Lava

lava flowlava flowspahoehoelava fountainpāhoehoeʻaʻāaaaa lavaa'a
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1200 C.wikipedia
2,296 Related Articles

Types of volcanic eruptions

volcanic eruptioneruptionvolcanic eruptions
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1200 C. The structures resulting from subsequent solidification and cooling are also sometimes described as lava.
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists.

Igneous rock

igneousigneous rocksdecompression melting
When it has stopped moving, lava solidifies to form igneous rock.
Igneous rock is formed through the cooling and solidification of magma or lava.

Effusive eruption

effusiveeffusive activityeffusive volcanism
A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption.
An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground.

Lava dome

lava domesdomecryptodome
Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, lava domes or "coulees" (which are thick, short lava flows) and are associated with pyroclastic (fragmental) deposits.
In volcanology, a lava dome or volcanic dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano.

Lava spine

Spinesvolcanic spinevolcanic spires
Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, lava domes or "coulees" (which are thick, short lava flows) and are associated with pyroclastic (fragmental) deposits.
A lava spine is a vertically growing monolith of viscous lava that is slowly forced from a volcanic vent, such as those growing on a lava dome (Bates & Jackson, 1987).

Basalt

basalticcolumnar basaltpillow basalt
Mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °C.
Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon.

Shield volcano

shield volcanoesshieldlava shield
Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent. They range in shape from shield volcanoes with broad, shallow slopes formed from predominantly effusive eruptions of relatively fluid basaltic lava flows, to steeply-sided stratovolcanoes (also known as composite volcanoes) made of alternating layers of ash and more viscous lava flows typical of intermediate and felsic lavas.
A shield volcano is a type of volcano usually composed almost entirely of fluid lava flows.

Rhyolite

rhyoliticrhyolitesliparite
Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, lava domes or "coulees" (which are thick, short lava flows) and are associated with pyroclastic (fragmental) deposits. Lavas with high viscosity are rhyolite, dacite, andesite and trachyte, with cooled basaltic lava also quite viscous; those with low viscosities are freshly erupted basalt, carbonatite and occasionally andesite.
Due to their high content of silica and low iron and magnesium contents, rhyolitic magmas form highly viscous lavas.

Flood basalt

basaltbasalt floodbasalt flow
Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent.
A flood 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.

Pillow lava

pillow lavaspillowedpillow basalt
Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land.
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion.

Carbonatite

carbonatitescarbonaticcarbonatite complex
Lavas with high viscosity are rhyolite, dacite, andesite and trachyte, with cooled basaltic lava also quite viscous; those with low viscosities are freshly erupted basalt, carbonatite and occasionally andesite.
This is because carbonatite lava flows, being composed largely of soluble carbonates, are easily weathered and are therefore unlikely to be preserved in the geologic record.

Cryovolcano

cryovolcanismcryovolcaniccryovolcanoes
(See cryovolcanism).
A cryovolcano (sometimes informally called an ice volcano) is a type of volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock.

Natrocarbonatite

Natrocarbonatite is a rare carbonatite lava which erupts from the Ol Doinyo Lengai volcano in Tanzania within the East African Rift of eastern Africa.

Lastarria

Lastarria is formed by two volcanic edifices and one subsidiary lava flow field.

Komatiite

komatiiteskomatiitic
Ultramafic lavas such as komatiite and highly magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme.
Basaltic lavas normally have eruption temperatures of about 1100 to 1250 °C.

Volcanology

volcanologistsvolcanologistvulcanology
General features of volcanology can be used to classify volcanic edifices and provide information on the eruptions which formed the lava flow, even if the sequence of lavas have been buried or metamorphosed.
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena (volcanism).

Volcanic gas

gasgasesgaseous content
These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating directly from lava or indirectly through ground water heated by volcanic action.

Tuff

welded tufftuffaceoustuffs
Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent.

Ol Doinyo Lengai

Oldonyo LengaiOldoinyo LengaiLengai
Part of the volcanic system of the East African Rift, it uniquely produces natrocarbonatite lava.

Lava tube

lava tubeslava tunnellava-tunnels
It also forms lava tubes where the minimal heat loss maintains low viscosity.
A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow.

Xenolith

xenocrystxenolithsxenocrysts
Lavas also may contain many other components, sometimes including solid crystals of various minerals, fragments of exotic rocks known as xenoliths and fragments of previously solidified lava.
Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme or picked up along the base of a flowing body of lava on the Earth's surface.

Stratovolcano

stratovolcanoescomposite volcanostratovolcanic
They range in shape from shield volcanoes with broad, shallow slopes formed from predominantly effusive eruptions of relatively fluid basaltic lava flows, to steeply-sided stratovolcanoes (also known as composite volcanoes) made of alternating layers of ash and more viscous lava flows typical of intermediate and felsic lavas.
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash.

Sill (geology)

sillsillsigneous sill
Discriminating between an intrusive sill and a lava flow in ancient rock sequences can be difficult.
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock.

Volcano

volcanicvolcanoesvolcanic igneous activity
A lava fountain is a volcanic phenomenon in which lava is forcefully but non-explosively ejected from a crater, vent, or fissure.
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Breccia

brecciasvolcanic brecciaimpact breccia
The ideal lava flow will have a brecciated top, either as pillow lava development, autobreccia and rubble typical of aā and viscous flows, or a vesicular or frothy carapace such as scoria or pumice.
Volcanic pyroclastic rocks are formed by explosive eruption of lava and any rocks which are entrained within the eruptive column.