Volcanic plateau up by foundering of the Earth's crust to form the present ocean basin. The Earth features numerous subaerial and submarine volcanic plateaus such as the Columbia River Plateau (subaerial) and the vast Ontong Java Plateau (submarine). Pyroclastic plateaus are produced by massive pyroclastic flows and they are underlain by pyroclastic rocks: agglomerates, tephra, volcanic ashes cemented into tuffs, mafic or felsic. Examples include Shirasu-Daichi which covers almost all of Southern Kyūshū, Japan and the North Island Volcanic Plateau in New Zealand. Volcanic plateau A volcanic plateau is a plateau produced by volcanic activity. There are two main types: lava plateaus
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