A heterogeneous lithosphere on Venus

Venus has a radius that is 95% of the Earth and probably has a similar composition and radiogenic heat production, but the geodynamical mechanism governing its internal thermal evolution remains controversial. Much of the planet surface (77%) is covered by volcanic plains, characterized by basaltic flood lavas, some of which emanate from volcanoes whereas others have no identifiable sources. Here we show that the volcanic plains contain three provinces with statistically different properties of the lithosphere. Apart from the plains around the Beta-Atla-Themis region characterized by a thick crust with a wide range of effective elastic thickness of the lithosphere, the remaining volcanic plains (61% of the surface) display a dichotomous nature, with the northern plains showing a thinner lithosphere and twice the number of volcanoes per unit area compared to the southern plains. These global-scale differences imply a complex geodynamical regime, with large lateral variations in mechanical properties and/or geodynamical processes, which must be addressed by competing models of mantle convection and planetary evolution.