Regional Correlations in the Layered Deposits of Arabia Terra, Mars

In the mid-equatorial region of Arabia Terra, Mars, dozens of moderately sized impact craters (10 to 100 km diameter) contain layered sedimentary deposits. Previous work has found that these layers are resolvable at the meter scale and that they are quasiperiodic in expression. However, the interrelationships of these deposits, along with their formative depositional process, has not yet been determined. Proposed formation mechanisms include fluviolacustrine deposition, groundwater upwelling and evaporation, and aeolian or distal volcanic air fall. For this study, we measured layer thicknesses from stereo image-derived topography within nine craters. We find two regionally extensive layered units with characteristic average bed thicknesses of 12 and 3.5 m and a possible third unit of intermediate thickness. Each unit was identified in a number of craters forming regionally consistent groups. These proposed units represent the first regional correlations of isolated sedimentary deposits in Arabia Terra and point to blanketing regional deposition over at least two separate geologic periods.