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
Archean felsic volcanic rocks ultramafic and mafic units make up the major volume of the volcanic units. The remaining volcanic units are extensive but thin felsic volcanic layers, such as Duffer Formation of the Warrawoona Group. The greenstone belts may be subsequently intruded by dome-shaped magma chambers. The intrusion deformed the felsic volcanic rocks along with the volcano-sedimentary sequences. Observing modern volcanic processes is relatively easier than observing Archean volcanism, because erosion constantly started removing earlier formed materials. So, studying the Archean supracrustal rocks back in deep time may be subjected to sampling bias. The meaning of "felsic" refers to high silica (SiO) content