AN UPDATED GEOLOGIC MAP OF PORT AU PORT PENINSULA, NEWFOUNDLAND, USING SUBSURFACE 3D MODELING

The Port au Port Peninsula is located in western Newfoundland, at the structural front of the Northern Appalachians. The peninsula displays both a platform succession representing the early Paleozoic Laurentian shelf and the thin-skinned Humber Arm Allochthon recording the continental slope and rise, together with several distinct foreland basin successions from Middle Ordovician to Early Devonian. The frontal thrust of the Appalachian orogen is exposed along the west coast of the peninsula and allows a unique glimpse into kinematics of the orogen. Given the pivotal role of the Port au Port Peninsula in understanding orogen formation, it is critical to produce an updated version of the geologic map. Our aim is to create a detailed map of the Port au Port Peninsula, resolving formation-level detail and major faults.

To re-interpret formation contacts and fault traces, we take advantage of available field data collected between 1988 and 2015, and a high-resolution digital elevation model in combination with recent satellite imagery. Combined with 2D seismic lines, from oil exploration efforts in the area, we generate a detailed provisional 3D model of the Port au Port Peninsula. The resulting model includes three surfaces corresponding to the base, middle, and top of the carbonate platform, representing the strongest reflectors in the 2D survey. During the seismic-to-well tie process, we tie specific Formation tops to the identified reflectors and calculate the depths of the remaining Formation tops based on true formation thicknesses corrected from well data. Subsequently, we project surfaces of all encountered formations to the topographic surface, providing outcrop traces where field data are missing or exposure is poor.

Our new geologic map of the Port au Port Peninsula highlights the effectiveness of surface mapping in combination with seismic interpretation and 3D modeling. It exemplifies a robust methodology applicable to analogous geological settings worldwide where outcrop conditions are poor but seismic data are available. The updated version of the geologic map of the Port au Port Peninsula significantly advances our understanding of the Appalachian orogen and can be used for further studies along the deformation front.