Stratovolcano Stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive
Archean felsic volcanic rocks their mineral assemblages, rock chemistry and rock layer relationship in the sequences. Archean felsic volcanic rocks are utilised to date the timing of geological events and match distant rock units in separated Archean cratons. They are important to reconstruct Archean geological environments. Felsic granitoids are the most prevalent rock type in Archean terranes. These intrusive felsic igneous rocks include TTG suites (Tonalite-Trondhjemite-Granodiorite) that contributes over half the portion of Archean cratons. They have implications in finding how the felsic volcanic rocks were formed and related to the granitoids. Archean felsic volcanic rocks are only preserved in Archean cratons. A craton