Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals)

The Shatak Formation, comprising a part of the Mashak Suite (RF2), is located on western slope Southern Urals. It consists various rock types, including sedimentary rocks, such as conglomerates, polymictic sandstones, aleurolites, and carbonaceous clayey shales, well igneous picrites, basalts, dacites, rhyodacites, rhyolites, volcanogenic–sedimentary tuffs tuff breccias. In this article, oxyfluoride (La, Ce) (OnFm)3 mineralization, occurring in contact zone between metabasalts quartz described for first time literature. This represented by compounds variable compositions forming an isomorphic series: trifluoride, Ce)F3–oxyfluoride, Ce)OF–oxide, Ce)2O3. By analyzing several binary phase diagrams, significant coordination oxygen, fluorine, cerium chemical composition oxyfluorides has been highlighted. However, behavior lanthanum shown to exhibit some irregularity. genesis mineralization attributed regional metamorphism rocks within Formation. During hydrothermal process, decomposition fluorapatite, which unstable during both supergene processes, resulted release potentially cerium. Variations oxyfluorides, are formed presence excess oxygen resulting from water dissociation, determined local differences content main components microfractures.