MICROFACIES AND TRACE ELEMENT VARIATION ACROSS THE FRASNIAN PUNCTATA EVENT WITHIN THE BEAR BILTMORE DRILL CORE (ALBERTA, CANADA)

Late Devonian oxygen isotope records show an increase in global sea surface temperature by as much as 9°C over the Frasnian stage (382.7-372.7 Ma), coincident with deposition of regional black shale horizons and global perturbation of the carbon isotope record. Previous studies of Devonian strata within the Western Canadian Sedimentary Basin have shown that pulses of terrestrial input during the mid-Frasnian punctata event are associated with increases in primary productivity and suboxic to anoxic marine conditions.

This investigation focused on understanding variations in sedimentation and ocean chemistry over 150ft of a single Frasnian section from northeastern Alberta, the Bear Biltmore drill core (7-11-87-17W4). Unlike previously-studied Frasnian sections from western Canada, samples from the Bear Biltmore core provide insight into more proximal reef to lower slope environments. 196 samples from 150ft of the core cover the middle to upper Frasnian within the Duvernay and Cooking Lake formations, including the globally recognized punctata carbon isotope excursion.

Initial results of microfacies work show a succession through the punctata interval from reef-derived bioclastic and intraclastic floatstones to a microbially-influenced shelf environment, followed by rapid transgression and transition into a fine-grained carbonate shelf environment. Results from x-ray fluorescence spectrometry of major, minor and trace elements over the study interval are currently undergoing data analysis. Taken together, microfacies and trace element variation will provide insight into the punctata isotope excursion as well as environmental change over the middle Frasnian.