TheTectonicEvolutionoftheCentralAndeanPlateauandGeodynamicImplicationsfortheGrowthofPlateaus

CarmalaGarzione,EarthandEnvironmentalScience,UniversityofRochester

Collaborators:CAUGHTContinentalDynamicsprojectteamSusanL.Beck(UArizona),AlanD.Chapman(Macalester),MihaiN.Ducea(UArizona),Todd.A.Ehlers(UTubingen),NathanEichelberger(StructureSolverLLC),BrianK.Horton(UTAustin),NandiniKar(WashU),RichardO.Lease(USGSAnchorage),NadineMcQuarrie(UPittsburgh),NicholasD.Perez(TexanA&M),ChristopherJ.Poulsen(UMichigan),JoelE.Saylor(UHouston),LaraS.Wagner(DTMCarnegieInst),KevinM.Ward(UUtah),GeorgeZandt(UArizona)

Acknowledgements:NSF Tectonics & Continental Dynamics programs

ArizonaStateAug.30,2017

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GeologicSetting

• Altiplano:internallydrainedwithlowrelieftopographyandanaveragemodernelevationof~4km

• Altiplano region:Overliesazoneofnormalsubduction(~30° dip)ofNazcaplatebetweentwozonesofflatslabsubduction

Key Questions in the Central Andes• GeodynamicprocessesforbuildingtheAndeanplateau?

- Long-termcrustalshortening/thickeningcausesgradualisostatic surfaceuplift- Isostatic surfaceupliftbymagmaticaddition- Surfaceupliftbydelamination/convective removalofdenselowerlithosphere- Redistributionofcrustalmaterialbymidtolowercrustalflow

Altiplano basin evolution

Garzioneetal.(2017,AREPS)

DeCelles andHorton(2003,GSAB)

Western Cordillera

reworked tuff

Altiplano – Corque section

Eastern Cordillera – Salla Formation

EndMemberModelISlowandGradualSurfaceUplift

McQuarrie(2002)

Garzioneetal.(2017,AREPS)

• MECHANISMS: CrustalCrustalshortening,Ablativesubduction

• PREDICTIONS: deformationcoupledwithsurfaceuplift

Surfaceupliftrates=0to0.25mm/yr

Crustalthickening/continuoussubductionofforelandlithosphere

EndMemberModelsIIRapidPulsesofSurfaceUplift

• MECHANISMS: Removalofdenselowerlithosphere,lowercrustalflow

• PREDICTIONS: Decoupleddeformationandsurfaceuplift

modifiedfromHussonandSempere,2003

Removaloflowerlithosphere LowercrustalflowSurfaceupliftrates>0.4mm/yr

Garzioneetal.(2017,AREPS)

EndMemberModelIIRapidSurfaceUplift

• Decoupleddeformationandsurfaceuplift

• ProposedMechanisms:Removalofdenselowerlithosphereand/orlowercrustalflow

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Fig. 1Garzione et al.

Salla

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2s uncertainties = ±0.8 km2.5 ± 0.8 km of surface uplift

Garzioneetal.(2006,EPSL;2008,Science);Ghoshetal.(2006,Science)Paleobotany:Gregory-Wodzicki

(2000)

LargemagnitudesurfaceupliftofthecentralAltiplanobetween10and6Ma.

DEBATE:EndMemberModelISlowandGradualSurfaceUplift

EhlersandPoulsen(2009,EPSL);Poulsenetal.(2010,Science)

• MECHANISMS: Crustalshortening,Ablativesubduction• PREDICTIONS: deformationcoupledwithsurfaceuplift

Surfaceupliftrates=0to0.25mm/yr

UsedclimatemodelingtoshowthatsurfaceupliftoftheAndescausesnon-linearcoolingoflandsurfaceandincreaseinconvectiverainfall.Arguedthatgradualsurfaceupliftispermissiblewithourdata.

