Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth's most saline lake and implications for Mars.

7.1 MB·English

by  Dickson, James L.

Don Juan Pond, Antarctica: Near-surface
CaCl -brine feeding Earth’s most saline
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SUBJECTAREAS: lake and implications for Mars
INNERPLANETS
ENVIRONMENTALSCIENCES
JamesL.Dickson1,JamesW.Head1,JosephS.Levy2&DavidR.Marchant3
CLIMATESCIENCES
PLANETARYSCIENCE
1DepartmentofGeologicalSciences,BrownUniversity,Providence,RhodeIsland02912,USA,2CollegeofEarth,Ocean,and
AtmosphericSciences,OregonStateUniversity,Corvallis,Oregon97331,USA,3DepartmentofEarthandEnvironment,Boston
Received University,Boston,Massachusetts02215,USA.
25October2012
Accepted ThediscoveryonMarsofrecurringslopelineae(RSL),thoughttorepresentseasonalbrines,hassparked
19December2012 interestinanalogousenvironmentsonEarth.WereportonnewstudiesofDonJuanPond(DJP),which
existsattheupperlimitofephemeralwaterintheMcMurdoDryValleys(MDV)ofAntarctica,andis
Published adjacenttoseveralsteep-slopedwatertracks,theclosestanalogforRSL.ThesourceofDJPhasbeen
30January2013 interpretedtobedeepgroundwater.Wepresenttime-lapsedataandmeteorologicalmeasurementsthat
confirmdeliquescencewithintheDJPwatershedandshowthatthis,togetherwithsmallamountsof
meltwater,arecapableofgeneratingbrinesthatcontrolsummertimewaterlevels.Groundwaterinputwas
notobserved.InadditiontoprovidingananalogforRSLformation,CaCl brinesandchloridedepositsin
Correspondenceand 2
basinsmayprovidecluestotheoriginofancientchloridedepositsonMarsdatingfromthetransitionperiod
requestsformaterials
from‘‘warm/wet’’to‘‘cold/dry’’climates.
shouldbeaddressedto
J.L.D.(jdickson@
brown.edu) DonJuanPond(DJP),foundatthelowestpoint intheSouthForkofUpperWrightValley,Antarctica
(Figure1a),isthemostsalinenaturalbodyofwaterintheworld1.Asaconsequence,itrarelyfreezes,even
whenthesurfacetemperaturedescendsto250uCduringAustralwinteranditisauniquesiteforthestudy
ofhabitabilityinextremeenvironmentsonEarth2–4,andpotentiallyforlifeonMars2,3.Unlikelarger,ice-covered
lakesintheMcMurdoDryValleys(MDV),DJPisisolatedfromfresh,glacialrunoffasitisboundedtothenorth
andsouthbysteepinclinesthatexposeoutcropsofgraniticbasementmaterialandJurassic-ageddoleritesills5,to
thewestbyachannel-incisedandice-cementedsedimentlobe(alsomappedasaninactiverockglacier)6,7,andto
theeast byashallow slope characterized by,20 cm ofcolluvium above an impermeable, ice-cemented per-
mafrostlayer8.Multiplewatertracks8areobservedwithinthecolluviumtotheeastofDJP7,asisastream-channel
systemattheeasternmostextentoftheDonJuanbasin(Figure1b).
Inadditiontothehyper-salinityofDJP(,40%bymass)1,2,10–14,thecompositionofthebrineisunlikeanyother
bodyofwaterintheworld,as,90%ofthesaltisCaCl 1,2,10–14.Thus,anymodelthatcansuccessfullyexplainhow
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saltsaretransportedtoDJPmustalsoexplainhowtheCaCl isisolated.Previousstudieshaveproposedbothdeep
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groundwater13andnear-surfaceactivelayertransportfortheDJPbrine14,withthemajorityofstudiesfavoring
upwellingfromaweathered-doleriteaquifer2,3,13,15.Wesoughttodocumentinputintothepondbymonitoring
DJP during Austral spring/summer with high-resolution, long-duration, high-frequency time-lapse pho-
tography.Theseobservations,synchronizedwithasuiteofmeteorologicalmeasurementsandviewedincon-
junctionwithpreviousstudiesofthegeochemistryofDonJuanbasin,permitareassessmentofthemostlikely
contributorstotheunprecedentedsalinityofDonJuanPond.
Results
SourcesofWaterinDonJuanbasin.SeveralpotentialsourcesforwaterareavailablewithinDonJuanbasin12,14
(Figure 1): (1) direct precipitation (snow); (2) stream input from the western lobe; (3) upwelling of a deep
groundwateraquifer;and(4)activelayertransportatopthepermafrosttablewithinthecolluviumeastofDJP.
