallyH2O)Figure10-4.DryperidotitesoliduscomparedtoseveralexperimentsonH2O-saturatedperidotites.Experimentsonmeltingenrichedvs.depletedmantlesamples:Tholeiite（拉斑玄武巖）easilycreatedby10-30%PMMoresilicasaturatedatlowerPGradestowardalkalicathigherP1.DepletedMantleFigure10-17a.Resultsofpartialmeltingexperimentsondepletedlherzolites.Dashedlinesarecontoursrepresentingpercentpartialmeltproduced.Stronglycurvedlinesarecontoursofthenormativeolivinecontentofthemelt.“Opxout”and“Cpxout”representthedegreeofmeltingatwhichthesephasesarecompletelyconsumedinthemelt.AfterJaquesandGreen(1980).

Contrib.Mineral.Petrol.,73,287-310.

Experimentsonmeltingenrichedvs.depletedmantlesamples:TholeiitesextendtohigherPthanforDMAlkalinebasaltfieldathigherPyetAndlower%PM2.EnrichedMantleFigure10-17b.Resultsofpartialmeltingexperimentsonfertilelherzolites.Dashedlinesarecontoursrepresentingpercentpartialmeltproduced.Stronglycurvedlinesarecontoursofthenormativeolivinecontentofthemelt.“Opxout”and“Cpxout”representthedegreeofmeltingatwhichthesephasesarecompletelyconsumedinthemelt.Theshadedarearepresentstheconditionsrequiredforthegenerationofalkalinebasalticmagmas.AfterJaquesandGreen(1980).

Contrib.Mineral.Petrol.,73,287-310.

MeltingofmantleT,PCaO-Al2O3plotshowingtherangeofmantlecompositionofdifferentages

(O’Reillyetal.,2001)

DEPLETIONLherzolitefromHannuoba,NorthChinaCratonDeepestmantlesamplesfromtransitionzone:

Majorite-BearingXenolithsfromMalaita,OntongJavaOceanicPlateau-9.5GPa(260km)to22GPa(570km).

Collersonetal.,2000,Science,288:1215-1223MantlephasediagramCommonlherzolitexenolithscomefromadepthof50-80km:lithospherePhasediagramforaluminous4-phaselherzolite:Plagioclaseshallow(<50km)Spinel50-80kmGarnet80-400kmSi?VIcoord.>400kmAl-phase=Figure10-2

Phasediagramofaluminouslherzolitewithmeltinginterval(gray),sub-solidusreactions,andgeothermalgradient.AfterWyllie,P.J.(1981).Geol.Rundsch.70,128-153.

StructureoflithosphereNyblade,2001LithosphereevolutionineasternNorthChinacraton

(AfterO’Reillyetal.,2001)

EstimationofPrimitiveMantleCompositionMantlemodelcirca1975Figure10-16a

AfterBasalticVolcanismStudyProject(1981).LunarandPlanetaryInstitute.NewermantlemodelUpperdepletedmantle=MORB+crustsourcesLowerundepleted&enrichedOIBsourceFigure10-16b

AfterBasalticVolcanismStudyProject(1981).LunarandPlanetaryInstitute.PrimitivevsmetasomatismPrimitive:FlatREEMetasomatism:LREEenrichedREEdistributionofperidotiteshowingeffectofmantlemetasomatismContinental

CrustMORBGarnet

harzburgiteSpinel

lherzolitePrimitive

Mantle10210110-1100LaCePrNdSmEuGdTbDyHoErTmYbLuChondritenormalizationCriteriaforestimatingPrimitiveMantleCompositionShouldhaverefractorylithophileelementratiosthataresimilartoCIchondrite.VariationswithMgOinperidotite（橄欖巖）Constantrefractory

elementratiosinperidotites(橄欖巖)Elementalratiosinchondriticmeteorites

(McDonoughandSun,1995)Variationofrefractorylithophileelementratiosinperidotites

(McDonoughandSun,1995)Estimatingrefractory

lithophileelements

inbulksilicateEarth

(McDonoughandSun,1995)EstimatesofSilicateEarth

-MajorelementsEstimatesofSilicateEarth

-TraceelementsPart3-2TheCoreandBulkEarthTheEarth’sInteriorCore:Fe-NimetallicalloyOuterCore

isliquidNoS-wavesInnerCore

issolidFigure1-2.MajorsubdivisionsoftheEarth.Winter(2001)AnIntroductiontoIgneousandMetamorphicPetrology.PrenticeHall.CompositionoftheCorePoorlyconstrainedbeyonditsmajorconstituents(i.e.,anFe-Nialloy).Presenceof5-15%oflightelement(s)(S,O,Si).ThedominantdepositoryofsiderophileelementsintheEarth.LimitsonthecompositionsofthecoreandbulkEarth

