Archean felsic volcanic rocks in felsic rocks. Timing of felsic volcanism and tectonic constraints can be identified by radiometric dating and isotopic analysis. In Archean, underwater eruptions of felsic lava were common. Submarine eruption is evident by coarse volcanic breccia formed in situ, hyaloclastite or underwater pyroclastic deposits (clastic rock, composed of tephra only). Since felsic magma is viscous, volcanic eruptions that form dacite or rhyolite are explosive and violent. The Archean felsic eruption may be assigned to Vesuvius eruption type in the present day. Submarine rhyolitic flows were widespread in Archean but it is uncommon in the modern volcanic environment. Viscous felsic eruption
Archean felsic volcanic rocks heavy rare-earth elements than other Archean felsic volcanic rocks) has no plutonic equivalent in the same period. The composition of felsic volcanic rocks are being altered concurrently with shifting granitoid composition. The older GMS-like felsic volcanic rocks formed with similar age of TTG has two implications: Revealing the relationship between Archean felsic volcanic rocks and the granitoids may be difficult. It is because weathering alters the geochemical signatures of the felsic rocks above the Earth's surface. The earliest weathering record can be traced back to 3.8 Ga during Eoarchean. Potassium is enriched but sodium is depleted in these weathered felsic