Anatomy of a Venusian hot spot - Geology, gravity, and mantle dynamics of Eistla Regio

Results of a study of the western and central portions of the Venusian hot spot Eistla Regio are presented. Magellan radar images were mapped to elucidate the general geologic history of the region. Radial fracture systems both on the rises and volcanoes indicate that uplift and associated faulting accompanied volcanic construction. Prominent fracture zones strike WNW to NW, parallel to the long axis of the highlands. The largest of these, Guor Linea, exhibits a progressive deformation history that may include minor clockwise rotation in addition to bulk NNE-SSW extension. Pioneer Venus line-of-sight accelerations were inverted for vertical gravity which, when combined with topography, were used to solve for mass anomalies on the crust-mantle boundary and in the upper levels of the mantle convective system.