Abstract
Abstract The role and predictive power of translithospheric faults in localizing large magmatic Ni-Cu (±platinum group metal, Co) sulfide deposits at subprovince, district, and prospect scales are tested with new regional structural interpretations for 72 global deposit case studies. The most prospective target areas are shown to be in the hanging wall ≤30 km from paleocraton edge-parallel translithospheric faults. Large Ni deposits in intracontinental settings, but not in highly deformed pericratonic or Archaean komatiite settings, are also mostly located ≤30 km from transverse translithospheric fault intersections. Prioritizing target proximity to the most prominent translithospheric fault intersections can significantly reduce subprovince search areas (104–105 km2) to a few prospective districts (102 km2). The largest deposits are found closest to translithospheric faults, which allows for optimization of search criteria for giant discoveries. Deposit-scale controls for emplacement of mineralized channel-like flows and chonoliths are typically more stratigraphic than structural; where overpressured, high-temperature magmas self-generate pathways through rheologically weak and highly fusible metasedimentary or gneissic units. A new magmatic model is proposed where the mantle root zones of translithospheric fault intersections initially channel fertile mantle melts into the deep crust, and ascent of buoyant overpressured magmas is dispersed up to a few tens of kilometers laterally to inclined master fault conduits through dike-sill-dike networks along hanging-wall shortcut faults, their damage zones, and along rheologically weak contacts. The extreme magma flux required to form large Ni sulfide deposits results from positive feedback between magma transfer and lithospheric fault activation that led to bottom-up self-organization.
Published Version
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