INCLUSIONS OF UNUSUAL LATE MAGMATIC MELTS IN QUARTZ FROM THE OKTYABR'SKAYA PEGMATITE VEIN, MALKHAN FIELD (CENTRAL TRANSBAIKAL REGION)

Abstract

The primary magmatic origin of the majority of granitic pegmatites is beyond question. The PT parameters of the magmatic stage are best known for rock crystal and topaz–beryl (with sub-rare-metals) pegmatites [1, 2]. They are also known for pegmatites at the Ehrenfried-ersdorf Sn–W deposit in Saxony [3]. Some evidence for crystallization conditions of rare metal miarolitic (with sub-rare-metals) [1, 4] and rare metal [5] pegmatites is also available. We began the systematic studies of mineral-forming media in order to estimate the role of volatile components and rare elements in the formation of granitic pegmatites with different specializations. In particular, we established the important role of orthoboric acid in the formation of miarolitic pegmatites enriched or depleted in boric mineralization [6, 7].