C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
Geography 441/541S/15
Dr. Christine M. Rodrigue
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The “Orders of Relief” for Martian Landscapes– The first order was the great crustal dichotomy and the
Tharsis bulge:_ Northern lowlands: ~ 1/3_ Southern highlands: ~2/3_ Tharsis: ~1/4
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The “Orders of Relief” for Martian Landscapes
– The second order is tonight’s focus: _ The largest craters: Hellas, Argyre, Isidis, Utopia_ Elysium volcanic rises_ Valles Marineris rifting and landslides_ Chryse Trough: possible fluvial drainage?_ Kasei Valles: jökulhlaup outflow_ Thaumasia block: mega-landslide?_ Syrtis Major: æolian process exposing basalt
_ The polar ice caps: CO2 and H
2O glaciation
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia, Argyre Planitia, Isidis Planitia, Utopia Planitia
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Great Impact Basins– Late Heavy Bombardment
_ The organization of the solar system ~ 4.6 Ga_ Accretion of dust and ices into clumps and planetesimals_ As they grew, interactions became more forceful_ Outer solar system gas giants gravitational interactions_ Uranus and Neptune pushed out by Jupiter and Saturn_ Smaller objects out there lobbed inward → LHB_ LHB peaked ~4 Ga, tapering off ~3.75 Ga_ This history dominated the Noachian period
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia
• Huge: 30 of latitude by 50 of longitude• ~2,300 km across• ~8 km deep in local topography; 6.5 km below the geoid!
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia– NASA/JPL/GSFC
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia: Modifications after impact
• Depositional features: volcanic outflows and wrinkle ridges
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia: Modifications after impact
• Erosional features (MGS MOC): – outflow channels Dao Vallis, Niger Vallis, and Harmakhis Vallis
along Hellas’ eastern wall– ~ 1 km deep and 8-40 km wide (must have been some outflow)
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia: Modifications after impact
• Erosional features (MGS MOC): boulder tracks down cliffs
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia: Modifications after impact
• Depositional features (MGS MOC): lacustrine, shoreline
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia: Modifications after impact
• Depositional features (MGS MOC): Viscous flow? Water? Ice?
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Hellas Planitia
• Depositional features (MGS MOC): dunes in southeastern Hellas
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Argyre Planitia
• Part of hydraulic system?
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Argyre Planitia: Modifications
• Wind deposition: dune (HRSC)• Wind erosion: dust devils (MOC)
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Argyre Planitia: Modifications
_ Fluvial erosion: gullies in Galle_ Complexity: impact, consolidation,
wind erosion
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Argyre Planitia: Modifications
_ Radial and circumferential massifs_ Fluvial erosion: gullies on massif to northwest (HiRISE)
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Isidis Planitia
• Where Beagle was to land• 1500 km wide crater basin• Missing NE rim
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Isidis Planitia: Modifications
• Thermal inertia (map: Caprarelli & Orosei 2015)
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Isidis Planitia: Modifications
• Dunes• Thumbprint terrain• Rootless cones?• Moraines and eskers?
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Isidis Planitia: Modifications
• Thumbprint terrain (MOC)• Rootless cones?• Moraines and eskers?
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Utopia Planitia
_ Circular grabens, some of them double_ Draping of cover material (sediment?) over buried craters_ Folding and compaction into depressions creates grabens on
inner slopes of buried craters’ rims_ Sometimes shrinkage of cover material exerts tension
leading to grabens just beyond buried crater rim
C.M. Rodrigue, 2015Geography, CSULB
Mars: Second Order Landscapes
• The Impact Basins– Utopia Planitia
• Lava basin antipodal to Argyre
• Viking 2 frost documentation