GEO 330 Study Guide - Final Guide: Valles Marineris, Hellas Planitia, Husband Hill
14 May 2018
School
Department
Course
Professor
Tectonics and Global Structure
It is unknown why such a large rift like Valles Marineris formed only to the west of Tharsis
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It is unknown how much of the volume of the canyons is due purely to faulting and how
much is due to erosion, mass wasting, etc.
○
Faulting that formed canyons is part of a radial network of faults around Tharsis
•
Downfaulting…?
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Formation of Valles Marineris
Tharsis is being built up, HUGE VOLCANIC COMPLEX that is put on top of the surface and it puts a
lot of stress on the lithosphere surrounding Tharsis. The basic idea is that you form a whole series
of radial fracture and concentric fractures, and they work to release the stress that is on the
lithosphere that is put on by Tharsis. Tectonic feature that formed as the result of Tharsis being on
the top of Tharsis on Mars. Initially formed as a Tectonic Feature!!!! Basically Valles Marineris is a
tectonic fracture on Mars caused by the formation of Tharsis
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Evidence, or lack thereof, suggests that there is no such thing as plate tectonics on Mars due it its
thick rigid lithosphere preventing movement
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Lack of plate tectonics on Mars
Noachian age of deformation features related to Tharsis
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Direction of valley network flow down Tharsis-induced topography
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Likely Noachian-aged volcanics (km's thick) exposed in canyons in eastern Tharsis
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Geophysical modeling indicating that Tharsis must have been about the same scale it is
today by the late Noachian
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Evidence for early formation (end of Noachian) of Tharsis includes:
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One or more sustained mantle plumes?
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Transport of magma through fractured thin lithosphere?
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Initiation by impact-induced thermal anomaly?
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Related to antipodal Hellas impact basin?
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Reason for localization of volcanic activity is unclear
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Recent modeling suggests that Tharsis formed by intrusive and extrusive magmatic activity rather
than active uplift
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Formation of Tharsis deformed Mars on a global scale
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Formation of Tharsis
Landing Sites
Characterized by relatively flat, rocky plains -- pretty similar to Viking/Pathfinder landing sites
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Rocks are angular to subangular and show no evidence of rounding indicating transport by water
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Rocks are fine-grained with vessicles and vugs, suggesting volcanic origin
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No extrusive centers observable within Gusev
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No flows from Appolinaris Patera can be traced into Gusev
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Rocks on plains are volcanic, but no obvious source
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Bedrock not found on plains
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Vents then covered, and hidden by lava or impact ejecta
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Rocks probably originated as lava flows from fissure vents
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All rocks have ~1mm thick rind of altered rock and clinging dust/regolith
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Gusev rocks and soils both have less K, indicating that there is still some local control on soil
composition
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Rocks on the Gusev Plains
Exam 3 - Review
Wednesday, May 9, 2018
6:36 PM
GEO 330 Page 1
composition
Plains are a rocky surface crossed by poorly defined ridges and numerous shallow
hollows that are probably secondary craters
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Between rocks, surface is covered with light-toned reddish regolith
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Surface of Gusev is Hesperian in age, which is younger than Ma’adim Vallis
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If there were sediments, they were probably buried by lava flows
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Where are the lake sediments?
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Soils essentially have basaltic compositions with added S and Cl
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Ventifacted volcanic rocks
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Depositional features such as drifts, ripples, and tails downwind of rocks
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Rock coatings
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Dust devils
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Wind-related features common on Gusev plains
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Gusev Plains
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A chain of small hills inside Gusev crater ~8 x 4km across
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Form orbit, appear to have a rough texture, especially towards the southern end
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Geologic mapping indicates that plains lap up onto the hills, indicating that the hills
are older than surrounding plains
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Spirit started climbing the Columbia Hills at West Spur, sampling rocks and soils on its
way to the summit of Husband Hill
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Highly variable in composition and texture
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Rocks and soils are very different from plains
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Based on chemical composition, several classes of rocks and soils have been identified
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Columbia Hills
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Differences
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Differences and similarities between Gusev Plains and Columbia Hills rocks
Search for evidence for life on Mars
1.
Characterize the surface and atmosphere of Mars
2.
Obtain higher resolution images of Martian surface
3.
Major goals of missions were to
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Goals
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Moisture added to soil sample, with the intention of "reviving" dormant
organisms
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"Chicken Soup Mode" -- wet nutrients added to soil to encourage metabolism
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Designed to look for life in two different operating modes
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Gas Exchange Experiment
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Sample put in chamber with organic nutrients doped with radioactive 14C
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If microbes are present, they would metabolize 14C and release radioactive CO2to be
measured by Geiger counter
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PI (Gilbert Levin) believes that results from experiment are best explained by life in
sample
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Labeled Release Experiment
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Soil sample exposed to 14C-doped CO2and CO, assuming that microbes had the
capability to turn these gases into organic matter in the absence of water
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Samples were baked to 625°C to turn organic matter into CO2and look for 14C
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Pyrolitic Release Experiment
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Experiments
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Major goals of and scientific experiments on the Viking lander missions
From orbit, hematite only present on the top surface
Orbital
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Characteristics of the Meridiani Planum landing site; orbital vs. in situ measurements
GEO 330 Page 2
Document Summary
Faulting that formed canyons is part of a radial network of faults around tharsis. It is unknown why such a large rift like valles marineris formed only to the west of tharsis. It is unknown how much of the volume of the canyons is due purely to faulting and how much is due to erosion, mass wasting, etc. Tharsis is being built up, huge volcanic complex that is put on top of the surface and it puts a lot of stress on the lithosphere surrounding tharsis. The basic idea is that you form a whole series of radial fracture and concentric fractures, and they work to release the stress that is on the lithosphere that is put on by tharsis. Tectonic feature that formed as the result of tharsis being on the top of tharsis on mars. Basically valles marineris is a tectonic fracture on mars caused by the formation of tharsis.
