The isotope geochemistry (eNd(t) 4.8–5.4, 206Pb/204Pb in 18.05–18.36, 207Pb/204Pbin 15.53–15.57, 208Pb/204Pb in 37.59–37.83, 87Sr/86Sr(t) 0.7048–0.7057, δ18OSMOW 8–10.5‰) and trace element composition of the Kiya–Shaltyr gabbro–urtite pluton allow us to suggest a heterogeneous source and complex geodynamic settings of the Devonian alkali magmatism in the Kuznetsk Alatau. It is assumed that its evolution took place under conditions of partial mingling of matter of the depleted (PREMA) and enriched (EM) mantle with crustal contamination of the evolving melt. Such an interaction could have been a result of superposition of a mantle plume and an active margin (OIB and IAB components). In fold belts this led to the formation of hybrid high-alumina foidoite magmas.