Petrogenesis of mesozoic, peraluminous granites in the Lamoille canyon area, Ruby mountains, Nevada, USA

Two groups of closely associated, peraluminous, two-mica granitic gneiss were identified in the area. The older, sparsely distributed unit is equigranular (EG) with initial ε_Nd ∼ − 8·8 and initial ⁸⁷Sr/⁸⁶Sr ∼0·7098. Its age is uncertain. The younger unit is Late Cretaceous (∼80 Ma), pegmatitic, and sillimanite-bearing (KPG), with ε_Nd from −15·8 to −17·3 and initial ⁸⁷Sr/⁸⁶Sr from 0·7157 to 0·7198. The concentrations of Fe, Mg, Na, Ca, Sr, V, Zr, Zn and Hf are higher, and K, Rb and Th are lower in the EG. Major- and trace-element models indicate that the KPG was derived by muscovite dehydration melting (