Groundwater-Controlled Deposition of Equatorial Layered Deposits in Central Arabia Terra, Mars

Abstract

Equatorial Layered Deposits (ELDs) reveal aspects of past depositional environments useful for timing climatic and geological events on Mars. However, their formation has several contending hypotheses which reflect a diverse range of possible environments. To better constrain their formation mechanism, we analyzed the stratigraphic and mineralogical characteristics and mapped the distribution of ELDs within three close craters, Sera, Jiji, and an unnamed crater in central Arabia Terra. Analyses of craters' geology allowed us to reconstruct the paleo-environments where ELDs have been deposited. Thinning and thickening sequence trends show shared and repeated variations in the depositional environment, reflecting sediment accumulation strongly controlled by a regional groundwater reservoir. Layered deposits are characterized by monohydrated and polyhydrated sulfate signatures implying an interaction between water and rock in acidic conditions. Our study contributes to the understanding of regional geological processes in Arabia Terra revealing long-term aqueous activity.