Mars Surface

The geometry, scale, and distribution of sedimentary structures on Mars have proven to be strikingly similar to deposits found on Earth, allowing the methods and principals of terrestrial-based sedimentology to be utilized on Martian analogs. The high-resolution ground-based imaging and mobility provided by the Mars Exploration Rovers (MER) have, for the first time, allowed geological analysis of non-terrestrial outcrops to be performed at a level of detail comparable to field studies on Earth. The quality and variety of data being returned from Mars by the MER spacecraft have begun to bridge the gap between the terrestrial and planetary geological communities. I am interested in using remote sensing images of Mars taken both from orbit and from the surface to study the history of the ancient aqueous environments preserved in the rock record.

An  example of such a study was conducted at Victoria Crater, a 750 m diameter crater in Meridiani Planum, which the Opportunity spacecraft studied from 2004 to 2008. Stratified sedimentary rocks observed in the crater walls of Meridiani Planum chronicle the  paleo-environments of Terra Meridiani and provide glimpses into the broader history of early Mars. The stratigraphy at Victoria Crater includes the best examples of meter-scale cross-bedding observed on Mars to-date. The Cape St. Mary promontory 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 strikes 110 degrees away from Cape St. Mary, shows tabular-planar stratification indicative of climbing bedforms with meter to decameter-scale dune heights.

(Below) Opportunity landing site and traverse area, focusing in on Victoria Crater (Panels B & C)

(Below) Cape St. Mary outcrop showing trough
cross bedding indicative of sinuous dunes migrating
perpendicular to the outcrop face

The findings at Cape St. Mary and Cape St. Vincent are combined with other outcrop faces to produce an eolian deposition model for stratification exposed at Victoria Crater. Promontories located between Cape St. Mary and Cape St. Vincent contain superposed stratigraphic units with northward and southward dipping beds separated by outcrop-scale erosional contacts. Any depositional model used to explain the bedding must conform to reversing N-S, S-N, and NW-SE paleobedform migration directions. In addition to stratified outcrop, a bright band is observed to overprint bedding and lie on an equipotential parallel to the pre-impact surface. Super-resolution images show that the band transects and cross-cuts existing bedding, suggesting a diagenetic origin. Meter-scale cross bedding at Victoria Crater is similar to terrestrial eolian deposits and is interpreted as a dry dune field, comparable to Jurassic-age eolian deposits in the western US. You can read more about Victoria Crater in a publication recently submitted to the Journal of Geophyical Research: Planets