Plumes, cratons and nickel sulphide deposits

The formation of giant nickel sulphide deposits occurs most commonly during, or close to, the peak of supercontinent formation, and is related to the melting of large "alpha" mantle plumes. These plumes are part of a bloom of plumes that occurs in response to the build up of subducted lithosphere at the Core Mantle Boundary. The spatial localization of deposits is governed by the 3-dimensional geometry of the lithosphere-asthenosphere boundary. Plume melting will be maximized and focused in zones of thin lithosphere adjacent to large areas of thick lithosphere typical of cratons. This "craton-margin" setting is the most favourable site where active translithospheric faults provide discrete points of melt introduction into the upper crust. At a continental-scale, narrow marginal basins and intra-continental settings provide the best sites for plume melt focus and deposit preservation.