DOCSLIB.ORG

Thermal Studies of Martian Channels and Valleys Using Termoskan Data

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Thermal Studies of Martian Channels and Valleys Using Termoskan Data JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 99, NO. El, PAGES 1983-1996, JANUARY 25, 1994 Thermal studiesof Martian channelsand valleys using Termoskan data BruceH. Betts andBruce C. Murray Divisionof Geologicaland PlanetarySciences, California Institute of Technology,Pasadena The Tennoskaninstrument on boardthe Phobos '88 spacecraftacquired the highestspatial resolution thermal infraredemission data ever obtained for Mars. Included in thethermal images are 2 km/pixel,midday observations of severalmajor channel and valley systems including significant portions of Shalbatana,Ravi, A1-Qahira,and Ma'adimValles, the channelconnecting Vailes Marineris with HydraotesChaos, and channelmaterial in Eos Chasma.Tennoskan also observed small portions of thesouthern beginnings of Simud,Tiu, andAres Vailes and somechannel material in GangisChasma. Simultaneousbroadband visible reflectance data were obtainedfor all but Ma'adimVallis. We find thatmost of the channelsand valleys have higher thermal inertias than their surroundings,consistent with previousthermal studies. We show for the first time that the thermal inertia boundariesclosely match flat channelfloor boundaries.Also, butteswithin channelshave inertiassimilar to the plainssurrounding the channels,suggesting the buttesare remnants of a contiguousplains surface. Lower bounds ontypical channel thermal inertias range from 8.4 to 12.5(10 -3 cal cm-2 s-1/2 K-I) (352to 523 in SI unitsof J m-2 s-l/2K-l). Lowerbounds on inertia differences with the surrounding heavily cratered plains range from 1.1 to 3.5 (46 to 147 sr). Atmosphericand geometriceffects are not sufficientto causethe observedchannel inertia enhancements.We favornonaeolian explanations of the overall channel inertia enhancements based primarily upon the channelfloors' thermal homogeneity and the strongcorrelation of thermalboundaries with floor boundaries. However,localized, dark regions within some channels are likely aeolian in natureas reported previously. Most channelswith increasedinertias have fretted morphologies such as flat floorswith steepwalls. EasternRavi and southernAres Vailes, the only major channel sections observed that have obvious catastrophic flood bedforms, do nothave enhanced inertias. Therefore, we favorfretting processes over catastrophic flooding for explainingthe inertiaenhancements. We postulatethat the inertia enhancements were caused either by the original fretting process or by a processinvolving the bondingof finesdue to an increasedavailability of water,either initially or secondarily. INTRODUCTION missions.The term channelhas beenwidely used for Mars, Enormouschannels and valleys are some of Mars' most althoughit is somewhaterroneous in itsusage [Sharp and Malin, intriguingfeatures. Most, includingthose studied here, are now 1975;Carr, 1981]. For simplicity,we usethe termchannel to generallyaccepted to have been cut by water or ice related refer collectivelyto featurespreviously classed as channelsor processes[Carr, 1981;Baker, 1982;Baker et al., 1992]. These valleys. processesprobably included catastrophic flooding and sapping processes.Studies of Martian channelsurface properties and BACKGROUND morphologiesyield importantimplications for Mars' geologic, hydrologic,and climatic history. The Termoskan Instrument and Data The SovietPhobos '88 Termoskaninstrument provided the In Februaryand March 1989 the Termoskaninstrument on highestspatial resolution thermal data obtainedso far for Mars boardthe Phobos'88 spacecraftof the USSR acquireda limited [Selivanovet al., 1989; Murray et al., 1991; Betts, 1993], set of very high spatial resolutionsimultaneous observations of includingobservations of severallarge equatorial channels and reflected solar flux and emitted thermal flux from Mars' valleys.Here we presentthe results of thefirst detailed study of equatorialregion. Theseimage panoramas cover a largeportion channelsusing the Termoskan data. We includea descriptionof of the equatorialregion from 30øS to 6øN latitude. Termoskan theinstrument and the observations, a description of thechannels was an optical-mechanicalscanning radiometer with one visible observed,a review of geologicclassifications and previous channel(0.5-1.0 g,m) and one thermal infrared channel (8.5-12.0 thermalstudies, qualitative results and implications, quantitative gm). Theinstrument was fixed to thespacecraft, pointing in the thermal inertia determinationsand implications,critiques of antisolardirection. Thus, all observationsare at 0ø phaseangle possiblehypotheses, and proposedtests using future Mars andonly daytime observations were acquired. More complete descriptionsof the Termoskaninstrument and data appearin Murray et al. [1991] andBetts [1993]. 