Volcanic-plutonic alkaline complexes from Lugiin Gol, Mushgai Khudag and Bayan Khoshuu,
southern Mongolia (244, 139 and 131 Ma, respectively) occur within grabens in
E-W lineaments. They are represented by syenitic rock-types (silica
undersaturated to slightly silica oversaturated) potassic rocks and are
associated to stockworks of carbonatitic veins, dykes and so on. Geochemical
characteristics and isotope systematics point to a veined mantle source
particularly enriched in LILE and LREE. The carbonatitic veins show high
contents of Ba, Sr, Th and REE and are suitable as potential ore deposits.