C.M. Rodrigue, 2007 Geography, CSULB Mars: Second Order Landscapes Geography 494-01 S/07 Dr....

C.M. Rodrigue, 2007Geography, CSULB

Mars: Second Order Landscapes

Geography 494-01

S/07

Dr. Christine M. Rodrigue



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 is tonight’s focus: Tharsis and Elysium rises The largest craters: Hellas, Argyre, Isidis, Utopia Valles Marineris The polar ice caps



The Volcanic Rises Tharsis




8,000 km across Nearly 10 km thick Single big hotspot plume?




Impact-generated?


Mars: Second Order Landscapes The Volcanic Rises

Elysium “Only” 6 km thick “Only” 2,000 km across



The Volcanic Rises Elysium

Recent volcanic activity: Hecates



The Volcanic Rises Elysium

Glacial features on Hecates? Argued to be snow derived during an ice age produced by a greater obliquity



The Impact Basins Hellas Planitia

Huge: 30 of latitude by 50 of longitude ~2,300 km across ~8 km deep in local topography; 4 km below the geoid!




Depositional features: volcanic outflows and wrinkle ridges




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)




Erosional features (MGS MOC): boulder tracks down cliffs




Depositional features (MGS MOC): lacustrine, shoreline




Depositional features (MGS MOC): hunh? Water? Ice?




Depositional features (MGS MOC): dunes in southern Hellas



The Impact Basins Argyre Planitia

Hydraulic system




Wind deposition: dune (HRSC) Wind erosion: dust devils (MOC)




Fluvial erosion: gullies in Galle Complexity



The Impact Basins Isidis Planitia

Where Beagle was to land



The Impact Basins Isidis Planitia

Another complex history 1,500 km big impact



The Impact Basins Utopia Planitia

Lava basin antipodal to Argyre

Viking 2 frost documentation



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



The Great Canyons Valles Marineris




Subsidiary chasmata




Not your ordinary grand canyon (east end is actually higher than the middle)

Valles cut into layered material (sediments? lava?) Extensional rifting (perhaps like East Africa?) Pitting (suggests extension) Alcoves (suggesting subsurface flow) Landsliding widens the rifts Massive jökulhlhaup-like outflows


Mars: Second Order Landscapes The Great Canyons

Valles Marineris Looks like a canyon draining into Margaritifer and then Chryse But look at the elevations of the central and eastern ends




Layering in walls of Melas Chasma

Dunes covering floor




Layering in walls of Hebes Chasma And 100 in Candor Chasma below




Extensional rifting in Tithonium Chasma Pitting (suggests extension)




Extensional rifting in Coprates Chasma and Catena Pitting (suggests extension)



The Great Canyons Melas, Candor, Ophir Chasmata

Theatre-headed tributaries Like Canyonlands, Utah Sapping of groundwater



The Great Canyons Landslides

South Candor Chasma



The Great Canyons Jökulhlhaup?

On Earth, they are massive floods created when a glacier becomes a dam, as here at Russell Lake behind Hubbard Glacier in Alaska in 1986 and 2002, and the dam breaks



The Great Canyons Jökulhlhaup?

If Ares and Kasei valles were formed by outwash floods, here’s how they’d compare to various Earth measures!



The Great Canyons Cerberus Fossæ

Seem tectonic: faulting Lava flow from a fissure?



The Polar Ice Caps North Polar Cap

Water ice cap Seasonal CO2 veneer



The Polar Ice Caps South Polar Cap

CO2 Water ice cap

underneath?




Layering Drainage from beneath




Sublimation of CO2 creates pits on surface?

Geyser-like jets of CO2 in spring?

C.M. Rodrigue, 2007 Geography, CSULB Mars: Second Order Landscapes Geography 494-01 S/07 Dr....

Documents

Transcript of C.M. Rodrigue, 2007 Geography, CSULB Mars: Second Order Landscapes Geography 494-01 S/07 Dr....