The study area is underlain by Archean rocks of the Superior Province assigned to the Douglas Harbour, Lepelle and Utsalik domains. These Archean rocks are intruded by Paleoproterozoic dykes (Payne River dykes and Klotz dykes) and partially overlain by thrust sheets. These thrust sheets, composed of Paleoproterozoic supracrustal sequences, belong to the Ungava Trough. In the eastern part of the area lies the Douglas Harbour Domain, which consists of the Qimussinguat and Faribault-Thury complexes, two complexes essentially composed of gneissic tonalites. Gneissic tonalites in the Qimussinguat Complex contain orthopyroxene and clinopyroxene. These tonalites host mafic and metasedimentary enclaves metamorphosed to the granulite facies. In the Faribault-Thury Complex, gneissic tonalites contain hornblende and biotite. They enclose volcano-sedimentary remnants metamorphosed to the amphibolite facies. Rocks of the Qimussinguat and Faribault-Thury complexes are intruded by granodiorites and granites assigned to the Leridon Suite. Two syenite plutons, grouped in the Kimber alkaline Suite, are observed in the rocks of the Qimussinguat Complex. In the western part of the area, we find the Lepelle and Utsalik domains. Wedged between the two, the Pélican-Nantais Complex contains lithologies comparable to those observed in the Faribault-Thury Complex. The Pélican-Nantais Complex consists of biotite-hornblende gneissic tonalites enclosing volcano-sedimentary bands metamorphosed to the amphibolite facies. However, assemblages typical of the granulite facies are observed locally. The Lepelle and Utsalik domains also contain rafts of gneissic biotite-hornblende tonalite several kilometres in size, assigned to the Kapijuq Suite. Rocks of the Pélican-Nantais Complex and the Kapijuq Suite are enclosed by large masses of granodiorite and granite. These granodiorites and granites are generally foliated, and typically contain hornblende and clinopyroxene. These composite intrusions form the Lepelle and Châtelain suites. The two suites are separated by an axis occupied by the Pélican-Nantais Complex, and by large ductile deformation zones oriented N-S that transect the entire area. Granodioritic and granitic bodies assigned to the Lepelle and Châtelain suites also contain foliated orthopyroxene-bearing intrusions ranging from tonalitic to granitic and dioritic in composition, grouped in the MacMahon Suite. Late Archean intrusions, tabular in shape and oriented parallel to the regional N-S fabric are observed in the Lepelle and Utsalik domains. These consist of massive or foliated granitic, monzogranitic and monzonitic rocks that locally display a porphyritic texture. These felsic intrusions belong to the La Chevrotière Suite. A regional structural study reveals five deformation episodes, along with an anorogenic episode. The first three episodes of deformation (D1, D2 and D3) are ductile and Archean in age. Deformation D1 consists of an early foliation or gneissocity, oriented N-S and steeply dipping. The peak of deformation resulted in the development of isoclinal and intrafolial folds. Deformation D2 corresponds to open folds that generated weak undulations of the regional fabric. This deformation is discrete and weakly developed. Deformation D3 corresponds to ductile shear zones located along major lithotectonic discontinuities. These Archean deformation episodes were followed by a Paleoproterozoic anorogenic event, during which two gabbro dyke swarms were emplaced (Payne River dykes and Klotz dykes). The emplacement of these dykes was followed by another Paleoproterozoic event (D4), which corresponds to the Ungava Orogen. A final episode of late deformation (D5) followed the two Paleoproterozoic events. It consists of rectilinear brittle faults that transect the entire area. Apart from the sector underlain by rocks of the Ungava Trough, the mineral potential of the study area was very poorly known. During the geological survey carried out in the summer 2000, a few mineral occurrences were identified. These showings are essentially located in the Nantais and Kimber volcano-sedimentary belts. In the Nantais belt, the mineralization consists of Au, Ag, Zn, Pb, Cu. This area shows strong potential for "gold-bearing volcanogenic massive sulphide"-type deposits. In the Kimber belt, high rare earth element concentrations were observed in carbonate rocks. Furthermore, this volcano-sedimentary sequence represents a favourable environment for epithermal or porphyry-type deposits.