Transcript First order of relief

Mars: First Order Landscapes
The Great Crustal Dichotomy
Geography 441/541
S/16
Dr. Christine M. Rodrigue
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, CSULB
Mars: First Order
Landscapes
• The “Orders of Relief” for
• Martian Landscapes
– Northern Lowlands
• Regional subdivisions:
_ Vastitas Borealis
_ Utopia Planitia
_ Embayments:
_ Acidalia Planitia
_ Chryse Planitia
_ Amazonis Planitia
_ Arcadia Planitia
_ Isidis Planitia
_ Elysium Planitia
C.M. Rodrigue, 2016
Geography, 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, with some of them dissolving
_ 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2016
Geography, 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, 2016
Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, CSULB
Mars: First Order Landscapes
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian
Landscapes
– Northern Lowlands
• Rampart craters
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian
Landscapes
– Northern Lowlands
• Patterned ground
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian
Landscapes
– Northern Lowlands
• Thumbprint terrain
• Rootless cones
C.M. Rodrigue, 2016
Geography, CSULB
Mars: First Order Landscapes
• The “Orders of
Relief” for Martian
Landscapes
– Northern Lowlands
• Dunes
C.M. Rodrigue, 2016
Geography, 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, 2016
Geography, CSULB
Mars: First Order Landscapes
• The “Orders of Relief” for Martian Landscapes
– Southern Highlands: Ancient, battered terrain
• Arabia Terra
C.M. Rodrigue, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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, 2016
Geography, 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
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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
C.M. Rodrigue, 2016
Geography, CSULB