2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 202-3
Presentation Time: 8:40 AM

GROUND-BASED OBSERVATIONS OF PHYSICAL SEDIMENTOLOGY IN GALE CRATER, MARS


RUBIN, David M.1, GROTZINGER, John2, GUPTA, Sanjeev3, EDGAR, Lauren A.4, EDGETT, Kenneth S.5, LEWIS, Kevin6, STACK, Kathryn M.2, SUMNER, Dawn Y.7, WILLIAMS, Rebecca M.E.8 and SCIENCE TEAM, MSL9, (1)Earth and Planetary Sciences, UC Santa Cruz, 1156 High St, Santa Cruz, CA 950604, (2)Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, (3)Earth Science and Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom, (4)School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, (5)Jet Propulsion Laboratory, California Institute of Technolgy, 4800 Oak Grove Drive, Pasadena, CA 91109, (6)Department of Geosciences, Princeton, Princeton, NJ 08544, (7)Earth and Planetary Sciences, UC Davis, Davis, CA 95616, (8)Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719, (9)Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91011

Gale crater was selected as the Mars Science Laboratory landing site largely because remote images suggested the crater contains a thick sequence of sedimentary rocks interpreted to be eolian, fluvial, and lacustrine deposits (previous work summarized by Anderson and Bell, 2010). In the year since landing, the rover, Curiosity, identified and examined deposits of all three of these depositional environments.

Eolian deposits examined by Curiosityinclude small dunes that are observable in HiRISE images, the Rocknest sand shadow, and thin sandstone beds with pinstripe laminae deposited by migrating wind ripples. On its route to Mt. Sharp, it is likely that the rover will pass near larger active eolian dunes and “washboard” deposits that have previously been interpreted as preserved eolian dunes.

Fluvial deposits examined by Curiosity include both conglomerates and sandstones. The conglomerates have textures of fluvial conglomerates and contain rounded pebbles indicating substantial abrasion (Williams et al., 2013). The fluvial sandstones are cross-bedded (including compound cross-bedding), with dip directions indicating transport generally toward the southeast (toward Mt. Sharp rather than away from it). Fractures interpreted to be desiccation cracks and interbedded eolian (pinstriped) sandstones suggest that fluvial activity alternated with dry, windy, periods. Curiosityalso examined deposits interpreted as distal fluvial or lacustrine mudstones (Sheepbed mudstone) at a location that is topographically lower than the fluvial sandstones and conglomerates.

Since passing through Dingo Gap, Curiosityhas repeatedly encountered outcrops containing sets of cross-beds that dip south toward Mt. Sharp. Origin of these deposits is still uncertain, but they likely were deposited by southward migration of fluvial bars or small deltas.

References

Anderson, R.B., and Bell, J.F. III, 2010, Geologic mapping and characterization of Gale Crater and implications for its potential as a Mars Science Laboratory landing site: Mars 5, 76-128.

Blake, D.F., 2013, Curiosity at Gale crater, Mars: characterization and analysis of the Rocknest sand shadow: Science, 341, DOI: 10.1126/science.1239505

Williams, R.M.E., et al., 2013, Martian fluvial conglomerates at Gale Crater: Science, 340, 1068-1072.

Session No. 202

T225. MicroMars to MegaMars: Integration of Surface and Orbital Investigations
Tuesday, 21 October 2014: 8:00 AM-12:00 PM
301 (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.496
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