Volcanic Plateau on:
[Wikipedia]
[Google]
[Amazon]
A volcanic plateau is a
Lava plateaus are formed by highly fluid
A volcanic plateau is a plateau
In geology and physical geography, a plateau (; ; ), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides ...
produced by volcanic activity
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...
. There are two main types: lava plateaus and pyroclastic plateaus.
Lava plateau
Lava plateaus are formed by highly fluid basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
ic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions). These eruptions are quiet because of low viscosity of lava, so that it is very fluid and contains a small amount of trapped gases. The resulting sheet lava flows may be extruded from linear fissures or rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics.
Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...
s or gigantic volcanic eruptions through multiple vents characteristic of the prehistoric era which produced giant flood basalt
A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...
s. Multiple successive and extensive lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
flows cover the original landscape to eventually form a plateau, which may contain lava fields, cinder cones, shield volcanoes and other volcanic landforms. In some cases, a lava plateau may be part of a single volcano. An example is the massive Level Mountain
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located north-northwest of Telegraph Creek and west of Dease Lake on the Nahlin Plateau. With a maximum elevation of , it is the second-h ...
shield volcano in northern British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, which covers an area of and a volume of .
Perhaps the most extensive of all the subaerial basaltic plateaus existed during the Paleogene and possibly extended over of the northern Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
region. This region, known as the Thulean Plateau, is generally believed to have been broken up by foundering of the Earth's crust to form the present ocean basin
In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, ocean basins are large geologic basins that are below sea level.
Most commonly the ocean is divided into basins fol ...
.
Earth features numerous subaerial and submarine volcanic plateaus such as the Columbia River Plateau
The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbi ...
(subaerial) and the vast Ontong Java Plateau
The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands.
The OJP was formed around (Ma) with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific ...
(submarine).
Pyroclastic plateau
Pyroclastic plateaus are produced by massive pyroclastic flows. They are underlain by pyroclastic rocks: agglomerates,tephra
Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism.
Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they re ...
, volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
es cemented into tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...
s, mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks incl ...
or felsic. Pyroclastic plateaus are also called ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surro ...
plateaus.
Examples include Shirasu-Daichi which covers almost all of southern Kyūshū, Japan and the North Island Volcanic Plateau
The North Island Volcanic Plateau (often called the Central Plateau and occasionally the Waimarino Plateau) is a volcanic plateau covering much of central North Island of New Zealand with volcanoes, lava plateaus, and crater lakes. It contains ...
in New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
.
See also
*References