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.

Spherical‐Harmonic Distribution Analysis of Coronae in Relation to Volcanic Features on Venus

“…We identify a new subset of coronae that have undergone topographic changes within the fracture annuli since the emplacement of lava flows. This phenomenon, previously described by Tucker and Dombard (2023a) in detail at Atete and Aruru Coronae, suggests a magmatic influence on corona topography. To extend our understanding, we employ spatial analysis techniques and spherical harmonics to investigate the global distribution and characteristics of volcanoes, coronae, and subsets of these data.…”

“…In contrast, Venus may have two modes of mantle plumes: continuous axisymmetric mantle upwellings and transient thermals (Johnson & Richards, 2003; Robin et al., 2007). The interaction of the latter with the lithosphere produces the surface expression of a corona, although the precise mechanism remains a matter of debate (e.g., Dombard et al., 2007; Gülcher et al., 2020; Smrekar & Stofan, 1997; Tucker & Dombard, 2023a). The spectral analysis of the spatial distribution of coronae and volcanic features provides valuable insights into these complex geodynamic processes.…”

“…Full resolution (∼75 m/pix) Magellan synthetic aperture radar (SAR) images are imported into ESRI ArcMap and stretched to enable the identification of discrete lobate and digitate flow features. At coronae with suitable flow features (see Figure 5 of Tucker & Dombard, 2023a), flow centerlines are mapped, and the azimuthal orientation is determined using the start and end points.…”

“…Building on our preliminary work on Aruru and Atete Coronae and using the same methodology (Tucker & Dombard, 2023a), we have identified coronae with lava flows within their fracture annuli that diverge from the modern downhill slope direction in the combined corona dataset. Full resolution (∼75 m/pix) Magellan synthetic aperture radar (SAR) images are imported into ESRI ArcMap and stretched to enable the identification of discrete lobate and digitate flow features.…”

“…Large lava flow fields, of the order of terrestrial flood basalts, have been linked to sources associated with coronae (e.g., Roberts & Head, 1993). Individual lava flows are also observable within and radiating from the fracture annuli (e.g., Tucker & Dombard, 2023a). Additionally, other volcanic edifices, such as tholi or small shield volcanoes, are often found within or on corona annuli (e.g., Lang & López, 2015; Roberts & Head, 1993; Russell & Johnson, 2021; and cf.…”