Transcript Mars: First Order Landforms

Mars: Fourth Order Landscapes
Geography 441/541
S/14
Dr. Christine M. Rodrigue
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
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
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
C.M. Rodrigue, 2014
Geography, CSULB
Mars: Fourth Order Landscapes
Secondary cratering issue: (W.K. Hartmann painting
http://psi.edu/hartmann/)
C.M. Rodrigue, 2014
Geography, CSULB
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
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
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
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 goodnessof-fit test
– a <15° departure of azimuths from that of the nearest
neighbor pair was considered “aligned”
C.M. Rodrigue, 2014
Geography, CSULB
Mars: Fourth Order Landscapes
• Secondary cratering issue:
– My attempt to detect crater rays came out kinda groovy!
C.M. Rodrigue, 2014
Geography, CSULB
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
Mars: Fourth Order Landscapes
• Folded and Faulted Mountains:
– Grabens and folds
– Thaumasia Highlands
C.M. Rodrigue, 2014
Geography, CSULB
Mars: Fourth Order Landscapes
• Lava Tubes:
– Lava flows under a
crust, which may
collapse
– Pavonis
– Check out catena
C.M. Rodrigue, 2014
Geography, CSULB
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
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
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
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
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
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
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
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
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
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
Mars: Fourth Order
Landscapes
• Dunes:
– Depositional æolian
features
– Endurance Crater and its
load of dunes
C.M. Rodrigue, 2014
Geography, CSULB
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
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
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
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
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
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
Mars: Fourth Order
Landscapes
• Softened Craters:
– Rims eroded
– Burns Ridge (Opportunity)
– Floors filled
– Dust and ice (Mars Exp)
C.M. Rodrigue, 2014
Geography, CSULB
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
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
Mars: Fourth Order Landscapes
• Softened Craters:
– Floors REALLY worked over
– Arabia Terra Crater (MOC)
C.M. Rodrigue, 2014
Geography, CSULB