A new analysis of the spatial relationships between volcanic features and rifts on Venus
provides new constraints on models of planetary evolution. We developed a new database of volcanic
features for the Beta-Atla-Themis (BAT) region and used nearest neighbor measurements to determine
relationships between different types of volcanic features and the rifts. Nearest neighbor analysis shows that
all the dome-type and corona-type subpopulations tend to cluster. Rift associations were inferred from the
deviation of a feature’s population distribution (as a function of distance from rift) from that of a random
population. Dome-type features in general have no discernible relationship with rifts. Most corona-type
features have a strong association with rifts, with intermediate and large volcanoes also tending to occur
close to or on rifts. Shield fields, on the other hand, tend to occur away from rifts. Our new evidence
supports classifications of rifts on Venus into different types, possibly by age, with a shift from globally
dispersed (more uniform) volcanism toward the more rift-focused distribution, which suggests a shift
in tectonic regime. Our observations are consistent with recent models proposing the evolution of Venus
from a stagnant lid regime to a subcrustal spreading regime. We also present evidence for a failed rift on
Venus and note that this process may be analogous, albeit on a larger scale, to a proposed model for the
evolution of the East African rift system.