Komatiite volcanology, volcanological setting and primary geochemical properties of komatiite-associated nickel deposits

Abstract

Komatiite-associated nickel sulphide deposits formed in long-lived lava conduits fed vast komatiite flow fields during the evolution of Archaean Greenstone Belt stratigraphy. Such komatiite flow fields exhibit complex internal volcanic stratigraphy and facies variations. This complex volcanic architecture renders the meaningful interpretation of geophysical and geochemical exploration data almost impossible, without a knowledge of the eruptive processes controlling the emplacement of the flow fields and their associated nickel deposits. Accordingly, this paper presents an effective model for komatiite volcanism which is derived from a synthesis of extensive geological mapping, geochemistry, and petrology of Archaean komatiites in Western Australia, and studies of Recent and active basaltic eruptions. It discusses the implications of this inflationary model for the interpretation of the geological and geochemical properties of various volcanic facies, and the genesis and geochemical properties of the ore deposits and their immediate environments. It is hoped that this treatize will act as a ‘precautionary tale’ for those formulating nickel exploration programs and interpreting regolith geochemical data.