DOCSLIB.ORG

Comprehensive Analysis of Glaciated Martian Crater Greg ⇑ William K

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Comprehensive Analysis of Glaciated Martian Crater Greg ⇑ William K Icarus 228 (2014) 96–120 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Comprehensive analysis of glaciated martian crater Greg ⇑ William K. Hartmann a, , Veronique Ansan b, Daniel C. Berman a, Nicolas Mangold b, François Forget c a Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ 85719-2395, USA b Université de Nantes, 1, quai de Tourville, BP 13522, 44035 Nantes cedex 1, France c Laboratoire de Météorologie Dynamique, CNRS/UPMC/IPSL, 4 place Jussieu, BP99, 75252 Paris Cedex 05, France article info abstract Article history: The 66-km diameter martian crater, Greg, east of Hellas, hosts various distinctive features, including den- Received 13 August 2012 dritic valleys filled with chevron-textured masses (south wall), and lobate tongues a few kilometers long Revised 20 September 2013 (north wall). We analyze these features by various quantitative techniques to illuminate martian geologic Accepted 21 September 2013 and climatic history. Crater retention model ages indicate that Greg is at least 1–3 Gy old, but surface lay- Available online 2 October 2013 ers of mantles and glacial features are orders of magnitude younger. Properties of the dendritic valleys, combined with climate models, suggest that fluvial activity began under a thicker, warmer atmosphere, Keywords: soon after the crater’s formation. The oldest exposed fluvial systems have surface crater retention ages of Mars a few hundred My, indicating runoff in recent geologic time. Much of Greg is covered by ice-rich mantle Mars, climate Ices deposits, for which we infer gradual accumulation and depths of order 30–85 m; they mask pre-existing Cratering landforms. The lobate tongues are interpreted as glaciers with mean slope of 10.2 ± 2.3° and average thickness of 33 ± 19 m. Our calculations and data suggest that these glaciers were originally ice-rich and that their surface layers have been depleted by volatile loss. The glaciers probably formed when ice-rich mantle deposits reached critical thickness and flowed downhill. The top 5–10 m of the mantle and glaciers show crater survival times of order a few My to 15 My, which, remarkably, is the time since the last 1–4 episodes of obliquity >45°. Global climate models affirm that Greg lies in one of two non- polar areas with extremes of ice deposition during high-obliquity epochs. This match with observations supports the use of such models in studies of planetary climate change. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction evolve over much longer periods? How thick is the mantling in this area? Was liquid water involved during the glacial evolution? This paper focuses on a 66-km-diameter crater in the region Here, we analyze the evolution of Greg crater’s ice-related and li- east of Hellas basin. Located at 38.5°S and 113.1°E (246.9°W), it quid water-related landforms. We see this study as more than an contains an unusual concentration of features that we interpret investigation of one martian crater, however. Rather, we attempt as glacial landforms (see Section 2). In 2010, the crater was named to demonstrate how a number of different types of quantitative Greg. It lies in a region several hundred km wide, notable for debris measurement, from crater counts and topographic measurements aprons, which have been long considered suggestive of ice flow to climate models, can be combined in a carefully chosen diagnos- phenomena (Squyres, 1978; Lucchitta, 1981; Crown et al., 1992). tic landscape to unravel larger issues of martian geologic/climatic Independent of geomorphology, analysis of obliquity change evolution. Section 2 summarizes the overall context. Section 3 pre- indicated that insolation and climatic conditions vary with time sents our methodology. Section 4 presents geomorphologic obser- (Laskar et al., 2002, 2004; Touma and Wisdom, 1993). Forget vations and interpretation of crater counts on four main terrain et al. (2006) ran global climate models and found that Greg lies types inside Greg crater. Section 5 summarizes the chronology in one of two martian non-polar locales of highest ice deposition and evolution, and Section 6 discusses the results with regard to rate during periods of high obliquity. Fassett et al. (2010), in study- the climatic evolution of Mars. ing various features of the region, aptly called the area an ‘‘epicen- ter of ice accumulation.’’ Forget et al. (2006) noted that the putative glacial features ap- 2. Background and context pear geologically young, but had no absolute age estimates. Are they formed as recently as the last obliquity cycles, or did they In 2001 or 2002, the then-unnamed crater, Greg (Figs. 1 and 2), was noted independently by two of us (WKH and DCB), using Mars ⇑ Corresponding author. Fax: +1 520 622 8060. Global Surveyor’s Mars Observer Camera images, as hosting an E-mail address: [email protected] (W.K. Hartmann). unusual concentration of lobate tongue-shaped features (Fig. 3) 0019-1035/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.icarus.2013.09.016 W.K. Hartmann et al. / Icarus 228 (2014) 96–120 97 Fig. 1. Crater Greg (38.5°S, 113°E) located on the eastern part of Hellas basin. (a) Location on global topographic MOLA map. (b) THEMIS IR day image mosaic of Greg and Reull Vallis region at resolution of 100 m/pixel. (c) THEMIS IR night image mosaic. on its north inner (pole-facing) wall (Hartmann et al., 2002). Later, terrestrial glaciers, and described the tongues as possible glaciers visible-light THEMIS images revealed additional, adjacent lobate or rock glaciers. They emphasized arcuate ridges, such as shown tongues on that same wall. The features, typically 1 Â 4 km, give in Fig. 4a. This is not to say that all features discussed as ‘‘gullies’’ a strong visual impression of downhill flow. Such features are not are associated with glaciations (Dundas et al., 2012), but rather unique, but these are the best-developed and most clustered that the type of glacial formations we see on Greg’s north wall examples. Similar but less well developed features were discussed likely are associated with the type of crater-wall gullies defined by Milliken et al. (2003) and Berman et al. (2009). by Malin and Edgett (2000). Hartmann et al. (2002, 2003) suggested that lobate tongues are Head et al. (2005) documented evidence of glaciation at low lat- a residual, short-lived glacial form in which some of the original ice itudes where glaciation had been considered unlikely under pres- has sublimed, and that km-scale arcuate ridges at the tongue’s base ent conditions. Berman et al. (2005, 2009) surveyed mid-latitude strongly resemble arcuate ridges at the base of martian hillside craters and found strong latitude dependence among the kinds of gullies, suggesting a relationship between lobate tongues and hill- features found in Greg. In their study area east of Hellas, they found side gullies. These ideas were developed further by Hartmann et al. 24 craters that had lobate tongues (23% of those surveyed); Fig. 4a (2003) and Hartmann (2003a,b), which referred to a lobate tongue shows an example. Equatorward of 45°, 100% of the tongues faced as a possible rock glacier. Hartmann et al. (2003) suggested that as the pole (as in Greg, at 38°). Recent Malin–Edgett crater-wall gul- flow proceeds, ‘‘ice is continually brought within a few meters of lies followed a similar pattern (Balme et al., 2006; Berman et al., the porous layers of surface debris, so that the ice sublimes and 2009), supporting the possible connection of glaciers, the mantling the ice content of the formation decreases, with the ice-rich central process, and gullies. These gullies may indeed be features created part of the flow collapsing due to sublimation loss of the ice.’’ That by basal melting beneath the ice-dominated lobate tongues. Ber- paper indicated a young age for glaciers, citing calculations by Tur- man et al. (2005) showed that when arcuate ridges occur at the tle et al. (2001) that such masses of ice or ice/soil might flow on bases of gullied walls, the crater floors tend to slope downhill away timescales as short as 10,000 years. Milliken et al. (2003) also cal- from the gullied wall, indicating substantial mass wasting from culated short timescales for glacial flow on Mars, not more than walls onto the floor (Fig. 4a). Berman et al. (2009) showed that 10 My. The short calculated flow times, however, do not prove that Greg’s floor indeed slopes downhill away from the north wall, as the present glacial bulk interior is very young, as it may result from seen in Fig. 2e. many cycles of advance, retreat, and recharge, reaching some near- A strong morphologic relationship of lobate tongues to ice-rich equilibrium as its initial ice was depleted by sublimation, but re- debris aprons is also now clear. For example, Fig. 4c and d shows a charged by mantling. lobate tongue and remnant arcuate ridges on the pole-facing Hartmann (2005, Fig. 14) gave the first crater counts on the lo- slopes of a mountain surrounded by a prominent debris apron, bate tongues and found young crater retention model ages (sur- roughly 500 km north of Greg. As with Greg, the lobate tongue vival times) of order 10–100 My for the larger craters (D 31– and arcuate ridges are only on the pole-facing slope. Radar data 63 m), but even younger survival times of 3–10 My for smaller cra- showed that debris aprons in this area contain relatively pure ters (D = 11–31 m).
