Remote predictive mapping of a potential vent complex in the southern Antigonish Highlands using lidar, magnetics, and field mapping

Abstract

The southern Antigonish Highlands, Nova Scotia, is typical of many terrains in the Appalachian mountain belt. It has relatively poor exposure and limited outcrop, in part because of the overprinting and deposition of sediment from the last glaciation. Regional-scale magnetic and gravity data and geologic mapping have highlighted an igneous complex in the southern highlands that may represent a vent complex that has been truncated by the Cobequid–Chedabucto Fault System, which is a local expression of the Meguma–Avalon terrane boundary. A recent lidar survey in leaf-off conditions facilitates the production of a high-resolution DEM in the vicinity of the terrane boundary. By integrating lidar DEM, second vertical gradient derivative magnetic data, geological mapping, and petrographic and geochemical analysis of representative samples, we produce a new interpretation of the bedrock geology and structure of the study area. The lidar-magnetic hybrid image provided a clearer definition of the magnetic anomalies and their spatial distribution. Although it did not provide significant detail to test the hypothesis of a vent complex, the hybrid image provides important new insights into the structure of the igneous complex and allows the identification of three potential faults and the revision of some of the geological boundaries. The identification of these faults is significant in that it assists in understanding the field relationships between outcrops, the structural history of the southern highlands, and the potential for the occurrence of economically important mineral deposits.