The surface of Venus hosts hundreds of circular to elongate features, ranging from 60 to 2600 km, and averaging somewhat over 200 km, in diameter. These enigmatic structures have been termed "coronae" and attributed to either tectonovolcanic or impact-related mechanisms. A quantitative analysis of symmetry and topography is applied to coronae and similarly sized craters to evaluate the hypothesized impact origin of these features. Based on the morphology and global distribution of coronae, as well as crater density within and near coronae, we reject the impact origin for most coronae. The high level of modification of craters within coronae supports their tectonic nature. The relatively young Beta-Atla-Themis region has a high coronal concentration, and within this region individual coronae are closely associated with the chasmata system. Models for coronae as diapirs show evolution through a sequence of stages, starting with uplift, followed by volcanism and development of annuli, and ending with collapse. With the assumption of this model, a classification of coronae is developed based merely on their interior topography. This classification yields corona types corresponding to stages that have a systematic variation of characteristics. We find that younger coronae tend toward being larger, more eccentric, and flatter than older ones, and generally occur at higher geoid and topography levels.
|Original language||English (US)|
|Number of pages||20|
|Journal||Special Paper of the Geological Society of America|
|State||Published - Jan 1 2007|
- Impact craters
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