Potential aeolian deposition of intra-crater layering: A case study of Henry crater, Mars

Abstract

Abstract Layered deposits occur on Mars in a wide variety of settings and morphologies, including inside craters as large mounds. Many origins have been proposed for these intra-crater layered deposits, but recent work has suggested the possibility of deposition by ancient aeolian dunes. Distinguishing dune deposits requires identifying cross-strata which may not be resolvable even with the highest spatial resolution imaging of Mars. In this work, we employ an alternative method and attempt to eliminate the possibility of aeolian deposition by comparing martian layer geometries to the angles and thicknesses of aeolian sets on Earth. Layering in Henry crater falls within the expected bounds for aeolian strata, and if ancient dunes deposited these layers, then the sets record the passage of dunes with 10–100 m spacing that were generally migrating toward the center of the crater. The Henry crater mound comprises ∼8000 km3 of sediment, and if all layers reflect dune deposition, we estimate mound deposition would then take at least ∼0.5 m.y. As a whole, ∼20,000 km3 of sediment are preserved in intra-crater layered deposits in Arabia Terra. Results from this case study of Henry crater suggest that at least some of this volume may be from aeolian dunes, in which case intra-crater layered mounds may host an untapped record of very ancient martian aeolian activity.