Load more

Recommended publications
  • Geologic Map of the Tempe-Mareotis Region of Mars
    U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP 1-2727 U.S. GEOLOGICAL SURVEY GEOLOGIC MAP OF THE TEMPE-MAREOTIS REGION OF MARS By Henry J. Moore INTRODUCTION GEOGRAPHIC SETTING A principal motivation for mapping the Tempe- The Tempe-Mareotis region lies along the northeast Mareotis region is to examine the low volcanic shields trend of the Tharsis Montes volcanic chain, which and lava plains that represent a style of volcanism unlike includes four large, superposed volcanoes: Arsia, Pavo­ the styles of volcanism of the vast ridged plains and the nis, and Ascraeus Montes and Uranius Patera (fig. 1). large Tharsis Montes volcanoes. The goal is to place the The region also includes the elevated western margin volcanism in a spatial and temporal context with other of Tempe Terra and adjacent plains to the west (fig. volcanism on Mars, especially the volcanism that pro­ 2; U.S. Geological Survey, 1985, 1989). In the north- duced the Tharsis Montes volcanic chain (Arsia, Pavonis, central part of the region, terraced highlands are tran­ and Ascraeus Montes). The Tempe-Mareotis region lies sected by the deep, north-south canyons of Tanais Fossae along a great circle that passes through the Tharsis shield along the western margin of Tempe Terra. Farther west, volcanoes and Uranius Patera (fig. 1, see map sheet for all isolated, irregular- to northeast-trending mountains (Tana- figures). Also of interest is the predominantly extensional ica Montes and Gonnus Mons) rise above the western tectonism that preceded, accompanied, and followed the plains, and Enipeus Vallis, a channel system, stretches 480 volcanism.
    [Show full text]
  • Geomorphology of the Tempe Terra Lobate Debris Aprons
    41st Lunar and Planetary Science Conference (2010) 2324.pdf GEOMORPHOLOGY OF THE TEMPE TERRA LOBATE DEBRIS APRONS. S. van Gasselt1, E. Hauber2, A.-P. Rossi3, A. Dumke1, G. Neukum3, 1Freie Universitaet Berlin, Insitute of Geological Sciences, Planetary Sciences and Remote Sensing, Malteserstr. 74-100, D-12249 Berlin, 2German Aerospace Center, Institute for Planetary Research, Rutherfordstr. 2, D-12489 Berlin, 3International Space Science Institute (ISSI), Hallerstr. 6, 3012 Bern, Switzerland. ([email protected]). Introduction and Background: The fretted terrain at thern lowland terrain and the southern cratered high- the Martian dichotomy boundary hosts an abundance land terrain; both units are seperated by a steep escarp- of landforms related to the creep of mountain debris ment which marks the global dichotmoy boundary. and ice which have become known as so–called loba- Within the Tempe Terra/Mareotis Fossae embayment, te debris aprons and units of lineated valley fills and several simple and complex–shaped isolated remnant concentric crater fills [1-6]. Although such features are and massifs occur that are delineated by lobate–shaped related to different morphologic settings, there is a ge- debris aprons extending up to several hundred meters neral consensus that these features are in principle ge- from the remnant massifs. At several locations, these netically connected to the process of ice-assisted creep. aprons coalesce and form a complex and irregularily– Such creep–related landforms are generally considered shaped apron constructs. East and west of the Tempe to be indicators for the existence of past and present ice Terra embayment, remnant massifs become relatively in the near subsurface of Mars [1-2, 5, 7].
