Feldspar and Quartz Crystals Unveil the Petrogenesis of the Lithium-rich Moblan Pegmatite (Quebec)

Victoria Maneta1, Don R Baker2 and William G Minarik2, (1)McGill University, Earth and Planetary Sciences, Montreal, Canada, (2)McGill University, Earth and Planetary Sciences, Montreal, QC, Canada

Contact First Author: Victoria Maneta; viktoria.maneta@mail.mcgill.ca

Previously Published Material: Experimental evidence for the supersaturation of pegmatite-forming melts in Li-aluminosilicates was presented in the GSA meeting  in Vancouver in October 2014 and the GAC-MAC conference in Fredericton in May 2014. Part of the findings summarized in this abstract have been submitted for publication to the journal Contributions to Mineralogy and Petrology.

Abstract ID#: 36099

 

English Abstract:
The main sill of the Moblan spodumene-pegmatite in Quebec is characterized by simple aplite and albite-rich wall zones that surround a central core rich in quartz and spodumene. The Li concentration of the core is estimated at approximately 13000 ppm with feldspar and quartz crystals from various zones of the pegmatite incorporating up to 350 ppm Li. The simple mineralogy and restricted dimensions of the wall zones, the elevated Li concentration of quartz and feldspar crystals and the unusually high Li content of the core suggest extreme enrichment of the pegmatite-forming melt in Li prior to emplacement.

The Li concentration of the main minerals from different zones of the Moblan pegmatite is used in combination with experimental results in order to evaluate the Li enrichment of the granitic melt that generated the central sill. The Li concentration of the melt that coexisted with Li-rich feldspar and quartz crystals can reach up to ~7000 ppm, suggesting supersaturation of the pegmatite-forming melt in Li-aluminosilicate phases. In addition, the uncommon geochemical signature of Li in feldspar can be used as a useful exploration tool for the identification and targeting of Li-rich pegmatites.

Back to: Pegmatitic Rocks and Their Ore Deposits Posters