Spatiotemporal Relationships of the Groove Belts, Coronal Structures, and Rift Zones of Venus

Abstract

We have analyzed the spatial and age relationships of volcano-tectonic units that have developed on the surface of Venus: groove belts, coronae, and rift zones. Most of the coronae (60%) are spatially and stratigraphically associated with the groove belts. Those are mainly circular and calderic coronae. Some of the coronae (20%) are associated with the rift zones. Such coronae are classified as domal and are concentrated in the Beta–Atla–Themis (BAT) region. The spatial association of coronal structures with regional extension zones and predominance of extensional structures (grooves) in the corona rims suggests that these units also formed in extensional environments. The spacing of fractures (the distance between adjacent fractures) in the rims of both older and younger coronae has a typical value of 1.1 ± 0.4 km, which is approximately half the characteristic spacing of the structures of young rift zones (1.8 ± 0.4 km) and nearly coincides with the spacing of fractures in ancient groove belts (1.2 ± 0.3 km). We interpret the coincidence of the characteristic spacing of fractures in the corona rims and in the groove belts as a possible indication of an older age of the coronae, which coincides with the age of the formation of the groove belts.