Sedimentology of Upper Ordovician – Silurian sequences on New World Island, Newfoundland: separate fault-controlled basins?

Abstract

Remapping of northeast New World Island, Newfoundland demonstrates that two major faults separate three distinct sedimentary sequences, Paleontology and sedimentology indicate that these sequences are partly equivalent in age but were deposited in separate basins of deposition that were adjacent to each other. Active Silurian faults, the Boyds Island and Byrne Cove Faults (new names), bounded the margins of these basins and directly influenced sedimentation by uplifting Ordovician volcanics, limestone, and black shale, which are found both in situ and as blocks within Silurian sediments. Silurian sediments deposited adjacent to these faults are dominated by pebbly mudstones and chaotic bedding interpreted as debris flow deposits and slumped horizons. Away from the fault scarps sedimentation was predominantly axial; it comprises resedimented conglomerates and thick- and thin-bedded sandstone turbidites.West of New World Island, similar synsedimentary faults are confined to a narrow belt south of the Lukes Arm – Sops Head Fault. Two stages of Acadian deformation overprint all structures associated with the Silurian faulting.