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
Grenville Province orogeny and metamorphism. Pinwarian magmatism has stopped by this time. Gabbros were formed in the northern Grenville Province around 1.46-1.43 Ga, named the Michael-Shabogamo gabbros. From 1.42 to 1.35 Ga, there is no magmatic activity. After this period and until the end of the mid-Elsonian, the Nain Plutonic Suite is emplaced in Labrador. Felsic magmatism dominates the north and south areas of Labrador while mafic magmatism dominates the central area of Labrador. Felsic magmatism ceases and accretion of island arcs occurs in the Central Metasedimentary Belt. Mixed compression and extension caused broad mafic magmatism during this time. This could be