Basalt (pronounced /ˈbæsɒlt, bəˈsɔːlt/) is a common mafic extrusive volcanic rock. Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" Extrusive refers to the mode of Igneous Volcanic rock formation in which hot Magma from inside the Earth flows out (extrudes onto the surface Volcanic rock is an Igneous rock of volcanic origin Texture Volcanic rocks are usually fine-grained or Aphanitic to glassy in It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded Vesicular texture is a Volcanic rock texture characterised by or containing many vesicles Scoria is a textural term for macrovesicular Volcanic rock. It is commonly but not exclusively Basaltic or andesitic in composition Unweathered basalt is black or gray.

On Earth, most basalt magmas have formed by decompression melting of the mantle. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Basalt has also formed on Earth's Moon, Mars, Venus, and even on the asteroid Vesta. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Source rocks for the partial melts probably include both peridotite and pyroxenite (e. A peridotite is a dense coarse-grained Igneous rock, consisting mostly of the minerals Olivine and Pyroxene. Pyroxenite is an Ultramafic Igneous rock consisting essentially of Minerals of the Pyroxene group such as Augite and g. , Sobolev et al. , 2007). The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below ocean ridges. In Geology, a crust is the outermost solid shell of a planet or moon An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by

The term basalt is at times applied to shallow intrusive rocks with a composition typical of basalt, but rocks of this composition with a phaneritic (coarse) groundmass are generally referred to as dolerite (also called diabase) or gabbro. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. Phaneritic is a term usually used to refer to igneous rock grain size. Diabase (ˈdaɪəbeɪs or Dolerite is a Mafic, Holocrystalline, Igneous rock equivalent to Volcanic Basalt or plutonic Diabase (ˈdaɪəbeɪs or Dolerite is a Mafic, Holocrystalline, Igneous rock equivalent to Volcanic Basalt or plutonic Gabbro (ˈɡæbrəʊ is a dark coarse-grained intrusive Igneous rock chemically equivalent to Basalt.

Contents 1 Types of basalt 2 Petrology 3 Geochemistry 4 Morphology and textures 4.1 Subaerial eruptions 4.1.1 Columnar basalt 4.2 Submarine eruptions 4.2.1 Pillow basalts 4.2.2 Life on basaltic rocks 5 Distribution 6 Lunar and Martian basalt 7 Metamorphism 8 See also 9 References 10 External links

Types of basalt

• Tholeiitic basalt is relatively poor in silica and poor in sodium. Tholeiitic basalt is an Igneous rock, a type of Basalt. Like all basalt the rock type is dominated by Clinopyroxene plus Plagioclase, with minor The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. A flood basalt or trap basalt is the result of a giant Volcanic eruption or series of Eruptions that coats large stretches of land or the Ocean floor The Columbia River Basalt Group is a Large igneous province that lies across parts of the states of Washington, Oregon, and Idaho in the
  • MORB (Mid Ocean Ridge Basalt), is characteristically low in incompatible elements. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by Incompatible element is a term used in Petrology and Geochemistry. MORB is commonly erupted only at ocean ridges. MORB itself has been subdivided into varieties such as NMORB and EMORB (slightly more enriched in incompatible elements). ^{[1] [2]}

• High alumina basalt may be silica-undersaturated or -oversaturated (see normative mineralogy). Normative mineralogy is a geochemical calculation of the whole rock geochemistry of a rock sample which estimates the idealised mineralogy of a rock according to the principles It has greater than 17% alumina (Al₂O₃) and is intermediate in composition between tholeiite and alkali basalt; the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. A phenocryst is a relatively large and usually conspicuous Crystal distinctly larger than the grains of the rock groundmass of a Porphyritic Igneous Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family

• Alkali basalt is relatively poor in silica and rich in sodium. It is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Normative mineralogy is a geochemical calculation of the whole rock geochemistry of a rock sample which estimates the idealised mineralogy of a rock according to the principles The feldspathoids are a group of tectosilicate Minerals which resemble Feldspars but have a different structure and much lower Silica content In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Phlogopite is a yellow greenish or reddish-brown member of the Mica family of phyllosilicates.