(McDonough&Sun,1995)Liquidsilicate-liquidmetalpartitioncoefficientsComparisonofelementdistributionsintheEarthandcarbonaceouschondritesTheEarthismorestronglydepletedinvolatileelementsFigure1-5.Relativeatomicabundancesofthesevenmostcommonelementsthatcomprise97%oftheEarth'smass.AnIntroductiontoIgneousandMetamorphicPetrology,byJohnWinter,PrenticeHall.Part3-3TheOceaniccrustTheEarth’sCrustOceaniccrustThin:10kmRelativelyuniformstratigraphy =ophiolitesuite:

Sedimentspillowbasaltsheeteddikesmoremassivegabbroultramafic(mantle)ContinentalCrustThicker:20-90kmaverage~35kmHighlyvariablecompositionAverage~granodioriteMethodsofstudyOphiolite（蛇綠巖）OceandrillingSeismicstudiesStructureofoceaniccrustPlateTectonics–IgneousGenesis

1.

Mid-oceanRidges2.

IntracontinentalRifts3.IslandArcs4.

ActiveContinental Margins

5.

Back-arcBasins6.

OceanIslandBasalts7.

MiscellaneousIntra- ContinentalActivitykimberlites,carbonatites,anorthosites...CompositionoftheOceanicCrust(TaylorandMcLennan,1995)ImportanceofDeterminingCrustalCompositionBasicconstraintsonevolutionoftheEarth.MostaccessiblepartoftheEarthandthebestknown.Placeforformationofmostoforedeposits.Importantdepositoryforhighlyincompatibleelements(U,K,Cs).Essentialforenvironmentalstudiesandgeochemicalexploration.StudyofthecompositionofthecontinentalcrustcanbetracedbacktoearlieststageofgeochemicalstudiesF.M.Clarke,1889F.M.ClarkeandH.S.Washington,1924V.M.Goldschmidt,1933,whoisregardedasthefatherofmoderngeochemistry.S.R.Taylor,1994D.M.Shaw,1967S.R.TaylorandS.M.McLennan,1985K.H.Wedepohl,1992WhatistheContinentalCrust?ExtendsverticallyfromthesurfacetotheMohorovicicdiscontinuity,ajumpincompressionalwaveVpspeedsfrom~7km/sto~8km/sthatisinterpretedtomarkthecrust-mantleboundary.Stratificationinseismicvelocityandthusrocktypeandchemicalcomposition.Lateralandverticallyheterogeneousandgreatdiversityinrocktype.Structureandcompositionalmodelofthecontinentalcrust

(Wedepohl,1995)MetamorphicFaciesFig.25-2.

Temperature-pressurediagramshowingthegenerallyacceptedlimitsofthevariousfaciesusedinthistext.Boundariesareapproximateandgradational.The“typical”oraveragecontinentalgeothermisfromBrownandMussett(1993).Winter(2001)AnIntroductiontoIgneousandMetamorphicPetrology.PrenticeHall.UppercrustMiddleCrustLowerCrustPart3-4-1TheUpperContinentalCrust:themostaccessiblepartoftheEarthMethodsofStudiesLarge-scaleregionalsampling(e.g.,theCanadianShield)Usingfine-grainedclasticsedimentsExamples:TheCanadianShieldandEasternChina.Themostreliablemethodforuppercrustalcompositionestimation.Theonlymethodformajorelementcompositionstudies.Expensiveandtime-consuming.Notpertainto(適合)thestudyofuppercrustalcompositioninthegeologicalhistory.Large-scaleregionalsamplingXRFX-rayfluorescenceX射線熒光INAAInstrumentalNeutronAtivationAnalysisFine-GrainedClasticSedimentsasNaturalSamplingoftheExposedUpperContinentalCrustShale,mudstone,siltstone,graywackgraywacke['ɡrei,w?k?]n.雜砂巖；硬砂巖（等于greywacke）,tillite（冰磧巖）,andloess（黃土）.Simpleandmuchlessexpensive.Theonlywayforstudyinguppercrustalcompositioningeologicalhistory.Unsuitabletoprovidingthemajorelementcomposition.LimitedtoREE,Y,Th,Sc,Co.Geologicalinfluencesonsedimentaryrockcomposition-SolubilityWater-uppercrustpartitioncoefficient（分配系數(shù)）:

Ky=Naturalwater/UppercrustSeawaterresidencetime

y:timeforreplacementofseawaterelementconcentration.