1Nowat the San Juan Capistrano Research Institute, San Juan Capistrano, California. Termoskan'sbest resolution per pixel was 1.8 km for threeof the panoramasacquired and 300 m for the remainingpanorama Copyright1994 by the AmericanGeophysical Union. [Selivanovet al., 1989;Murray et al., 1991]. Theseresolutions are much better than thoseobtained by the Viking infrared Paper number93JE03173. thermalmapper (IRTM) (approximately5 to 170 km/pixel,with 0148-0227/94/93 JE03173505.00 onlya smallfraction of the datanear 5 km/pixel,and a typical 1983 1984 BETTS AND MURRAY: THERMAL STUDIES OF MARTIAN CHANNELS valueof 30 [Christensen,1986]). Termoskan'sspatial resolution In addition to Ravi Vallis, several other channels lead either is also better than the 3 km/pixel that was expectedfor Mars into or out of HydraoresChaos (see Figure 1). A large, flat Observer'sthermal emission spectrometer (TES), althoughTES channelenters Hydraores Chaos from Valles Marineris to the observationswould have providedglobal 1400 and 0200 local south. We will refer to this channelby the unofficial name, time(LT) spectralcoverage. HydraoresChannel. Regionsof chaoticterrain occur both to the Thermal inertia, a bulk measure of the resistance of a unit southand to the northof this channel. Anotherflat, steepwalled surfacearea to changesin temperature,is commonlyused to channel at the northwestcomer of HydraoresChaos begins characterizethe insulatingproperties of planetarysurfaces. It is Simud Vallis. Only approximately75 km of this channelwere definedasI = (kpcp)112,where kis the thermal conductivity, pis observed north of the chaos. At the northeast corner of thedensity, and c3 is thespecific heat. Low-inertia materials Hydraores Chaos, Termoskanobserved about 150 km of a exhibit the largestday-to-night temperature variation and the channel(here called Tiu West) that splitsaround a large butte. smallestthermal skin depths. We use the units for thermal This channelthen meets anotherobserved channel (here called inertia often usedfor the Martian surface[e.g., Kieffer et al., Tiu East) comingfrom HydaspisChaos to the east. When these 1977]:10 '3 calcm '2 K'1 s'it2. Thermalinertias in SI units(J m'2 setsof channelsmeet north of the Termoskancoverage area, they K'1 s '1/2) can be obtained bymultiplying by41.86. form Tiu Vallis proper. Smallportions of the headwardreaches of AresVallis were alsoobserved. Most of thispart of Aresdoes ChannelDescriptions and Geographic and Geologic Settings not show flat floors, but rather appearsscoured and is locally Termoskanobserved several large channelsnear the eastern anastomofic[Sharp and Malin, 1975]. Simud, Tiu, and Ares, end of Valles Marineris including significantportions of like ShalbatanaVallis, all debouchinto ChrysePlanifia several hundred kilometers downstream. ShalbatanaVallis, Ravi Vallis, the channelconnecting Valles Channel materials were also observed in two of the eastern Marineriswith HydraotesChaos, and channelmaterial in Eos Chasma. In the sameregion, Termoskan also observed small Valles MarinerisChasma: Eos andGangis (see Figure 1). Flow portionsof the southernbeginnings of Simud,Tiu, and Ares from theseregions presumably headed to the eastand eventually Valles as well as channelmaterial in the northernportions of northeastin the directionof HydraoresChannel and Chaos. Only GangisChasma. On the otherside of the planet,Termoskan the northernmostpart of Gangis was observed. A separate observedtwo majorvalleys in the AeolisQuadrangle: A1-Qahira Termoskanpanorama shows most of EosChasma. Both chasma Vallis and Ma'adim Vallis (see Table 1). All the channel contain flat, smooth appearingareas classifiedby Scott and sectionsobserved by Termoskancut throughancient cratered Tanaka [1986] as Hesperianchannel materials. The channel terrainof Noachianage [Scottand Tanaka,1986; Greeleyand materialsare situatednext to steepwalls, buttes,and at leastin Guest, 1987]. EosChasma, between regions of chaoticterrain. ShalbatanaVallis (see Figure 1) appearsto emanatefrom a Termoskan also observedMa'adim Vallis and A1-Qahira zone of chaotic terrain at 0øN, 46øW and heads northward.It Vallis, two isolated channels in the Aeolis qua&angle. narrowsto a low-sinuositychannel with a reasonablyuniform Termoskanobserved the northernmost(distal) 350 km of the 700 width of approximately10 km. It eventuallysplits into two km long,gently winding, 15- to 25-km-wideMa'adim Vallis. It distributaries. In all, it extendsover 1000 km. Termoskan headsnorthward until hookingnorthwest after breachinga 30-km observedapproximately the southern400 km of the channel. crater. It debouches into another 30-km crater. Ma'adim is Just to the east of Shalbatanais the 300-km-longRavi Vallis, unusuallyold for a large channel[Baker, 1982; Masurskyet al., whichalso emanates from a regionof chaoticterrain (Aromatum
Load more

Recommended publications
  • Planetary Geologic Mappers Annual Meeting
    Program Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 Planetary Geologic Mappers Annual Meeting June 12–14, 2018 • Knoxville, Tennessee Institutional Support Lunar and Planetary Institute Universities Space Research Association Convener Devon Burr Earth and Planetary Sciences Department, University of Tennessee Knoxville Science Organizing Committee David Williams, Chair Arizona State University Devon Burr Earth and Planetary Sciences Department, University of Tennessee Knoxville Robert Jacobsen Earth and Planetary Sciences Department, University of Tennessee Knoxville Bradley Thomson Earth and Planetary Sciences Department, University of Tennessee Knoxville Abstracts for this meeting are available via the meeting website at https://www.hou.usra.edu/meetings/pgm2018/ Abstracts can be cited as Author A. B. and Author C. D. (2018) Title of abstract. In Planetary Geologic Mappers Annual Meeting, Abstract #XXXX. LPI Contribution No. 2066, Lunar and Planetary Institute, Houston. Guide to Sessions Tuesday, June 12, 2018 9:00 a.m. Strong Hall Meeting Room Introduction and Mercury and Venus Maps 1:00 p.m. Strong Hall Meeting Room Mars Maps 5:30 p.m. Strong Hall Poster Area Poster Session: 2018 Planetary Geologic Mappers Meeting Wednesday, June 13, 2018 8:30 a.m. Strong Hall Meeting Room GIS and Planetary Mapping Techniques and Lunar Maps 1:15 p.m. Strong Hall Meeting Room Asteroid, Dwarf Planet, and Outer Planet Satellite Maps Thursday, June 14, 2018 8:30 a.m. Strong Hall Optional Field Trip to Appalachian Mountains Program Tuesday, June 12, 2018 INTRODUCTION AND MERCURY AND VENUS MAPS 9:00 a.m. Strong Hall Meeting Room Chairs: David Williams Devon Burr 9:00 a.m.
    [Show full text]
  • Formation of Mangala Valles Outflow Channel, Mars: Morphological Development and Water Discharge and Duration Estimates Harald J
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, E08003, doi:10.1029/2006JE002851, 2007 Click Here for Full Article Formation of Mangala Valles outflow channel, Mars: Morphological development and water discharge and duration estimates Harald J. Leask,1 Lionel Wilson,1 and Karl L. Mitchell1,2 Received 24 October 2006; revised 3 April 2007; accepted 24 April 2007; published 4 August 2007. [1] The morphology of features on the floor of the Mangala Valles suggests that the channel system was not bank-full for most of the duration of its formation by water being released from its source, the Mangala Fossa graben. For an estimated typical 50 m water depth, local slopes of sin a = 0.002 imply a discharge of 1 Â 107 m3 sÀ1, a water flow speed of 9msÀ1, and a subcritical Froude number of 0.7–0.8. For a range of published estimates of the volume of material eroded from the channel system this implies a duration of 17 days if the sediment carrying capacity of the 15,000 km3 of water involved had been 40% by volume. If the sediment load had been 20% by volume, the duration would have been 46 days and the water volume required would have been 40,000 km3. Implied bed erosion rates lie in the range 1to12 m/day. If the system had been bank-full during the early stages of channel development the discharge could have been up to 108 m3 sÀ1, with flow speeds of 15 m sÀ1 and a subcritical Froude number of 0.4–0.5.
