Constraining deformational processes on Venus from rheology and lithospheric structure

Surface feature morphology can reflect the lithospheric and rheological structure as well as the deformational processes of a region. On Venus the lithospheric structure is poorly known. Also, Venus' lack of surface water, high surface temperatures and pressures produce unique rheological conditions. As a result, the deformational processes that have acted, particularly within complex ridged terrain, are varied. We aim to constrain the deformational processes, lithospheric and rheological structure at the volcanic rises of Atla and Beta Regio as well as the complex ridged terrain of Fortuna Tessera. We have used LitMod3D and data sets from Magellan to constrain a proposed lithospheric structure below each of these regions. Most of the central rise topography at Atla and Beta Regio could be isostatically compensated by a thin thermal lithosphere, whilst Fortuna Tessera can be characterised by a thicker thermal lithosphere. LitMod3D also provides estimates of surface heat flow, temperature, density and pressure distributions, which were used as rheological controls in our numerical models. Our simulations show that rheology varies between our different areas and their associated defomational processes. By constraining the lithospheric structure and rheology below each of these areas we have consequently restricted the deformational processes that could have acted to sculpt the surface.