Two-stage evolution in an Archean tonalite suite: the Taschereau stock, Abitibi (Quebec, Canada)
The Taschereau stock occurs north of Timmins and Val-d'Or, Quebec, in the Abitibi greenstone belt of the Superior Province. This late Archean composite pluton is composed mainly of diorite–tonalite–trondhjemite cut by granitic rocks. Gold–molybdenum occurrences are associated with a zone of albite-rich rocks surrounding the granitic rocks. Diabase dykes and shear zones postdate all rock units. Field and geochemical evidence suggests that the Taschereau stock was emplaced diachronously. Trace-element geochemical modelling shows that trace-element abundances (rare-earth elements, Ti, Zr) of Taschereau granitic rocks are consistent with partial melting of preexisting Taschereau tonalitic rocks and implies that these two rock types are not end members of a single magma that evolved through fractional crystallization.