DISTRIBUTION OF TRACE AND RARE EARTH ELEMENTS IN TITANITE FROM TUNGSTEN AND MOLYBDENUM DEPOSITS IN YUKON AND BRITISH COLUMBIA, CANADA

摘要

The chemical compositions of titanite in igneous rocks, hydrothermal veins, skarns, and homfels from eight tungsten and molybdenum deposits in Yukon and British Columbia, Canada, were examined by electron probe and LA-ICP-MS. Four kinds of titanite were grouped in our study on the basis of genesis: magmatic titanite from the igneous rocks, hydrothermal titanite from the igneous rocks and hydrothermal veins, metasomatic titanite from the skarn samples, and metamorphic titanite from the homfels samples. Magmatic titanite is hundreds of urn long, euhedral or subhedral, and in planar contact with magmatic K-feldspar, plagioclase, and quartz. Compared to hydrothermal titanite, early magmatic titanite (cores) is enriched in Ti, HSFE, and REE, but depleted in Al and F. Magmatic titanite can be enriched in W or Mo, reflecting high concentrations of these elements in the source melt and suggesting that titanite has potential for identifying fertile W or Mo intrusions. The titanite from W skam samples are enriched in W, Sn, and Nb, which also has a potential application as an indicator for W exploration.