the tectonic evolution of the central andean plateau and ...corque fig. 1garzione et al. salla 0 370...
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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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Fig. 1Garzione et al.
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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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
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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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185Kilometers
0 m
5000 mElevation
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
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
75°W
75°W
70°W
70°W
65°W
65°W
25°S
20°S
15°S
185Kilometers
0 m
5000 mElevation
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
Leier etal.(2013,EPSL)
centralEasternCordilleraLargemagnitudesurfaceupliftofthecentralEasternCordillerabetween24and17Ma.2 ± 1 km of
surface uplift
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
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leaf physiognomy, southern
Elev
atio
n (K
M)
Modern Altiplano Elevation
∆47
modifiedfromGarzioneetal.(2014,EPSL)&Karetal.(2016,EPSL)
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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.
modernelevation
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Bolivia Peru
Argentina
Chile
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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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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
75°W
70°W
70°W
65°W
65°W
25°S
20°S
15°S
185Kilometers
0 m
5000 mElevation
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