Embryos of TTGs in Gore Mountain garnet megacrysts from water-fluxed melting of the lower crust

The garnet megacrysts of Gore Mountain (Adirondacks, US) are world-renown crystals due to their size, up 1 m in historical record, which makes them the largest known garnets on planet. We show here that they also host first primary inclusions trondhjemitic melt found natural mafic rocks. petrological and experimental investigation inclusions, coupled with phase equilibrium modelling, shows this is result H2O-fluxed partial melting at T>900 °C a lower crustal gabbro. compositional similarity between tonalitic–trondhjemitic–granodioritic (TTGs) melts these direct evidence rocks generates TTG-like melts, provides us possibility clarify processes responsible for formation early continental crust. These TTG embryos represent end-member whose emplacement upper levels, after being modified by mixing crystallization-related processes, leads terranes. Moreover, our study how from crust has mismatched major trace element signatures, previously interpreted as very different pressures. This poses serious limitations established use some chemical features identify geodynamic settings (e.g. subduction versus thickened crust) TTGs generation growth