TY - JOUR AV - public Y1 - 2001/11/15/ EP - 4270 TI - Preliminary analysis of an expanded corona database for Venus KW - Tectonics KW - Evolution KW - Features KW - Hotspots KW - Models KW - Origin PB - AMER GEOPHYSICAL UNION N2 - 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. ID - discovery113429 IS - 22 N1 - Copyright 2001 by the American Geophysical Union VL - 28 SP - 4267 A1 - Stofan, ER A1 - Smrekar, SE A1 - Tapper, SW A1 - Guest, JE A1 - Grindrod, PM JF - Geophysical Research Letters UR - http://dx.doi.org/10.1029/2001GL013307 SN - 0094-8276 ER -