Metallogenesis in relation to mantle heterogeneity

Abstract

Regional variations in the type and abundance of metalliferous mineral deposits formed at a given time depend on environmental factors operating not only at the sites of deposition but also in the source regions supplying the metals. The extent to which chemical heterogeneities in the mantle may have helped to determine such patterns of variation can be most effectively explored by concentrating on types of ore deposit that are genetically related to magmatism originating in the mantle. Attention is focused particularly on regions where phases of mineralization involving the same metal or group of metals have been repeated over a long time-span and/or in widely different tectonic settings. Chromium, platinum, nickel, tin and uranium are of interest in this context. Although the two latter elements are often considered to have crustal sources, it is suggested that mantle-derived volatiles have played a part in the processes leading to their enrichment in certain acid magmas.