    [Show full text]
  • Table 1: Classical Albedo Names from Ancient Geography
    Gangale & Dudley-Flores Proposed Additions to the Cartographic Database of Mars 18 Table 1: Classical Albedo Names From Ancient Geography Feature Name Type Latitude East Longitude Origin Usage Abalos Undae Undae 78.52 272.5 A district of Scandinavia, thought to be an island, noted for amber. Abalos Colles Colles 76.83 288.35 A district of Scandinavia, thought to be an island, noted for amber. Abalos Mensa Mensa 81.17 284.4 A district of Scandinavia, thought to be an island, noted for amber. Abalos Scopuli Scopuli 80.72 283.44 A district of Scandinavia, thought to be an island, noted for amber. Abus Vallis Vallis -5.49 212.8 Classical name for Humber River in England. Acheron Catena Catena 37.47 259.2 "Joyless" in Greek. 1) A river of Bithynia, falling into the Euxine near Heraclea. 2) A river of Bruttium, falling into the Crathis flume near Consentia. 3) A river of Epirus, falling into the Adriatic at Glykys portus. There was an oracle on its banks, where the dead were evoked. In Greek mythology, the son of Gaea and Demeter, turned into the river of woe in the underworld as a punishment for supplying the Titans with water in their struggle with Zeus. 4) a River of Triphylia, falling into the Alpheus near Typana. Gangale & Dudley-Flores Proposed Additions to the Cartographic Database of Mars 19 Feature Name Type Latitude East Longitude Origin Usage Acheron Fossae Fossae 38.27 224.98 "Joyless" in Greek. 1) A river of Bithynia, falling into the Euxine near Heraclea. 2) A river of Bruttium, falling into the Crathis flume near Consentia.
    [Show full text]
  • The Stratigraphy of Mars
    PROCEEDINGS OF THE SEVENTEENTH LUNAR AND PLANETARY SCIENCE CONFERENCE, PART 1 JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 91, NO. B13, PAGES E139-E158, NOVEMBER 30, 1986 The Stratigraphyof Mars KENNETH L. TANAKA U. $. GeologicalSurvey, Flagstaff A detailedplanetwide stratigraphy for Mars hasbeen developed from global mapping based on Viking imagesand cratercounting of geologicunits. The originalNoachian, Hesperian, and AmazonianSystems are divided into eight seriescorresponding to stratigraphicreferents. Characteristic crater densitiesand materialreferents of eachseries are (1) Lower NoaehianIN(16)] (numberof eraten > 16 km in diameter perl06 km 2) > 200]basement material; (2) MiddleNoachian IN(16) = 100-200]cratered terrain material; (3) Upper Noaehian[N(16)= 25-100; N(5) = 200-400]intercrater plains material; (4) Lower Hesperian IN(5) = 125-200]ridged plains material; (5) Upper Hesperian[N(5) = 67-125;N(2) = 400-750]complex plainsmaterial; (6) LowerAmazonian IN(2) = 150-400]smooth plains material in southernAcidalia Planitia; (7) Middle AmazonianIN(2) = 40-150] lava flowsin AmazonisPlanitia; and (8) UpperAmazonian IN(2) < 40] flood-plainmaterial in southernElysium Planitia. Correlations between various crater size-frequency distributionsof highland materials on the moon and Mars suggestthat rocks of the Middle Noachian Seriesare about 3.92-3.85b.y. old. Stratigraphicages eompi!ed for unitsand featuresof variousorigins show that volcanism,tectonism, and meteoritebombardment have generallydecreased through Mars' geologichistory. In recenttime,
    [Show full text]
  • Crustal Structure of Mars from Gravity and Topography G
    Crustal structure of Mars from gravity and topography G. Neumann, M.T. Zuber, Mark A. Wieczorek, David E. Smith, Franck G Lemoine, Patrick Mcgovern To cite this version: G. Neumann, M.T. Zuber, Mark A. Wieczorek, David E. Smith, Franck G Lemoine, et al.. Crustal structure of Mars from gravity and topography. Journal of Geophysical Research. Planets, Wiley- Blackwell, 2004, 109 (E8), pp.E08002. 10.1029/2004JE002262. hal-02458525 HAL Id: hal-02458525 https://hal.archives-ouvertes.fr/hal-02458525 Submitted on 26 Jun 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, E08002, doi:10.1029/2004JE002262, 2004 Crustal structure of Mars from gravity and topography G. A. Neumann,1,2 M. T. Zuber,1,2 M. A. Wieczorek,3 P. J. McGovern,4 F. G. Lemoine,2 and D. E. Smith2 Received 9 March 2004; revised 1 June 2004; accepted 11 June 2004; published 10 August 2004. [1] Mars Orbiter Laser Altimeter (MOLA) topography and gravity models from 5 years of Mars Global Surveyor (MGS) spacecraft tracking provide a window into the structure of the Martian crust and upper mantle.
