A Global Survey of Lithospheric Flexure at Steep‐Sided Domical Volcanoes on Venus Reveals Intermediate Elastic Thicknesses

Abstract

Properties of the lithosphere set the upper boundary condition for the evolution of planetary interiors. Interior dynamics in turn govern surface conditions over geologic time via volcanism, tectonics, and atmospheric outgassing (e.g., Foley & Driscoll, 2016;Smrekar et al., 2018). Venus's lithosphere is currently poorly understood, but we can use surface observations to learn about the interior and evolution of Earth's "evil twin." In particular, the elastic thickness of the lithosphere might control the morphology of volcanoes. McGovern et al. (2013) used two different magma ascent criteria to explore how coronae, steep-sided domes, and large conical edifices would form. Steep-sided domes, also called "pancake domes," appear nearly circular and flat from above (e.g., Gleason et al.

Dynamics and Evolution of Venus’ Mantle Through Time

“…However, a thinner lithosphere (100-150 km) may be more compatible with melt generation rates estimated at Venus' hotspots (Smrekar and Parmentier 1996;Nimmo and McKenzie 1998). The elastic thickness is always less than the thermal thickness and can be estimated from flexural models applied to geological features on Venus (Solomon and Head 1990;Johnson and Sandwell 1994;O'Rourke and Smrekar 2018;Borrelli et al 2021) and from global admittance maps (Anderson and Smrekar 2006). For most of the planet, the elastic thickness could be as little as 20 km (Anderson and Smrekar 2006), which may indicate a warm lithosphere possibly promoted by intrusive magmatism (Lourenço et al 2020;Plesa and Breuer 2021) and plume-lithosphere interactions (Gülcher et al 2020).…”

Lithospheric Structure of Venusian Crustal Plateaus

“…Gravity and topography studies of Venusian volcanic rises, including Atla, Bell and Eistla regiones, lead to heat flows estimations of 21-35 mW m −2 (Phillips et al, 1997), which are very similar to our results for Alpha Regio. In addition, flexural studies based on topography data indicate that coronae are associated with major heat flow anomalies, reaching up to ∼100 mW m −2 (O'Rourke & Smrekar, 2018;Russell & Johnson, 2021), while steep-sided domes are associated with regional heat flows of 40 mW m −2 (Borrelli et al, 2021).…”

Mantle Degassing Lifetimes through Galactic Time and the Maximum Age Stagnant-lid Rocky Exoplanets can Support Temperate Climates

“…Moreover, it is possible that Venus is experiencing volcanism due to lying in a tectonic regime intermediate to stagnant lid and plate tectonic end members, and therefore having a thinner lithosphere than expected for a purely stagnant-lid planet. There is evidence for limited plate-tectonics-like subduction (Sandwell & Schubert 1992;Davaille et al 2017) and relative movement of crustal blocks on the surface (Byrne et al 2021), as well a relatively thin lithosphere and high heat flux, compared to pure stagnant-lid models (Borrelli et al 2021). Venus, therefore, demonstrates that planets may operate in a regime intermediate to the end-member plate tectonics and stagnant-lid regimes, leading to longer-lived volcanism than our pessimistic stagnant-lid models predict.…”