Seminar of Michaël Marsset

Abstract:

Studies of micrometeorites in mid-Ordovician limestones and Earth’s impact craters reveal that our planet experienced a massive infall of ordinary L chondrite material approximately 466 million years ago. This event is believed to have triggered the mid-Ordovician ice age, sea level fall, and major faunal turnovers (Schmitz et al. 2019). The breakup of a large asteroid in the main belt is the likely cause of this massive infall. In modern times, material originating from this breakup still dominates meteorite falls (~37% of all falls). I will present spectroscopic observations and dynamical evidence showing that we have identified the only plausible source of this remarkable event and the most abundant class of meteorites falling on Earth today.