Stress analysis of Tellus Regio, Venus, based on gravity and topography: Comparison with Venera 15/16 radar images

Abstract

The tectonics of the Tellus Regio highland of Venus have been examined using Pioneer Venus altimetry and gravity data and Venera 15/16 radar images. A thin elastic shell model has incorporated the Pioneer Venus data to calculate both global, long‐wavelength and regional, shorter‐wavelength stresses for various assumed values of crust, lithosphere, and mantle thickness and modes of compensation. The effects of these parameters on the calculated stress magnitudes have been examined. The model also allows calculation of crustal thickness and mantle density anomalies. The resulting calculated stress fields have been compared to the surface morphology observed in the Venera 15/16 radar images and interpreted in terms of the stress history. The best fitting parameters are consistent with minor amounts of lithospheric flexure being necessary to produce the observed surface features. The highland region is underlain by a thick (15–20 km) crust which is responsible for most of the topographic support. A positive density anomaly exists below this crust. The denser mantle may represent the down welling portion of a flow field, in which the horizontal flow feeding the downwelling has entrained mobile crustal material, dynamically maintaining a thickened crustal root near the stagnation point of the flow below Tellus Regio. This hot crustal material may have intruded the overlying cooler crust, causing lithospheric inflation and surface volcanism. This scenario is in agreement with the available gravity and radar data and can explain the general surface morphology of Tellus Regio.