Sedimentary deposits record d18O and T of surface water:Used to quantify paleoelevations

Poage and Chamberlain (2006)

Stable isotope paleoelevation estimates:• Ghosh et al. (2006) – 13C-18O clumped isotope thermometer compared

paleotemperature and d18Omw from authigenic calcite to modern T - d18Omwvs. altitude gradients

• Garzione et al. (2006) – d18O paleoaltimetry compared d18Omw- dDmw from authigenic calcite to modern d18O vs. altitude gradient

& dD & dD

Sedimentary deposits record d18O and T of surface water:Used to quantify Paleoelevations

Poage and Chamberlain (2006)

Stable isotope paleoelevation estimates:• Ghosh et al. (2006) – 13C-18O clumped isotope thermometer compared

paleotemperature and d18Omw from authigenic calcite to modern T - d18Omwvs. altitude gradients

• Garzione et al. (2006) – d18O paleoaltimetry compared d18Omw- dDmw from authigenic calcite to modern d18O - dDmw vs. altitude gradient

& dD & dD

Inseletal.(2013)

d18O-Altitude Relationship of Meteoric Waters

linear regression through rainfall data

data from Gonfiantini et al. (2001); Garzione et al. (2007); Bershaw et al. (2010)

h=-536.4x– 3202R2 =0.92

Temperature-Altitude Relationship

DatafromtheweatherstationsinthenorthernAndes(www.weatherbase.com)Gonfiantinietal.,2001

Karetal.(inreview);modifiedfromGarzioneetal.(2014)

Temperaturecorrectedat≤2kmforwarmerconditionsunderlowerAndesscenarios(EhlersandPoulsen,2009).

Meteoric Water d18O

• Sedimentary carbonates: δ18Ocarbonate depends on δ18Ometeroric water (mw), evaporation, and temperature of carbonate precipitation

• Temperature dependent fractionation: 1000lnα (Calcite-H20) = 18.03 ( 103T-1) - 32.42 (KimandO’Neil,1997)

18O/16Osample18O/16Oreference

-1*1000(permil)d18O=

paleosols lakecarbonates

Transpiration

BiosyntheticFractionation

Soil-waterevaporation

+dD

-dD

ApparentFractionation

MeteoricWater

n-C25,n-C27,n-C29,n-C31

Soil-water

XylemWater

Plant Waxes: dD of C25 to C31 n-Alkanes

e

LeafWater

Hrenetal.(2014)

RapidSurfaceUpliftvs.GradualSurfaceUplift

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Salla

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Garzioneetal.(2006,2008);Ghoshetal.(2006);Gregory-Wodzicki (2000)

2s uncertainties = ±0.8 km2.5 ± 0.8 km of surface uplift

EhlersandPoulsen(2009)Poulsen etal.(2010)

EndMemberModelIIRapidSurfaceUplift

• Decoupleddeformationandsurfaceuplift

• ProposedMechanisms:Removalofdenselowerlithosphereand/orlowercrustalflow

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Argentina

Chile

P u

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W e s t e r n C o r d i l l e r a

Jakkokota

Callapa

Potosì

E a s t e r n C o r d i l l e r a

A l t i p l a n o

Corque

Fig. 1Garzione et al.

Salla

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Leier etal.(2013,EPSL)

centralEasternCordilleraLargemagnitudesurfaceupliftofthecentralEasternCordillerabetween24and17Ma.2 ± 1 km of

surface uplift

Along-strikevariationsinsurfaceuplift

Age (Ma)

0

1

2

3

4

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51015202530 0

∆47 , north-central

leaf physiognomy, north-centralδ 18 O of precipitation, north-central

, southern

Figure 5

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leaf physiognomy, southern

Elev

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M)

Modern Altiplano Elevation

∆47

modifiedfromGarzioneetal.(2014,EPSL)&Karetal.(2016,EPSL)

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Fig. 1Garzione et al.

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LargemagnitudesurfaceupliftoftheAltiplanoPropagatesfromStoNfrommiddletolateMiocenetime.

modernelevation

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Fig. 1Garzione et al.

Salla

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CentralAndeanPlateauTopographicHistory

~10MaPaleosurface:

Gubbels etal.(1993);Kennanetal.(1997);Barke andLamb(2006);HokeandGarzione(2008)

CentralAndeanPlateau

HokeandGarzione(2008,EPSL)

~45MaPaleotopography

Evidenceforalong-livedmagmaticarcsuggeststhattherewassignificantreliefintheWesternCordillera;stableisotopeevidence– Sayloretal.(2014)

~45– ~25MaPaleotopography

• Basinanalysis,structuralevidence,andthermochronologyindicatethattheEasternCordillerabegantodeformby~45to40Ma(Hortonetal.,2001;McQuarrie,2002;Gillisetal.,2006;Barnesetal.,2008)

• Paleoelevation estimatesfromSalla Fm (Leier etal.,2013)alsosupportthis

~20to~10MaPaleotopography

Leieretal.(2013)resultssuggestthattheEasternCordilleraexperiencesarapidpulseofsurfaceupliftbetween~24and17Ma.

