Lithospheric Structure of Venusian Crustal Plateaus

Crustal plateaus are Venusian highlands characterized by tectonized terrains. It is commonly interpreted that their topography is isostatically supported and that they represent fossils of an extinct tectonic regime. Using gravity and topography we perform a comprehensive investigation of the lithospheric structure of six crustal plateaus. We computed the admittance (gravity to topography wavelength‐dependent ratio) for each region and compared them to modeled admittances. Three compensation scenarios were tested: Airy isostasy, a surface‐loading flexural model, and a flexural model with surface and subsurface loads. Our results show that the topography of most plateaus is supported by crustal thickening and that the addition of a mantle support component is not necessary at the investigated wavelengths. The elastic thickness was constrained to be less than 35 km with a best‐fitting average of 15 km, confirming that these regions are consistent with an isostatic regime. The average crustal thickness of the plateaus ranges from 15 to 34 km, and if they are in Airy isostasy, this implies that the global average crustal thickness of Venus is about 20 km. Phoebe Regio is the sole exception of our analysis in that crustal thicknesses that are compatible with the other plateaus are obtained only when a buoyant layer is included. Heat flow estimations computed from the elastic thickness indicate that the plateaus formed under higher heat flow conditions compared to the current global average and could have caused localized melting. Present‐day heat flow predictions suggest that eclogitization could occur where the crust is thickest. Plain Language Summary Crustal plateaus are large and highly deformed highlands observed uniquely on Venus. It is generally assumed that these features are in an Airy isostasy regime, where the weight of the topography is balanced by a crustal root floating over a higher‐density mantle, and that the geologic processes responsible for their formation are no longer taking place. However, their origin, structure, and evolution are still topics of great debate. This study aims to investigate the lithosphere and crustal structure of six of these regions making use gravity and topography data. We use the observed topography and geophysical models of the lithosphere to predict the gravitational signature of each region which is then compared to the observed gravity. With this analysis we constrained the thickness of the elastic lithosphere,