4/25 NAI Director's Seminar

Jay Kaufman 'Irreversible Oxidation of the Exosphere and Acceleration of the Biosphere Across the Archean-paleoproterozoic Transition'

Join us for the next NAI Director's Seminar!

Date/Time: Monday, April 25, 2011 11:00AM Pacific

Presenter: Jay Kaufman (University of Maryland)

Abstract:

Around two and half billion years ago a harmonic convergence of tectonic, volcanic, oceanographic, atmospheric, and biological events resulted in the irreversible oxidation of Earth's thin crust and surface environments. Lithological and geochemical evidence of this terrestrial metamorphosis - which stimulated global environmental, climatic, and biological innovations - is preserved in sedimentary archives sampled in outcrop and deep time drill cores from ancient continental fragments scattered about the globe. Recent time-series investigations of geochemical change in the shallow Archean and Paleoproterozoic oceans predict stepwise growth in atmospheric oxygen and ozone, the planetary sunscreen, and in seawater nitrate and sulfate, which sustain key microbial ecosystems. In this evolutionary seminar we will explore the possible sources and sinks of oxygen on the early Earth and the effect of its geologically sudden rise (coined by Dick Holland as the Great Oxidation Event or GOE) on weathering, climate, and the onset of a modern-style carbon cycle. Participation Instructions:

TO JOIN USING A VIDEOCONFERENCING SYSTEM:

Please RSVP to Marco Boldt (Marco.Boldt@nasa.gov) if you will be joining by Polycom. To view the slides, connect to http://connect.arc.nasa.gov/nai_directors_seminar/

TO JOIN USING A WEB BROWSER:

The slides and audio/video for this meeting will be presented using Adobe Connect. To join the meeting, connect to: http://connect.arc.nasa.gov/nai_directors_seminar/

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