• Boninite is a high-magnesium form of basalt or andesite that is erupted generally in back-arc basins, distinguished by its low titanium content and trace element composition. Boninite is a Mafic Extrusive rock high in both Magnesium and silica formed in fore-arc environments typically during the early stages For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate Back-arc basins (or retro-arc basins are geologic features submarine basins associated with Island arcs and Subduction zones. Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22

Petrology

The mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene. Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Olivine can also be a significant constituent. The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg Accessory minerals present in relatively minor amounts include iron oxides and iron-titanium oxides, such as magnetite, ulvospinel, and ilmenite. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Altogether there are sixteen known Iron Oxides and oxyhydroxides Magnetite is not to be confused with Magnesite or Maghemite. Magnetite is a ferrimagnetic Mineral with chemical Ulvöspinel or ulvospinel is an iron titanium oxide mineral with formula Fe 2 Ti[[oxygen O]]4 Ilmenite is a weakly magnetic titanium-iron oxide Mineral which is iron-black or steel-gray Because of the presence of such oxide minerals, basalt can acquire strong magnetic signatures as it cools, and paleomagnetic studies have made extensive use of basalt. An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various Magnetic Minerals through time

In tholeiitic basalt, pyroxene (augite and orthopyroxene or pigeonite) and calcium-rich plagioclase are common phenocryst minerals. The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Augite is a single chain inosilicate Mineral described chemically as (CaMgFeSiO3 or Calcium Magnesium Iron The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Pigeonite is a mineral in the Clinopyroxene group It has a general formula of ( Ca, Mg, Fe)(MgFe Si 2 O 6 Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family A phenocryst is a relatively large and usually conspicuous Crystal distinctly larger than the grains of the rock groundmass of a Porphyritic Igneous Olivine may also be a phenocryst, and when present, may have rims of pigeonite. Pigeonite is a mineral in the Clinopyroxene group It has a general formula of ( Ca, Mg, Fe)(MgFe Si 2 O 6 The groundmass contains interstitial quartz or tridymite or cristobalite. The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Tridymite is a high-temperature polymorph of Quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal Triclinic crystals or scales The mineral cristobalite is a high-temperature polymorph of Quartz and Tridymite. Olivine tholeiite has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass. The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded

.

Alkali basalts typically have mineral assemblages that lack orthopyroxene but contain olivine. The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg Feldspar phenocrysts typically are labradorite to andesine in composition. Labradorite ((CaNa(AlSi4O8 a Feldspar Mineral, is an intermediate to calcic member of the Plagioclase series Andesine is a Feldspar Mineral, a part of the Plagioclase series Augite is rich in titanium compared to augite in tholeiitic basalt. Augite is a single chain inosilicate Mineral described chemically as (CaMgFeSiO3 or Calcium Magnesium Iron Minerals such as alkali feldspar, leucite, nepheline, sodalite, phlogopite mica, and apatite may be present in the groundmass. Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Leucite is a rock -forming Mineral composed of Potassium and Aluminium tectosilicate K Nepheline, also called nephelite (from Greek: nephos, "cloud" is a Feldspathoid: a silica-undersaturated aluminosilicate Na Sodalite is a rich royal blue Mineral widely enjoyed as an Ornamental stone. Phlogopite is a yellow greenish or reddish-brown member of the Mica family of phyllosilicates.

Basalt has high liquidus and solidus temperatures -- values at the Earth's surface are near or above 1200 °C (liquidus) and near or below 1000 °C (solidus); these values are higher than those of other common igneous rocks. The liquidus temperature, TL or Tliq is mostly used for Glasses and Alloys It specifies the maximum temperature at which Crystals Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock

The majority of tholeiites are formed at approximately 50-100 km depth within the mantle. Many alkali basalts may be formed at greater depths, perhaps as deep as 150-200 km. The origin of high-alumina basalt continues to be controversial, with interpretations that it is a primary melt and that instead it is derived from other basalt types (e. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet g. , Ozerov, 2000).

