According to Sauvage and Savard (1985) this complex comprises an early alkaline intrusion which has been cut and strongly fenitized by later carbonatites. The alkaline rocks are predominantly ijolites and urtites with some nepheline syenites and pyroxenites. The carbonatites form not only numerous irregular intrusions and dykes throughout the complex, but are also abundant within the country rocks, particularly to the north. Two types of carbonatite have been distinguished. An early white sovite locally contains large crystals of pyroxene and alkali feldspar with apatite and zircon. There followed a series of dolomitic brown and brecciated carbonatites which sometimes contain abundant pyrochlore and magnetite. The carbonatites fenitize the country rock schists as well as the alkaline rocks and hydrothermal activity associated with this process led to deposition of veins of barite.