Abstract

This study investigates the geological characteristics, ore-forming processes, and mineral resources of rare earth element (REE) deposits in Mongolia. REE deposits in Mongolia are primarily associated with two distinct geological settings: Mesozoic carbonatites and Paleozoic peralkaline granitic rocks. Carbonatite-related deposits are found within alkaline silicate-carbonatite complexes in the Gobi-Tien Shan rift zone of southern Mongolia. These complexes consist of nepheline syenite and their volcanic equivalents. In these carbonatites, REE are mainly associated with bastnäsite, synchysite, parisite, and apatite. REE mineralization linked to peralkaline granitoid rocks is mainly located in the Mongolian Altai region in the northwest. Here, REE is found in minerals like elpidite, monazite, xenotime, and various fluorocarbonates. These minerals typically form during the final stages of magma differentiation. Mongolia hosts several promising rare earth deposits, with three showing significant economic potential: the Devonian Khalzan Buregtei peralkaline granites, and the Mesozoic Mushgai Khudag and Khotgor carbonatites. Many other promising locations have yet to be fully investigated. Further geological investigations and exploration efforts could substantially expand Mongolia's known rare earth element resources.

Keywords rare earth elements, Mongolia, carbonatite, peralkaline granitoid rocks, ore-forming processes