Evidence of Topographic Change Recorded by Lava Flows at Atete and Aruru Coronae on Venus

Abstract

Coronae are quasi-circular volcano-tectonic features on Venus. Four critical observations have been identified within the coronae population, including fracture annuli, a wide range of diameters, complex and varied topography, and various types of associated volcanic features. Geophysical models have attempted to replicate their formation from a variety of lithospheric processes but struggle to recreate all four of the critical observations. Volcanism is an often overlooked characteristic in corona formation models. Paleotopographic techniques are applied to lava flows associated with Atete Corona and Aruru Corona in the Beta-Atla-Themis region to investigate post-emplacement changes in topography. Our results indicate marked divergence between lava flow orientation and the modern slope within the fracture annuli of the coronae. Intra-annular flows at Atete Corona were emplaced on a surface that was reoriented by up to ∼180°. Intra-annular flows at Aruru Corona were emplaced on a surface that was reoriented between 90° and 145°. Lava flows on the flanks of both coronae diverge less than those within the fractures. This finding suggests a progression of volcanism that starts at the interior of the corona and migrates outward to the fracture annuli. The role of volcanism, both intrusive and extrusive, is likely to play a more substantial role in the corona formation. Incorporating melt migration into geophysical models could significantly enhance our comprehension of the processes underlying the formation of coronae.