Abraded Pyroclastic Linear Paleodunes In Syria And Daedalia Plana, Mars

In the aeolian-dominated conditions of modern Mars, wind-driven sediment deposition and erosion produce a wide range of enigmatic landforms on the planet's surface. In this work, we explore a widespread occurrence of paleodunes on the surface of Mars. These fossilized bedforms preserve morphologies consistent with transverse dunes, implying an approximately unimodal ancient sediment transport azimuth and abundant sediment supply. These bedforms have previously been interpreted as layered dust deposits, and their bland, dust-like reflectance spectra are consistent with volcanic ash. Additionally, these paleodunes have undergone induration and have been significantly eroded by recent winds, causing a superimposed yardang-like erosional texture on the older dune morphology. We propose that these unusual bedforms most likely occurred as wind-mobilized pyroclastics that welded or were cemented in place after deposition and have since eroded into a field of hybrid paleobedform/protoyardangs. (C) 2020 Elsevier B.V. All rights reserved.