Geochemistry

Basalt compositions are rich in MgO and CaO and low in SiO₂ and Na₂O plus K₂O relative to most common igneous rocks, consistent with the TAS classification. Magnesium oxide, or magnesia, is a white solid Mineral that occurs naturally as Periclase and is a source Calcium oxide ( CaO) commonly known as burnt lime, lime or quicklime, is a widely used Chemical compound. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Sodium oxide is a Chemical compound with the formula Na 2 O. It is used in Ceramics and Glasses Treatment with water Potassium oxide is a compound of Potassium and Oxygen. This pale yellow solid the simplest oxide of potassium is a rarely encountered highly reactive Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock The TAS classification can be used to assign names to many common types of Volcanic rocks based upon the relationships between the combined alkali content and the silica content

Basalt generally has a composition of 45-55 wt% SiO₂, 2-6 wt% total alkalis, 0. 5-2. 0 wt% TiO₂, 5-14 wt% FeO and 14 wt% or more Al₂O₃. Titanium dioxide, also known as titanium(IV oxide or titania, is the naturally occurring Oxide of Titanium, chemical formula Ti[[oxygen Iron(II oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted Contents of CaO are commonly near 10 wt%, those of MgO commonly in the range 5 to 12 wt%.

High alumina basalts have aluminium contents of 17-19 wt% Al₂O₃; boninites have magnesium contents of up to 15% MgO. Rare feldspathoid-rich mafic rocks, akin to alkali basalts, may have Na₂O plus K₂O contents of 12% or more. The feldspathoids are a group of tectosilicate Minerals which resemble Feldspars but have a different structure and much lower Silica content Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric"

MORB basalts and their intrusive equivalents, gabbros, are the characteristic igneous rocks formed at mid-ocean ridges. Gabbro (ˈɡæbrəʊ is a dark coarse-grained intrusive Igneous rock chemically equivalent to Basalt. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by They are tholeiites particularly low in total alkalis and in incompatible trace elements, and they have relatively flat REE patterns normalised to mantle or chondrite values. Tholeiitic basalt is an Igneous rock, a type of Basalt. Like all basalt the rock type is dominated by Clinopyroxene plus Plagioclase, with minor Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely Chondrites are stony Meteorites that have not been modified due to Melting or Differentiation of the parent body In contrast, alkali basalts have normalized patterns highly enriched in the light REE, and with greater abundances of the REE and of other incompatible elements. Because MORB basalt is considered a key to understanding plate tectonics, its compositions have been much studied. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Although MORB compositions are distinctive relative to average compositions of basalts erupted in other environments, they are not uniform. For instance, compositions change with position along the Mid-Atlantic ridge, and the compositions also define different ranges in different ocean basins (Hofmann, 2003). The Mid-Atlantic Ridge (MAR is a Mid-ocean ridge, a Divergent tectonic plate boundary located along the floor of the Atlantic Ocean.

Isotope ratios of elements such as strontium, neodymium, lead, hafnium, and osmium in basalts have been much-studied, so as to learn about evolution of the Earth's mantle. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Strontium (ˈstrɒntiəm /ˈstrɒnʃiəm/) is a Chemical element with the symbol Sr and the Atomic number 38 Neodymium (ˌniːoʊˈdɪmiəm is a Chemical element with the symbol Nd and Atomic number 60 Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Hafnium (ˈhæfniəm is a Chemical element that has the symbol Hf and Atomic number 72 Osmium (ˈɒzmiəm is a Chemical element that has the symbol Os and Atomic number 76 The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided Isotopic ratios of noble gases, such as ³He/⁴He, are also of great value: for instance, ratios for basalts range from 6 to 10 for mid-ocean ridge tholeiite (normalized to atmospheric values), but to 15-24+ for ocean island basalts thought to be derived from mantle plumes. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle.

