Abstract DGP2026-25

Venus's surface is dominated by endogenic processes, with coronae (circular to elliptical volcanic-tectonic structures spanning tens to thousands of kilometers) providing critical constraints on mantle-lithosphere interactions. Unlike Earth's plate tectonics, Venus exhibits alternative geodynamic regimes, including stagnant lid [1], episodic lid [2], and plutonic squishy lid [3] modes, controlled by its thermal state and lithospheric properties. Multiple mechanisms have been proposed for corona formation, including diapir-driven doming with gravitational relaxation [4,5], retrograde subduction [6], plume-lithosphere interactions generating lithospheric instabilities [4], plume-induced subduction [7], episodic subduction and underplating [8], peel-back delamination [4], and melt accumulation dynamics [9,10]. Despite advances through numerical modeling, fundamental questions about corona formation mechanisms remain unresolved. We present an innovative dual methodology employing comprehensive remote sensing analysis alongside 3D scaled planetary analog experiments to demonstrate that retreating lithospheric instabilities provide a unified explanation for observed deformation patterns in coronae.

We conducted detailed remote sensing analysis of asymmetric Atahensik Corona (700×900 km diameter) using Magellan Synthetic Aperture Radar (SAR) imagery and altimetry data. Systematic structural mapping identified high-density radial, oblique, and concentric fracture systems, with cross-cutting relationships establishing concentric fractures as the youngest generation. Quantitative topographic analysis reveals arcuate ridges (elevations >2 km), adjacent arcuate troughs (depths ~2 km below datum), and outer rises. Fracture density analysis indicates localized strain concentration along the northern ridge edge, which may suggest active lithospheric dripping. The southern sector exhibits extensive crustal extension from inner rifts to outer troughs, with fault scarp morphologies documenting progressive deformation.

Here, we employ 3D scaled planetary analog experiments at the Planetary Analog Laboratory, Albert-Ludwigs-University Freiburg, supported by the Freiburg Institute for Advanced Studies (FRIAS). Our experimental program employs rigorously scaled PDMS materials with appropriate rheological conditions representing Venusian lithospheric behavior. Advanced Particle Image Velocimetry (PIV) measurements quantify surface deformation fields throughout experiments. We utilize 3D geometrical reconstruction using Move software (Petex) to restore deformation sequences and quantify strain evolution. Surface topography data reveal spatial correlations between crustal thickening and subsurface downwelling zones, coupled with tensile regimes producing localized crustal extension. Our experiments reproduce topographic features observed at Atahensik, including arcuate ridges with elevated topography in zones of crustal shortening, adjacent trenches, and outer rises. The experimental extensional domains appear consistent with southern sector deformation patterns identified through remote sensing. The agreement between satellite observations and laboratory experiments suggests that lithospheric downwellings may influence Venusian corona evolution.

References
[1] Solomatov & Moresi, (1996) [2] Turcotte, D. L. (1993) [3] Lourenço, D. L., et al. (2020) [4] Adams, G.F., et al. (2022) [5] Janes, D.M., et al. (1992) [6] Sandwell, D.T. and Schubert, G. (1992) [7] Davaille, A., et al. (2017) [8] Piskorz, D., et al. (2014) [9] Gülcher, A.J.P., et al. (2020) [10] Schools, J.W. and Smrekar, S.E. (2024).