Rare Earth Element Mineralogy, Geochemistry, and Preliminary Resource Assessment of the Khanneshin Carbonatite Complex, Helmand Province, Afghanistan

The Khanneshin carbonatite is a deeply dissected igneous complex of Quaternary age that rises approximately 700 meters (m) above the Neogene sedimentary rocks of the Registan Desert, Helmand Province, Afghanistan. The complex consists almost exclusively of carbonate-rich intrusive and extrusive igneous rocks, crudely circular in outline, with three small hypabyssal plugs of leucite phonolite and leucitite outcropping in the southeast part of the complex. The igneous complex is broadly divisible into a central intrusive vent (or massif), approximately 4 kilometers (km) in diameter, consisting of coarse-grained sövite and brecciated and agglomeratic barite-ankerite alvikite; a thin marginal zone (