Temagami Greenstone Belt shear throughout the Link Lake Deformation Zone. These dark compressed pyroclastics have been interpreted to be pumice. Some of the subsequence pyroclastic deposits contain fragments of pyrite and quartz, suggesting that discharged sulfide hydrothermal activity took place throughout the volcanic source area. Resedimented felsic, epiclastic and turbiditic sediments compose the Turtle Lake Formation. The base of this formation consists of a heterolithic, volcaniclastic, matrix-supported conglomerate unit that overlies felsic lava flows and pillowed, calc-alkaline basalts of the Link Lake Formation. Many rounded to subangular felsic and mafic volcanic fragments are known to occur in the unit, as well as rare
Felsic although sometimes used as a synonym, refers to a high-silica-content (greater than 63% SiO by weight) volcanic rock, such as rhyolite. The term was used more broadly in older geologic literature. It is considered archaic now, as the terms "acidic" and "basic rock" were based on an incorrect idea, dating from the 19th century, that "silicic acid" was the chief form of silicon occurring in rocks. The term "felsic" combines the words "feldspar" and "silica". The similarity of the term "felsic" to the German words "Fels", meaning "rock", and "felsig", meaning "rocky", is purely accidental, as "feldspar" is a borrowing