First, while the pond is subject to direct snow precipitation, this produces only between 5 and 10 g/cm2
annually12, most of which is lost via sublimation12,16. Further, while direct snowfall inputs salt into the pond,
thereisnoreasonforsnow-depositedsaltstoproduceafractionationinfavorofCaCl 17.Thus,directsnowfallis
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notconsideredasignificantsourceofwaterand/orCaCl withinDJP.
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Figure1| (A)DonJuanbasinintheSouthForkofUpperWrightValley,McMurdoDryValleys,Antarctica.DonJuanPondisfoundatthelowestpointof
thebasin.Thepondisboundedbysteep(,30u)slopestothenorthandsouth,adebris-coveredlobetothewest,andcolluvium-mantledterrainto
theeast,wherethemostprominentwatertracksareobserved.IKONOSorbitalcolorimage,acquiredonFebruary1,2009.(B)Theeastern-mostchannels
withinDonJuanbasin.Whenactive,thesechannelsproducewatertracksattheirterminithatconnecttothewatertrackonthethalwegeastofDonJuan
Pond(Figure2).IKONOSorbitalpan-chromaticimage,acquiredonJanuary31,2003.(C)InsetofDonJuanPondonFebruary1,2009.
Second,theviscouslobetothewestofDJP6,7isincisedbyasmall DJP,inwhichupwellingfromaweathereddoleriteaquiferat,60 m
network of 1–2 m-wide channels (Figure 1a) that drain into DJP depththroughanunfrozenstratumoflakesedimentsfeedsthepond.
during peaksummer conditions through distributaries adjacent to Finally,multiplestudieshaveshownthatwaterflowsacrossthe
thewesternedgeofthepond(Figure1c).Severalinvestigations10,12,13 top of the permafrost table east of DJP8,13,18. At the surface, this
involvingmajorionanalysisofwaterinthisstreamhaveshownthat processismanifestedaswatertracks8,9,21,22,zonesofhighsoilmois-
itislowsalinity(TDS,500 ppm)12andisdepletedinCa21andCl2 ture that act as downslope paths for saline liquids on top of the
relative to Na1 and SO 22, respectively13, suggesting a snowmelt permafrost table (,10 cm depth) that wick up to the surface in
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origin for the water and salt ratios that preclude it from being a low-slope,fine-grainedsoils,creatinglinearpatternsofseasonalsur-
candidate for the source of CaCl in DJP. This corroborates our facedarkening8,9(Figure1a,b).Geochemicalmeasurements14ofthis
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ownfieldobservationsthatthiswaterissourcedbychannel-trapped liquidtotheeastofDJPshowedthat,likeDJP,itisenrichedinCa21
snowonthesurfaceofthewesternlobe. relativetoNa1andhaslowNa1/Cl2ratios,consistentwithrecent
Third, previous studies have attributed the extreme salinity to measurements of water tracks in the Lake Hoare basin in Taylor
upwellingofarelativelydeep(tensofmeters)bedrockaquifer2,13,15. Valley6.ThisCa21andCl2enrichmentledWilson14toproposethat
Electricaldepthsoundings19,20andseismicprofiles20providedcon- salts left by sublimated snow at the surface are separated when
sistentfindingsthattheterrainbeneathDJPisunfrozentodepthsof humidityfrontspassthroughDonJuanbasin.Saltsthatdeliquesce
tensofmeters.Abruptshiftsinbothseismicvelocityandresistivity at lower relative humidity (like CaCl ) are more mobile. During
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wereobservedat,30 mdepthontheeasternmarginofthepond, humidity optima, they preferentially deliquesce and percolate
andthisinterfaceslopedto,60 mdepthbelowthewesternmargin through the colluvium until they encounter the impermeable per-
ofDJP.Thegeophysicalpropertiesofeachmediumwereinterpreted mafrosttable.Oncethere,humidity-separatedbrinescanbetrans-
as unfrozen basement rock superposed by wet lacustrine deposits portedtoDJPviaflushingbyseasonalsnowmelt8from(1)astream
immediatelyunderlyingthepond20.Samplesofwatercollecteddur- channelattheeasternmostextentofDonJuanbasin(Figure1b)or
ingtheDryValleyDrillingProject(DVDP)showedthatsubsurface (2) alcove-trapped snowpacks that accumulate above steep-sloped
waterbeneaththepondwasenrichedinCaCl ,thoughtherewasa watertracks(Figure1a)8.
