Impactor control of central peak and peak-ring formation

The relation between the depth and diameter of excavation for impacts typically is assumed to be proportional. Such an assumption is consistent with the constant aspect ratio (diameter:depth) observed for simple craters found in a wide range of planetary settings and crater-scaling laws derived from laboratory experiments. Although complex craters exhibit evidence for floor uplift and rim collapse of a transient profile, they are typically thought to resemble initially smaller, simple craters. At large scales, however, early-time processes consume a greater fraction of crater growth and the assumption of late-time equivalence of energy release as a point source becomes inappropriate. The authors propose instead that crater diameter, depth, and impactor penetration represent separable dependent variables that underscore the fundamental difference between impact and point-source explosion excavation processes. An important consequence of this perspective is that central pits, peaks, and rings may represent contrasting target responses to impactor penetration and could provide an important indicator of impactor dimensions.