Oxidation of the LaBlache Lake Titaniferous Magnetite Deposit, Quebec

TLDR: The LaBlache Lake titaniferous-magnetite deposit was studied to determine, first, the cause of oxidation-exsolution of ilmenite from Titaniferous magnetite in plutonio rocks and, second, the effect of oxidation on oxygen-isotope exchange as mentioned in this paper.

Abstract: The LaBlache Lake titaniferous-magnetite deposit was studied to determine, first, the cause of oxidation-exsolution of ilmenite from titaniferous magnetite in plutonio rocks and, second, the effect of oxidation on oxygen-isotope exchange, application of the magnetite-ilmenite geothermometer-oxygen barometer, and the distribution of manganese between titaniferous magnetite and ilmenite. The compositions and modal proportions of coexisting titaniferous magnetite and ilmenite (determined by electron-probe X-ray microanalysis and by weighing mineral separates) correlate closely with that predicted according to progressive oxidation-exsolution of ilmenite from titaniferous magnetite in a system open only to oxygen. The igneous titaniferous magnetite probably contained up to about the equivalent of 5 weight per cent of $R_{2}O_{3}$ as excess oxygen. This $R_{2}O_{3}$ probably exsolved as ilmenite above about 800° C. An additional 7 per cent of ilmenite may have resulted from oxidation-exsolution by trapped wate...