Bedding Scale Correlation on Mars in Western Arabia Terra

Layered rocks in the Arabia Terra region of Mars preserve a record of the planet's ancient climate. However, the exact formation mechanism of these rhythmically layered deposits is currently unknown. We previously proposed two distinct regionally correlative units of the Arabia Terra layered deposits based on their bedding thicknesses, orientation, and morphology from High Resolution Imaging Science Experiment stereo observations. For this work, we selected two adjacent craters in Arabia Terra, Sera and Jiji, for further study to test the proposed stratigraphic correlation. We constructed vertical stratigraphic sections of the deposits from dip-corrected bed thickness measurements and local stratigraphic correlations. We found that individual beds maintain a consistent thickness over kilometer scales but are somewhat variable at the basin scale. Each crater exhibited strata with a thinning-upward trend that terminated at terraces with inconsistent bedding, possibly indicating an equilibrium elevation for the formation mechanism. We also identified a probable stratigraphic correlation between basins using the similarities in bedding characteristics and patterns of measurable differences in bed-to-bed thicknesses, indicating synchronous strata. The planar bedding and uniform thickness of the beds within the deposits are consistent with airfall deposition over a prolonged geologic period. This process likely occurred under comparably dry conditions relative to the previously proposed depositional and diagenetic formation mechanisms.