Preliminary analysis of an expanded corona database for Venus

Abstract

Abstract. We have conducted an extensive survey of the Magellan data to reassess the population of coronae. We identify a new type of coronae, here referred to as 'Type 2 coronae', having the same basic morphology as previously identified coronae (Type 1), but lacking a significant (>50%) annulus of closely spaced fractures. 106 Type 2 coronae are included in the new database giving a total of 515 coronae on Venus. The characteristics of the expanded population of Type 1 coronae are similar to those of the previously described population, but the Type 2 coronae are smaller, tend to have relatively flat interiors surrounded by a topographic tim, and are more likely to be found isolated from other features. Our observations, in particular the morphology and setting of the Type 2 coronae, may provide supporting evidence for the existence of a depleted mantle layer under the venusian plains.

Lithospheric structure of Venus from gravity and topography

“…We find that there is not a significant correlation between lithospheric parameters and the frequency distribution of volcanoes and coronae, whose patterns closely mimic the distribution of T e and F on the surface. Although we do not show it here for brevity, there are no significant differences in lithospheric properties between Type 1 and Type 2 coronae (see Coronae Type definition by Stofan et al, 2001), confirming the previous observations of Smrekar and Stofan (2003). The only noticeable difference is a slight trend towards smaller F values, and maybe towards higher T e values, in the frequency distribution of coronae.…”

“…We compare our T e and F frequency estimates (Fig. 11a) with volcanoes (from the USGS Venus Volcano Catalog; Schaber et al, 1998) and coronae (Stofan et al, 2001) frequency distributions (Fig. 11b and c).…”

The history of tectonism on Venus: A stratigraphic analysis

“…14b). Within the western cluster, coronae of type 1 (Stofan et al, 2001) are more evenly distributed throughout its territory, whereas in the eastern cluster they are strongly concentrated within the BAT region (Fig. 14a).…”

Volcanism and tectonism across the inner solar system: an overview

“…These structures have been interpreted as linear zones of mantle upwelling and lithospheric extension, in several cases punctuated by single plumes or plume clusters manifest as volcanic rises, shield volcanoes, coronae and radiating graben-fissure systems (e.g. Schaber 1982;Head & Crumpler 1987;Hansen & Phillips 1993;Baer et al 1994;Hamilton & Stofan 1996;Aittola & Kostama 2000;Magee & Head 2001;Stofan et al 2001;Krassilnikov & Head 2003;Harris & Bédard 2014a). On the basis of structural observations and gravitational data, further major extensional rifts have been proposed to follow plains' depressions that were later covered by volcanic materials (Sullivan & Head 1984;Harris & Bédard 2014b).…”

“…Coronae ( Fig. 5d & e) are annular forms dominated by either positive or negative topography, and which are encircled by concentric systems of fractures and ridges (Type 1 coronae) or by a rim alone (Type 2) Squyres et al 1992;Stofan et al 1992Stofan et al , 2001). Coronae are often associated with radiating, graben -fissure systems ( Fig.…”