Morphology and textures

The shape, structure and texture of a basalt is diagnostic of how and where it erupted - whether into the sea, in an explosive cinder eruption or as creeping pahoehoe lava flows, the classical image of Hawaiian basalt eruptions. Rock microstructure includes the texture of a rock and the small scale rock structures A cinder is a pyroclastic material Cinders are extrusive Igneous rocks Cinders are similar to Pumice, which has so many cavities and is such low-density Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the

Subaerial eruptions

Basalt which erupts under open air (that is, subaerially) forms three distinct types of lava or volcanic deposits: scoria, ash or cinder; breccia and lava flows. In geology the term joint refers to a fracture in rock where there has been no lateral movement in the plane of the fracture (up down or sideways of one side The term subaerial, mainly used in Geology, describes events or structures located at the Earth 's surface "under the air" Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Breccia (ˈbrɛtʃiə ˈbrɛʃiə breach is a rock composed of angular fragments of several Minerals or rocks in a matrix, that is a cementing material

Basalt in the tops of subaerial lava flows and cinder cones will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. A cinder cone or scoria cone is a steep conical Hill of volcanic fragments that accumulate around and downwind from a Volcanic vent. Vesicular texture is a Volcanic rock texture characterised by or containing many vesicles Basaltic cinders are often red, coloured by oxidised iron from weathered iron-rich minerals such as pyroxene. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks.

‘A‘a types of blocky, cinder and breccia flows of thick, viscous basaltic lava are common in Hawaii. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Pahoehoe is a highly fluid, hot form of basalt which tends to form thin aprons of molten lava which fill up hollows and sometimes forms lava lakes. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Lava lakes are large volumes of molten Lava, usually Basaltic, contained in a vent Volcanic crater, or broad depression Lava tubes are common features of pahoehoe eruptions. Lava tubes are natural conduits through which Lava travels beneath the surface of a lava flow expelled by a Volcano during an eruption

Basaltic tuff or pyroclastic rocks are rare but not unknown. Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks Usually basalt is too hot and fluid to build up sufficient pressure to form explosive lava eruptions but occasionally this will happen by trapping of the lava within the volcanic throat and build up of volcanic gases. Volcanic gases include a variety of substances given off by active (or at times by dormant Volcanoes These include gases trapped in cavities ( Vesicles) in Hawaii's Mauna Loa volcano erupted in this way in the 19th century, as did Mount Tarawera, New Zealand in its violent 1886 eruption. Mauna Loa is the largest volcano on earth and one of five volcanoes that form the Island of Hawaii in the U Mount Tarawera is a volcanic Mountain 241 kilometres southeast of Rotorua in the North Island of New Zealand.

Maar volcanoes are typical of small basalt tuffs, formed by explosive eruption of basalt through the crust, forming an apron of mixed basalt and wall rock breccia and a fan of basalt tuff further out from the volcano. In geology the term joint refers to a fracture in rock where there has been no lateral movement in the plane of the fracture (up down or sideways of one side The Giant's Causeway (or Clochán na bhFómharach is an area of about 40000 interlocking Basalt columns the result of an ancient volcanic eruption Northern Ireland (Tuaisceart Éireann Ulster Scots: Norlin Airlann) is a Country within the United Kingdom, lying in the northeast of A maar is a broad low- Relief Volcanic crater that is caused by a Phreatomagmatic eruption, an Explosion caused by Groundwater

Amygdaloidal structure is common in relict vesicles and beautifully crystallized species of zeolites, quartz or calcite are frequently found. Vesicular texture is a Volcanic rock texture characterised by or containing many vesicles In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Zeolites (Greek zein, "to boil" lithos, "a stone" are hydrated Aluminosilicate Minerals and have a micro-porous structure Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3

