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Mars: Fourth Order Landscapes

Geography 441/541 S/14 Dr. Christine M. Rodrigue. Mars: Fourth Order Landscapes. Mars: Fourth Order Landscapes. The “Orders of Relief” for Martian Landscapes The first order was the great crustal dichotomy: Northern lowlands: ~ 1/3 Southern highlands: ~2/3

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Mars: Fourth Order Landscapes

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  1. Geography 441/541 S/14 Dr. Christine M. Rodrigue Mars: Fourth Order Landscapes C.M. Rodrigue, 2014 Geography, CSULB

  2. C.M. Rodrigue, 2014 Geography, CSULB Mars: Fourth Order Landscapes • The “Orders of Relief” for Martian Landscapes • The first order was the great crustal dichotomy: • Northern lowlands: ~ 1/3 • Southern highlands: ~2/3 • The second order was the large regional features: • Tharsis and Elysium rises • The largest craters: Hellas, Argyre, Isidis, Utopia • Valles Marineris • The polar ice caps

  3. C.M. Rodrigue, 2014 Geography, CSULB Mars: Fourth Order Landscapes • The “Orders of Relief” for Martian Landscapes • The third order was the somewhat smaller major regions associated with the araeological eras: • In many ways, this is a cross-cutting category • It addresses the “geological column” or relative ages of all Martian landscapes in terms of the three regional units that gave the three-part sequences of Mars’ evolution their names: • The Noachian Era • The Hesperian Era • The Amazonian Era

  4. C.M. Rodrigue, 2014 Geography, CSULB Mars: Fourth Order Landscapes • The “Orders of Relief” for Martian Landscapes • The fourth order is “in order” now: • These are smaller features (a few kilometers to a few hundred km): • They are landscapes dominated by one or two processes • Fluvial valleys • Sapping alcoves • Outwash channels • Linear fossæ • Folded and faulted mountains of Thaumasia • Lava tubes • Layered mesas • Patterned ground • Wind abraded/etched landscapes • Dune fields • Evidence of mass wasting

  5. Mars: Fourth Order Landscapes Secondary cratering issue: (W.K. Hartmann painting http://psi.edu/hartmann/) C.M. Rodrigue, 2014 Geography, CSULB

  6. Mars: Fourth Order Landscapes • Secondary cratering issue: • Secondary cratering from a primary impact event can be hard to detect • odd-shaped craters are often described as secondaries • lower velocity impacts don't produce a symmetrical detonation C.M. Rodrigue, 2014 Geography, CSULB

  7. Mars: Fourth Order Landscapes • Secondary cratering issue: • Secondary cratering from a primary impact event can be hard to detect just from odd shapes • Plot complication: really low angle impacts, <15° , can also produce odd shapes, if rarely • Orchus Patera (340 x 140 km)? • Terra Sabæa near Huygens (80 x 20 km) • crater N of Acheron Fossæ C.M. Rodrigue, 2014 Geography, CSULB

  8. Mars: Fourth Order Landscapes • Secondary cratering issue: • Secondary cratering often produces linear chains of craters • THEMIS, +19 at 348E( Trouvelot Crater) • MOC, +16 at 325° (Margaritifer Terra) • MRO image of Candor Chasma wall with this weird chain cutting across at an angle to gravity • This can result from forces in the ejecta curtain organizing the debris into linear, unsorted rays, as seen (and preserved) on the moon C.M. Rodrigue, 2014 Geography, CSULB

  9. Mars: Fourth Order Landscapes • Secondary cratering issue: • My attempt to detect crater rays • 6th order nearest neighbors • calculated azimuths from each crater to its 6th order nearest neighbors • compensated for random “alignments” by counting craters at various standards of “alignment” and comparing the counts with the binomial distribution using a Chi-square goodness-of-fit test • a <15° departure of azimuths from that of the nearest neighbor pair was considered “aligned” C.M. Rodrigue, 2014 Geography, CSULB

  10. Mars: Fourth Order Landscapes • Secondary cratering issue: • My attempt to detect crater rays came out kinda groovy! C.M. Rodrigue, 2014 Geography, CSULB

  11. Mars: Fourth Order Landscapes • Secondary cratering issue: • Robbins and Head (2011) • mapped crater clusters • drew great circle routes • several great circles converged on Lyot Crater north of Arabia Terra C.M. Rodrigue, 2014 Geography, CSULB

  12. Mars: Fourth Order Landscapes • Folded and Faulted Mountains: • Grabens and folds • Thaumasia Highlands C.M. Rodrigue, 2014 Geography, CSULB

  13. Mars: Fourth Order Landscapes • Lava Tubes: • Lava flows under a crust, which may collapse • Pavonis • Check out catena C.M. Rodrigue, 2014 Geography, CSULB

  14. Mars: Fourth Order Landscapes • Lava Tubes: • Lava flows under a crust, which may collapse • Pavonis • Check out catena inside a graben or dike or lava tube C.M. Rodrigue, 2014 Geography, CSULB

  15. Mars: Fourth Order Landscapes • Layered Mensæ: • Resistant caprocks protect less resistant materials below • Artist: Marilynn Flynn www.tharsisartworks.com C.M. Rodrigue, 2014 Geography, CSULB