    [Show full text]
  • Evidence for Volcanism in and Near the Chaotic Terrains East of Valles Marineris, Mars
    43rd Lunar and Planetary Science Conference (2012) 1057.pdf EVIDENCE FOR VOLCANISM IN AND NEAR THE CHAOTIC TERRAINS EAST OF VALLES MARINERIS, MARS. Tanya N. Harrison, Malin Space Science Systems ([email protected]; P.O. Box 910148, San Diego, CA 92191). Introduction: Martian chaotic terrain was first de- ple chaotic regions are visible in CTX images (Figs. scribed by [1] from Mariner 6 and 7 data as a “rough, 1,2). These fractures have widened since the formation irregular complex of short ridges, knobs, and irregular- of the flows. The flows overtop and/or bank up upon ly shaped troughs and depressions,” attributing this pre-existing topography such as crater ejecta blankets morphology to subsidence and suggesting volcanism (Fig. 2c). Flows are also observed originating from as a possible cause. McCauley et al. [2], who were the fractures within some craters in the vicinity of the cha- first to note the presence of large outflow channels that os regions. Potential lava flows are observed on a por- appeared to originate from the chaotic terrains in Mar- tion of the floor as Hydaspis Chaos, possibly associat- iner 9 data, proposed localized geothermal melting ed with fissures on the chaos floor. As in Hydraotes, followed by catastrophic release as the formation these flows bank up against blocks on the chaos floor, mechanism of chaotic terrain. Variants of this model implying that if the flows are volcanic in origin, the have subsequently been detailed by a number of au- volcanism occurred after the formation of Hydaspis thors [e.g. 3,4,5]. Meresse et al.
    [Show full text]
  • Portal Valiant Integrated Com My Policy
    Portal Valiant Integrated Com My Policy Bejeweled Leonhard usually tickling some Kulturkreis or vacillates soundlessly. Drier and honeycombed Kurtis disunites almost traitorously, though Tann harasses his Mombasa neighbours. Vindictive and unsolicitous Matthiew blast her chirm qualifies or retorts refutably. Where policy and my very great efficiencies and automated sms and handmade gifts for valiant portal has given your supervisor and. WatchGuard has deployed nearly a million integrated multi-function threat management appliances worldwide. Backbase Press & Latest News Backbase. Wholesale Club Holdings Inc. Joint Deployment Energy Planning and Logistics Optimization Initiative J-DEPLOI Video Portal. Active bidding campaigns, my son who killed anyone! Drop your anchor than a better harbor! And relieve want to link my ship to JIRA but I can't fetch an asset. News 'Network of faith' for Hawaii's military DVIDS. Vessel Registration The Texas General society Office. Inkfidel is my name is an integrated resources activity rooms that productivity, integration with policies, and operated business and. Rosalyn. Having something new data integration continues to valiant integrated population to rest of communication provides a recently, texas area to learn best alongside the agglomeration of. We created Exteriors Denver, llc to raise excellent products and services to you. Backbase and Mambu partner to deliver high end-to-end integrated SaaS banking solution. IBSA invites both individuals and businesses to delay more hand our work drop the communities we serve. It was reading much my own idea. Mstxs is the small business men, that she worked together to join forces case studies on the market helped me give us take a specific individuals.
    [Show full text]
  • Mars Frontier
    THE MARS FRONTIER Vol. 10 Challenges of Diversity Copyright © 2009 Robert H. Stockman All rights reserved Contents 1. The Arrivals 2 2. Welcomes 19 3. Asteroid Belt Commission 35 4. Challenges 47 5. Departures 70 6. Selection 92 7. New Years 113 8. Emergency 137 9. Investigation 167 10. Findings 179 11. Devolution 194 12. Kasei 227 13. Departures 240 1 1. Arrivals February-April 2055 The shuttle Simud fell rapidly towards the surface of Mars, its large, rounded bottom still glowing ruddy from the heat of atmospheric entry. Among the passengers packed like sardines in the cabin was Dr. Forest Rivers, age 40. He was dressed in a pressure suit without a helmet; his slightly balding head had a short blond ponytail. He watched the screen closely as it showed the easternmost canyon of the Valles Marineris system rolling by them, the northern escarpment sharp and clear just fifteen kilometers below. “Parachute deployment in three seconds,” announced the pilot. “Here we go.” They could hear the mortar go off, blowing the drogue chute upward into the shuttle’s supersonic slipstream, then the cord tightened and the shuttle jerked as the chute inflated. Gravity increased noticeably. Some passengers were startled, but Rivers remained unperturbed. Then a few seconds later there was a series of three pops as mortars fired out the main chutes, followed by a wrenching jolt as they inflated against the thin Martian air screaming past the shuttle at nearly two thousand kilometers per hour. That startled, if not frightened, some of the passengers; simulations never fully captured the reality of landing on Mars.
