LATE NEOPROTEROZOIC TO EARLIEST PALEOZOIC STRATIGRAPHY OF THE AVALON ZONE IN THE BONAVISTA PENINSULA, NEWFOUNDLAND: AN UPDATE

Abstract

Recent regional mapping and stratigraphic studies of the eastern Bonavista Peninsula, together with the discovery of a diverse suite of Ediacaran fossils near Catalina, have confirmed the correlation of the Late Proterozoic succession east of the newly defined Spillars Cove–English Harbour fault zone with parts of the Conception, St. John’s and Signal Hill groups. This regional tectonic boundary delimits the western extent of these three groups in the Avalon Zone and the eastern extent of the Musgravetown Group on the Bonavista Peninsula. Despite some differences in facies development, there is pronounced similarity between late Neoproterozoic lithostratigraphy and biostratigraphy of the Bonavista Peninsula east of the Spillars Cove–English Harbour fault zone and that of the western Conception Bay and southern shore regions of the Avalon Peninsula. Mapping in the area west of the fault zone has corroborated and further refined the authors’ previously published facies subdivision of the Musgravetown Group, and has necessitated expansion of that group to include a distinctive, siliceous sedimentary facies previously considered as possible Conception Group. Work on fossiliferous Cambrian and adjacent latest Neoproterozoic rocks in the northwestern Bonavista Peninsula has demonstrated the conformable and broadly gradational nature of the Random Formation–upper Musgravetown Group contact, the lack of angular discordance at the base of the overlying fossiliferous Cambrian shale succession, and the existence of similar styles of sediment-hosted stratiform copper mineralization in Early Cambrian and late Neoproterozoic rocks above and below the Random Formation.