Modeling Lithospheric Delamination on Venus

• Applicant: Dr. Andrea Adams
• Subject Area: Geophysics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556832329

Although often called Earth’s twin, due to its similar size, mass, and potentially composition, present-day Venus is very different than our home planet. While the surface of the Earth is divided into tectonic plates with clearly defined plate boundaries, the tectonic framework on present-day Venus is not well understood. Thousands of kilometers of possible subduction sites have been identified on Venus as having a narrow, arcuate trench with a large outer rise curvature comparable to certain subduction zones on Earth. However, subduction on Venus is inhibited by the presence of positively buoyant lithosphere that in some locations is thick and resistant to forming instabilities. Recently, a new tectonic regime called peel-back delamination (PBD) was shown to be a viable mechanism of recycling thick, positively buoyant lithosphere near chasma rift zones on Venus. Rather than recycling the entire lithosphere like in subduction, PBD occurs when dense lithospheric mantle is destabilized at a pre-existing rift zone and peels away from a layer of positively buoyant crust at the surface. However, the investigation of the 3D surface expression of this process and detailed comparison with tectonic features on Venus are still missing. The key objectives of this project are to investigate the 3D surface expression of PBD and identify specific features on Venus that may have formed by PBD. A series of 3D geodynamical models will investigate the role of lithospheric thickness and strength, mantle temperature, and chasma rift zone geometry on the surface expression of PBD. Model topography will be compared to three subduction sites, specifically Artemis Corona, Derceto Plateau, and Quetzalpetlatl Corona, which are chosen for their differences in size, shape, flexural topography, thermal uplift, and surface volcanism. This will be the first study to combine all of these surface observations as constraints to better understand the local variations in mantle and lithosphere properties on Venus. This work will also test a hybrid model that includes both PBD and plume-induced subduction depending primarily on local lithospheric thickness to determine the diversity of lithospheric recycling processes on Venus. The results will advance our understanding of Venus’ current tectonic regime as well as constrain the heat loss associated with lithospheric recycling. Since melt production will be affected by lithospheric recycling, partial melting could help to further distinguish the characteristics of PBD compared to plume-induced subduction. Lithospheric recycling is also important for the link between Venus’ interior and atmosphere, which will have implications for planetary habitability. In addition to using existing surface observations in a novel way, gravity and topography calculated in PBD models will help guide the interpretation of future high-resolution gravity and topography data collected by the EnVision and VERITAS missions to Venus in the coming decade.

• DFG Programme: Research Grants