Astrobiology (general)

11/24 NAI Director's Seminar: Roger Summons, "The Great Mass Extinction – a Sudden Event or a Slow Moving Train-Wreck?"

By Keith Cowing
November 15, 2008

Date/Time: Monday, November 24, 2008 11:00 AM Pacific

Presenter: Roger Summons (Department of Earth, Atmospheric and Planetary Sciences, MIT)

Abstract: A great mass extinction took place 252 million years ago when approximately 90% of the existing marine taxa were lost. Both the magnitude of the extinction and the slowness of the subsequent faunal radiation are enigmatic. The event is also known for the number and diversity of theories about its cause(s) including catastrophic volcanism, sudden climate change, overturn of stagnant oceans and bolide impact. Studies of molecular fossils confirm that the oceans were stagnant (euxinic) for some considerable period of time before and after the main biological turnover. Accordingly this event appears to be the culmination of particular paleo-oceanographic circumstances that happened on a geological timescale.

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