Venus: The corona conundrum

Coronae are large circular features on Venus, whose complex structure, with traces of tectonic and volcanic activity, mean that their origin remains enigmatic. Their nonrandom distribution, complex geological histories and associated volcanic features have been explained most successfully by models involving mantle upwelling. In this paper we summarize the models of their formation to date, paying particular attention to the success, as well as shortcomings, of these mantle upwelling models. We also describe recent models and theories that have highlighted the need for further investigation into the origin of coronae, with the aim of better understanding the evolution of the interior and surface of Venus.