Melanite-bearing nepheline syenite fragments and 40Ar/39Ar age of phlogopite megacrysts in conduit breccia from the Poços de Caldas Alkaline Massif (MG/SP), and implications - Vlach, Silvio Roberto Farias; Ulbrich, H.; Ulbrich, Mabel N. C.; Vasconcelos, Paulo Marcos (Brazilian Journal of Geology, 2018)