Volume Of Impact-derived Ejecta And Constraints On Aeolian Processes And Yardang Formation On Venus

Abstract

Since the high temperatures on the surface of Venus prohibit fluvial processes, the dominant mechanism of sediment production is impact cratering. Sediment produced during impact events is deposited in extensive ejecta blankets and eventually redistributed across Venus' surface by surface winds. Despite the apparent importance of aeolian processes for sediment transport, however, aeolian deposits such as dunes are rare. There is a disconnect between our knowledge of sediment production and the fate of venusian sediment, as the total volume of sediment on the surface of Venus and the volume accounted for by aeolian features are not well constrained. Here we map the distribution and volume of sediment across the surface of Venus and estimate the planet's total budget of sediment to be a minimum of 2.9 ⇥ 10 5 km 3 . We also quantify the volume of sediment held in aeolian fields, and find that 10 5 km 3 of sediment is not accounted for by the aeolian deposits observed. Our maps show that two ostensible fields of yardangs near Mead crater have predicted volumes much larger than the original volume of material deposited by the Mead impact, and thus require an extra source of sediment. By comparing our composite and aeolian volume estimates, we have identified three potential sources of additional sediment on Venus: pyroclastics, chemical weathering, and impact deposits only identifiable in Magellan emissivity data. We also hypothesize that lithification and fields of as yet unidentified aeolian features are sinks for impact-derived sediment. This work is a step towards further constraining the nature of aeolian processes and sediment cycling on Venus.