The thermal structure of the central Nova Scotia Slope (eastern Canada): seafloor heat flow and thermal maturation models

Abstract

The thermal history and maturation potential of the central Scotian Slope is constrained using a combination of 47 recently acquired seafloor heat flow measurements, two-dimensional (2D) seismic reflection data, available well data, simple lithospheric rift models, and thermal and petroleum systems modelling. Consistent heat flow values of 41–46 mW·m−2 were measured seaward of the salt diapiric province and across the slope away from the influence of salt structures. Significant but highly variable increases in heat flow were measured for stations overlying salt diapiric structures, reaching values upwards of 72 mW·m−2. Simple models of conductive heat transfer with static salt geometries constrained from reflection profiles indicate that two of the four models fit the data, whereas two indicate much higher values suggestive of additional, convective effects. Dynamic 2D thermal models were developed to incorporate the effects of lithospheric rifting, crustal stretching, and radiogenic heat production in the sediment and basement. These models help constrain the hydrocarbon maturation potential of the central Scotian Slope, where deep borehole data are lacking. Our results suggest that a potential Late Jurassic source rock interval rests primarily within the late oil window and that salt structures act primarily to reduce maturation in the adjacent deep sediment layers.