New thermal evidence related to carbonate-hosted metal ores in the Northwest Territories

Abstract

A modern geothermal gradient map of an area in northwestern Alberta, northeastern British Columbia and southern Northwest Territories was constructed using temperature records obtained from geophysical borehole logs, all corrected for drilling disturbance. The map illustrates the thermal regime present in theMackenzie shale basin to the north of the Presqu'ile Barrier Complex, and within the Barrier itself. It also covers the evaporitic Elk Point Basin behind the Barrier as well as the regime associated with the carbonate shelves situated in northern Alberta between the Barrier and the northern extent of the fringing reef rimming the Peace River Arch. The geothermal gradient varies from 20 to 80 mK/m (°C/km). A significant regional trend indicating a general northward increase of geothermal gradient is observed in the map area. The northward increase in heat flow likely signifies a transition between high-strength crust in the south to lower strength crust in the north.