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A global survey and regional scale study of coronae on Venus

Tapper, Simon Warwick; (1998) A global survey and regional scale study of coronae on Venus. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Coronae are large-scale geological structures on Venus normally consisting of a planimetrically circular topographic rim which encircles a basin. They are considered to have formed by plume activity. The thesis describes and examines the characteristics of coronae using a new and comprehensive database which is used to further understanding of corona properties and the geological evolution of Venus. Topographic data were surveyed to identify coronae which are not easily detectable in synthetic aperture radar (SAR) images because they lack the annulus of brittle scale fractures that were previously considered to characterise all coronae. Data used to describe the distribution, morphology, geological setting and associated volcanic and tectonic structures were obtained from altimetry, high resolution Synthetic Aperture Radar (SAR) images returned by the 1990 Magellan mission and synthetic stereo images generated from Magellan data. Detailed geological mapping of the Scarpellini Quadrangle was then used to examine coronae on a regional scale and study their geological context and history. The 229 coronae identified by the survey were found in a variety of geological settings and materials. They occur on topographic rises and their margins and on ridge belts north of the Beta-Atla-Themis region. They have widths comparable to those described by earlier surveys but tend to be lower in height. A range of morphologies were identified, including a new class which have complexly deformed interiors. Most of the coronae have irregular fractures aligned with their rim topography, but fracture networks and radial structure are also seen. The large numbers of additional coronae strongly imply that they are a far more important global heat loss mechanism than previously thought. The results indicate that the plume's ability to deform lithospheric materials varies not only spatially with lithospheric thickness but also with other factors such as regional stress regime. The morphological and stratigraphic evidence presented here indicates that coronae can develop in episodes, rather than by a continuous process of formation as suggested by some authorities.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: A global survey and regional scale study of coronae on Venus
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; Earth sciences; Venus
URI: https://discovery.ucl.ac.uk/id/eprint/10097436
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