The Amanda property straddles the La Grande and Opinaca subprovinces in the center of the James Bay territory. The La Grande Subprovince is a greenstone belt dominated by multiphase intrusions of dioritic, tonalitic, granodioritic and granitic composition, injected into the volcano-sedimentary sequences of the Eastmain Group. The belt is oriented East-West and extends over approximately 300 km in length and a width which varies from 10 to 70 km. It consists of sequences of volcano-sedimentary rocks which have been released in an oceanic environment and which are injected by calc-alkaline intrusions of gabbroic to monzogranitic compositions.
The Opinaca Subprovince is made up of migmatitized paragneiss, diatexite and strips of amphibolite belonging to the Laguiche Complex. These rocks are injected by intrusions of granodiorite, granite or pegmatite from the Janin and Boyd suites. Proterozoic diabase dikes belonging to the Matachewan, Senneterre and Mistassini swarms cut across all of the region’s Archean units.