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contrastinweightpercentofthetotalsolutionbetweensamplesat Time-lapseobservationsandmeasurementsofrelativehumidity
thesurfaceandsamplesatdepth:17%and18%CaCl concentration thatweobtainedofthethalwegeastofDonJuanPond(Figure1a)in
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forsamplesfrom15 mand58 mdepth,respectively,versus34%for December,2010,showthatwatertracksrapidlyrespondtomoistair
surfacewaters13.Giventhatevaporationatthesurfacecouldconcen- byhydratinganddarkening(Figure2),demonstratingthatdeliques-
tratethesalts,thisledtotheprevailingmodelfortransportofsaltsto cence and brine hydration is an active process within the DJP
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Figure2|Framesfromatime-lapsesequenceofwatertrackdarkeningonthethalwegofSouthFork(locationinFigure1a). Fullsequencecanbe
accessedviasupplementaryinformation.DarkeningoccurswhiletheentiresceneisundertheshadowoftheAsgardRangetothesouth,ensuringthat
darkeningisnotaphotometriceffectfromvariablesolarincidenceangle.Thedarkeningdirectlycorrelateswithasteepincreaseinrelativehumidity,such
thatsaltsinthewatertrackareabsorbingwaterfromtheatmosphere(deliquescence),andthathydrationofthesebrinesmoistensthesurface.
RelativehumiditymeasurementisfromameteorologicalstationontheedgeofDJP,,975mupvalley/downslopefromtheobservation(Figure1c).This
samesteepincreaseinrelativehumiditywasobserved15minutesearlieratanothermetstation1.1kmdownvalley/upslopefromthissite.Thisis
consistentwithamassofmoistairmovinginlandfromthecoasttowardstheicecap.
watershed. Since the water track on the thalweg east of DJP was proxy for volume) from (1) deep groundwater upwelling from the
alreadyrelativelydampcomparedtothesurroundingterrainatthe centralandsouthernportionofthepond,(2)watertrackdischarge
outset due to drainage from snowmelt channels found upslope fromtheeast,wherewatertracksareobserved,and(3)freshsnow-fed
(Figure1b),thisprocessappearstoconcentrateatmospheric-derived stream discharge from the west. This imaging campaign was per-
moistureinhighsalinitysoils,ratherthanuniformlydampeningall formed in concert with soil moisture measurements on one of the
soils23. steep-slopewatertracksabovethepondtotheeast(Figure1a),aswell
Here, we evaluate the relative importance of these hydrological asasuiteofmeteorologicalobservationsacquiredfromtheeastern-
processesbyexamininginteractionsamongwatertracks,snow-fed mostportionofthesaltpansurroundingthepond(Figure1c).
steams,andputativegroundwaterdischarge.Sinceitisnotrecharged Ourtime-lapseobservationsofDJPshowthatdischargeintothe
by glacial meltwater, DJP is very shallow (generally , 10 cm1,10 pondiscontrolledbydiurnalsurfacetemperaturecycles,whicharea
thoughitcandeepento,23 cm20).Thus,detailedmonitoringdur- functionofinsolation(Figure3).Whilethesundoesnotastronom-
ing a relatively low precipitation year provides the opportunity to icallysetduringthistimeperiodintheMDV,thesteepsouthernwall
detect inputs into the pond. During the 2009–2010 summer field ofUpperWrightValleycreatesadiurnalshadowingofthefloorof
season, we imaged the pond at 5-minute intervals from late theDonJuanbasin(Figure1a),suchthatsurfaceconditionspermit
November 2009 through January 2010 from the southern end of meltingofnear-surface/surfaceiceduringthedaybutnotatnight,
the Dais, a mesa perched ,750 m above DJP (see Figure 1a for when the sun is behind the Asgard Range to the south (approxi-
vantage point). From the 16,280 acquired images during this mately22:00to06:15thenextmorningatsummersolstice).
timespan,wemappedallevidenceforinputintothepondinorder Usingpondsurfaceareaasaproxyforvolume,time-lapseimage
to evaluate the magnitude of contributions to lake surface area (a datarevealthatthemostsignificantinputofliquidintoDJPcomes
Figure3|Time-lapseimagepairofdischargeintoDonJuanPondonDecember11,2009,withdischargeobservedfromboththewestandtheeast.Full
time-lapsesequenceshowingactivitythroughoutlate-spring/early-summercanbeaccessedviasupplementaryinformation.Imageswereacquiredat5-
minuteintervalsfromthesouthernmarginoftheDais(seeFigure1aforvantagepoint).Dailypulsesoffreshwaterinputfromstreamactivityatopthe
adjacentdebris-coveredlobeareobservedtocomefromthewest,whilesmallswarmsofdischargeareobservedtocomefromtheeasternmarginofthe
pond.TheseseepsareinterpretedtobedischargeofCaCl -richbrinesthataretransportedthroughthedryactivelayereastofthepondonthetopofthe
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permafrosttable.Pulsescorrelatewithdiurnalincreasesinsurfacetemperature(measurementsacquiredfromameteorologicalstationonthe
easternmostedgeoftheDJPsaltpan–seeFigure1cforlocation).
