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