PRELIMINARY GEOLOGICAL MAP OF THE CURIOSITY LANDING ELLIPSE, GALE CRATER, MARS

In the weeks prior to landing, more than 20 members of the Mars Science Laboratory team volunteered to map 0.025° x 0.025° quads of Curiosity’s landing ellipse and surrounding areas. These individual maps were compiled into a single geological map representing genetically related rock units as well as geomorphic surfaces. The stratigraphically oldest unit consists of bedded, moderately high albedo rocks exposed in the central to northern parts of the ellipse. These rocks have a high thermal inertia (450-700 J·m2·K-1·s-½) and commonly show 5-20 m-wide polygons defined by fractures with a geometry consistent with post-depositional contraction. Individual beds are on the order of 1 m thick and dip ≤1° to the southeast. Some exposures of this unit encompass <1 km² areas of smooth-weathering, unbedded, darker rocks. In some cases, these darker exposures appear to be interbedded with, or at the base of, the bedded unit, whereas in others, darker sediment infills erosional topography on top of the bedded unit. The bedded unit is stratigraphically capped by cratered surfaces or by hummocky surfaces with rare to frequent mesas and scarps. The cratered surfaces are interpreted as relatively long-lived hiatuses during deposition of the bedded unit or as an unconformity developed on the underlying bedded unit after deposition. Most hummocky surfaces are interpreted as composed of sediment overlying bedrock with mesas and scarps of bedrock protruding from below. The origins of the sediment are currently poorly constrained. The youngest units consist of eolian bedforms, which occur as isolated patches within craters and depressions, as well as in a >10 km long dune field in the southeast of the landing ellipse. Dune field bedforms are at least locally active. These stratigraphic relationships demonstrate diverse processes influenced accumulation of strata exposed in Curiosity’s landing ellipse. Refinement in mapping and integration of results from Curiosity will provide an improved understanding of these processes and the depositional environments represented by the rock units.