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Figure4|ThesurfacetemperaturerecordfromthesaltpansurroundingDonJuanPondwithdischargeeventsfromtheeasternmarginofDJP
(reddashedlines).Dischargefromtheeasternmarginofthepondisdirectlycorrelatedwithsteepincreasesinsurfacetemperature,whichiscontrolledby
diurnalcyclesinpeakinsolation.
from the freshwater stream that incises the lobe adjacent to the The other observed input to DJP is discharge from the eastern
westernmarginofthepond(Figure3).Snowandicetrappedwithin marginofthepond(Figure 3),observable on30ofthe52days of
the channel melt and produce surface area-expanding pulses that thestudy(Figure4).Insteadofonemajorpulse,asisobservedfrom
extend nearly across the entire pond on particularly warm days the freshwater stream to the west of the pond, this discharge is
(Figure 3). These pulses occur at the same time of day as sudden characterized by smallswarms ofindividual pulses that startfrom
spikesinthehydrographmeasurementsofHarrisandCartwright13 large boulders embedded in the lake sediments (Figure 5) and
fromearlyDecember1975thattheyinterpretedasseiches.Thewater migratetowards thecenterofthepond. Likethelarger freshwater
pulsessoakintotheunderlyinglacustrinesedimentsonthefloorof pulsesfromthewest,thesepulsesarestronglycorrelatedwithsteep
thepond,fillingporespacesinthepondshorezone.Samplesfrom increases in surface temperature (,8–10uC over ,5–7 hours), as
previousstudieshaveshownthatthiswaterisfresh10,12,13andhasan activity is always observed during peak insolation conditions
ionic ratio that precludes it from being the primary driver of DJP (Figure 4). There is little to no lag between peak temperature and
chemistry. discharge, suggesting that warming is not propagating into a deep
aquifer.In16,280images,thesesmallpulsesareonlyobservedonthe
easternmarginofthepond,whichisaboveandoutsideofthepoten-
tialgroundwaterdischargezoneidentifiedbyHarris&Cartwright13.
Detailedobservationsofthebouldersontheeasternmarginofthe
saltpanofDJP(Figure5)showthattheyfrequentlyhostpondliquid
intheirannularmoats,whileothershostbrighthalosofevaporites,
relationshipsnotcommonlyobservedaroundotherportionsofthe
pond. In some cases, the pond liquids overtop their moats in the
direction of the center of the pond and flow downslope
(Figure5d).BouldersgeneratebreaksinslopeinotherDryValley
watertracks,wheretheyactasspringsthatdischargeattheground
surface9,24,25,asobservedelsewhereinSouthFork26.
In order to determine if liquids were flowingthrough thewater
trackseastofDJP(Figure1a)atthetimethatdischargewasobserved
on the eastern margin of DJP (Figure 3), we instrumented one of
thesteep-sloped watertracks8withDecagonECH Osoilmoisture
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probesonandoffofthetrackstartingonDecember10,2009(loca-
tion in Figure 1a). Soil moisture onthe water track is consistently
greater than soil moisture 1 m off the track’s eastern margin
(Figure 6). A noticeable increase in soil moisture on the track
Figure5|(A)DischargelocationsontheeasternmarginofDonJuanPond occurredcloseto1January,whichfollowedaweek-longperiodof
(seeFigure1cforlocation).(B)Multiplenearbybouldersareobservedto extremelywarmconditionswhensurfacetemperatureswerenever
haveliquiddischargedatthesurface,consistentwithbouldersdepressing below 0uC and peak surface temperatures approached 20uC. This
thenear-surfacepermafrosttable.(C)Alargeboulderhostsliquidinthe ,1-weeklagbetweenincreasedsurfacetemperatureandwatertrack
downslopeportionofitsannularmoat.(D)Aboulderisnearlyburiedby moistureincreasesisrepeatedseveraltimesthroughourthree-year
dischargedliquidthatisflowingdownslope,inthedirectionofDJP.Image temperature/soil-moisture record of this site (austral spring 2009
wasacquiredonDecember8,2009,whentime-lapseobservationsshow through austral summer 2012), which favors a scenario by which
dischargefromthisportionofthepond(Figure4). fresh meltwater from (1) seasonal snow trapped in alcoves at
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Figure6|Soilmoisturerecordedonandoffofoneofthemajorsteep-slopedwatertracksonthesouthern(equator-facing)wallaboveDonJuanPond
(seeFigure1aforlocation). Sensorswereplaced1-meteronthetrackand1-meteroffthetrack.Valueswererecordedevery15minutes,andplottedas
24-houraverages.Activityisclearlyconcentratedentirelywithinthetrack.Increasedsoil-moistureactivityduringthemiddleofJanuarycorrespondsto
themostconcentratedactivityofdischargeintoDJPfromitseasternmargin.
