Seeking a Pattern: Linking Mantle Convection to Surface Features on Venus

The geologic history of Venus has been the subject of debate for years. Though it shares many characteristics with its sister planet, Earth, the processes occurring on the Venusian surface appear to be distinct. There is evidence for modern-day deformation of the lithosphere, as well as surface features with no analogous formations on Earth. Due to these differences, Venus is hypothesized to be in a stagnant-lid regime. Recent work suggests that quasi-circular, surface features on Venus, known as coronae, could be the surface expressions of mantle plumes. In the absence of Earth-like plate tectonics, mantle plumes could be the dominant driver of change on the Venusian surface. It has also been suggested that there is a possibility to form a stable plume structure at high Rayleigh number in Venus-like conditions. Models showed that a strong spherical harmonic pattern of degree 8 order 4 would emerge and remain stable for over one billion years. Here we present calculations illustrating this (8,4) spherical harmonic structure showing the stable pattern of convection. We also compare the internal structures in these calculations with the pattern of known surface features on Venus, primarily clusters of coronae and large chasms. We argue that stagnant-lid convection produces long-lived, stable conditions in the Venusian mantle allowing for convection and lithospheric alteration through geologic time.