Tectono‐Magmatic Evolution of Asymmetric Coronae on Venus: Topographic Classification and 3D Thermo‐Mechanical Modeling

Abstract

AbstractVenus is the only other Earth‐sized planet in the Solar System but it does not exhibit evidence of plate tectonics that dominates geological processes on Earth. Surface deformation on Venus is mainly driven by mantle convection and plume‐lithosphere interactions, likely represented by the widespread development of the circular volcano‐tectonic features known as coronae. Here, we present a joint study of mission data analysis and 3D modeling of asymmetric coronae on Venus. We systematically analyze 155 of the largest coronae on Venus in terms of surface topography and morphology. We establish that 75% of those coronae are radially asymmetric, and further sub‐categorize them based on their adjacent topography. This analysis reveals that many asymmetric coronae are positioned at a topographic transition between a lowland and plateau (termed topographic margin). With state‐of‐the‐art 3D numerical models, we investigate the physical processes behind plume‐margin interactions on Venus. We find that several tectonic styles may be responsible for asymmetric coronae at topographic margins, including lowland‐sided subduction, plateau‐sided lithospheric dripping, and an embedded plume. The gradient in lithospheric strength across the topographic margin controls these tectonic styles, and larger gradients enhance lithospheric resurfacing and the lifetime of the coronae. We also find that the density increase associated with the basalt‐to‐eclogite phase change provides the extra negative gravitational force required for downgoing crust to be recycled into the mantle. The models presented in this study reproduce a wide set of asymmetrical corona features found on Venus and suggest that they are generally more long‐lived than symmetric coronae.