Reconstructing the infilling history within Robert Sharp Crater, Mars: Insights from morphology and stratigraphy

According to recent mineralogical study, the presence of an iron oxi-hydroxide (akaganeite) which form under specific conditions, has been detected in Robert Sharp crater, located in the equatorial region of Mars (133.59°'E, -4.12°N), implying an acidic and oxidizing environment in this region. These deposits of akaganeite might be the ultimate alteration phase of a drying lake or lagoon within Robert Sharp. Morphological and stratigraphical studies and, as well, age determination has been carried out in order to constrain the geological and hydrological history of Robert Sharp. Robert Sharp has known a varied geological history, including the formation of fretted terrains and an aerial/aeolian filling during the Hesperian epoch. The presence of valleys and fan-shaped deposits, and the detection of several aqueous minerals, in the crater suggest the presence of a fluvio-lacustrine activity phase in the crater during the last period of the Martian chronology, the Amazonian epoch. The existence of a putative paleo-lake should be short-time and estimated between 1.3 Ga and 500 Ma. Thus, this study shows that Mars has known several phases of aqueous activities well after the late Noachian/ early Hesperian period.