Columnar basalt

During the cooling of a thick lava flow, contractional joints or fractures form. In geology the term joint refers to a fracture in rock where there has been no lateral movement in the plane of the fracture (up down or sideways of one side If a flow cools relatively rapidly, significant contraction forces build up. While a flow can shrink in the vertical dimension without fracturing, it cannot easily accommodate shrinking in the horizontal direction unless cracks form. The extensive fracture network that develops results in the formation of columns. The topology of the lateral shapes of these columns can broadly be classed as a random cellular network. These structures are often erroneously described as being predominantly hexagonal. In reality, the mean number of sides of all the columns in such a structure is indeed six (by geometrical definition), but polygons with three to twelve or more sides can be observed^[3]. In Statistics, mean has two related meanings the Arithmetic mean (and is distinguished from the Geometric mean or Harmonic mean Note that the size of the columns depends loosely on the rate of cooling; very rapid cooling may result in very small (<1 cm diameter) columns, while slow cooling is more likely to produce large columns. A centimetre ( American spelling: centimeter, symbol cm) is a unit of Length in the Metric system, equal to one hundredth

Perhaps the most famous basalt flow in the world is the Giant's Causeway on the northern coast of Ireland, in which the vertical joints form hexagonal columns and give the impression of having been artificially constructed. The Giant's Causeway (or Clochán na bhFómharach is an area of about 40000 interlocking Basalt columns the result of an ancient volcanic eruption Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world Regular hexagon The internal Angles of a regular hexagon (one where all sides and all angles are equal are all 120 ° and the hexagon has 720 degrees

An ancient 13th century religious complex, called Nan Madol, was built on the Pacific island of Pohnpei, using columnar basalt quarried from various locations on the island. Nan Madol is a ruined city that lies off the eastern shore of the island of Pohnpei (presently one of the four states in the Federated States of Micronesia) and used Pohnpei "upon ( pohn) a stone altar ( pei)" (formerly known as Ponape) is the name of one of the four states in the Federated The massive ruins remain to this day.

• Notable columnar basalts:
  • Giant's Causeway, Northern Ireland
  • Borgarvirki Fortress, Iceland
  • Devil's Postpile, California
  • Narooma Basalt, Narooma, New South Wales, Australia
  • Samson's ribs, Scotland
  • Staffa, Scotland
  • Pwisehn Malek, Pohnpei, Federated States of Micronesia ^[4]
  • Basalt Island area, Hong Kong; including High Island Reservoir area, Hong Kong SAR, China
  • Reynisdrangar, Vík í Mýrdal, Iceland
  • Thunderstruck Rocks (Detunatele), Romania

Submarine eruptions

Pillow basalts

When basalt erupts underwater or flows into the sea, the cold water quenches the surface and the lava forms a distinctive pillow shape, through which the hot lava breaks to form another pillow. The Giant's Causeway (or Clochán na bhFómharach is an area of about 40000 interlocking Basalt columns the result of an ancient volcanic eruption Borgarvirki lies between Vesturhóp and Víðidalur in the north of Iceland, and at 177m above sea level it dominates the surrounding region Devils Postpile is a dark cliff of Columnar basalt near Mammoth Mountain in For a topic outline on this subject see List of basic Australia topics. Holyrood Park (also called Queen's Park, and formerly King's Park) is a royal park in central Edinburgh, Scotland. Staffa ( Scottish Gaelic: Stafa, s̪t̪afa from the Old Norse for stave or pillar island is an island of the Inner Hebrides in Argyll and Pohnpei "upon ( pohn) a stone altar ( pei)" (formerly known as Ponape) is the name of one of the four states in the Federated The Federated States of Micronesia is an Island nation located in the Pacific Ocean, north of Papua New Guinea. Reynisdrangar are basalt sea stacks situated under the mountain Reynisfjall near the village Vík í Mýrdal, southern Iceland. The village Vík in the south of Iceland is indicated on road signs from a long distance (about 180  km from Reykjavík) despite its This pillow texture is very common in underwater basaltic flows and is diagnostic of an underwater eruption environment when found in ancient rocks. Pillows typically consist of a fine-grained core with a glassy crust and have radial jointing. The size of individual pillows varies from 10 cm up to several metres.

