Y–REE-Rich zircons of the Timan region: Geochemistry and economic significance

Resumo

Mineralogical–geochemical studies of zircon from the Ichet’yu occurrence revealed unusually high Y and HREE contents (correlative with the P content) in the inner parts and zones of approximately 10% of the grains. They represent the intermediate members of the zircon–xenotime join with a heterovalent scheme of isomorphism Zr⁴⁺ + Si⁴⁺ → (Y + HREE)³⁺ + P⁵⁺. Geochronological and mineralogical–geochemical data suggest that the Middle Timan basement (the most probable source of zircon of the Ichet’yu occurrence) is made up of the Paleoproterozoic rocks and possibly represents a continuation beneath the Mezen syneclise and Middle Timan of the Paleoproterozoic collisional structure, to which the Arkhangelsk diamond province is confined.