Approximately 130 core and drillhole cuttings samples taken from the Palaeozoic and Mesozoic of northwestern Melville Island were examined using reflected-light microscopy and Rock-Eval pyrolysis. The Triassic Schei Point marine silty shales, known to be good-quality source rocks in certain parts of the Sverdrup Basin, are dominated by kerogen Types I and II, have hydrogen index (HI) values as high as 625 mg hydrocarbon (HC)/g organic carbon, a total organic carbon (TOC) content as high as 8.07o, but are marginally mature at best. Source potential decreases drastically in the Jurassic and Cretaceous parts of the succession