A model for the formation of wrinkle ridges in volcanic plains on Venus

Ridged plains, the most abundant geologic terrain on Venus, are volcanic plains deformed by wrinkle ridges after their emplacement. It has been suggested that the ridges are the product of thermal stresses induced in the lithosphere by the increase of surface temperature due to the greenhouse effect of gases released during the emplacement of the volcanic plains. A model for the formation of wrinkle ridges is proposed where the ridges are assumed to be the surface effect of dislocations produced by compressive stress in the Venusian lithosphere. The lithosphere is modeled as a thermoelastic half-space, the surface of which is subject to a linear temperature increase during 100 Ma. The state of stress is calculated and the maximum distance is obtained at which dislocations can be placed in order that the compressive stress at the Venusian surface is everywhere lower than the rock strength. The model predictions in terms of dislocation density and crustal shortening appear to be consistent with observations.