y=My/Fy

whereMyisthemassofelementyintheoceansandFyistheannualmeanfluxofelementythroughtheoceanreservoir.WeatheringCa,NaandSrarelostK,Rb,CsandBaareretained.Al,Ga,HSFE(Ti,Zr,Hf,Ta,Th)andREE,Y,Scareimmobile.CIA:ChemicalIndexofAlterationCIA=Al2O3/(Al2O3+CaO*+Na2O+K2O)

inmolecularproportionPlagioclaseisthedominantphaseinthecontinentalcrustsubjectedtoweathering.Pleistocene['plaist?usi:n]n.更新世；更新世巖Till冰磧beidellite[bai'delait]n.貝德石；鋁膨潤石ErosionandtransportationThesand-sizeeffect.Quartzandheavyminerals(zircon鋯石,rutile金紅石,magnetite磁鐵礦,chromite鉻鐵礦)areenrichedinsandstone.DiagenesisSensitivetoredox

氧化還原反應(yīng)

conditionsFeandMnaresolubleinanoxic（缺氧的）

conditions.Fe,Cu,Mo,Pb,Zn,V,Ni,S,Careclearlyenrichedinanoxicsedimentsduetoincorporationinsulphidesand/orabsorptiononorganiccompounds.Uisenrichedalsoinanoxicsedimentsduetoreductionofsoluble6+Utoinsoluble4+U.MetamorphismPoorlyunderstood.LiandPbmayincrease.MostelementsandparticularlyREE,Y,Th,HFSE,CrandScareimmobile.SedimentaryrocksascrustalsamplesInsolubleelements(log

4;Ksw

-4)arelikelytobetransferredalmostquantitativelyintoclasticsedimentsandgivethebestinformationregardingthesource-exposeduppercrust.REEinfine-grainedsedimentsprovidequantitativeinfoontheuppercrustcompositionQuantitativelytransferredintofine-grainedclasticsedimentsREEcomparisonof

shalesanduppercrustConstantelement（常量元素）ratiosintheuppercrustEstimationofuppercrustalcompositionMajorelements:

large-scalesamplingTraceelements:

large-scalesampling

fine-grainedclasticsediments

usingREEandtheirratiostootherelementsVariousuppercrustalmajorelementestimates

Taylor&McLennanShawetal.WedepohlCondieGaoetal.Rudnick&Gao

198519671995199319982002SiO26664.9364.9366.2165.4665.84TiO20.50.520.520.550.650.60Al2O315.214.6314.6314.9613.6514.31FeOT4.503.973.974.705.134.92MnO0.070.0680.070.10.10MgO2.22.242.242.422.522.47CaO4.24.124.123.63.313.46Na2O3.93.463.463.512.753.13K2O3.43.13.12.732.582.66H2O0.790.792.112.11P2O50.20.150.150.120.150.14Total100.1797.9897.9898.8098.4199.71Uppercrustalcompositionalestimates

(TaylorandMcLennan,1985)Comparisonofloessanduppercrustalcompositions(TaylorandMcLennan,1985)Part3-4-2ThedeepcrustMethodsofStudiesAmphibolite角閃巖-andgranulite-faciesxenolithsentrained攜帶mostlyinbasalts.ExposeddeepcrustalsectionsCorrelationofseismicvelocitiesofrockswithlithologiesHeatflowconstraintsCrustalstructurebasedondeepcrusalxenoliths

(Mengeletal.,1992)DeepCrustalXenolithsMostlygranulite-faciesExposedDeepCrustalSectionModelforexposeddeepcrustalcross-section

(PercivalandFountain,1992)P-waveandPoisson’s（泊松）ratiostructurealongtheexposedKapuskasingdeepcrustalsection

(PercivalandFountain,1994)P-wavevelocity(km)Poisson’sratioContrastsbetweengranulitexenolithsandterraingranulites

麻

粒

巖

地

體

麻

粒

巖

包

體

時

代

太古－

元古宙

后太古宙

壓

力700-1000MPa1000-1500MPa

深

度25-35km35-50km

巖

性中性和長英質(zhì)為主

鎂鐵質(zhì)－超鎂鐵質(zhì)為主

SiO255-75%40-55%CorrelationofseismicvelocitieswithrocktypesCompressionalP-wavevelocity(Vp)ShearS-wavevelocity(Vs)Poisson’sratio(

)

=0.5{1–1/[(Vp/Vs)2–1]}Measurementof

seismicvelocities

ofrocksCalculationofvelocitiesindepthV(z)=V(0)+[(dV/dP)T

P+(dV/dT)PT]dzWhereV(0)andV(z)arevelcitiesatareferencestateandatdepthz.Forcommonrocks,(dV/dP)T=2

