Correlation between the depth to the lower-crustal high conductive layer and heat flow in the Canadian Cordillera

Abstract

In much of the southern Canadian Cordillera, the top of the lower-crustal electrical conductor coexists with the 450°C isotherm. A statistical correlation between the depth to the top of the lower-crustal electrical conductor, heat flow and 450°C isotherm are shown, based on MT and heat flow results in southern British Columbia, Canada. The depth to the lower-crustal conductor and the depth to the 450°C isotherm vary from 20–35 km in western B.C. (Insular Belt, Coast Plutonic Complex, Intermontane Belt) to less than 10 km in the eastern part of the Canadian Cordillera (Omineca Belt). The largest depths are in the Insular Belt (35 km). The coexistence of the top of the lower-crustal electrical conductor, top of the zone of lower-crustal seismic reflectors, and 450°C isotherm supports the hypothesis that the 450°C isotherm defines the top of the zone over which interconnected fluid can exist in the lower crust.