A fluid inclusion study of calcium metasomatism and Zr-Y-REE-Nb-Be mineralization in peralkaline granite at Strange Lake, Laborador-Québec, Canada /

The Strange Lake deposit is located on the Quebec-Labrador border. This large deposit of Zr, Y, REE, Nb and Be mineralization is hosted by a Late Proterozoic high-level stock that was intruded into high-grade graphitic gneisses. The intrusive rocks consist of leucocratic and melanocratic peralkaline granites. The occurrence of plastically deformed melanocratic xenoliths in the leucogranite and vice versa indicate that the two granite types were intruded coevally.The stock is extensively altered, especially in the north. Early alteration is manifested by the replacement of arfvedsonite with aegirine. Later alteration involved an exchange of calcium for sodium. Zr, Ti, Y, REE, Nb, Be are concentrated in Ca-bearing minerals that, together with quartz, commonly pseudomorph Na-bearing minerals. Hematite typically coats the rare-metal enriched minerals.Pseudomorph outlines are frequently delineated by trains of fluid inclusions.A model is proposed in which the intrusion of a peralkaline granite to high crustal levels initiated a meteoric water-dominated hydrothermal system in the adjacent gneisses