the heads of the steep-sloped water tracks8 and (2) perennial readings14,includingthosewithwatertrackswithintheirwatershed9.
snowbanksatthebaseoftheneighboringAsgardRange27percolates Water tracks that drain into larger fresh-water lakes contribute
downslope and flushes the deliquescence-derived CaCl2 brine CaCl -rich brines that are denser than the more-abundant
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downslope towards DJP, using the channel system at the eastern- freshwater9.Therefore,thebrinesshouldbeconcentratedatthebase,
mostextentofDonJuanbasinasaconduit(Figure1b).Soilmoisture a trend that is observed14. Furthermore, water circulation in the
on the track also remained elevated from January 7 through the absence of a deep groundwater connection makes this a plausible
end of the month (Figure 6). On the eastern margin of DJP, modelforahydrologicsystemonpresent-dayMars,whereextremely
pulses from the east were observed on 13 of the 15 days from low temperatures (255uC annual average, 127uC maximum,
January7untilJanuary22,whendatacollectionceasedfortheseason 2143uC minimum; in comparison with an annual average of
(Figure4). 220uC,monthlyaveragemaximumof11uC,andmonthlyaverage
minimumof254uC)atalllatitudes and aglobalpermafrostlayer
Discussion shouldlargelyprecludedeepaquiferinteractionwiththesurface,and
OurobservationsindicatethatdischargeofCaCl -richbrinesthatflow forancientMars,whensurfacewatersweremoreabundant.
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across the top of the permafrost table are the likely source for the ThefeaturesthatfeedCaCl toDJP,watertracks(Figure1a,b),are
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extremesalinitymeasuredinDJP.EvidenceforinternalfillingofDJP similar in planform morphology to recently discovered Recurring
fromupwellingofadeepaquiferwasnotfoundduringourimaging Slope Lineae (RSL) in the southern mid-latitudes of Mars: low-
campaign. The only two liquid sources that provided measurable albedostreaksofsoilonsteep(,30u)slopesthatadvanceandrecede
changes to DJP surface area from November 27, 2009 to January each martian year, initiating when surface temperatures approach
22,2010werefreshwaterstreamdischargefromthewestand active the melting point of H O28. Downslope propagation rates for RSL
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water track transport fromthe east. Evaporative mixtures ofstream andAntarcticwatertracksareconsistentwitheachbeingformedby
waterandwatertrackfluidscanaccountforthechemistryofDJPand brineflowthroughashallowregolith,basedonremotelymeasured
produce the observed filling and hydrograph patterns reported by averagepermeabilityvaluesof1028to1029 cm2forRSLand1026to
HarrisandCartwright13.Asthistransportmechanismmoreeffectively 1027 cm2, which are consistent with fluid flow through sandy,
explainstheabundanceofCaCl comparedtoothersalts11,itreadily unconsolidatedsediments29.
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accountsforallofthegeochemicalmeasurements11–14inadditionto CouldaDJP-likehydrologicalsystembeactiveonmodernMars?
theflow-directionobservationsdocumentedinthisstudy(Figure3). Chloride-bearingsaltshavebeendocumentedonMarsfrombothin-
Theseresultsalsoprovideamodelinwhichitispossibletomain- situ30andremote31observations,andpeakdailytemperaturesonthe
tain ecosystem-sustaining hydrological systems in Earth’s coldest warm,equator-facingslopeswhereRSLareobservedfrequentlysur-
and driest environments entirely through atmospheric interaction pass 0uC28. Seasonal water frost is observed on the surface in
with the surface, without invoking deep groundwater resources. hyperspectraldataatlatitudesaslowas12uinthesouthernhemi-
Therefore, this model may have broad implications, explaining sphere32,33,suchthatsufficientatmosphericwatervaporisavailable
whylarger,ice-coveredMDVlakestendtohavehighbasalsalinity to initiate relative deliquescence at mid-latitudes, where RSL are
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found.Therefore,theessentialconditionsforaDJP-likehydrological 6. Hassinger,J.M.&Mayewski,P.A.Morphologyanddynamicsoftherockglaciers
systemmaybetransientlyachievableoncontemporaryMarsatRSL- inSouthernVictoriaLand,Antarctica.ArcticAlpineRes.15,351–368(1983).