<6MaPaleotopography

• xxx

Stableisotoperesultsandincisionhistoriessuggestarapidpulseofsurfaceupliftbetween10and6MathatestablishedthemoderntopographyofthecentralportionoftheAndeanplateau.

Along-strikevariationsinpaleotopography

Garzioneetal.(2017,AREPS)

Garzioneetal.(2017,AREPS)

Along-strikevariationsinpaleotopography

Observation: Contractional deformation ceased in the central Altiplano and propagated eastward into the Subandes.

Prediction: Rapid removal of lower lithosphere -surface uplift decreases the horizontal

compressive stress in the Andean plateau

Age HokeandGarzione(2008,EPSL)

Middle-late Miocene events in the Andean plateau

Barke and Lamb (2006)

Garzioneetal.(2008,Science)(Sedimentationrate)

(2006)

Middle-late Miocene events in the Andean plateau

Barke and Lamb (2006)

Garzioneetal.(2008,Science)

(2006)

(Sedimentationrate)

Whatmechanismsformbroad,highelevation,lowrelieforogenicplateaus?

CAUGHT– CentralAndeanUpliftandtheGeodynamicsofHighTopography

• Incisionhistory• Crustalstructure• Shorteninghistory• Volcanics• Mantlestructure

Collaborators:CAUGHTContinentalDynamicsprojectteamSusanL.Beck(UArizona),AlanD.Chapman(Macalester),MihaiN.Ducea(UArizona),Todd.A.Ehlers(UTubingen),NathanEichelberger(StructureSolverLLC),BrianK.Horton(UTAustin),NandiniKar(WashU),RichardO.Lease(USGSAnchorage),NadineMcQuarrie(UPittsburgh),NicholasD.PerezTexanA&M),ChristopherJ.Poulsen(UMichigan),JoelE.Saylor(UHouston),LaraS.Wagner(DTMCarnegieInst),KevinM.Ward(UUtah),GeorgeZandt(UArizona)

Garzioneetal.(2017– AREPS)

Thecaseforconvectiveremovalofthelowerlithosphere

• Crustalthickeningprecedespulsesofsurfaceuplift

• Pulsesofsurfaceupliftshouldcorrespondwithanoutwardjumpindeformation

• Ifhighdensityeclogiticlowercrustdriveslowerlithosphereremoval,thencrustalthickeninghistorywouldpredictcrustalthicknessinexcessofmodernthickness.

• Crustalandmantlestructuremayshowevidenceofrecentorongoingconvectiveremovaloflowerlithosphere.

Along-strikevariationsinsurfaceuplift

Age (Ma)

0

1

2

3

4

5

51015202530 0

∆47 , north-central

leaf physiognomy, north-centralδ 18 O of precipitation, north-central

, southern

Figure 5

6

?

leaf physiognomy, southern

Elev

atio

n (K

M)

Modern Altiplano Elevation

∆47

modifiedfromGarzioneetal.(2014,EPSL)&Karetal.(2016,EPSL)

75°W

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65°W

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15°S

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Bolivia Peru

Argentina

Chile

P u

n a

W e s t e r n C o r d i l l e r a

Jakkokota

Callapa

Potosì

E a s t e r n C o r d i l l e r a

A l t i p l a n o

Corque

Fig. 1Garzione et al.

Salla

0 370

LargemagnitudesurfaceupliftoftheAltiplanoPropagatesfromStoNfrommiddletolateMiocenetime.

• MiddleMiocenearidificationofthesouthernAltiplanoandwesternslopeversuslateMiocenearidificationofthenorthernAltiplano

• MiddleMioceneonsetofsouthernSubandeandeformationversuslateMioceneonsetofsouthernSubandeandeformation

Along-strikevariationsintheoutwardjumpindeformation&aridificationoftheAltiplano

Leaseetal.(2016)

Along-strikevariationsincrustalshortening

Garzioneetal.(2017,AREPS)

CrustalshorteninghistoryCentralCentralAndeanPlateau

SouthernCentralAndeanPlateau

Exhumationtimingandmagnitude

Exhumationtimingandmagnitude

Garzioneetal.(2017,AREPS),fromMcQuarrieetal.(2002,2008),Barnesetal.(2012)