    [Show full text]
  • This Article Appeared in a Journal Published by Elsevier. the Attached Copy Is Furnished to the Author for Internal Non-Commerci
    This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Journal of Volcanology and Geothermal Research 185 (2009) 139–156 Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.elsevier.com/locate/jvolgeores Claritas rise, Mars: Pre-Tharsis magmatism? James M. Dohm a,b,⁎, Robert C. Anderson c,d, Jean-Pierre Williams d, Javier Ruiz e, Patrick C. McGuire f, Debra L. Buczkowski g, Ruye Wang h, Lucas Scharenbroich c, Trent M. Hare i, J.E.P. Connerney j, Victor R. Baker a,b, Shawn J. Wheelock a, Justin C. Ferris k, Hirdy Miyamoto l a Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ, 85721, USA b Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, USA c Jet Propulsion Laboratory, Pasadena, CA, 91109, USA d Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA e Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain f McDonnell Center for the Space Sciences, Department of Earth and Planetary Sciences and Department of Physics, Washington University, St.
    [Show full text]
  • Plains Volcanism in Tharsis Region on Mars: Ages and Rheology of Eruption Products
    Plains volcanism in Tharsis region on Mars: Ages and Rheology of Eruption Products Vulkanismus plání v oblasti Tharsis na Marsu: Stáří a reologické vlastnosti vyvřelých hornin A DISSERTATION SUBMITTED FOR THE THE MASTER OF SCIENCE DEGREE IN GEOLOGY by Bc. Petr Brož Supervisors: Mgr. Prokop Závada, PhD. and Doc. RNDr. František Holub, CSc. Charles University in Prague, Faculty of Science, Institute of Petrology and Structural Geology Plains volcanism in Tharsis region on Mars: Ages and Rheology of Eruption Products Remote sensing data show clusters of low shield volcanoes in Tharsis volcanic province on Mars (Hauber et al., 2009). These low shield volcanoes and associated landforms are comparable with terrestrial plain-style volcanic products (Plescia, 1981) as defined by Greeley (1982) in the Snake River Plain in Idaho, which represents an intermediate style of volcanic activity ranging between flood basalts and the Hawaiian shields. While a number of recent studies addressed some aspects of low shield volcanoes, in particular their morphology, morphometry, and lava rheology, no systematic study including the chronology for the entire region of Tharsis is available so far. The goal of this work is to determine relative and absolute ages of low shield volcanoes and surrounding lava flows and their basic rheological properties. We used crater size-frequency distribution method (CSFD) developed by Hartman and Neukum (2001) and Ivanov (2001) for determination of absolute dating of the surface. For calculation of the rheological properties of the lava, we used methods established by Hiesinger et al. (2007). It is known that the low shield volcanoes on Mars consist of basaltic lavas that had low viscosities during their effusion, which can be attributed either due to the high effusion rates, high temperatures of erupting lava or low content of Si coupled with high content of Fe-Mg components in the melt.
