Regional thermal maturity in the Franklinian Mobile Belt, Melville Island, Arctic Canada

Abstract

The thermal maturity and source rock potential of the Palaeozoic sediments in the Franklinian Mobile Belt, Melville Island, Arctic Canada, have been studied using reflected light microscopy of approximately 400 polished whole-rock samples. Organic matter in the Palaeozoic strata of the Franklinian Mobile Belt is represented mainly by bitumen in the Ordovician and Silurian and a combination of liptinite and vitrinite in the Devonian. Different bitumen types have been identified depending on their morphology, reflectance range and association to the enclosing mineral matrix. Thermal maturity of the Palaeozoic strata, based on vitrinite-equivalent reflectance calculated from bitumen reflectance, is high, an indication that the strata are in the overmature stage of hydrocarbon generation and that only dry gas should be expected. The presence of numerous types of bitumen indicates that hydrocarbons have been generated and migrated through the sediments. Regional variations in the thermal maturity of Palaeozoic sediments in the Franklinian Mobile Belt are mostly a function of depth of burial, which is affected by subsidence, folding and amount of erosion. © 1993.