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
Archean felsic volcanic rocks ultramafic and mafic units make up the major volume of the volcanic units. The remaining volcanic units are extensive but thin felsic volcanic layers, such as Duffer Formation of the Warrawoona Group. The greenstone belts may be subsequently intruded by dome-shaped magma chambers. The intrusion deformed the felsic volcanic rocks along with the volcano-sedimentary sequences. Observing modern volcanic processes is relatively easier than observing Archean volcanism, because erosion constantly started removing earlier formed materials. So, studying the Archean supracrustal rocks back in deep time may be subjected to sampling bias. The meaning of "felsic" refers to high silica (SiO) content