Reassessment of the Volumes of Sediment Sources and Sinks on Venus

Abstract

The dominant source of sediment on Venus is thought to be impact cratering, wherein crater ejecta is redistributed across the planet by winds. Here we provide a refined global sediment budget for Venus by mapping and quantifying the volume of sediment from impact craters observable in Magellan data using updated methodology. We improve on previous estimates of the volume of impact-generated sediment by mapping the impact deposits for all craters ≥11 km on Venus. We estimate the planet’s total budget of impact sediment to be a minimum of 290,000 km3, which corresponds to a global layer of sediment 63 cm thick. If erosional processes have been active over the average surface age (500 Ma–1 Ga), the transportable fraction of this volume implies a sediment mobilization rate between 0.18 and 0.36 nm yr−1, comparable to the late Hesperian–Amazonian era of Mars. We requantify the volume of sediment held in recognized eolian features by (1) applying morphometric studies of planetary analogs to assess the volumes of observed Venusian dune and yardang fields and (2) estimating the volume of proposed microdune fields. We also identify a new yardang field near Mead crater. Globally, we find that >100,000 km3 of available sediment is not accounted for by eolian deposits, concurring that lithification, resurfacing, and fields of as yet unidentified eolian features are other potential sinks for sediment. However, locally, individual eolian fields contain more sediment than can be derived from nearby craters, indicating that these fields contain additional sediment from other sources.