5. Geodynamic Context of Metallogeny

Geodynamics is the dynamics of the Earth. Metallogeny is the genesis of metals, rather the metal-bearing mineral deposits. So, ‘Geodynamic context of metallogeny’ relates metallogeny to geodynamics. We generally refer to geodynamics in terms of plates and plumes, that ultimately control magmatism, sedimentation, and metamorphism and hence ore genesis in the crust-mantle system. The solid earth is made up of physically distinct layers (from surface downward) of lithosphere, asthenosphere, mesosphere, outer core, and an inner core. The lithosphere is presently divided in to seven large and a few small pieces (‘plates’). They underwent making, breaking, and remaking several times during much of the Earth’s history, giving rise to what we call supercontinents and supercycles today. Formation of mineral deposits, which are in fact products of petrogenesis of sorts, controlled by tectonics, therefore varied in time and space. Tectonic setting of mineralization are today accepted to be as follows: continental hot spot produce Cr, Ni–Pt–Cu deposits, diamonds, certain stratiform base metal deposits, and even granite-related mineralization of Sn. Constructive plate boundaries host Fe-, Mn-oxides along the rifted ridge, and also Alpine-type chromite deposits. Passive continental margins localize deposition of evaporites, phosphates, BIFs, carbonate-hosted Pb–Zn deposits. Subduction zones produce porphyry type Cu–Mo–(Au) deposits and may be also Cu + Au skarn deposits. Continental collision zones contain podiform chromite, VMS, U and porphyry Cu deposits. Greenstone belts (ancient volcano-plutonic arcs?) are known for being the major localizer of orogenic gold, komatiite-related Cu–Ni deposits and also Cu–Zn mineralizations. Intracratonic settings are credited with IOCG mineralization. Tectonically stable regions with plateau-like relief and located in tropical and sub-tropical regions are best suited for lateritization.