Dehydration Melting and Proterozoic Granite Petrogenesis in a Collisional Orogen—A Case from the Svecofennian of Southern Finland

Dehydration melting of metasupracrustal rocks at mid- to deep-crustal levels can generate water undersaturated granitic melt. In this study, we evaluate the potential ?1.89–1.88 Ga Precambrian southern Finland as source for 1.86–1.79 late-orogenic leucogranites in region, using Rhyolite-MELTS approach. Melt close composition leucogranite is produced over a range realistic pressures (5 8 kbar) and temperatures (800 850 °C), 20%–30% partial melting, allowing separation melt from unmelted residue. The solid residue dry, enderbitic charnoenderbitic ganulite depleted incompatible components, will only yield further above 1 000–1 050 °C, when rapidly increasing fractions increasingly calcic (granodioritic tonalitic) melts are formed. after extraction incapable producing syenogranitic magmas similar Mid-Proterozoic, A-type rapakivi granites on heating. fraction complexes must thus have been formed by different chain processes, involving mantle-derived mafic crustal rock types not conditioned preceding Svecofennian anatexis.