Studies of Impact Craters

START project Y 58 Studies of Impact Craters Christian KÖBERL 28.06.1996 In the six years that are covered by the START proposal, I would like to work on a variety of topics related to impact crater research. In the past, impact cratering as a geological process has been rather unappreciated by the general geological community, despite the fact that on all other planets and satellites with a solid surface, impact cratering is the most important process that alters the surface at the present time, and during most of the history of the solar system. Detailed studies, mainly since the 1960s, have led to the recognition of about 150 impact structures on earth. Over the last 15 years, new studies related to the events that caused the extinction of the majority of all life on earth at the end of the Cretaceous period led to the hypothesis that a large-scale asteroid or comet impact occurred 65 Ma ago. The main goal of the studies proposed here would be to engage in interdisciplinary and international collaborations, to thoroughly study several impact structures from a geochemical, petrological, mineralogical, and geological point of view, including also aspects of age dating and geophysics. The type of interdisciplinary research that I envision is similar to the work I have already done (or begun) on, for example, the Manson structure (Iowa) and the Roter Kamm crater (Namibia); this has been documented in numerous research publications (see enclosed publication list). Impact crater research is of relevance in the general earth sciences, as we can learn something about a fundamental process that shapes the surfaces of the terrestrial planets, including the earth, and because of the observation that some impact events severely affected the geological and biological evolution on earth; even small impacts can disrupt the biosphere and lead to local devastation. Thus, the understanding of impact structures and the processes by which they form should be of interest not only to earth scientists, but also to society in general.