High-temperature granulites and supercontinents

摘要: The formation of continents involves a combination magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where pressure-temperature (P-T) conditions (ultra) high-temperature granulites rocks are similar. Continents grow laterally, bymagmatic activity above oceanic subduction zones (high-pressure setting), and vertically by accumulation mantle-derived magmas base crust (high-temperature metamorphic setting). Both events separated from each other in time; vertical accretion postdating lateral growth several tens millions years. Fluid inclusion data indicate that during the high-temperature episode granulite lower is invaded large amounts low H2O-activity fluids including high-density CO2 concentrated saline solutions (brines). These fluids are expelled to higher crustal levels end high-grade metamorphic event. final amalgamation supercontinents corresponds episodes ultra-high temperature metamorphism involving large-scale these low-water crust. This causes tectonic instability, which together with heat input subcontinental lithospheric mantle, leads disruption supercontinents. Thus, fragmentation of a supercontinent already programmed time its