Avolcanic plateau is aplateau produced byvolcanic activity. There are two main types: lava plateaus and pyroclastic plateaus.
Lava plateaus are formed by highly fluidbasaltic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions). These eruptions are quiet because of the low viscosity of the lava and the small amount of trapped gases. The resulting sheet lava flows may be extruded from linearfissures orrifts or gigantic volcanic eruptions through multiple vents characteristic of the prehistoric era which produced giantflood basalts. Multiple successive and extensivelava flows cover the original landscape to eventually form a plateau, which may containlava fields,cinder cones,shield volcanoes and othervolcanic landforms. In some cases, a lava plateau may be part of a single volcano. An example is the massiveLevel Mountainshield volcano in northernBritish Columbia,Canada, which covers an area of 1,800 km2 (690 sq mi) and a volume of 860 km3 (210 cu mi).[1]
Perhaps the most extensive of all thesubaerial basaltic plateaus existed during thePaleogene[2] and possibly extended over 1,800,000 km2 (690,000 sq mi) of the northernAtlantic Ocean region. This region, known as theThulean Plateau, is generally believed to have been broken up by the foundering of the Earth's crust to form the presentocean basin.
Earth features numerous subaerial andsubmarine volcanic plateaus, such as theColumbia River Plateau (subaerial) and the vastOntong Java Plateau (submarine).
Pyroclastic plateaus are produced by massivepyroclastic flows. They are underlain bypyroclastic rocks:agglomerates,tephra,volcanic ashes cemented intotuffs,mafic orfelsic. Pyroclastic plateaus are also calledignimbrite plateaus.
Examples include theShirasu-Daichi, which makes up almost all of southernKyūshū,Japan,[3] and theNorth Island Volcanic Plateau inNew Zealand.