Revealing tectonic processes at large coronae on Venus by joint analysis of modelled topography and gravity

Understanding the interior processes shaping Venus surface is one of the fundamental tasks for the next decade of Venus science. Even in the absence of plate tectonics, Venus’ surface is covered with many tectonic and/or volcanic structures, including the so-called “coronae” (Latin for crown). Coronae range in diameter from 60 km to up to 2600 km and are defined by rings of closely spaced concentric fractures.  These enigmatic structures are widely distributed across the surface and are considered crucial to understanding the planet's geodynamic regime and resurfacing history. Coronae showcase diverse topographic morphologies, volcanic features, and fracture patterns. Geodynamic modelling studies have provided various scenarios for corona formation, often involving some type of plume-lithosphere interaction.

In this work, four end-member geodynamic cases for large coronae formation from  Gülcher et al. (2020) are used to compute the expected gravity signal for different scenarios through time. Results demonstrate that the addition of gravity field constraints helps to distinguish different formation scenarios that may lead to similar surface expressions. A detailed classification of coronae based on gravity requires a resolution that is greater than currently available. By carefully rescaling our models to Magellan resolution we assess a set of macro-characteristics allowing us to apply this methodology to current datasets, notably pertaining the end-member formation class and the evolution stage of the corona. By applying these concepts to the Magellan topography and gravity maps of Venus we classify several coronae as active/inactive and assess whether their formation could imply crustal recycling. Importantly, we find that 47 coronae bear signatures of present-day plume-induced activity with various styles of tectonic processes at play.

The next decade will be marked by multiple missions flying to Venus aiming to gather updated, and fundamentally more accurate gravity. Anticipating the future VERITAS mission’s gravity data, we provide an overview of the resolving power of the higher resolution dataset and what additional information on coronae formation may be forthcoming.

 

 

Gülcher, A. J. P., Gerya, T. V., Montési, L. G. J., and Munch, J. (2020). Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus. Nature Geoscience, 13(8):547–554. https://doi.org/10.1038/s41561-020-0606-1