P53F-02
Sedimentary structures and stratal geometries at the foothills of Mount Sharp: their role in paleoenvironmental interpretation

Friday, 18 December 2015: 13:55
2007 (Moscone West)
Sanjeev Gupta1, David M Rubin2, Dawn Y Sumner3, John P Grotzinger4, Kevin W Lewis5, Kathryn Stack6, Linda C Kah7, Steven Banham1 and Kenneth S Edgett8, (1)Imperial College London, London, United Kingdom, (2)University of California-Santa Cruz, Santa Cruz, CA, United States, (3)University of California, Davis, Earth and Planetary Sciences, Davis, CA, United States, (4)California Institute of Technology, Pasadena, CA, United States, (5)Johns Hopkins University, Baltimore, MD, United States, (6)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (7)University of Tennessee, Knoxville, TN, United States, (8)Malin Space Science Systems, San Diego, CA, United States
Abstract:
The Mars Science Laboratory Curiosity rover has been exploring sedimentary rocks at the foothills of Mount Sharp since August 2014. Robust interpretation of the paleoenvironmental contexts requires detailed facies analysis of these rocks including analysis and interpretation of sedimentary structures and sediment body geometries. Here, we describe some of the detailed sedimentary structures and sedimentary geometries observed by Curiosity between the Pahrump_Hills field site and its current location at Marias Pass.

The Pahrump Hills sedimentary section comprises a succession dominated by finely laminated mudstones of the Murray formation that are interpreted to have been deposited in an ancient lake within Gale crater. Toward the top of the Pahump Hills succession, we observe the appearance of coarser-grained sandstones that are interstratified within the lacustrine mudstones. These sandstones that include Whale Rock and Newspaper Rock show lenticular geometries, and are pervasively cross-stratified. These features indicate that currents eroded shallow scours in the lake beds that were then infilled by deposition from migrating subaqueous dunes. The paleoenvironmental setting may represent either a gullied delta front setting or one in which lake level fall caused fluvial erosion and infilling of the shallow scours.

Since leaving Pahrump_Hills, Curiosity has imaged extensive exposures of strata that are partly correlative with and stratigraphically overlie the uppermost part of the Pahrump section. Isolated cross-bedded sandstones and possible interstratified conglomerates beds occur within Murray formation mudstones. Capping sandstones with a likely variety of environmental contexts overlie mudstones. Where imaged in detail, sedimentary structures, such as trough-cross bedding and possible eolian pinstriping, provide constraints on plausible sedimentary processes and bounds on depositional setting.

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