C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order LandscapesThe Great Crustal Dichotomy
Geography 441/541S/15
Dr. Christine M. Rodrigue
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– On Earth, the orders of relief scheme
• Is sometimes seen in geography textbooks• Organizes topographic variation in a scale-dependent manner• Geographers often focus on
_ Spatial analysis of particular phenomena_ Regional synthesis to integrate assemblages of phenomena_ Scales at which processes and regional patterns operate_ The interactions among phenomena at different scales
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Examples of interactions among scales
_ In spatial statistics: the Modifiable Areal Unit Problem (MAUP) _ In human geography: local cultural and political responses to
global economic and political processes _ Biogeography: alpha, beta, and gamma measures of biodiversity _ Geomorphology: "megageomorphology" has emerged as remote
sensing technology has made the simultaneous examination of form and process at large scale (small map scale) possible
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– For Mars, a handy descriptive scheme for handling the
regional variations in Mars’ physical landscapes• The “First Order of Relief” = the crustal dichotomy
□ The Northern Lowlands□ The Southern Highlands
• If Earth’s oceans evaporated (which they will …), there would remain a crustal dichotomy here
Former ocean basins: low elevation, thin crust, basaltic, with a veneer of pelagic sediments
Former continents: high elevation, thick crust, granitic rocks and their extrusive igneous, sedimentary, and metamorphic derivatives
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for • Martian Landscapes
– Northern Lowlands• Regional subdivisions:
_ Utopia Planitia _ Vastitas Borealis_ Embayments:
_ Acidalia Planitia_ Chryse Planitia_ Amazonis Planitia_ Arcadia Planitia_ Isidis Planitia
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Relatively young surface– Smooth with few craters– This is exactly what you’d expect if Mars had had an ocean
_ It could be expected to receive sediments from rivers, floods, and coastal processes and create terrigenous sediments nearshore
_ They would be turned into minerals that would eventually precipitate out of the water column onto the abyssal floor
_ The oceans would thus cover the underlying original rock surface, much as pelagic sediments here do
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Further suggestions of an ocean:_ Drainage of Martian outflow channels and valley
networks_ This is also exactly what you’d expect if Mars had had an
ocean to serve as base level for stream networks
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes• The “Orders of Relief” for Martian Landscapes
– Northern Lowlands• Drainage:
_ Valles Marineris' outflow channels, which drain into Chryse Planitia_ Nanedis north of Ganges_ Ares and Aram Chaos _ Argyre to Aram and Ares
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Even better: Coastlines!?– Transition between the southern highlands and the
northern lowlands is quite abrupt
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Even better: Coastlines!?– Terraces on the Arcadia side of Alba Mons
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Vastitas Borealis
• Even better: Coastlines!?– Tim Parker’s analysis of Viking imagery
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Even better: Coastlines!?_ Tim Parker’s analysis of Viking imagery (1994)_ His and others’ re-analysis using MOC imagery seemed
to debunk his argument, which even he admitted in 2001_ But it’s as though the new imagery is so fine in resolution
that it can’t detect the coarser scale at which this putative ocean’s coastline features might exist
_ MOLA suggests that, in fact, at least one of the “coastlines” is at the same elevation (water seeks a level constant with respect to the geoid)
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Plot complication_ That "ocean" floor is dominated by andesitic rock (on
Earth, it's basalt)_ Not sediments with minerologies consistent with
precipitation out of water. _ No carbonates! No ocean?
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• About those andesites_ "Surface Type 1"
(basalts dominating the southern highlands)
_ "Surface Type 2" (andesites and andesitic basalts dominating the northern lowlands)
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Rampart craters
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Patterned ground
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Thumbprint terrain• Rootless cones
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Northern Lowlands
• Dunes
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes• The “Orders of Relief” for Martian Landscapes– The Southern Highlands
_ Mostly 1-5 km above the mean martian geoid _ Versus 0-3 km below for the Northern Lowlands_ ~1-3 km scarp dividing the two
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Arabia Terra
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Thaumasia Highlands: snow-fed channels?
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands:
Ancient, battered terrain_ Noachis Terra to right_ Amenthes Planum below_ Signs of water or fluid
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Hellas, with Isidis and Utopia from the Northern Lowlands beyond
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Noachis Terra, Holden Crater, alluvial fan/bajada?
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Syrtis Major Planum, volcanic province, basaltic, not dusty
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes– Southern Highlands: Ancient, battered terrain
• Dust devil track• Promethei Terra on left• Syrtis Major on right
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes• The “Orders of Relief” for Martian Landscapes
– Southern Highlands: Ancient, battered terrain• Terrain softening at higher latitudes • Cimmeria Terra to left• Noachis Terra to right
C.M. Rodrigue, 2015Geography, CSULB
Mars: First Order Landscapes• The “Orders of Relief” for Martian Landscapes
– Basalt terrain and dust dominate the Southern Highlands while andesite is quite prevalent in the Northern Lowlands_ Spectra showing high proportions of basalt shown in the green_ Andesite shown in the red channel_ Hæmatite shown in blue (small area)_ Dust-dominated areas come out brown
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