126-9 New Limits for Combustion in Low Oxygen Redefine Paleoatmospheric Predictions for the Mesozoic

See more from this Division: Topical Sessions
See more from this Session: What Good Are (Fossil) Plants Anyway? New Methods for Investigating Old Problems

Sunday, 5 October 2008: 10:25 AM
George R. Brown Convention Center, 351CF

Claire M. Belcher and Jennifer C. McElwain, School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
Abstract:
Numerous studies have sought to test combustion under varying concentrations of oxygen however, none have been able to assess the limits of combustion within a fully controlled and realistic atmospheric environment. Experimental burns were performed at 20 degrees centigrade at oxygen concentrations ranging from 9 to 21%, and at ambient and high (2000ppm) carbon dioxide, in a new experimental atmospheres and climate facility, equipped with a thermal imaging system and full atmospheric, temperature and humidity control. Our data reveal that the lower oxygen limit for combustion within the long-held “fire window” (12-35%) should be increased from 12 to 15%. These results, coupled with a new record of Mesozoic paleowildfires are incompatible with the prediction of prolonged intervals of super-low atmospheric oxygen levels (10-12%) in the Mesozoic. Paleowildfire provides a key proxy for testing super-low oxygen events in the geological record and must be studied in order to test hypotheses suggesting that short-term super-low oxygen periods drove faunal and floral diversity loss across major mass extinction events.

See more from this Division: Topical Sessions
See more from this Session: What Good Are (Fossil) Plants Anyway? New Methods for Investigating Old Problems