    [Show full text]
  • Detailed Structural Mapping of the Tempe Terra Region, Mars
    EPSC Abstracts Vol. 15, EPSC2021-315, 2021 https://doi.org/10.5194/epsc2021-315 Europlanet Science Congress 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Detailed structural mapping of the Tempe Terra region, Mars Claire Orlov1,2, Emma Bramham1, Mark Thomas1, Paul K. Byrne3, Estelle Mortimer1, and Sandra Piazolo2 1Institute of Applied Geoscience, School of Earth and Environment, University of Leeds, UK ([email protected]) 2Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, UK 3Planetary Research Group, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, USA Introduction The structurally complex region of Tempe Terra, at the north-eastern edge of the Tharsis Rise, is of substantial interest for understanding the tectonic history of Tharsis, and Mars more broadly. Tempe Terra is a plateau consisting largely of Noachian to Hesperian volcanic and highland units [1], and it preserves evidence of tectonic activity across the lifespan of the Tharsis complex, from faulting of ancient Noachian crust to volcanic and tectonic activity through the Amazonian [2]. Fundamental work on the structural evolution of Tempe Terra [e.g. 2–5] was done with Viking Orbiter imagery and the 1986 geological map of Scott and Tanaka [6]. But in light of revised geological unit ages [1] and the higher-resolution image data now available, that structural evolution requires revisiting. We present an updated inventory of structures in the Tempe Terra region, based on interpretation of recent, high resolution data. We utilised a detailed mapping approach at a regional scale to capture the area’s full tectonic complexity.
    [Show full text]
  • Back Matter (PDF)
    Index Page numbers in italic refer to Figures. Page numbers in bold refer to Tables. Abalos Colles 257, 258, 259 channel networks 5–6 cratered cones 259, 271, 275 formation 9 layered cones 258, 259, 260, 261, Lethe Vallis 206–226 268–271, 273–275 anastomosing patterns 220 erosion 261, 268 outflow 11–12, 12 Abalos Mensa 258, 267 Sulci Gordii 231, 232–255 ablation, solar, Chasma Boreale 277 chaos regions 12 adsorption 146 interior layered deposits 281, 282, 284, 285, Adventdalen, Spitzbergen 113, 114 286, 289–290, 292, 294 periglacial landforms 118 comparison with Valles Marineris 295–296 comparison with Mars 115–118 Chasma Boreale 257, 258, 259, 267 ice-wedge polygons 121 elevation 262–263, 264, 269 aeolian processes 10, 13, 15 formation 276–277 air-fall accumulation, Chasma Boreale 277 air-fall accumulation 277 alases 133, 143 wind erosion 277 Alba Patera Formation 50 outflow event 275, 277 albedo 5, 6 Chryse Planitia, sublimation landforms, ejecta alcove-channel-apron gully morphology 151, 152, 153 blankets 141 alluvial flow clastic forms gully formation 174 blockfields 92, 93, 95, 98, 107 slope–area analysis 185 circles 92, 94, 103 Earth study sites 183, 184, 186, 189 garlands 92, 103 Amazonian epoch 9 islands 90–91, 92, 108 Amazonis Planitia 5 lobate 93–94, 98, 103, 105 thaw 88 Spitzbergen 116, 117 Aorounga Impact Crater, Chad 33 Thaumasia 76, 77–78, 79, 80, 81,82 Arabia Terra 5 nets 91, 92 Aram Chaos, interior layered deposits 282, 285, 286 protalus lobes and ramparts, Arcadia Formation 50 Spitzbergen 117 Ares Vallis stripes 92, 93–94,
    [Show full text]
  • Craters.Mars 24
    Mars ObitOrbiter Laser AltiAltitmetry DtData From “Geoblemes” To “Astroblemes” Grove K. Gilber t RbRobert SDiS. Dietz (1843-1918) (1914-1995) 174 Identified Impact Structures On Earth What can we learn by studying ICImpact Craters on M?Mars? Acidalia Planita Utopia Planita Discoveries from Mars >40, 000 crater ≥ 5km Pristine, simple Oblique Dark, wind deposits Rampart, complex V07252002 V04333003 Craters with Concentric Ridges b a 5km 5km ~13.2 km crater at 35. 1° N844N, 84.4° E ~9.2 km crater (section from V18095023) at 33.1° N, 81.1° E (section from V1908101) Craters with Concentric Ridges Tempe Fossae, Mareotis Fossae, Phlegra Montes, & Utopia Planitia - lack of craters in Equatorial Region (±30°) Sqqyuyres 1979 ; S qyquyres Zimbelmann et al. 1988 and Carr 1986 • Ice-rich mass wasting • Aeolian depositional • Evidence: occurrence model and similarity to debris • Evidence against ice- aprons; sharp break in creep model: uniform slope between the rim layering; lack of flow and floor. outside of rim and around obstacles; small strain rates needed Craters with Concentric Ridges b a 5 km 5km ~13.2 km crater at 35.1° N, 84.4° E ~9. 2 km crater (section from V18095023) at 33.1° N, 81.1° E 11 separate concentric ridges , ~287 m (section from V1908101) circular mounds, ~161-242 m Web-like pattern perpendicular Wall slope for these craters typically ranges from ~4°-1° Ice-Enhanced Mass Wasting? C b -2950 A -3000 ) m ( n -3050 o i t a B v e l -3100 E -3150 Rim Flow C (ap18823l) -3200 01.02.03.0 Distance (km) Thick ness: 126 m ~12 km crater length: 1.78 km at 36.0° N, 80.5° E A (section from V20354002) Crater fill material around obstacles Flows originating at the rim with compressional ridges around obstacles - convex B Craters Pitted-floor Texture V0328003 ~17 km Unnamed Crater at 41.4° N, 87.7° E Quasi-linear furrows or grooves Length: ~2-6 km; Width: ~373 m Zimbelman et al.
