Chapter 12 Flashcards
(22 cards)
Volcano
A hill or mountain constructed from the accumulation of erupted lava and pyroclasts.
Volcanic Geosystem
The total system of rocks, magmas, and processes needed to describe the entire sequence of events from melting to the eruption of lava from a volcano at Earth’s surface.
Basaltic Lava
A lava type of mafic composition that has a low silica content, erupts at high temperatures, and flows readily.
Andesitic Lava
A lava type of intermediate composition that has a higher silica content than basalt, erupts at lower temperatures, and is more viscous.
Rhyolitic Lavas
The lava type that is the richest in silica, erupts at the lowest temperatures, and is the most viscous.
Tuffs
A volcanic rock formed by the lithification of small by pyroclasts.
Breccias
A volcanic rock formed by lithification of large pyroclasts.
Pyroclastic Flows
A glowing cloud of hot ash, dust, and gases ejected by a volcanic eruption that rolls downhill at high speeds.
Shield Volcanoes
A broad, shield-shaped volcano many tens of kilometers in circumference and more than 2 km high, built by successive flows of basaltic lava from a central vent.
Stratovolcanoes
A concave-shaped volcano formed from alternating layers of lava flows and beds of pyroclasts.
Crater
- Bowl shaped pit found at the summit of most volcanoes, centered on the vent
- A depression caused by the impact of a meteorite
Caldera
A large, steep-walled, basin-shaped depression formed by a violent volcanic eruption in which large volumes of magma are discharged rapidly from a large magma chamber, causing the overlying volcanic structure to collapse catastrophically through the roof of the emptied chamber.
Diatreme
A structure formed when a volcanic vent and the feeder channel below it are left full of breccia as an explosive eruption wanes.
Fissure Eruptions
A volcanic eruption emanating from a large, nearly vertical crack in the Earth’s surface rather than a central vent.
Flood Basalts
An immense basalt plateau formed by fissure eruptions of highly fluid basaltic lava
Ash-flow deposits
An extensive sheet of hard volcanic tuff produced by a continental eruption of pyroclasts.
Hydrothermal Activity
The circulation of water through hot volcanic rocks and magmas.
Hot Spots
A region of intense, localized volcanism found far from a plate boundary; hypothesized to be the surface expression of a mantle plume.
Mantle Plumes
A narrow, cylindrical jet of hot, solid material rising from deep within the mantle, thought to be responsible for intraplate volcanism.
Large Igneous Provinces
A voluminous emplacement of predominantly mafic extrusive and intrusive igneous rock who origins lie in processes other than normal seafloor spreading LIPs include continental flood basalts, oceanic basalt plateaus, and aseismic ridges produced by hot spots.
Lahars
A torrential mudflow of wet volcanic debris.
Geothermal energy
Energy produced when underground water is heated as it passes through a subsurface region of hot rock.
