The Permian Extinction Event

GSM LECTURE, MONDAY, OCTOBER 6, 2008

Geological Society of Minnesota - Seminar Series

The Permian Extinction Event

Ray Rogers, Ph.D., Macalaster College, Professor of Geology, Chair Geology Department

Date:  Monday, October 6, 2008      Lecture Begins:  7:30 PM

Location:  The University of Minnesota, East Bank, Electrical Engineering/Computer Science Bldg., Room 3-210

ABSTRACT:  

The Permian–Triassic (P–Tr) extinction event, was an extinction event that occurred 251.4 million years ago, forming the boundary between the Permian and Triassic geologic periods.  It was the Earth's most severe extinction event, with up to 96 percent of all marine species and 70 percent of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects, with 57% of all insect families and 83% of all insect genera being killed. Because so much biodiversity was lost, the recovery of life on earth took significantly longer than after other extinction events.  This event has been described as the "mother of all mass extinctions".   The pattern of extinction is still disputed, as different studies suggest one to three different pulses. There are several proposed mechanisms for the extinctions; the earlier peak was likely due to gradualistic environmental change, while the later was probably due to a catastrophic event. Possible mechanisms for the latter include large or multiple bolide impact events, increased volcanism, or sudden release of methane hydrates from the sea floor; gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.

RESUME:

B.S. from Northern Arizona University, M.S. from the University of Montana and Ph.D. from the University of Chicago. 

Raymond P. Rogers is a sedimentary geologist and taphonomist interested in studying terrestrial and marginal marine depositional systems, especially those with abundant fossils.  Current research focuses on understanding how fossilization of vertebrate remains transpires in different depositional settings (lakes vs. rivers vs. soils). To this end, Ray and his students have been exploring the diagenesis of vertebrate fossils from the Cretaceous of Montana (specifically the Two Medicine and Judith River Formations) and Madagascar using a variety of analytical techniques, including SEM-EDS, LA-ICP-MS, and standard petrographic microscopy.  Additional on-going research interest is the reconstruction of terrestrial ecosystems using sedimentological and taphonomic lines of evidence. This work has taken Ray to the Cretaceous foreland basin of Montana, the Triassic Ischigualasto Basin of Argentina, the Triassic-Jurassic Karoo-equivalent rocks of southern Zimbabwe, and the Mahajanga Basin of Madagascar.  Rogers teaches a selection of courses at Macalester College that relate to his research interests, including: (1) History and Evolution of Earth (GEOL 155), (2) Paleobiology (GEOL 300), and (3) Sedimentology and Stratigraphy (GEOL 265).  A significant part of his time is spent mentoring of student research, working with students both in the laboratory and in the field.

Sent by Bill Robbins  

651-739-1146  robbins.wb@comcast.net