Thermal Evolution and Magmatic History of Venus

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Venus is referred to as the Earth’s twin because of their similar mass and radius, but the present-day surface conditions on Venus are significantly different than on Earth. The hot and dense atmosphere does not allow for liquid water to be stable, however, the situation might have been different in the past. At what point in their thermochemical history Venus and Earth started to diverge is still debated, but it is well accepted that magmatic activity has considerably shaped Venus’ surface and interior through time and may be still ongoing today. Observations of thermal anomalies have been proposed to suggest recent volcanic activity in the Ganiki Chasma region on Venus. Emissivity data recorded by the VEM spectrometer on board Venus Express suggest the presence of young lava flows at several locations that were found to lack surface weathering. Variations in SO2, a volcanic gas produced during magmatic eruptions, have been recorded in measurements of Pioneer Venus and later Venus Express, and provides an additional line of evidence that magmatic processes could still be active on Venus. In turn, magmatic processes that may be ongoing on Venus are the most direct window into the planet’s interior. They provide a link between the planet’s interior composition and dynamics and the surface geology. In this project we will perform melting experiments on proposed Venus compositions and derive melting parametrizations that will be included in a geodynamical model. The latter will be used to model the thermochemical history of Venus and to provide predictions about the present-day level of volcanic and tectonic activity, as well as the degree of chemical heterogeneitiy in the interior and at the surface of Venus. Our main objectives for this project are to investigate the effects of composition on partial melting in the interior of Venus and to understand what are the consequences of crustal recycling in the presence of volatiles such as S, CO2 and Cl with and without the addition of water for chemical heterogeneities at the surface of Venus. In particular, we will investigate the role of water for the formation of tesserae which are the oldest regions on Venus, whose composition has been suggested to resemble that of the continental crust on Earth.Our coupled experiments-numerical modeling approach will provide a significant contribution to improve our understanding of the magmatic history of Venus. Furthermore, such an approach can be used to make predictions for upcoming measurements for the recently selected ESA’s EnVision and NASA’s VERITAS missions.