When pahoehoe lava enters the sea it usually forms pillow basalts. However when a'a enters the ocean it forms a littoral cone, a small cone-shaped accumulation of tuffaceous debris formed when the blocky a'a lava enters the water and explodes from built-up steam.

The island of Surtsey in the Atlantic Ocean is a basalt volcano which breached the ocean surface in 1963. Surtsey ( Icelandic: " Surtur's island" is a volcanic Island off the southern The initial phase of Surtsey's eruption was highly explosive, as the magma was quite wet, causing the rock to be blown apart by the boiling steam to form a tuff and cinder cone. This has subsequently moved to a typical pahoehoe type behaviour.

Volcanic glass may be present, particularly as rinds on rapidly chilled surfaces of lava flows, and is commonly (but not exclusively) associated with underwater eruptions. Volcanic glass can refer to any of several types of Vitreous Igneous rocks Most commonly it refers to Obsidian, a Rhyolitic

Life on basaltic rocks

The common corrosion features of underwater volcanic basalt suggest that microbial activity may play a significant role in the chemical exchange between basaltic rocks and seawater. The significant amounts of reduced iron, Fe(II), and manganese, Mn(II), present in basaltic rocks provide potential energy sources for bacteria. Recent research has shown that some Fe(II)-oxidizing bacteria cultured from iron-sulfide surfaces are also able to grow with basaltic rock as a source of Fe(II). ^[5] In recent work at Loihi Seamount, Fe- and Mn- oxidizing bacteria have been cultured from weathered basalts. Lōihi is a Seamount and undersea Volcano in the Hawaiian archipelago, located at 18 ^[6] The impact of bacteria on altering the chemical composition of basaltic glass (and thus, the oceanic crust) and seawater suggest that these interactions may lead to an application of hydrothermal vents to the origin of life. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins A hydrothermal vent is a Fissure in a planet's surface from which geothermally heated Water issues In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic

Distribution

The lava flows of the Deccan Traps in India, the Paraná Traps in Brazil, the Siberian Traps in Russia, the Columbia River Plateau of Washington and Oregon, as well as parts of the California inner coastal ranges in the United States, as well as the Triassic lavas of eastern North America are basalts. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures The Deccan Traps are a Large igneous province located on the Deccan Plateau of west-central India (between 17-24N 73-74E and one of the largest Volcanic India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country The Siberian Traps (Сибирские траппы form a Large igneous province in Siberia. Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending The Columbia River Plateau is a geologic and geographic region that lies across parts of the U Washington ( is a state in the Pacific Northwest region of the United States. Oregon ( is a state in the Pacific Northwest region of the United States. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The United States of America —commonly referred to as the The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago Other famous accumulations of basalts include Iceland, the Karoo flood basalt province in South Africa and the islands of the Hawaii volcanic chain, forming above a mantle plume. Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( The Karoo (a Khoisan word of uncertain etymology) is a semi- Desert region of South Africa. A flood basalt or trap basalt is the result of a giant Volcanic eruption or series of Eruptions that coats large stretches of land or the Ocean floor The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle. Basalt is the rock most typical of large igneous provinces. Large Igneous provinces (LIPS were originally defined by Coffin and Eldholm (1992 as areas of Earth's surface that contain very large volumes of magmatic rocks (typically

Ancient Precambrian basalts are usually only found in fold and thrust belts, and are often heavily metamorphosed. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current These are known as greenstone belts, because low-grade metamorphism of basalt produces chlorite, actinolite, epidote and other green minerals. Greenstone belts are zones of variably metamorphosed Mafic to Ultramafic Volcanic sequences with associated Sedimentary rocks that Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution For the community in Canada see Actinolite Ontario. For the Sailor Moon character Epidote is a Calcium Aluminium Iron sorosilicate Mineral, Ca2Al2(Fe3+Al(SiO4(Si2O7O(OH