7. Morgan,G.A.,Head,J.W.,Marchant,D.R.,Dickson,J.L.&Levy,J.S.Interaction
bearinglocations.
betweengulliesandlobatedebristonguesonMarsandintheAntarcticDry
Chloride-bearing units exposed within topographic basin floors Valleys.LunarPlanet.Sci.Conf.39,2303(2008).
have also been mapped from orbit in the southern hemisphere of 8. Head,J.W.,Marchant,D.R.,Dickson,J.L.,Levy,J.S.&Morgan,G.A.Slope
Mars31.UnlikeRSL,whichareactivetoday,theseunitsareprimarily streaksintheAntarcticDryValleys:Characteristics,candidateformation
mechanisms,andimplicationsforslopestreakformationintheMartian
found within ,4 Gyr old Noachian terrain, suggesting that they
environment.OnlineProc.ofthe10thISAES#177(2007).
were deposited early in Mars’ history when conditions were more 9. Levy,J.S.,Fountain,A.G.,Gooseff,M.N.,Welch,K.A.&Lyons,W.B.Water
conducivetoliquidwaterstabilitythantoday.Thechemicalsepara- tracksandpermafrostinTaylorValley,Antarctica:Extensiveandshallow
groundwaterconnectivityinacolddesertecosystem.GSABulletin123,
tion and transport mechanisms that produced these units are
2295–2311(2011).
notwellunderstood,butthecold-desertmodelprovidedbyDJPof
10.Yamagata,N.,Torii,T.&Murata,S.Chemicalcompositionoflakewaters.Report
humidity-induced relative deliquescence may be applicable, pro- oftheJapaneseSummerPartiesinDryValleys,VictoriaLand,1963–19655,
videdthattheywereformedintheabsenceofpluvialactivity14. 53–75(1967).
11.Torii,T.,Yamagata,N.,Ossaka,J.&Murata,S.SaltbalanceintheDonJuanbasin.
While the volumes of freshwater available to these hydrologic
AntarcticRecord(NIPR)58,116–130.
systems on Mars is unknown, recent work in the Atacama desert
12.Harris,H.J.H.,Cartwright,K.&Torii,T.Dynamicchemicalequilibriumina
hasprovidedin-situdocumentationofcyanobacteriathatarecap- polardesertpond:Asensitiveindexofmeteorologicalcycles.Science204,
ableofsubsistingentirelyonthebrinescreatedfromdeliquescencein 301–303(1979).
haliterocks34,averylocalizedecological modelthat hasbeenpro- 13.Harris,H.J.H.&Cartwright,K.HydrologyoftheDonJuanBasin,WrightValley,
Antarctica.InDryValleyDrillingProject,Ant.Res.Ser.33,ed.McGinnis,L.D.
posed for Mars in the past35. Furthermore, work in the MDV has
AmericanGeophysicalUnion,Washington,D.C.,161–184(1981).
shown that certain organisms are capable of being preserved in a 14.Wilson,A.T.GeochemicalproblemsoftheAntarcticdryareas.Nature280,
cryptobioticstatefordecades,thenflourishonceexposedtostream 205–208(1979).
waters36.Thus,ifRSLandchloride-bearingbasinfloorunitsonMars 15.Carlson,C.A.,Phillips,F.M.,Elmore,D.&Bentley,H.W.Chlorine-36tracingof
salinitysourcesintheDryValleysofVictoriaLand,Antarctica.Geochim.
dorepresentDJP-likehydrologicsystems,theymayhavesignificant
Cosmochim.Acta54,311–318(1990).
potential for hosting resilient microbiota, and the most habitable 16.Fountain,A.G.,Nylen,T.H.,Monaghan,A.,Basagic,H.J.&Bromwich,D.Snow
placesonMarsmaymimictheleasthabitableplacesonEarth. intheMcMurdoDryValleys,Antarctica.Int.J.Climatol.30,633–642(2010).
17.Lyons,W.B.,Welch,K.A.,Fountain,A.G.,Dana,G.L.,Vaughn,B.H.&
McKnight,D.M.SurfaceglaciochemistryofTaylorValley,southernVictoria
Methods Land,Antarcticaanditsrelationshiptostreamchemistry.HydrologicalProcesses
ThecolorimageinFigure1aand1cwasacquiredonFebruary1,2009andis 17,115–130(2003).
composedof4m/pixelIKONOSmulti-spectraldata(Blue:0.445–0.516mm;Green: 18.Levy,J.S.,Head,J.W.&Marchant,D.R.Theroleofthermalcontractioncrack
0.506–0.595mm;Red:0.632–0.698mm),pan-sharpenedinENVIto1m/pixelusing polygonsincold-desertfluvialsystems.AntarcticScience20,565–579(2008).
1m/pixelpanchromaticimagery(0.45–0.90mm).ThegrayscaleimageinFigure1b 19.McGinnis,L.D.&Jensen,T.E.Permafrost-hydrogeologicregimenintwoice-free
wasacquiredonJanuary31,2003andconsistsof1m/pxpanchromaticimagery valleys,Antarctica,fromelectricaldepthsounding.QuaternaryResearch1,
(0.45–0.90mm).BothimageswereorthorectifiedinENVIusing200m/pixel 389–409(1971).
