Two intraorogenic sedimentary basins with a total prospective area for hydrocarbons of 665,000 sq mi (1,722,337 sq km) are present in the Canadian Arctic Islands. The Franklinian basin, which also extends across northern Greenland, is of late Proterozoic to Late Devonian age, and the Sverdrup basin of late Paleozoic to early Tertiary age. On extreme northeastern Greenland a late Paleozoic to Tertiary basin, the Wandel Sea basin, is present. The presence of Upper Cambrian beds in the Franklinian basin recently has been proved. A facies change extending 1,500 mi (2,414 km) separating Upper Ordovician to Lower Devonian shales from correlative carbonate strata is the most conspicuous feature of the sedimentary rocks in the basin.

The oldest beds in the successor Sverdrup basin are Mississippian. The rest of the upper Paleozoic sequence is typified by evaporites, and carbonate and clastic rocks. The Mesozoic is almost entirely a sandstone-shale sequence with complex facies relations. The presence of Jurassic beds in the Wandel Sea basin of extreme northeastern Greenland is reported for the first time.

Five orogenies can be recognized in the islands. Two of these terminated sedimentation in the Phanerozoic basins and produced numerous and varied structures.

Seven major gas fields and one, possibly significant, oil field have been discovered by the 115 wells drilled; their combined estimated ultimate reserves are calculated to be in the order of 14 Tcf (0.4 trillion cu m). All the major reserves are in Upper Triassic-Lower Jurassic sandstones. Geologic and geochemical studies indicate that much of the section in both basins is under or over maturated for oil and that the Arctic Islands sedimentary rocks are gas prone. Future activity presumably will concentrate on proving the presence of the 20 to 30 Tcf (0.57 to 0.85 trillion cu m) of gas required to justify construction of a pipeline to southern markets.