Grant: Discovery Grants Program - Individual

High-speed impact has played a fundamental role in creating and modifying planetary bodies since the birth of our Solar System. The cratered surfaces of now inactive bodies, such as our Moon, testify to the violent history they have undergone, especially during the first several hundred million years of their evolution. Earth's surface is deceptively uncratered because our planet is active, whereby plate tectonics, volcanism and erosional processes act to destroy or bury impact craters. Our current terrestrial crater inventory comprises only ~170 proven impact structures, most of which are geologically young (<500 million years old). Nevertheless, Earth provides the only accessible environment to study impact craters directly. We now know that impact processes may have exerted profound effects on the evolution of life, even causing some of the mass extinctions of the Phanerozoic eon (e.g., the Cretaceous-Tertiary boundary event). Given the significance of impact, we need to enhance our knowledge of the accompanying shock and deformation processes. We do not yet fully understand how a transient cavity, generated as a short-lived bowl-shaped basin by the projectile during complex crater formation, collapses during the gravity driven modification stage, or how high-speed tectonics facilitate central uplift generation in the larger craters. The interaction of shock waves with rocks and minerals needs to be investigated via new generation high-resolution micro-analytical tools. This project seeks to further our understanding of impact processes, including shock metamorphism, shock melting and deformation. This requires detailed field investigations of well-exposed terrestrial craters, followed by analytical electron microscopy and chemical analysis. Terrestrial research will be complemented by investigations of other planetary bodies via the study of lunar, martian and asteroid samples. The results will (1) improve our knowledge of impact craters as economic resources for hydrocarbons and metals; (2) characterize impact-induced metamorphism, melting and vaporization mechanisms; (3) further our understanding of hypervelocity impact as a builder and modifier of planetary systems.