Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Halite is a ubiquitous mineral in the Saint-Honoré carbonatite (Saguenay, Québec, Canada). It has remained present within the deposit as the deeper carbonatite has not been weathered. Halite is either disseminated or occurs as veinlets throughout the dolomitic unit associated with Nb mineralization. It is also found in pores of weakly to moderately altered pyrochlore crystals. The two main Nbbearing minerals, fluorcalciopyrochlore and columbite-(Fe), are related through hydrothermal alteration (columbitization). Sodium is from pyrochlore (magmatic) whereas Cl is from hydrothermal fluid as there is no significant Cl in any mineral, except columbite-(Fe), which is hydrothermal. These interpretations suggest that halite has a hybrid magmatohydrothermal origin. The role of Cl to the transport of REEs and the contribution of columbitization in the fenitization of the host rocks are investigated.