Stratigraphic architecture of bedrock reference section, Victoria Crater, Meridiani Planum, Mars

The Mars Exploration Rover Opportunity has investigated bedrock outcrops exposed in several craters at Meridiani Planum, Mars, in an effort to better understand the role of surface processes in its geologic history. Opportunity has recently completed its observations of Victoria crater, which is 750 m in diameter and exposes cliffs up to ;15 m high. The plains surrounding Victoria crater are ;10 m higher in elevation than those surrounding the previously explored Endurance crater, indicating that the Victoria crater exposes a stratigraphically higher section than does the Endurance crater; however, Victoria strata overlap in elevation with the rocks exposed at the Erebus crater. Victoria crater has a well-developed geomorphic pattern of promontories and embayments that define the crater wall and that reveal thick bedsets (3–7 m) of large-scale cross-bedding, interpreted as fossil eolian dunes. Opportunity was able to drive into the crater at Duck Bay, located on the western margin of Victoria crater. Data from the Microscopic Imager and Panoramic Camera reveal details about the structures, textures, and depositional and diagenetic events that influenced the Victoria bedrock. A lithostratigraphic subdivision of bedrock units was enabled by the presence of a light-toned band that lines much of the upper rim of the crater. In ascending order, three stratigraphic units are named Lyell, Smith, and Steno; Smith is the light-toned band. In the Reference Section exposed along the ingress path at Duck Bay, Smith is interpreted to represent a zone of diagenetic recrystallization; however, its upper contact also coincides with a primary erosional surface. Elsewhere in the crater the diagenetic band crosscuts the physical stratigraphy. Correlation with strata present at nearby promontory Cape Verde indicates that there is an erosional surface at the base of the cliff face that corresponds to the erosional contact below Steno. The erosional contact at the base of Cape Verde lies at a lower elevation, but within the same plane as the contact below Steno, which indicates that the material above the erosional contact was built on significant depositional paleotopography. The eolian dune forms exposed in Duck Bay and Cape Verde, combined with the geometry of the erosional surface, indicate that these outcrops may be part of a larger-scale draa architecture. This insight is possible only as a result of the larger-scale exposures at Victoria crater, which significantly exceed the more limited exposures at the Erebus, Endurance, and Eagle craters.

[1]  S. T. Elliot,et al.  Mars Exploration Rover Athena Panoramic Camera (Pancam) investigation , 2003 .

[2]  S. Fryberger.  A review of aeolian bounding surfaces, with examples from the Permian Minnelusa Formation, USA , 1993, Geological Society, London, Special Publications.

[3]  G. Kocurek,et al.  A preliminary study of the dynamics of a modern draa , 1988 .

[4]  Jeffrey R. Johnson,et al.  In Situ Evidence for an Ancient Aqueous Environment at Meridiani Planum, Mars , 2004, Science.

[5]  W. Dietrich,et al.  On the in situ aqueous alteration of soils on Mars , 2008 .

[6]  Raymond E. Arvidson,et al.  Rock Abrasion Tool: Mars Exploration Rover mission , 2003 .

[7]  I. Wilson.  DESERT SANDFLOW BASINS AND A MODEL FOR THE DEVELOPMENT OF ERGS , 1971 .

[8]  K. Wohletz,et al.  Impact origin of sediments at the Opportunity landing site on Mars , 2005, Nature.

[9]  S. McLennan,et al.  The Martian Surface: The sedimentary rock cycle of Mars , 2008 .

[10]  D. Rubin,et al.  Reconstructing Bedform Assemblages from Compound Crossbedding , 1983 .

[11]  Miles J. Johnson,et al.  Athena Microscopic Imager investigation , 2003 .

[12]  Alexander G. Hayes,et al.  Reconstruction of eolian bed forms and paleocurrents from cross‐bedded strata at Victoria Crater, Meridiani Planum, Mars , 2010 .

[13]  A. Knoll,et al.  Planetary science: Bedrock formation at Meridiani Planum , 2006, Nature.

[14]  T. J. McCoy,et al.  Exploration of Victoria Crater by the Mars Rover Opportunity , 2009, Science.

[15]  Raul A. Romero,et al.  Athena Mars rover science investigation , 2003 .

[16]  A. Knoll,et al.  Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars , 2005 .

[17]  B. Hynek,et al.  A volcanic environment for bedrock diagenesis at Meridiani Planum on Mars , 2005, Nature.

[18]  S. Squyres,et al.  Structure and stratigraphy of Home Plate from the Spirit Mars Exploration Rover , 2006 .

[19]  L. Borgman,et al.  Reconstructing random topography from preserved stratification , 1991 .

[20]  Miles J. Johnson,et al.  In‐flight calibration and performance of the Mars Exploration Rover Panoramic Camera (Pancam) instruments , 2006 .

[21]  Raymond E. Arvidson,et al.  Physical properties and localization investigations associated with the 2003 Mars Exploration rovers , 2003 .

[22]  R. E. Hunter.  Basic types of stratification in small eolian dunes , 1977 .

[23]  D. Rubin,et al.  Bedform climbing in theory and nature , 1982 .

[24]  A. Knoll,et al.  The Opportunity Rover's Athena Science Investigation at Meridiani Planum, Mars , 2004, Science.

[25]  D. Jerram,et al.  Relating eolian bounding-surface geometries to the bed forms that generated them: Etjo Formation, Cretaceous, Namibia , 1999 .

[26]  A. Knoll,et al.  Sedimentary textures formed by aqueous processes, Erebus crater, Meridiani Planum, Mars , 2006 .

[27]  Randolph L. Kirk,et al.  Degradation of Victoria crater, Mars , 2008 .

[28]  S. Squyres,et al.  Sulfate-Rich Eolian and Wet Interdune Deposits, Erebus Crater, Meridiani Planum, Mars , 2009 .

[29]  Edwin D. McKee,et al.  STRUCTURES OF DUNES AT WHITE SANDS NATIONAL MONUMENT, NEW MEXICO (AND A COMPARISON WITH STRUCTURES OF DUNES FROM OTHER SELECTED AREAS)1 , 1966 .

[30]  Jeffrey R. Johnson,et al.  Provenance and diagenesis of the evaporite-bearing Burns formation, Meridiani Planum, Mars , 2005 .