Venus coronae, craters, and chasmata

The distributions of Venus coronae and craters are related to chasmata, which are thought to be extensional zones. Coronae are almost twice as dense near the chasmata as a random set of the same size. Of the various types of coronae, the radial-concentric and multiple are even more highly concentrated near chasmata, whereas the concentric-caldera type are absent near the chasmata. Craters, to the first order, are randomly distributed, although when distributions are compared with random sets there is a deficit of about 15-20 craters close to the chasmata. The tectonized and embayed craters tend to be near the rift zones, and their distribution closely resembles that of the coronae. The higher proportion of tectonized, and especially embayed, craters within 5-10° of the arcs, is about the fraction that would be expected from modification of the full set of craters over a width of 100-200 km. Kolmogorov-Smirnov statistics are used to compare cumulative distributions for craters and coronae with a large random distribution and to compute probabilities. Craters and coronae fill disjoint regions that are more connected than regions of randomly assigned points. This suggests that the volcanotectonic process creating coronae may be the same one destroying craters.