Seminar

Planetary science has the same goal as terrestrial geology: determining the geologic history.  However, for Mars, this must be done with little to no field data save for some rover/lander observations. No samples have been returned to Earth and only ~100 meteorites (all shocked basalts from a narrow range of shock pressure) ejected from unknown locations have landed on Earth. Instead we depend on orbital data, which has some obvious challenges. Mars, with over a million impact craters greater than 1 km, likely has various types of impact glasses (to be described in detail) that are a part of the martian surface, soil, sediments, and sedimentary rocks. Further, glasses chemically alter to alteration minerals and clays at faster rates than the original, primary igneous minerals. I have conducted field work, sample collection, and laboratory analyses of samples from the only terrestrial analog containing shock metamorphosed basalt. Various levels of shock pressure will be shown petrographically and with other instrumentation, as well as pre-impact alteration (now shocked) and post-impact alteration of shocked basalt. This includes very rare shocked soils, shocked baked zones, and shocked basaltic sediments. The pressures and temperatures of shock metamorphism will be described and shown just as the products of contact and regional metamorphism are taught to young students. For those that can attend the seminar in person in JL 104, samples of shocked basalts shocked to varying levels of shock pressure will be passed around one-by-one in trays describing them. In these virus times, it is optional for participants to hold the friable samples to feel their frothiness and glassiness (similar to pumice), and examine fiamme-like squished glasses of labradorite composition. Gloves will be provided or bring your own.  Zoom participants are welcome to view 30+ slides but not any rocks to hold or see.