    [Show full text]
  • The 1997 Mars Pathfinder Spacecraft Landing Site: Spillover Deposits
    www.nature.com/scientificreports OPEN The 1997 Mars Pathfnder Spacecraft Landing Site: Spillover Deposits from an Early Mars Inland Sea Received: 13 June 2018 J. A. P. Rodriguez1, V. R. Baker2, T. Liu 2, M. Zarroca3, B. Travis1, T. Hui2, G. Komatsu 4, Accepted: 22 January 2019 D. C. Berman1, R. Linares3, M. V. Sykes1, M. E. Banks1,5 & J. S. Kargel1 Published: xx xx xxxx The Martian outfow channels comprise some of the largest known channels in the Solar System. Remote-sensing investigations indicate that cataclysmic foods likely excavated the channels ~3.4 Ga. Previous studies show that, in the southern circum-Chryse region, their fooding pathways include hundreds of kilometers of channel foors with upward gradients. However, the impact of the reversed channel-foor topography on the cataclysmic foods remains uncertain. Here, we show that these channel foors occur within a vast basin, which separates the downstream reaches of numerous outfow channels from the northern plains. Consequently, foods propagating through these channels must have ponded, producing an inland sea, before reaching the northern plains as enormous spillover discharges. The resulting paleohydrological reconstruction reinterprets the 1997 Pathfnder landing site as part of a marine spillway, which connected the inland sea to a hypothesized northern plains ocean. Our food simulation shows that the presence of the sea would have permitted the propagation of low-depth foods beyond the areas of reversed channel-foor topography. These results explain the formation at the landing site of possible fuvial features indicative of fow depths at least an order of magnitude lower than those apparent from the analyses of orbital remote-sensing observations.
    [Show full text]
  • Interior Layered Deposits in the Eastern Valles Marineris and Chaotic Terrains on Mars M
    Lunar and Planetary Science XXXVIII (2007) 1568.pdf Interior Layered Deposits in the Eastern Valles Marineris and Chaotic Terrains on Mars M. Sowe1, E. Hauber1, R. Jaumann1,4, K. Gwinner1, F. Fueten2, R. Stesky3, and G. Neukum4 1Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany, 2Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada, 3Pangaea Scientific, Brockville, Ontario, Canada, 4Department of Earth Sciences, Institute of Geosciences, Remote Sensing of the Earth and Planets, Freie Universitaet Berlin, Germany Introduction Interior Layered Deposits (ILDs) are widespread throughout the whole Valles Marineris. They have been known and analysed for many decades but their origin remains uncertain. There are several hypotheses concerning the origin of ILDs (eolian [1] or lacustrine deposition [2], pyroclastic volcanism in subaerial [3,4,5,6] or sub glacial environments [7,8]). They all imply that the ILDs A B are younger than the troughs in which they formed. Contrary ILDs may also be ancient deposits exhumed due to uplift of the basement [9,10]. We concentrate on ILDs in the eastern Valles Marineris and chaotic terrains and analyse their elevation, thickness, stratigraphic position, competence, state of alteration, and mineralogical composition. Overview The ILDs occur at different elevations from -6000 up to -800m but always lie below the surrounding plateau rim. In contrast to ILDs in the Eastern Valles Marineris (e.g. Candor, Hebes and Ophir Chasma) that reach or even overlap the canyon rim with elevations from ~ -5000 up to ~3500 m. ILDs vary in morphology. Mostly they appear as -2800 -3000 light-toned layered outcrops.