10-4to7

10-4kms-1MPa-1;(dV/dT)P=-2

10-4to-6

10-4kms-1

C-1

EffectofheatflowonVp

(RudnickandFountain,1995)150MPa

下侵入巖Vp隨成分的變化

(FountainandChristensen,1989)Relationbetween

SiO2andVpof

granulites

(RudnickandFountain,1995)DensityvsVpPeridotiteEclogiteMaficgranulitePeridotite

橄欖巖Eclogite

榴輝巖Gabbro

輝長巖1、蛇紋巖2、石英巖3、花崗巖4、花崗閃長巖5、角閃巖相長英質(zhì)片麻巖6、石英云母片巖7、綠片巖相變輝長巖8、輝長巖9、斜長角閃巖1、長英質(zhì)角閃片麻巖2、長英質(zhì)片麻巖3、中性麻粒巖4、斜長巖5、鎂鐵質(zhì)麻粒巖6、斜長角閃巖7、麻粒巖相變泥質(zhì)巖8、輝石巖9、榴輝巖10、純橄欖巖/二輝橄欖巖Holbrooketal.(1992)Crustalstructureinvarioustectonicsettings

(RudnickandFountain,1995)Normativemineral（標(biāo)準(zhǔn)礦物）

compositionofcontinentalcrust

(TaylorandMcLennan,1995)ilmenite[‘ilm?nait]n.[礦]鈦鐵礦hypersthene['haip?sθi:n]n.[礦]紫蘇輝石Comparisonofcontinentalcrustandvariousbasalts

(Hoffmann,1994)compatibility[k?m,p?t?'bil?ti]n.兼容性CompositionalcharacteristicsofcontinentalcrustTheuppercrustisgraniticwith66%SiO2andwithasignificantnegativeEuanomaly.Themiddlecrustistonalitic(閃長質(zhì))with61%SiO2.Thelowercrustismaficinmanyregionswith~52%SiO2andmaybemoreevolvedforsomecratons(e.g.,NorthChinaCraton)andcollisionbelts.RelativedepletioninNbandenrichmentinPbcharacterizethecontinentalcrustandcontinentalcrustalrocks-“thearcsignature”.Thetotalcontinentalcrusthasanandesitic（安山質(zhì)）/granodioriticbulkcompositionwith59-62%.ItcontainsasignificantproportionofthebulksilicateEarth’sincompatibleelementbudget(33-35%ofRb,Ba,K,Pb,ThandU).Schematicmodelforgrowthandevolutionofthecontinentalcrust

(TaylorandMcLennan,1995)bombardment[b?m'ba:dm?nt]n.轟炸；炮擊Continentalcrust

LaCePrNdSmEuGdTbDyHoErTmYbLu110100Rock/ChondriteEastChina(thisstudy;Eu/Eu*=0.80)Wedepohl(1995;Eu/Eu*=0.83)Rudnick&Fountain(1995;Eu/Eu*=0.98)Taylor&McLennan(1995;Eu/Eu*=1.00)TotalContinentalCrustContrastinglowercrustalvelocitiesforArcheanandProterozoicprovinces

(DurrheimandMooney,1991)ThefollowingslidesarenotusedinthelecturesGenerationoftholeiitic（拉斑玄武巖）andalkalinebasaltsfromachemicallyuniformmantleVariables(otherthanX)TemperaturePressureFigure10-2

Phasediagramofaluminouslherzolite（二輝橄欖巖）withmeltinginterval(gray),sub-solidusreactions,andgeothermalgradient.AfterWyllie,P.J.(1981).Geol.Rundsch.70,128-153.

Liquidsandresiduumofmeltedpyrolite（地幔巖）Figure10-9AfterGreenandRingwood(1967).

EarthPlanet.Sci.Lett.2,151-160.

tholeiite['θ?uli:ait]n.[地]拉斑玄武巖granophyre['ɡr?n?ufai?]n.花斑巖InitialConclusions:Tholeiitesfavoredbyshallowermelting25%meltingat<30km?tholeiite25%meltingat60km?olivinebasaltTholeiitesfavoredbygreater%partialmelting20%meltingat60km?alkalinebasaltincompatibles(alkalis)?initialmelts30%meltingat60km?tholeiiteCrystalFractionationofmagmasastheyriseTholeiite?alkalinebyFXatmedtohighPNotatlowPThermaldivideAlinpyroxenesatHiPLow-PFX?hi-Alshallowmagmas(“hi-Al”basalt)Figure10-10SchematicrepresentationofthefractionalcrystallizationschemeofGreenandRingwood(1967)andGreen(1969).AfterWyllie(1971).

TheDynamicEarth:TextbookinGeosciences.JohnWiley&Sons.

nephelinite['nefilinait]n.霞石巖picrite['pikrait]n.苦橄巖PrimarymagmasFormedatdepthandnotsubsequentlymodifiedbyFXorAssimilation（同化）CriteriaHighestMg#(100Mg/(Mg+Fe))really?

parentalmagmaExperimentalresultsoflherzolitemeltsMg#=66-75Cr>1000ppmNi>40