Sulfate-Rich Eolian and Wet Interdune Deposits, Erebus Crater, Meridiani Planum, Mars

Joannah M. Metz and John P. Grotzinger
Geological and Planetary Sciences, Caltech, Pasadena, CA

A long-standing goal of Mars environmental studies is to understand the role of water throughout its geologic history. The Mars Exploration Rover (MER) Opportunity has worked towards this goal by investigating bedrock exposures within craters in Meridiani Planum. Each crater provides an opportunity to test and refine models proposed for the formation of the Meridiani bedrock. The sulfate-rich bedrock exposed in crater walls at Eagle and Endurance has been interpreted by the MER team to have been deposited in an eolian dune-interdune environment. This study investigates three bedrock exposures at Erebus crater, located ~4 km south of Endurance crater. These outcrops, called Olympia, Payson and Yavapai, provide additional evidence in support of the dune-interdune model proposed for the formation of the deposits at the Opportunity landing site. There is evidence for the greater involvement of liquid water in the outcrop exposures of the Olympia outcrop than was observed in Eagle or Endurance craters. The Olympia outcrop likely formed in a wet interdune and sand sheet environment. The facies observed within the Payson outcrop, which is stratigraphically above the Olympia outcrop, indicate that it was deposited within a damp-wet interdune, sand sheet, and eolian dune environment. The Yavapai outcrop, which is stratigraphically above the Payson outcrop, indicates that it was deposited in primarily a sand sheet environment and also potentially within an eolian dune environment. These three outcrop exposures indicate an overall drying upward trend spanning the stratigraphic section from its base at the Olympia outcrop to its top at the Yavapai outcrop. This contrasts with the wetting-upward trend seen within Endurance and Eagle craters. Thus, the series of outcrops seen at Meridiani by Opportunity may comprise a full climatic cycle, evolving from dry to wet to dry conditions.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas