Climate Seminar Series presents...
Ice in Equatorial Pangaea
Lynn Soreghan
The University of Oklahoma School of Geology & Geophysics
26 February 2009, 1:00 PM
National Weather Center, Room 3902
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK
Directions to the NWC (.pdf, 60 kb)
The late Paleozoic, ~300 MY ago, records Earth’s most recent glaciation prior to our modern/recent state, and is marked by well-documented evidence for glaciation in the southern polar supercontinent of Gondwanaland. Emerging evidence from what was then equatorial Pangaea (the Ancestral Rocky Mountains of the western US), however, suggests the possibility of glaciation that extended to equatorial regions as well. Key evidence includes a landscape that is hypothesized to (1) date from 300 My ago, and (2) have been carved glacially, as well as associated sediments inferred to record ice-contact, proglacial, and periglacial deposition. Ice at the equator is not unique, but indications from the studied system suggest remarkably low elevations for cold conditions, implying anomalous cold in the Pangaean tropics and a global climate state intermediate in severity between those of the Proterozoic “snowballs” of 600-800 My ago, and the late Cenozoic glaciation of recent time. Models cannot yet achieve this level of cold, suggesting either that our interpretations are faulty, or that key boundary conditions or feedbacks are not adequately captured by the models.