Rare earth mineralization in volcanic-sedimentary rocks of the Shatak complex (Southern Urals)

Abstract

The paper presents materials on the study of rare earth mineralization in rocks of the Shatak complex, which belongs to the Mashak formation (RF2). Numerous rare earth minerals have been discovered and characterized in detail in terrigenous rocks, metabasalts and rhyodacites: allanite-(Ce), monazite-(Ce), monazite-(La), monazite-(Nd), nioboeschinite-(Y), aeshinite-(Y) , talenite-(Nd), talenite-(Dy), synchysite-(Ce), Ce–La–Fe oxide, cerite and unidentified compounds: yttrium silicate, cerium silicate, Ce–Fe compound, as well as REE-containing minerals: epidote and fluorapatite. In the contact zone between metabasalts and quartz sandstones, oxyfluoride – (La, Ce) (OnFm)3 mineralization, represented by compounds of variable composition, forming an isomorphic series: trifluoride (La, Ce)F3 – oxyfluoride (La, Ce)OF, is described for the first time in the world literature –oxide (La, Ce)2O3. It has been established that the determining factors in the formation of rare earth mineralization in the rocks of the Shatak complex are the conditions and nature of metamorphism and the chemistry of the mineral formation environment. The species diversity of rare earth minerals and the peculiarities of their chemical composition make the Shatak volcanic-sedimentary complex a unique object for studying the processes of rare earth mineral formation in various petrotypes of rocks formed in a single geotectonic setting and united by common thermobaric parameters of metamorphism.