Lithogeochemical Vectors for Hydrothermal Processes in theStrange Lake Peralkaline Granitic REE-Zr-Nb Deposit

摘要

Strange Lake is a mid-Proterozoic peralkaline granite pluton (Québec-Labrador, Canada) that underwent extreme enrichment in high field strength elements (HFSE), including the rare earth elements (REE). The HFSE mineralisation is confined to highly altered pegmatites and the most altered parts of the granites, implying a genetic association between hydrothermal fluids and HFSE enrichment. This study uses analyses of fluid inclusions to investigate the hydrothermal evolution of the Strange Lake pluton and the role of hydrothermal processes in concentrating the HFSE to potentially exploitable levels. Five groups of inclusions were distinguished. [...] Light rare earth elements (LREE) were remobilised over 10s to 100s of metres by the high temperature high salinity fluid (preserved as Group 1 and 2a inclusions), whereas heavy rare earth elements (HREE) were remobilised on a much smaller scale by a late, low temperature high salinity fluid (trapped as inclusion Group 5). Fluid preserved as inclusion Group 3 may have been responsible for remobilisation of Zr and Ti.