Fig. 5: Synoptic diagrams showing plausible end-member tectonic scenarios for water-present melting generating TTG crust during the Precambrian.
From: Oxygen isotope shifts reveal fluid-fluxed melting in continental anatexis
A A warm Precambrian subduction zone shows the opening of the mantle wedge during slab breakoff inducing heat, fluid circulation, mantle metasomatism and fluid flux of the mafic lower crust to produce TTG plutons. B TTG generation by fluid-fluxed melting of mafic crust in an intraplate setting where water is introduced in the mantle during vertical sinking of hydrated mafic–ultramafic crust.
