The Baie-des-Moutons intrusion is a ring complex predominantly of syenitic composition. However, the syenites are only marginally alkaline as indicated by the presence sometimes of green rims on pyroxenes (R.F. Martin, personal communication, 1983). Small northeast-trending carbonate-rich dykes less than 30 cm thick cut the syenites, particularly on islands off the coast. The dykes are calcitic and locally rich in biotite. They may be carbonatites or carbonate-rich lamprophyres.