RADARSATtopographydataandrenderedinArcMapinLambertConformalConic 20.McGinnis,L.D.,Nakao,K.&Clark,C.C.Geophysicalidentificationoffrozenand
projection(centralmeridian:162uE;StandardParallel1:76.66667uS;Standard unfrozenground,Antarctica.2ndInt.Conf.onPermafrost(N.A.Contribution),
Parallel2:79.33333uS;LatitudeofOrigin:78.0uS). 136–146(1973).
21.Hastings,S.J.,Luchessa,S.A.,Oechel,W.C.&Tenhunen,J.D.Standingbiomass
Thetime-lapseimageryfromDecember2010(Figure2)wasacquiredat2-minute
andproductioninwaterdrainagesofthefoothillsofthePhilipSmithMountains,
intervalswithafirmware-modifiedCanonPowerShotSX1digitalcamera,locatedat
Alaska.HolarcticEcology12,304–311(1989).
77.563uS,161.256uE.RelativeHumiditywasmeasuredusinganOnset12-bit
22.McNamara,J.P.,Kane,D.L.&Hinzman,L.D.Ananalysisofanarcticchannel
Temperature/RHprobe(S-THB-M002)insideasolarradiationshield,sampling
networkusingadigitalelevationmodel.Geomorphology29,339–353(1999).
every3minutes(averagedforonereadingevery15minutes)2mabovethesurfaceon
23.Levy,J.S.,Fountain,A.G.,Welch,K.A.&Lyons,W.B.Hypersaline‘‘wetpatches’’
theeasternmostedgeofthesaltpansurroundingDonJuanPond(77.563uS,
inTaylorValley,Antarctica.Geophys.Res.Lett.39,L05402(2012).
161.208uE).Dataandtime-lapseimageryweresynchronizedusingproprietary
24.Lyons,W.B.,Welch,K.A.,Carey,A.E.,Doran,P.T.,Wall,D.H.,Virginia,R.A.,
softwarewrittenbytheauthorsthatcorrelatestimestampsonimageswith
Fountain,A.G.,Tremper,C.M.&Csatho,B.M.GroundwaterseepsinTaylor
meteorologicaldatatables,suchthateachimageisnomorethan7.5minutesbefore/
ValleyAntarctica:anexampleofasubsurfacemeltevent.AnnalsofGlaciology40,
afterthecorrelatedmeasurement(whichisloggedevery15minutesinanOnset
200–206(2005).
HOBOMicrostation).
25.Harris,K.J.,Carey,A.E.,Lyons,W.B.,Welch,K.A.&Fountain,A.G.Soluteand
Thetime-lapseimageryfromJanuary2010(Figure3)wasacquiredat5-minute
isotopegeochemistryofsubsurfaceicemeltseepsinTaylorValley,Antarctica.
intervalswithafirmware-modifiedCanonPowershota590ISdigitalcamera,located
GSABulletin119,548–555(2007).
onthesouthernmarginoftheDais(77.551uS,161.176uE).Groundsurface
26.Levy,J.S.,Head,J.W.,Marchant,D.R.,Morgan,G.A.&Dickson,J.L.Gully
temperaturewasrecordedatthesurfaceoftheeasternmostedgeofthesaltpan
surfaceandshallowsubsurfacestructureintheSouthForkofWrightValley,
surroundingDonJuanPond(77.563uS,161.208uE)withanOnset12-bit
AntarcticDryValleys:ImplicationsforgullyactivityonMars.Lun.Planet.Sci.
Temperatureprobe(S-TMB-M002)located,2cmbelowthesurfaceloggedbyan
Conf.38,1728(2007).
OnsetHOBOMicrostation.
27.Head,J.W.,Marchant,D.R.,Dickson,J.L.,Levy,J.S.&Morgan,G.A.Transient
Figure5consistsofportionsofahigh-resolutionpanoramaofDonJuanPond streamsandgulliesintheAntarcticDryValleys:Geologicalsetting,processesand
acquiredfromthesouthernedgeoftheDais(77.551uS,161.176uE). analogstoMars.OnlineProc.ofthe10thISAES#151(2007).
SoilmoisturemeasurementsfromFigure6wereacquiredusingtwoidentical 28.McEwen,A.S.etal.SeasonalflowsonwarmMartianslopes.Science333,
DecagonECH2Osoilmoistureprobesplacedonthesurfaceofawatertrack(,2cm 740–743(2011).
belowthesurface)and1moffthesurfaceofthewatertrack(77.564uS,161.221uE), 29.Levy,J.S.HydrologicalcharacteristicsofrecurrentslopelineaeonMars:Evidence
loggedbyasingleOnsetHOBOMicrostation. forliquidflowthroughregolithandcomparisonswithAntarcticterrestrial
analogs.Icarus219,1–4(2012).
