Paper No. 12
Presentation Time: 9:00 AM-6:00 PM
PRIMARY PRODUCTIVITY AND PALEOXYGENATION FOLLOWING THE END-PERMIAN MASS EXTINCTION: A GEOCHEMICAL ANALYSIS OF GRIESBACHIAN SEDIMENTS FROM THE WESTERN CANADIAN SEDIMENTARY BASIN (ALBERTA, CANADA)
The recovery of primary producers following the End-Permian mass extinction (~252 Ma) is an inadequately studied niche of extinction recovery analysis. Although the recovery of primary producers is the foundation for ecological re-equilibration, most studies have instead focused on elucidating the recovery of macro flora and fauna. Thus, it is essential to quantify trends in the recovery of primary producers in order to better understand the way in which life rebounds after such a crisis. To that end, this study analyzed trace element variation in samples from a core extracted from the Lower Triassic (Griesbachian) Montney Formation of the Pedigree-Ring Border-Kantah River area, located within the Western Canadian Sedimentary Basin (WCSB) in modern day Alberta. Forty-four ~25mg samples from core 16-8-86/20W6 were examined for trace element concentrations using ICP OES (Perkin Elmer 7300 DV). Total organic carbon (TOC) contents of the samples were previously obtained using the Loss on Ignition method. Preliminary results demonstrate high concentrations of %TOC, Ba, Cu, Ni, and Zn, which are indicative of high productivity levels across the Griesbachian, and therefore a rapid, robust recovery of primary producers. High concentrations of V and low concentrations of Mo suggest anoxic, but not euxinic depositional conditions. Reduced benthic oxygenation levels characteristic of the samples are likely the result of a combination of high productivity and a deep, anoxic ocean water mass impinging onto the continental shelves. The results of this study support recent hypotheses that suggest high primary productivity in the aftermath of the extinction, perhaps as the result of increased nutrient input to the oceans (Algeo and Twitchett, 2010), and suggest that high primary productivity and productivity-driven anoxia may have acted as a stressor during the recovery interval. This research, combined with trace element analysis of samples from additional cores and outcrops, will provide a clearer picture of temporal and spatial trends in primary productivity, as well as an understanding of how productivity is related to the environmental conditions that contributed to recovery from the End-Permian mass extinction.