Evidence for present-day volcanism on Venus indicates that active sites are spatially
correlated with rift systems. In this work, we investigate subsurface melting at rift zones to
understand how extension and crustal thinning affect the concentration of magmatism, melt
distribution, and lifetimes of active magmatic systems in the Venusian lithosphere.
Analytic computations (one-dimensional) were done to determine the evolution of the
Venusian geotherm during rifting. These computations were done for three extension rates (5,
20, 50 mm/yr) selected from terrestrial hotspot-driven and tectonically-driven extensional
settings. The geotherm curves were compared to a pressure-temperature dependent melt fraction
curve for mantle peridotite to determine whether melting would initiate before the lithosphere
thins away completely. These results also provide a relation for extension rate-dependent magma
flux, which informs our numerical model setup.
We use a numerical magma dynamics model to simulate extension-driven melting as well as
thermochemical evolution of melts intruded into the lithosphere of Venus. This model computes
where and when magma reservoirs form in the crust, compositional evolution of generated melt,
melt fraction, and total reservoir area in a two-dimensional domain. Simulations run over time
periods corresponding to estimates for active lifetimes of rift zones on Venus, depending on
extension rate, to allow for analysis of thermal and chemical evolution within a magma reservoir
as it develops. The results of this work will provide implications for ongoing volcano-tectonic
interactions on Venus as well as estimates for intrusive-to-extrusive ratios that can be compared
with imagery and geophysical data returned by future missions.