Abstract Baffin Fan is a 12 km-thick sedimentary wedge of Eocene to Pleistocene age in northwestern Baffin Bay, with size and resource potential comparable to Beaufort–Mackenzie Basin. A widespread Moho detachment originating in Mesoproterozoic strata may have influenced development of Cretaceous–Palaeogene horst blocks and half-grabens throughout the region, and their transformation by later phases of inversion. Reflection profiles indicate 12 depositional sequences in lower Palaeozoic and Cretaceous to Pleistocene strata. Notable is syntectonic sedimentation with possible volcanism and rifting in the Cretaceous–Danian. Sequences associated with inversion in the later Paleocene and Eocene display out-of-graben thrust anticlines formed over horst blocks in Lady Ann and Lancaster Sound basins. The Oligocene to mid-Miocene is associated with fluvial–deltaic systems, replaced since then by glacial–interglacial sequences including submarine canyons and deepwater fans. Exploration targets are located in Lancaster Sound, and a Baffin Bay fairway that runs 220 km northwestward to east of Coburg Island. Sixty-five per cent of prospects are located under Neogene cover. Fourteen are each greater than 70 km 2 , and five are between 334 and 592 km 2 . Based on drilling success rates elsewhere and the existence of a petroleum system, 12 of the 40 mapped structures may contain hydrocarbons in significant quantity.

Abstract South of lat 28° N., the axis of the Gulf of California is associated with a gravity high of about 100 mgal Bouguer anomaly which falls off rapidly to about 0 mgal at the sides. This anomaly correlates closely with the deeper water and has been interpreted as a long, narrow strip of dense crust resembling an oceanic section, bordered on either side by a crust of continental type. North of lat 28° N., this dominant axial high is replaced by a patchwork pattern of anomalies whose magnitude rarely exceeds ±20 mgal. The most pronounced features are a number of relatively restricted areas of low negative anomaly located on both sides of the Gulf and elongated parallel to its general direction. These areas probably mark elongated basins of thicker-than-normal sediment associated with faults, although there is little corroboratory evidence for this interpretation. One of these features, on the mainland side of the Gulf near its head, could mark an extension of the San Jacinto fault.