The Labrador Trough consists of Paleoproterozoic sedimentary and volcanic rocks, which extend along the eastern margin of the Archean Superior Craton to Ungava Bay. It forms the western part of a larger orogenic belt called the New Québec Orogen. In southwestern Labrador, the Labrador Trough extends into the younger Grenville Province, where the sedimentary rocks were deformed and metamorphosed.

The western boundary of the Labrador Trough is the basal unconformity between Paleoproterozoic sedimentary rocks and the Archean basement. To the east, it is bounded by allochthonous deep-water sedimentary and volcanic rocks, possibly derived from an oceanic realm. The sedimentary sequence of the Labrador Trough, termed the Kaniapiskau Supergroup, is interpreted to include a lower rift-related sequence and an upper transgressive sequence that progresses from shelf sediments at the base through deepwater turbidites and into shallow marine and terrestrial rocks at the top.

Several large metataconite deposits are located in the Labrador City–Wabush area and adjacent Québec, and have been mined continuously since the 1960s. These deposits are all thought to represent a single stratigraphic horizon, and the economic deposits are largely developed by hinge-thickening and fold repetition.

The Carol Lake deposits consist of 13 separate ore bodies, of which two are currently active. Individual deposits are associated with thickening of the magnetite–hematite schist on the closures of synforms and its repetition by complex isoclinal folds, which increase the aggregate thickness of deposits to approximately 400 m, in places.

IOC’s Carol Lake project is the largest operation in the Labrador Trough, with an open-pit mine, concentrator and pellet plant in Labrador City.