  16. Mars: Fourth Order Landscapes • Layered Mensæ: • Resistant caprocks protect less resistant materials below • Cydonia and the Face on Mars C.M. Rodrigue, 2014 Geography, CSULB

  17. Mars: Fourth Order Landscapes • Layered Mensæ: • Resistant caprocks protect less resistant materials below • Cydonia • Face with HRSC and MOC C.M. Rodrigue, 2014 Geography, CSULB

  18. Mars: Fourth Order Landscapes • Layered Mensæ: • Resistant caprocks protect less resistant materials below • The heart on Mars south polar region, ~255 m across C.M. Rodrigue, 2014 Geography, CSULB

  19. Mars: Fourth Order Landscapes • Faces of Other Species, too! • Flow of younger lava? • The Elephant on Mars • Thanks to Ms. Stoddard • Okay, not a mensa... C.M. Rodrigue, 2014 Geography, CSULB

  20. Mars: Fourth Order Landscapes • Yardangs: • Erosional æolian features • Classic sandblasting south of Olympus Mons taken by HRSC (Mars Express) near +6 by 220 • Earth grooved terrain/yardangs (military source: location unknown) C.M. Rodrigue, 2014 Geography, CSULB

  21. Mars: Fourth Order Landscapes • Yardangs: • Erosional æolian features • Interesting parallel between Earth yardangs (again some unspecified military source) and Mars yardangs and layered terrain • The Mars yardangs (top) are from Æolis Mensæ, just south of Elysium on the margins of the southern highlands C.M. Rodrigue, 2014 Geography, CSULB

  22. Mars: Fourth Order Landscapes • Dunes: • Depositional æolian features • Classic barchans in Nili Pateræ, a volcanic depression in Syrtis Major C.M. Rodrigue, 2014 Geography, CSULB

  23. Mars: Fourth Order Landscapes • Dunes: • Depositional æolian features • Dune field in Endurance Crater imaged by Opportunity • Closest ridges < ~1 m • Blue color in slacks between dune crests reflect hæmatite blueberries • Lighter dust accumulates more on the lip of the crests than on the flanks • Like Earth star dune fields, probably reflect an unpredictable wind regime, as seen in this mystery military image (below) C.M. Rodrigue, 2014 Geography, CSULB

  24. Mars: Fourth Order Landscapes • Dunes: • Depositional æolian features • Endurance Crater and its load of dunes C.M. Rodrigue, 2014 Geography, CSULB

  25. Mars: Fourth Order Landscapes • Patterned Ground: • Polygons and permafrost • Mars -72 at 29 (MOC) • Earth NW Territories, Canada, Sharon Johnson’s GeoImages, UC Berkeley • Stresses from: • Freeze-thaw of water • Expansion-contraction of other materials with temperature changes • Sorting of rock material in the polygon boundaries C.M. Rodrigue, 2014 Geography, CSULB

  26. Mars: Fourth Order Landscapes • Patterned Ground: • Polygons and permafrost • Close up of boulders and other larger clasts caught in the boundaries among polygons C.M. Rodrigue, 2014 Geography, CSULB

  27. Mars: Fourth Order Landscapes • Eskers: • Subglacial streams • Basal melt feeds streams • Stream beds later exposed as sinuous, gravelly ridges • Dorsa Argentea, north of the South Polar Ice Cap Basal Unit, southwest of Hellas, southeast of Argyre C.M. Rodrigue, 2014 Geography, CSULB

  28. Mars: Fourth Order Landscapes • Mass Wasting: • Landslides • Common on crater gully walls at a small scale • Very evident as a major mechanism for the expansion of Valles Marineris • Ganges Chasma • Noctis Labyrinthus C.M. Rodrigue, 2014 Geography, CSULB

  29. Mars: Fourth Order Landscapes • Mass Wasting: • Landslides • Common on crater gully walls at a small scale • Very evident as a major mechanism for the expansion of Valles Marineris • South Candor Chasma C.M. Rodrigue, 2014 Geography, CSULB

  30. Mars: Fourth Order Landscapes • Mass Wasting: • Chaos • Collapsed, jumbled terrain • May be source of massive outflows, possibly explosive if CO2 is involved • Aram Chaos, which seems to feed into Ares Vallis C.M. Rodrigue, 2014 Geography, CSULB

  31. Mars: Fourth Order Landscapes • Softened Craters: • Rims eroded • Burns Ridge (Opportunity) • Floors filled • Dust and ice (Mars Exp) C.M. Rodrigue, 2014 Geography, CSULB

  32. Mars: Fourth Order Landscapes • Softened Craters: • Rims eroded possibly by oceanic currents and processes before the northern lowlands dried out or were resurfaced with younger lavas • Ground penetrating radar (MARSIS on ESA Mars Express) C.M. Rodrigue, 2014 Geography, CSULB

  33. Mars: Fourth Order Landscapes • Softened Craters: • Floors filled • Water – alluvial fans in Eberswalde Crater (below) • Floors re-excavated by wind • Arabia Terra crater layers (to right) C.M. Rodrigue, 2014 Geography, CSULB

  34. Mars: Fourth Order Landscapes • Softened Craters: • Floors REALLY worked over • Arabia Terra Crater (MOC) C.M. Rodrigue, 2014 Geography, CSULB

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