Nature of Rifting on Venus Revealed by Gravity-Derived Crustal Thickness

Understanding the interior of our sister planet ahead of the next generation of Venus missions has become more imperative as its current and past state has remained an enigma. Venus does not currently have a mobile lid like Earth, yet it has a more tectonically active surface than any other stagnant-lid body in our solar system. Rifting is particularly an important process to study because rifts are a crucial feature of a mobile-lid planet. Rifts on Venus are spatially correlated with coronae, indicating that rifts are influenced by mantle dynamics and magmatism. The tectonic deformation associated with rifting, the emplacement of plutons, and the viscous relaxation of the lower crust are all informed by gravity-derived crustal thickness.

The gravity field from the Magellan mission has heterogenous resolution with a degree strength as low as spherical harmonic 40 (spatial block size of 475 km), which is coarser than the scale of Venus’s rift zones, Nevertheless, we can study rifting on Venus by focusing on a number of rift zones in regions with a degree strength of 95 (spatial block size of ~200 km).. This study area includes a majority of the BAT region as well as many major rift zones, and we find systematic trends of crustal thickening in addition to crustal thinning . The higher-resolution gravity fields recovered by VERITAS and EnVision will allow us to resolve all rift zones on Venus to fully understand the role of rifting on Venus and how it may shape/shaped Venus’ surface.