%0 Journal Article %@ 0094-8276 %A Stofan, ER %A Smrekar, SE %A Tapper, SW %A Guest, JE %A Grindrod, PM %D 2001 %F discovery:113429 %I AMER GEOPHYSICAL UNION %J Geophysical Research Letters %K Tectonics, Evolution, Features, Hotspots, Models, Origin %N 22 %P 4267 - 4270 %T Preliminary analysis of an expanded corona database for Venus %U https://discovery.ucl.ac.uk/id/eprint/113429/ %V 28 %X 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 I 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 rim, 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. %Z Copyright 2001 by the American Geophysical Union