Temagami Greenstone Belt phases of volcanic activity. These two sequences, known as the Older and Younger volcanic complexes, consist of volcanic rocks ranging in composition from felsic to mafic. The Older Volcanic Complex is composed mainly of felsic lava flows and pyroclastic deposits with smaller amounts of mafic volcanic rocks. It underlies a large portion of northwestern Strathy Township and is penetrated by mafic intrusions, although the Kanichee Intrusion consists of peridotite and pyroxenite, which are ultramafic rocks. Just to the southeast, the Younger Volcanic Complex consists mainly of mafic volcanic rocks that form four geologic formations. The Arsenic Lake Formation is composed
Altiplano–Puna volcanic complex layer containing melts reaching down to the Moho that inhibits the ascent of mafic magmas because of its higher buoyancy. Instead, melts generated in this zone eventually reach the surface, generating felsic volcanism. Some mafic magmas escape sideward after stalling in the melt containing zone; these generate more mafic volcanic systems at the edge of the felsic volcanism, such as Cerro Bitiche. The magmas are mixtures of crust derived and mafic mantle-derived melts with a consistent petrological and chemical signature. The melt generation process may involve several different layers in the crust. Another model requires the intrusion of basaltic melts