The distribution of strontium between coexisting silicate and carbonate liquids at elevated pressures and temperatures

Strontium is characteristically enriched in carbonatites and associated igneous rocks. Experiments between 600 and 800°C at 5 and 10 kb show that Sr fractionates strongly toward both liquid phases of a carbonate liquid-silicate liquid-solid assemblage, with the crystalline phases depleted in Sr. Considering that the alkalic igneous rocks associated with carbonatites are not significantly depleted in Sr compared with the carbonatites, it is concluded that these complexes are formed by a pair of immiscible magmas, rather than the carbonatites being late-stage fractionation products of the alkalic silicate magmas.