Spatial and Genetic Relationships of Groove Belts, Rift Zones, and Lobate Plains on Venus

Abstract

Relationships of two types of extensional zones formed on the surface of Venus in different periods of geologic history—older groove belts and younger rift zones—have been analyzed. Rift zones are less abundant by area than groove belts on the surface of Venus. They are systematically more extensive than groove belts and characterized by contrast relief composed of grooves and horsts alternating with an amplitude of a few kilometers. The relief of groove belts is less expressed, and their amplitude is hundreds of meters. The rift fracturing is sparser and winding; it systematically exhibits more widely spaced fractures than those in groove belts, which are characterized by dense, linear, or weakly sinuous, fracturing. Rift zones and lobate plains spatially associated with them characterize the late volcano-tectonic resurfacing regime. The analysis of relationships of these units allows us to conclude that, during this regime, endogenous activity in the regions of joint development of lobate plains and rift zones more often started from the manifestation of volcanism followed by the rifting and, in most cases, the genesis of rifts coincided with the final evolution stages of various regions.