The tectonics and depositional history of the Ordovician and Silurian rocks of Notre Dame Bay, Newfoundland: Reply

Abstract

In the Notre Dame Bay region, ophiolitic rocks underlie a thick sequence of Lower Ordovician volcanic-arc rocks to the north of the Lobster Cove – Chanceport Fault. Neither this fault nor the Lukes Arm – Sops Head Fault shows evidence of very large strike-slip movements, as parts of the same arc, together with much arc-derived detritus, straddle both faults. Towards the east, this arc-derived detritus becomes more distal in aspect and passes laterally into the Dunnage Melange. During the Middle Ordovician Epoch (late Llandeilo and early Caradoc), most areas show a marked decrease in volcanic activity and in the amount of coarse detritus deposited. Coarse turbidites reappear, at different times in different areas, during the Late Ordovician. These are related to several fault-bounded basins and to movements on the Lukes Arm – Sops Head Fault. Many of these faults, particularly in the east, are marked by olistostromes, several of which can be dated by fossils as Late Ordovician and Early Silurian. The whole...