New mapping (NTS 27 B, C, 37 A, D) has characterized the supracrustal rocks of the Archean Mary River Group and their relationship to the underlying Archean basement orthogneiss units of the Rae Craton. The primary depositional unconformity that separates the base of the Paleoproterozoic Piling Group from the Rae Craton basement has been documented across the project area. The basal, clastic Dewar Lakes formation has been subdivided into 3 informal members. Significant primary variations in thickness of the Dewar Lakes and carbonate Flint Lake formations have been identified throughout the project area. Mafic volcanic rocks and ultramafic to mafic sills interlayered with siliciclastic rocks (Bravo Lakes formation) overlie the basal clastic rocks. Sulphidic pelite (Astarte River formation) overlies the three lowest formations. Psammite-pelite turbidite units (Longstaff Bluff formation) blanket the entire area, and are interpreted as an orogenic molasse. Deformation and consequent metamorphism occurred during the 1.8 Ga Trans-Hudson Orogen.

New mapping has refined the stratigraphic relationships within the Paleoproterozoic PilingGroup (NTS 37 A, 27 B), as well as its relationship to underlying Archean basement orthogneiss of the Rae Craton. Across the project area, basal quartzite and rare psammite (Dewar Lakes Formation) are in tectonic contact with underlying orthogneiss, and are interpreted as a subsidence-related clastic sheet deposited on Rae basement. In the northern part of the area, carbonate units (Flint Lake Formation) overlie the quartzite, and are overlain by sulphidic pelite and iron-formation (Astarte River Formation), interpreted as a shelf that subsequently foundered. In the south, quartzite is overlain by mafic volcanic rocks and ultramafic to mafic sills interlayered with siliciclastic rocks (Bravo Lake Formation). Psammite/ pelite turbidites (Longstaff Bluff Formation) blanket the entire area, and are interpreted as an orogenic molasse that might have had a source area other than the Rae Craton. Deformation and consequent metamorphism occurred during the1.8 Ga Trans-Hudson Orogeny.

Metasedimentary rocks and orthogneisses of the Markham Bay-Crooks Inlet area comprise folded and imbricated panels of a broadly south-verging thrust þ fold belt subsequently affected by orogen-parallel folding and cross-folding. Two assemblages of supracrustal rocks have been identified: the more extensive shelf sequence comprises the marbles, psammites, and semipelites of the ca. 1.93-1.86 Ga Lake Harbour Group, the second is characterized by thick successions of feldspathic quartzite and pelite, interpreted as a foreland basin sequence and intruded by layered ultramafic-mafic sills. Several types of orthogneiss have been recognized: 1) layered hornblende tonalite and monzogranite gneiss imbricated with supracrustal units in the southern part of the area, and 2) orthopyroxene tonalite with diorite sheets in the central part of the area that is in part 1.84-1.82 Ga. The ca. 1.85 Ga Cumberland monzogranite batholith postdates earliest imbrication, but is itself carried by youngest thrusts.

The principal structural components of Meta Incognita Peninsula, south Baffin Island, include a widespread penetrative foliation, four arrays of kinematically linked thrusts, and southwest-vergent folds up to tens of kilometres in wavelength. These structures collectively comprise the southwest-vergent Meta Incognita thrust belt. The thrusts are intruded and structurally overlain to the northeast by the Cumberland Batholith. The generalized structural sequence starts with formation of a low-angle foliation, followed by regional thrusting, folding, and localized strike-slip shearing. All preserved deformation structures formed at granulite facies. The Meta Incognita thrust belt is interpreted as the high temperature equivalent of the Cape Smith thrust belt, Ungava Orogen, northern Quebec.

This 3-D gocad model represents a collection of surface interpretations for late normal faults, major thrust faults and regionally significant stratigraphic horizon tops for the Paleoproterozoic rocks underlying three regional map sheets. The model extends across 1:50,000 map sheets (GSC Maps 1724A, 1725A, 1726A) covering approximately 80 km x 30 km (Figure 1), and is dominantly underlain by the 2.04-1.96 Ga Povungnituk Group; polydeformed mafic to ultramafic metavolcanic rocks, with a spectrum of semi-pelitic to arkosic metasedimentary rocks and and the primarily igneous 1.89 Ga Chukotat Group and associated peridotitic and gabbroic intrusive suite.