    [Show full text]
  • New Chryse and the Provinces
    New Chryse and the Provinces The city of New Chryse is actually several connected cities. The Upper City is located on a break in the crater rim, looking down past a steep rock to the Lower City. Inside the da Vinci crater rim lies the Inner City, also known as the Old City – Red Era tunnels and cave shelters, as well as several nanocomposite towers and cupolas on Mona Lys Ridge looking down on the lower parts of the city. The Lower city lies in a valley sloping down to the Harbour City, which fills a crater 20 kilometres to the East. The Harbour City crater is connected to Camiling Bay and the sea through two canyons and is very well protected from both wind and ice. South of the Lower City and Harbour City lies The Slopes, a straight slope into the sea that is covered with sprawl and slums. Mona Lys Ridge is a mixture of palatial estates surrounded by gardens, imposing official imperial buildings and towering ancient structures used by the highest ranks of the Empire. The central imperial administration and especially the Council is housed in the Deimos Needle, a diamondoid tower that together with its sibling the Phobos Needle dominate the skyline. Escalators allow swift and discreet transport down to the lower levels of the city, and can easily be defended by the police force. North of Mona Lys lies a secluded garden city for higher administrators, guild officials and lesser nobility. The Inner City is to a large extent part of Mona Lys, although most of the inhabitants of Mona Lys do not care much for the dusty old tunnels and hidden vaults – that is left to the Guild of Antiquarians who maintain and protect it.
    [Show full text]
  • NEW EVIDENCE for the SHALBATANA VALLIS PALEOLAKE, MARS, from the HIGH RESOLUTION IMAGING SCIENCE EXPERIMENT (Hirise)
    40th Lunar and Planetary Science Conference (2009) 1939.pdf NEW EVIDENCE FOR THE SHALBATANA VALLIS PALEOLAKE, MARS, FROM THE HIGH RESOLUTION IMAGING SCIENCE EXPERIMENT (HiRISE). G. Di Achille1, B. M. Hynek1,2, and M. L. Searls, 1Laboratory for Atmospheric and Space Physics, University of Colorado, 392 UCB, Boulder, CO 80309, United States, 2Department of Geological Sciences, University of Colorado, 392 UCB, CO 80309, United States. Introduction: A recent study has identified six possible fan-delta deposits, including a main Gilbert- type delta, at the mouths of the rare contributing chan- nels of Shalbatana Vallis, Mars, and has suggested that a former intravalley lake could have been present within one of the topographic depressions along the main valley (Fig. 1) [1]. The lake would have formed in the Hesperian (about 3.4 Ga) during the terminal hydrological activity of the valley and stabilized its main standing level at 2800 m below the Martian da- tum [1] (S1 in Fig. 1). However, no shorelines were identified on the deltas with the previous datasets, making the lacustrine interpretation questionable. Here, by using the analysis of a stereo pair of HiRISE images [2] coupled with morphometric observations from the Mars Orbiter Laser Altimeter (MOLA) topog- raphic dataset [3], we report the discovery of lake strandlines along the main Gilbert-type delta whithin Shalbatana Vallis (Fig. 2). Sub-meter scale observation of the Shalbatana Figure 1. HRSC color combination of the sedimentary de- Gilbert-type delta. The PSP_009683_1830 and posits (numbered from 1 to 6) along Shalbatana Vallis. PSP_010316_1830 HiRISE images [2] observed the central portion of Shalbatana Vallis at a resolution of of surface properties within a few hundreds of meters about 64 and 67 cm/pixel, respectively.
    [Show full text]
  • Formation of Aromatum Chaos, Mars: Morphological Development As a Result of Volcano-Ice Interactions Harald J
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, E08071, doi:10.1029/2005JE002549, 2006 Formation of Aromatum Chaos, Mars: Morphological development as a result of volcano-ice interactions Harald J. Leask,1 Lionel Wilson,1 and Karl L. Mitchell1,2 Received 3 August 2005; revised 10 May 2006; accepted 16 May 2006; published 17 August 2006. [1] Morphological examination of the Aromatum Chaos depression on Mars supports earlier suggestions that it is a site of cryosphere disruption and release of pressurized water trapped in an underlying aquifer. We infer that the cause of cryosphere disruption was intrusion of a volcanic sill, confined laterally by earlier intruded dikes, and consequent melting of ice by heat from the sill. The vertical extents and displacements of blocks of terrain on the floor of the depression, together with an estimate of the cryosphere thickness, constrain the vertical extent of ice melting and hence the thickness of the sill (100 m) and the depth at which it was intruded (2–5 km). At least 75% of the volume of material removed from Aromatum Chaos must have been crustal rock rather than melted ice. Water from melted cryosphere ice played a negligible role in creating the depression, the process being dominated by released aquifer water. For sediment loads of 30–40% by volume, 10,500–16,500 km3 of aquifer water must have passed through the depression to carry away rock as entrained sediment and erode the associated Ravi Vallis channel. These required water volumes are 2–3 times larger than the amount of water that could reasonably be contained in aquifers located beneath the area of incipiently collapsed ground to the west of Aromatum Chaos and suggest a much larger water source.
