Belskyy V. The physico-chemical formation conditions for rare earth elements and yttrium mineralization of Pryazovia (by fluid inclusions in minerals)

The thesis represents the case studies of the formation conditions for features, where concentrators of rare earth elements and yttrium are atypical minerals: britholite in the Azov Zr-REE deposit, allanite in the Anadol occurrence, and aspects of the formation Dibrova REE-U-Th occurrence. The syngenetic inclusions of britholite and mineral-satellite of britholite in primary magmatic inclusions in zircon indicate that the accumulation of main ore minerals occurred simultaneously with zircon at magmatic stage of formation of Azov Zr-REE deposits. The mass of REE oxides dissolved in 1 km3 of magma calculated by britholite solubility in glass inclusions (hardened magma microportions) is large enough for the formation of deposit. The genesis of Dibrova REE-U-Th deposit is an illustrative example of formation of hydrothermal system in consequence of prolonged CO2 fluid heating of aqueous solutions in the area of fractured rocks of Devladiv deep fault. The participation of CO2-solutions in the formation of such deposit is proved by PT-parameter definitions: a) primary CO2 fluid inclusions "stuck" to sillimanite needles in quartz of secondary quartzites (>(420-440) °C and >(240-220) MPa); b) formation conditions for inclusions of glass with "hat" (approximately 1000-1100 °C and 720-760 MPa), c) inclusion of homogeneous capture of heterogeneous "aqueous solution+ CO2-solution" system (230-235, 240-245 °C and some 110 MPa). Formation of allanite mineralization of Anadol "dikes" occurred in the broad temperature range from <850 (early generation of allanite) to <450 (late generation of allanite) and ~250-140 ° C (fluid inclusions in quartz). Secondary water inclusions found in quartz with phase of CO2 fluid shows the connection between forming of Anadol "dikes" with mafic and/or ultramafic rocks of the region.