Reconstruction of Eolian Bedforms from Cross-Bedded Strata at Victoria Crater, Meridiani Planum,
MarsA. Hayes1, J. Grotzinger1, S. Squyres2, K. Lewis1, J. Metz1, J. Bell1, and the ATHENA Science Team
1
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125,
Astronomy Department, Cornell University, 610 Space Sciences Bld., Ithaca, NY 14853;
hayes@gps.caltech.edu
2
Keywords: Mars, Stratigraphy, Cross-Bedding, Eolian
Outcrop exposures imaged by the Opportunity rover at Meridiani Planum have depicted crossbedded strata with geometries and scales similar to eolian and subaqeous deposits on Earth. On Earth
preserved cross-strata are rich in geologic information, providing insight into the depositional
environment and sediment transport directions. The high-resolution stratigraphy of these cross-bedded
strata can be used to reconstruct sedimentary bedforms on Mars to infer formation process and describe
the depositional environment. Meter-scale cross bedding at Victoria Crater is similar to terrestrial eolian
deposits and is interpreted as a dry dune field. Sets of cross-strata in the Cape St. Vincent and Cape St.
Mary sections of Victoria Crater are comparable to Jurassic-age eolian deposits of the western US.
The Opportunity Rover has spent ~300 sols traversing 90° of the rim of Victoria crater, obtaining
images of rock outcrops exposed by several promontories along the way. The outcrops at the Cape St.
Mary and Cape St. Vincent promontories, which are located at opposite ends of the traverse, have proven
to be the best examples of meter scale cross-bedding observed on Mars to date. Super-resolution imaging
techniques and long baseline stereo observations were utilized during an extended imaging campaign of
both outcrop faces. Cape St. Mary is characterized by meter-scale trough-style cross bedding, suggesting
sinuous crested dunes with scour pits migrating perpendicular to the outcrop face. Cape St. Vincent,
which is striking 110° away from Cape St. Mary, has layering indicative of a single climbing bedform
with dune heights of several meters. The findings at Cape St. Mary and Cape St. Vincent are combined
with other bedding faces to produce an eolian deposition model for layering exposed at Victoria Crater.
Any depositional model used to explain the bedding must conform to an observed N-S paleo-flow
direction. In addition to bedded layering, a bright band is observed which lies on an equipotential surface
and is ubiquitous around the crater. The super-resolution images of Cape St. Vincent show that bedforms
can be followed through the layer, suggesting that it is diagenetic in origin.