    [Show full text]
  • Volcanic Rifting at Martian Graben Daniel Mège, A.C
    Volcanic rifting at Martian graben Daniel Mège, A.C. Cook, Y. Lagabrielle, E. Garel, M.H. Cormier To cite this version: Daniel Mège, A.C. Cook, Y. Lagabrielle, E. Garel, M.H. Cormier. Volcanic rifting at Martian graben. Journal of Geophysical Research, American Geophysical Union, 2003, 108, 10, pp.1029-2002. 10.1029/2002je001852. hal-00023614 HAL Id: hal-00023614 https://hal.archives-ouvertes.fr/hal-00023614 Submitted on 28 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. E5, 5044, doi:10.1029/2002JE001852, 2003 Volcanic rifting at Martian grabens Daniel Me`ge,1 Anthony C. Cook,2,3 Erwan Garel,4 Yves Lagabrielle,5 and Marie-He´le`ne Cormier6 Received 28 January 2002; revised 17 January 2003; accepted 5 February 2003; published 22 May 2003. [1] A large fraction of surface extension on Mars occurred at segmented grabens having width/length ratios akin to oceanic rifts on Earth. Association with volcanic landforms such as pit craters clearly suggests interconnection between tectonic and magmatic processes. A Martian rift evolution model is proposed on the basis of new geomorphological and structural interpretations of imagery, high-resolution digital elevation models (DEMs), scaled experimental modeling and three-dimensional boundary element modeling of magmatic and tectonic processes, and a comparison with terrestrial rifts.
    [Show full text]
  • The Moons of Mars and the Earth-Approaching Asteroids
    11 / MARS VER THE PAST FOUR YEARS, I have spoken before many audiences on the capabilities of the Space Transportation System and the implications 0for space development. My talks generally follow the themes in this book and consequently emphasize exploration and utilization of the Moon. I find that almost all who have considered this topic view Mars as the long-term goal for human settlement.Schmitt capitalizes on the martian mystique to propose a national project as a symbolic theme for the technology and spirit of the new century. Many believe the Red Planet should be the next manned goal, bypassing the Moon because "we have already been there." King echoes these sentiments and lays out some arguments for that viewpoint based on scientific knowledge to be gained and the resources available for supporting exploration. All of us have experienced traveling on the Earth and intuitivelyexpect long journeys to take more energy and fuel than short ones. For destinations in the solar system, the bulk of the fuel is expended in the gravity field of the Earth. Therefore, a spacecraft capable of the round trip to GEO has the propulsive capacity to take payloads to lunar orbit or martian orbit. Payloads delivered to the martian system are smaller because propulsive departure from the Earth's orbit and propulsive insertion at the orbit of Mars demand additional fhel. Landing on and ascending from the surfaces of these planets requires extra capability. As O'Leary points out, the Space TransportationSystem of the next decades will open a variety of options for exploration,including the moons of Mars and the Earth-approaching asteroids.
    [Show full text]