Application of stable isotope studies to problems of magmatic sulphide ore genesis with special reference to the Duluth complex, Minnesota.

Abstract

Isotopic analysis of S, C, O and H in mafic igneous rocks may provide valuable information regarding the extent of contamination by continental crust material. Partial melting and devolatilization of country rocks are important processes in the generation of many Cu-Ni deposits associated with mafic igneous rocks. Zones of contamination are likely to be areas where factors which control sulphide solubility have been disturbed and are thus sites for ore generation. A study of the Duluth area has confirmed the importance of country rock contamination in the generation of Cu-Ni ores. Chemical diffusion, as well as fluid dynamic properties of mixing, are thought to control the isotopic inhomogeneity that characterises sulphide ore zones in the complex.-R.E.S.