OCCURRENCE AND COMPOSITIONS OF SOME TI-BEARING MINERALS IN THE STRANGE LAKE INTRUSIVE COMPLEX, QUEBEC-LABRADOR BOUNDARY

Ilmenite, bafertisite and Ti-bearing silicates of the Strange take per alkaline granite complex, Quebec-Labrador boundary, preserve a history of crystallization and reaction with the residual magma. Early-formed ilmenite and aenigmatite progressively gave way to astrophyllite, nep tunite, and narsarsukite. Sodic amphibole and pyroxene were also invol ved in the reactions. The entry of Nb into the Na-Ti-silicates can be modeled by NbR(3+)(R(4+))(-2). Fe3+ also entered the minerals through the model substitution R(2)(3+)(R(4+)R(2+))(-1), and, with fluorine, t hrough R(3+)F(R(4+)O)(-1). Neptunite was found to accept Nb, F and Fe3 + in its structure. Crystal sorting of Ti-silicates, including an unid entified silicocarbonate, may have influenced the evolution of the mag ma.