Syllabus
I. Crater types and structure: Impact hypothesis, its origin and development.
Types of impact craters and basic terms. Modeling of crater formation.
Asteroids and comets as craterforming bodies, their composition, velocities, and trajectories. Terrestrial impact craters and comparison to their extraterrestrial counterparts. II.
Specific features of shock metamorphism: Energy of impacts, shock waves, Rankine-Hugoniot equation, pressures and temperatures attained under shock metamorphism conditions, differences to other geological processes. III. Impact cratering record in rocks: Shock phenomena in minerals, geobarometers and thermometers used for shock metamorphism.
Shock metamorphism record in rocks, impactites and their classification, characteristics and distribution in impact craters. Economic potential of impact craters. IV.
Impact cratering as a geologic hazard: Impact frequencies. Origin of the Moon and Early Bombardment of the Earth.
Event Cretaceous/Paleogene (K/Pg), anomalies in geological record at the K/Pg boundary, distribution of K/Pg distal ejecta, shock metamorphism indicators in them, parent crater and possible reasons for Cretaceous biota extinction. Other boundaries where extinction is recorded, possible links to known impact structures and discrepancies in these hypotheses.
Risk of impact in present, event Tunguska, Torino scale.
Annotation
The lecture introduces the problem of hypervelocity impacts of extraterrestrial bodies onto Earth. Gives classification of craters and description of their structure. Explains crater formation and interaction of rocks with a shock wave excavating the crater. Points out the consequences of extraterrestrial bodies impacts on biota both in the geologic past and today or in the future.
Due to the pandemic situation, the course in the summer semester of the academic year 2020/2021 takes place in a combined online form and self-study of provided selected literature. Information on how to connect to an online lecture will be provided to enrolled students via e-mail.