Lunar and Martian basalt

The dark areas visible on Earth's moon, the lunar maria, are plains of flood basaltic lava flows. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions A flood basalt or trap basalt is the result of a giant Volcanic eruption or series of Eruptions that coats large stretches of land or the Ocean floor These rocks were sampled by the manned American Apollo program, the robotic Russian Luna program, and are represented among the lunar meteorites. The Luna programme (from the Russian word "Luna" meaning "Moon" occasionally called Lunik or Lunnik, was a series of Robotic spacecraft A Lunar meteorite is a Meteorite that is known to have originated on the Moon.

Lunar basalts differ from their terrestrial counterparts principally in their high iron contents, which typically range from about 17 to 22 wt% FeO. They also possess a stunning range of titanium concentrations (present in the mineral ilmenite), ranging from less than 1 wt% TiO₂, to about 13 wt. Ilmenite is a weakly magnetic titanium-iron oxide Mineral which is iron-black or steel-gray %. Traditionally, lunar basalts have been classified according to their titanium content, with classes being named high-Ti, low-Ti, and very-low-Ti. Nevertheless, global geochemical maps of titanium obtained from the Clementine mission demonstrate that the lunar maria possess a continuum of titanium concentrations, and that the highest concentrations are the least abundant. Spacecraft design The spacecraft was an octagonal prism 188 m high and 1

Lunar basalts show exotic textures and mineralogy, particularly shock metamorphism, lack of the oxidation typical of terrestrial basalts, and a complete lack of hydration. Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Mineral hydration is an inorganic chemical reaction where water is added to the Crystal structure of a Mineral, usually creating a new mineral usually called a While most of the Moon's basalts erupted between about 3 and 3. The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar 5 billion years ago, the oldest samples are 4. 2 billion years old, and the youngest flows, based on the age dating method of "crater counting," are estimated to have erupted only 1. 2 billion years ago.

Basalt is also a common rock on the surface of Mars, as determined by data sent back from the surface of Mars and by Martian meteorites. A Mars meteorite is a Meteorite that has landed on Earth and originated from Mars.

Metamorphism

Basalts are important rocks within metamorphic belts, as they can provide vital information on the conditions of metamorphism within the belt. Various metamorphic facies are named after the mineral assemblages and rock types formed by subjecting basalts to the temperatures and pressures of the metamorphic event. The term " Facies " can also refer to distinctive Facial expressions associated with conditions such as Williams syndrome. These are;

• Greenschist facies
• Blueschist facies
• Zeolite facies
• Granulite facies
• Eclogite facies

Metamorphosed basalts are important hosts for a variety of hydrothermal ore deposits, including gold deposits, copper deposits, volcanogenic massive sulfide ore deposits and others. Greenschist - also known as greenstone - is a general field petrologic term applied to metamorphic and/or altered Mafic Volcanic rock Blueschist (ˈbluːʃɪst is a rock that forms by the Metamorphism of Basalt and rocks with similar composition at high Pressures and low Zeolites (Greek zein, "to boil" lithos, "a stone" are hydrated Aluminosilicate Minerals and have a micro-porous structure Granulites are fine to medium–grained Metamorphic rocks that have experienced high Temperatures of metamorphism composed mainly of Feldspars sometimes associated Eclogite (ˈɛklədʒaɪt is a coarse-grained Mafic ( Basaltic in composition Metamorphic rock. Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Volcanogenic massive sulfide ore deposits or VMS are a type of Metal Sulfide ore deposit, mainly Cu - Zn which are associated with and

See also

• Basalt fiber
• Mafic rocks
• Volcanoes
• Igneous rocks
• Flood basalt

References

External links

• Lava - water interface
• Pillow lava USGS
• Petrology of Lunar Rocks and Mare Basalts
• Basalt in Northern Ireland
• Basalt Columns

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