Crustalthickeningversus surfaceuplift- CentralPlateau

Garzioneetal.(2017,AREPS),fromEichelbergeretal.(2015),Garzioneetal.(2006,2008),Leieretal.(2013)

EasternCordilleraAltiplanoAltiplano

Elevation(km)

CAUGHT-PULSE broadband station map

Crustalthicknessmap(receiverfunctions)&Crustal/mantlestructure

Garzioneetal.(2017,AREPS),fromWardetal.(2013,2016)&Ryanetal.(2016)

• LargestepinMohobeneathEasternCordillera,suggestingthatlowercrust(eclogite)hasbeenremoved

• Thisregionisassociatedwithhighestelevationsandgreatestmagnitudeofcrustalthickening

• HighvelocityAAanomalysuggestsa portionofthelowerlithosphere isstillattached

• This regionisassociatedwiththelowestAltiplanoelevations

Thecaseforlowercrustalflow

• Rapidsurfaceupliftduringtimeperiodsofcrustalthickeningthatisdecoupledfromcrustalshortening

• Moderncrustalthicknessexceedsthatwhichcanbeaccountedforbycrustalshortening

• Traceelementevidenceforrapidcrustalthickeningintheabsenceofshortening

• Exhumation/incisioneventstrackbothcrustalthickeningandsurfaceupliftintheabsenceofshortening

Crustalthicknessmap(receiverfunctions)&Crustal/mantlestructure

• NorthernAltiplanoshowsgreatestcrustalthicknessesinexcessof70km

• Thisregionisassociatedwithhighelevations,butlowmagnitudeofcrustalshortening

• Thisregionisassociatedwithamid.crustallowvelocityzone

Garzioneetal.(2017,AREPS),fromWardetal.(2013,2016)&Ryanetal.(2016)

Along-strikevariationsincrustalshortening

Garzioneetal.(2017,AREPS)

Crustalshorteninghistory

CentralCentralAndeanPlateauExhumationtimingandmagnitude

Garzioneetal.(2017,AREPS),fromMcQuarrieetal.(2002),Barnesetal.(2012),Perezetal.(2016)

NorthernCentralAndeanPlateauExhumationtimingandmagnitude

Crustalthickeningversus surfaceuplift

Garzioneetal.(2017,AREPS),fromEichelbergeretal.(2015),Karetal.(2016),Perezetal.(2016)

• Crustalshorteningcannotaccountforthemoderncrustalthicknessinthisregion

• Traceelementratiosshowthatdramaticcrustalthickeningoccursaftershorteningceased

• Simultaneouscrustalthickeningandsurfaceupliftimplicatecrustalflow

Pliocene–recentincision oftheNEAndeanplateau

• SurfaceupliftinthenorthernmostAltiplanoplateaumaybemorerecent(<4.8±1.1Ma)thaninthecentralAltiplanSurfaceupliftinthenorthernmostAltiplanoplateaumaybemorerecent(<4.8±1.1Ma)thaninthecentralAltiplano.

• o.4-0MaincisionisconsistentwithPliocenesurfaceuplift.

LeaseandEhlers(2013)

Summary– Pulsednatureofsurfaceuplift

• ThecentralCentralAndeanPlateaushowsatleasttwopulsesofrapidsurfaceuplift:earlyMioceneEasternCordilleraandlateMioceneEasternCordilleraandAltiplano.

• IntheAltiplano,rapidsurfaceupliftpropagatesfromsouthtonorthfrommiddleMiocenetolateMiocene/Pliocenetime.

Evidenceforlowerlithosphereremoval&lowercrustalflow

• Crustalthickeningpredictionsfrombalancedcrosssectionsshowthicknessexcessinregionsthathaveexperiencedmultiplepulsesofsurfaceupliftà suggestsconvectiveremovalofeclogiticlowercrust

• ThenorthernmostportionoftheAndeanplateaulacksthemagnitudeofcrustalshorteningrequiredtoaccountforthemoderncrustalthicknessà suggestscrustalflowintothisregion

• InthenorthernmostportionoftheAndes,HREEdepletion(i.e.,highLa/Yb) overpast~5Masuggestscrustalthickeningintheabsenceofcrustalshorteningoverthesametimeperiodassurfaceupliftàsuggestscrustalflowintothisregion