Dynamical implications of the petrology and distribution of impact melt rocks

Abstract

To increase our understanding of the formation of impact craters and the properties of their ejecta there must be an integration of data from theoretical models, cratering experiments, and observations of natural impact craters. Constraints provided by observations of natural craters can be applied to theoretical models as well as to the variables and scaling assumptions in experimentally produced craters. Studies of natural craters generally have concentrated on shape, size, and form on the moon, Mars, and Mercury or have concentrated on structures and petrographic shock effects on Earth. This paper summarizes. the petrologic and chemical data for samples of impact-melt rocks and associated breccias from various structural locations in and around eight terrestrial craters. These data provide constraints on the following five aspects of crater formation: (1) trajectories of melt, (2) extent of mixing in melt, (3) thermal energy from impact, (4) depth of excavation, and (5) timing of formation of structural modifications.