30.Hecht,M.H.etal.Detectionofperchlorateandthesolublechemistryofmartian
1. Meyer,G.H.,Morrow,M.B.,Wyss,O.,Berg,T.E.&Littlepage,J.L.Antarctica: soilatthePhoenixlandersite.Science325,64–67(2009).
Themicrobiologyofanunfrozensalinepond.Science138,1103–1104(1962). 31.Osterloo,M.M.,Hamilton,V.E.,Bandfield,J.L.,Glotch,T.D.,Baldridge,A.M.,
2. Siegel,B.Z.LifeinthecalciumchlorideenvironmentofDonJuanPond, Christensen,P.R.,Tornabene,L.L.&Anderson,F.S.Chloride-bearingmaterials
Antarctica.Nature280,828–829(1979). inthesouthernhighlandsofMars.Science319,1651–1654(2008).
3. Burt,D.M.&Knauth,L.P.Electricallyconducting,Ca-richbrines,ratherthan 32.Carrozzo,F.G.,Bellucci,G.,Altieri,F.,D’Aversa,E.&Bibring,J.-P.Mappingof
water,expectedintheMartiansubsurface.J.Geophys.Res.108,8026(2003). waterfrostandiceatlowlatitudesonMars.Icarus203,406–420.
4. Samarkin,V.A.,Madigan,M.T.,Bowles,M.W.,Casciotti,K.L.,Priscu,J.C., 33.Vincendon,M.,Forget,F.&Mustard,J.WatericeatlowtomidlatitudesonMars.
McKay,C.P.&Joye,S.B.Abioticnitrousoxideemissionfromthehypersaline J.Geophys.Res.115,E10001.
DonJuanPondinAntarctica.Nat.Geosci.3,341–344(2010). 34.Wierzchos,J.,Ascaso,C.&McKay,C.Endolithiccyanobacteriainhaliterocks
5. McKelvey,B.C.&Webb,P.N.GeologicalinvestigationsinsouthernVictoria fromthehyperaridcoreoftheAtacamadesert.Astrobiology6,415–422(2006).
land,Antarctica–Part3–GeologyofWrightValley.NZJ.Geol.Geophys.5, 35.Rothschild,L.J.EarthanalogsforMartianlife.Microbesinevaporites,anew
143–162(1962). modelsystemforlifeonMars.Icarus88,246–260(1990).
SCIENTIFICREPORTS |3:1166|DOI:10.1038/srep01166 6
www.nature.com/scientificreports
36.McKnight,D.M.,Tate,C.M.,Andrews,E.D.,Niyogi,D.K.,Cozzetto,K., Authorcontributions
Welch,K.,Lyons,W.B.&Capone,D.G.Reactivationofacryptobioticstream Conceivedanddesignedthetime-lapseexperiments:JD.Conceivedanddesignedthe
ecosystemintheMcMurdoDryValleys,Antarctica:Along-term meteorologicalexperiments:JD,JHandJL.Performedtheexperiments:JD,JHandJL.
geomorphologicalexperiment.Geomorphology89,186–204(2007). Wrotethepaper:JD,JH,JLandDM.
Additionalinformation
Acknowledgments Competingfinancialinterests:Theauthorsdeclarenocompetingfinancialinterests.
InvaluableengineeringassistancewasprovidedbyBrendanHermalynandJohnHuffman. License:ThisworkislicensedunderaCreativeCommons
WeappreciatefieldassistancefromMikeWyatt,MarkSalvatore,LauraKerber,Sylvain Attribution-NonCommercial-NoDerivs3.0UnportedLicense.Toviewacopyofthis
Piqueux,J.R.Skok,andDavidHollibaugh-Baker.InfrastructuresupportfromRaytheon license,visithttp://creativecommons.org/licenses/by-nc-nd/3.0/
PolarServicesatMcMurdoStationandhelicoptersupportfromPetroleumHelicopters Howtocitethisarticle:Dickson,J.L.,Head,J.W.,Levy,J.S.&Marchant,D.R.DonJuan
International(PHI)arealsogratefullyacknowledged.SoftwaresupportfromCalebFassett Pond,Antarctica:Near-surfaceCaCl2-brinefeedingEarth’smostsalinelakeand
expeditedtheanalysisportionofthispaper. implicationsforMars.Sci.Rep.3,1166;DOI:10.1038/srep01166(2013).
SCIENTIFICREPORTS |3:1166|DOI:10.1038/srep01166 7