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 va rious types of coronae, the radial-concentric and multiple are even mo re highly concentrated near chasmata, whereas the concentric-caldera t ype are absent near the chasmata. Craters, to the first order, are ran domly distributed, although when distributions are compared with rando m 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, a nd their distribution closely resembles that of the coronae. The highe r proportion of tectonized, and especially embayed, craters within 5-1 0 degrees of the rcs, is about the fraction that would be expected fro m modification of the full set of craters over a width of 100-200 km. Kolmogorov-Smirnov statistics are used to compare cumulative distribut ions for craters and coronae with a large random distribution and to c ompute probabilities. Craters and coronae fill disjoint regions that a re more connected than regions of randomly assigned points. This sugge sts that the volcano-tectonic process creating coronae may be the same one destroying craters.