Carbonatite shows on the quartz deposits “Vein 175” (Ufalei block, the Southern Urals)

Abstract

The subject of the study are manifestations of carbonatites in the quartz deposit “Vein № 175” - the largest deposit of granular quartz of Ufalei block in the Southern Urals. In the vein № 175 new outcrops of carbonatites are described; thin sections, plates and polished sections from 58 selected samples are made. Mineralogical and petrographic analysis of carbonatites and host rocks was carried out using Axiolab ZS and Olimpus BX 51 polarization microscopes with digital prefixes. The total mineral composition was determined by X-ray diffraction analysis. Fluid inclusions were studied in a Linkam THMSG-600 microcooler using the Olimpus BX 51-52 microscope and the LinkSistem 32 DVNS software. It was established that the deposition of vein quartz preceded to the formation of carbonatites. The quartz vein inherited a tectonic structure which controlled the deposition of carbonate material. The fragments of carbonatite bodies are observed throughout the quartz veins, where they have been preserved. It is established that the carbonatites of the “Vein 175” differ from the carbonatites of the Vishnevogorsk alkaline complex by a low content of rare metal minerals characteristic of carbonatites: pyrochlore, zircon, columbite, eshenite and monazite. It is obvious that the source of rare-metal minerals in the carbonatites of the Vishnevye Mountains, as well as in the magmatic carbonatites of zonal massifs with ultrabasic alkaline complexes, is the substance from which the alkaline rocks were formed. Carbonate rocks of these complexes concentrate rare-metal minerals and have the mantle spectrum of rare and rare-earth elements in their composition. The source of the carbonate material of “Veins № 175” can be sedimentary carbonates lying at the base of the crystalline basement. The absence of rare-metal minerals in the carbonatites confirm this thesis.