A New Occurrence of Maruyamaite

摘要

We report for the first time the occurrence of a maruyamaite (dravite with a high K content) + garnet + kyanite + biotite + muscovite + K-feldspar + quartz mineral assemblage in metamorphic rocks of the Barchi-Kol site (Kokchetav Massif). We estimate the conditions for the formation of mineral paragenesis with tourmaline based on petrological observations and thermodynamic calculations. The results were compared with the available data on the evolution of this metamorphic complex. As a result, we propose a new model for the formation of maruyamaite. Its presence in the rock is believed to indicate high K activity in the mineral-forming fluid.