Dichotomy retreat and aqueous alteration on Noachian Mars recorded in highland remnants.

ABSTRACT: The Mawrth Vallis region is a plateau situated on the highland side of Mars' hemispheric dichotomy boundary. It has a >200-m-thick phyllosilicate-bearing stratigraphic succession that indicates extensive aqueous alteration between 4.1 Ga and 3.7 Ga, during the Noachian Period. In addition, thousands of kilometre-scale isolated mounds in the lowlands north and west of Mawrth Vallis have been identified. Here we use geomorphological and spectroscopic analyses to show that the mounds are erosional remnants that formed through retreat of the highland plateau in the Noachian. Consequently, the escarpment that marks the surface expression of the dichotomy must have receded south-southeast by hundreds of kilometres in this area. Lateral and stratigraphic geochemical variation in the mounds show t

SUBMITTER: McNeil JD 

PROVIDER: S-EPMC11810793 | biostudies-literature | 2025

REPOSITORIES: biostudies-literature