SILURIAN CONODONT BIOSTRATIGRAPHY AND δ13C STRATIGRAPHY OF THE ERAMOSA FORMATION, SOUTHWESTERN ONTARIO, CANADA
This study is the first attempt to carry out a combined biostratigraphic and chemostratigraphic study of the Eramosa lithofacies in southwestern Ontario. This research will provide the detailed stratigraphic framework required to determine a more accurate age for this lithofacies, help clarify the stratigraphic relationship of the Eramosa lithofacies in this region with strata currently recognized as the Eramosa in the remainder of Ontario and western New York, and facilitate correlation into the Michigan Basin. Preliminary results indicate that the Eramosa lithofacies in the Wiarton area of the Bruce Peninsula (Ontario Highway 6 outcrop and Ledgerock Quarry composite stratigraphic section) is early Wenlock (early to middle Sheinwoodian) in age. Samples from the Wiarton area record the latter part of the positive δ13C excursion recognized as the Ireviken Excursion and have yielded Ozarkodina sagitta rhenana. The Eramosa lithofacies from two drill cores in the Guelph area, located more than 100 km to the south, appear to record the positive δ13C excursion recognized as the Mulde Excursion, thereby indicating a late Wenlock (Homerian) age. A recent report of Ctenognathodus cf. murchisoni in the Eramosa Lagerstätte at Hepworth, located 15 km south of Wiarton, suggests that the biota at this locality is within the Ctenognathodus murchisoni Zone, and therefore the Eramosa lithofacies in this area would also be late Wenlock (Homerian) in age.