INTERPRETATIONS OF THE DEPOSITIONAL ENVIRONMENTS OF THE SILURIAN ERAMOSA LAGERSTÄTTE

The middle Silurian (Wenlock Epoch; Sheinwoodian Age) Eramosa Formation of southern Ontario, Canada represents a variety of near-shore environments on the rim of the intra-cratonic Michigan Basin. In the Bruce Peninsula, it preserves a Lagerstätte assemblage of biomineralized and soft-bodied taxa, including chordates (heterostracan fish, articulated conodonts), arthropods (trilobites, eurypterids, scorpions, phyllocarids, ostracods), echinoderms (ophiuroids, crinoids, lepidocentrid echinoids), lobopodians, brachiopods, cephalopods, polychaetes, and dasyclad algae. Lagerstätten, while sites of exceptional preservation, are not free from the influences of paleo-environmental biases. The Eramosa Lagerstätte is found across multiple localities, with varying faunal compositions and depositional environments. Two historically understudied localities, Park Head and Hepworth, are described stratigraphically using micro-facies and microprobe analysis and compared to the type locality of the Lagerstätte in Wiarton, Ontario. Previously known from only near-surface material, the Park Head fauna is now identified to the Reformatory Quarry Member of the Eramosa Formation. Preservation of the soft-bodied taxa was investigated using scanning electron microscopy (SEM) and integrated energy dispersive X-ray spectrometry (EDS), allowing for taphonomic correlation with their paleo- environment, and a potential environmental depth gradient along a modern north-south axis.