    [Show full text]
  • Salt Triggered Melting of Permafrost in the Chaos Regions of Mars
    Lunar and Planetary Science XXXVII (2006) 2218.pdf SALT TRIGGERED MELTING OF PERMAFROST IN THE CHAOS REGIONS OF MARS. Popa I.C., Università degli Studi "G. d'Annunzio" Chieti-Pescara, Pescara, Viale Pindaro 42, Italy. ([email protected]) Introduction: Mars surface bears traces of many landing site (Chryse Planitia) is the place where Ares fluvial-like features, geomorphic identified as outflow outflow channel is depositing its transporting channels, valley networks etc. Among these a particular materials. The following Martian landers Pathfinder one stands above others from the dimensional point of [6] and MER A Spirit [7], and MER B Opportunity [8] view. Outflow channels bear unique water erosion also revealed high soluble salts contents in places characteristics, that led Baker and Milton (1974) [1] to possibly genetically connected. Recently OMEGA believe that are caused by a surface runoff of large aboard Mars Express spacecraft has proven the amounts of water, in short geological time. Water existence of gypsum and other highly soluble salts (e.g origin, necessary for these processes was the topic of kieserite and epsomite) in localized deposits in places around Valles Marineris, and Iani Chaos [9]. many works. Among these theories one generally Freezing point depression of water solutions: accepted idea considers that water is originating from The freezing point of pure water at 1 bar is 0°C melting of permafrost layers positioned in the places of (273K). This melting point can be easily depressed by today chaos’. Here is an investigation that takes into adding impurities or soluble salts to the solvent. In the account the exoergic salt-ice dissolution reaction, along case of halite (NaCl) salt it is known that a 10% NaCl with freezing point depression of formed salty solutions, solution lowers the melting point of about -6°C (267K) as a complentary or a stand-alone process in chaos- and a 20% salt solution lowers it to -16°C (257K).
    [Show full text]
  • 16. Ice in the Martian Regolith
    16. ICE IN THE MARTIAN REGOLITH S. W. SQUYRES Cornell University S. M. CLIFFORD Lunar and Planetary Institute R. O. KUZMIN V.I. Vernadsky Institute J. R. ZIMBELMAN Smithsonian Institution and F. M. COSTARD Laboratoire de Geographie Physique Geologic evidence indicates that the Martian surface has been substantially modified by the action of liquid water, and that much of that water still resides beneath the surface as ground ice. The pore volume of the Martian regolith is substantial, and a large amount of this volume can be expected to be at tem- peratures cold enough for ice to be present. Calculations of the thermodynamic stability of ground ice on Mars suggest that it can exist very close to the surface at high latitudes, but can persist only at substantial depths near the equator. Impact craters with distinctive lobale ejecta deposits are common on Mars. These rampart craters apparently owe their morphology to fluidhation of sub- surface materials, perhaps by the melting of ground ice, during impact events. If this interpretation is correct, then the size frequency distribution of rampart 523 524 S. W. SQUYRES ET AL. craters is broadly consistent with the depth distribution of ice inferred from stability calculations. A variety of observed Martian landforms can be attrib- uted to creep of the Martian regolith abetted by deformation of ground ice. Global mapping of creep features also supports the idea that ice is present in near-surface materials at latitudes higher than ± 30°, and suggests that ice is largely absent from such materials at lower latitudes. Other morphologic fea- tures on Mars that may result from the present or former existence of ground ice include chaotic terrain, thermokarst and patterned ground.
    [Show full text]