Dear All,
Our Smith Lecture speaker this week is Jonathan Payne, Stanford. He is speaking on The End-Permian Mass Extinction and its Aftermath: New Insights from Non-Traditional Isotope Systems. Abstract below.
Smith Lectures are Friday afternoons from 4:00 to 5:00 pm, in Room 1528 C.C. Little Building. A reception is held following the lecture in 2540 C.C. Little. The events are free and open to the public. A full schedule for the term may be found on our website:
http://www.lsa.umich.edu/earth/events/
Note that the start time for Smith Lectures will move to 3:00pm beginning September 26.
Best regards, -Anne
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Anne Hudon
Academic Student Services
Department of Earth and Environmental Sciences
University of Michigan
http://www.lsa.umich.edu/earth/
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Abstract:
The end-Permian mass extinction (ca. 252 Mya) was by all measures the most severe biotic catastrophe in the history of animal life, marked by approximately 80% loss of marine animal genus diversity. The coincidence of mass extinction with Siberian Trap volcanism, carbon cycle perturbation, and ocean anoxia has been known for several decades. However, the magnitude and duration of environmental change and its role in shaping not only extinction but also subsequent reconstruction of marine ecosystems remain poorly quantified. Recently, the development of non-traditional isotope systems has enabled the development of new, high-resolution isotope proxy records that can be used to constrain and quantify the pattern and timing of changes in ocean redox and acid-base chemistry. In this talk, I will present new evidence from calcium and uranium isotope measurements from marine stratigraphic sections in China and Turkey to demonstrate the global distribution of negative excursions in both d44Ca and d238U across the end-Permian extinction horizon. Together, these observations place quantitative constraints on the magnitude and isotopic composition of carbon released into the exogenic carbon cycle during Siberian Trap volcanism as well as the extent and duration of resulting ocean anoxia. Moreover, continuing perturbation of the marine Ca and U isotope systems during Early Triassic time adds to existing evidence for influence of environmental change on the reconstruction of marine ecosystems. Coupled with increasingly precise geochronological evidence for synchrony between Siberian Traps volcanism and end-Permian extinctions, information from non-traditional isotope proxies paints an increasingly detailed and quantitative picture of anoxic and temporarily acidified oceans during the biotic crisis. These findings suggest that the end-Permian mass extinction should be added to our growing catalogue of ancient analogs for 21st and 22nd century oceans.
