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Encyclopedia > Traprock
Basalt
Basalt

Basalt is a common gray to black volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black, characterized by a preponderance of calcic plagioclase feldspars and pyroxene together with minor amounts of accessory minerals such as olivine. This is a file from the Wikimedia Commons, a repository of free content hosted by the Wikimedia Foundation. ... This is a file from the Wikimedia Commons, a repository of free content hosted by the Wikimedia Foundation. ... Ignimbrite is a deposit of a pyroclastic flow. ... Look up lava, Aa, and pahoehoe in Wiktionary, the free dictionary. ... (For other meanings of Porphyr, see Porphyry) The baptismal font in the Cathedral of Magdeburg is made of rose porphyry from a site near Assuan, Egypt Porphyry is a very hard red, green or purple igneous rock consisting of large-grained crystals, such as feldspar or quartz, dispersed in a... The matrix or groundmass of an igneous rock consists of fine grained often microscopic crystals in which larger crystals (phenocrysts) are embedded. ... Vesicular texture is a volcanic rock texture characterised by, or containing, many vesicles. ... Scoria Scoria is a type of igneous rock containing many gas bubbles, or vesicules. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... Feldspar is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earths crust. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... Minerals are natural compounds formed through geological processes. ... Olivine The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 in which the ratio of magnesium and iron varies between the two endmembers of the series: forsterite (Mg-rich) and fayalite (Fe-rich). ...


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 should generally be referred to as dolerite or gabbro. The crustal portions of oceanic tectonic plates are predominantly made of basalt. Pluton redirects here. ... Phaneritic is a term usually used to refer to igneous rock grain size. ... Dolerite (from the Greek word doleros meaning deceptive), in petrology is the name given by Hauy to those basaltic rocks which are comparatively coarse grained. ... Gabbro specimen. ... [[Image:http://www. ... The tectonic plates of the world were mapped in the second half of the 20th century. ...

Contents


Morphology and textures

The shape, structure and texture of a basalt is diagnostic of the way it erupted 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. ... Cinders are nut-sized pieces of red or black rock fragments resulting from the ejection of liquid lava that are uncemented vitric, vesicular, pyroclastic material, more than 2. ... Lava is molten rock that a volcano expels during an eruption. ... Official language(s) Hawaiian and English Capital Largest city Honolulu Honolulu Area  - Total   - Width   - Length    - % water  - Latitude  - Longitude Ranked 43rd 10,941 sq mi  28,337 km² n/a miles  n/a km 1,522 miles  2,450 km 41. ...

Columnar jointed basalt in Turkey
Columnar jointed basalt in Turkey

Image File history File links Download high resolution version (2304x1728, 1708 KB)Basalt Columns in Boyabat Province, Sinop, Turkey (Black Sea Region). ... Image File history File links Download high resolution version (2304x1728, 1708 KB)Basalt Columns in Boyabat Province, Sinop, Turkey (Black Sea Region). ... A geological joint is a generally planar fracture formed in a rock from extensional stress. ...

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. Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash is the term for very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... Breccia, derived from the Latin word for broken, is a sedimentary rock composed of angular fragments in a matrix that may be of a similar or a different 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. Basaltic cinders are often red, coloured by oxidised iron from weathered iron-rich minerals such as pyroxene. Cinder Cone is a cinder cone volcano in Lassen Volcanic National Park. ... Vesicular texture is a volcanic rock texture characterised by, or containing, many vesicles. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ...


‘A‘a types of blocky, cinder and breccia flows of thick, viscous basaltic magma are common in Hawaii and other basalts which erupt slightly cooler. Pahoehoe is a highly fluid, hot form of basalt which tends to form thin aprons of molten lava which fill up hollows and form lava lakes. Lava tubes are common features of pahoehoe eruptions. Look up lava, Aa, and pahoehoe in Wiktionary, the free dictionary. ... Lava is molten rock that a volcano expels during an eruption. ... Thurston Lava Tube in Hawaii_Volcanoes_National_Park Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow. ...


Basaltic tuff or pyroclastic rocks are rare but not unknown. 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. Hawaii's Mauna Loa erupted in this way in the 19th century. Another example is the 0.2Ma Diamond Head Tuff, Hawaii. Welded tuff at Golden Gate in Yellowstone National Park Tuff (from the Italian tufo and pronounced tuf) is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. ... Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. ... Mauna Loa is an active shield volcano in the Hawaiian Islands, one of five volcanic peaks that together form the Island of Hawaii. ... Diamond Head is the name of a tuff cone on the Hawaiian island of Oahu and known to Hawaiians as LÄ“ahi (photograph at right). ...

Columnar jointing in the basalt of the Giant's Causeway in Ireland
Enlarge
Columnar jointing in the basalt of the Giant's Causeway in Ireland

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. Image File history File linksMetadata Download high resolution version (1024x768, 282 KB) Summary Hexagonal basaltic stones at the Giants Causeway in Nothern Ireland co. ... Image File history File linksMetadata Download high resolution version (1024x768, 282 KB) Summary Hexagonal basaltic stones at the Giants Causeway in Nothern Ireland co. ... A geological joint is a generally planar fracture formed in a rock from extensional stress. ... Basalt columns The Giants Causeway is an area of 40,000 tightly packed basalt columns resulting from a volcanic eruption 60 million years ago. ... This page describes the geological feature. ...


Amygdaloidal structure is common in relic vesicles and beautifully crystallized species of zeolites, quartz or calcite are frequently found. Columnar basalt is formed by cooling of a thick lava flow, which forms contractional joints or fractures. The typical hexagonal shape of the columnar jointing is caused by the presence of pyroxene, which is a hexagonal mineral, and a form of fractal influence on the joint formation by the pyroxene which dominates in the groundmass of the basalt. Pentagonal, heptagonal or octagonal joint patterns are also known, but are less common. In Geology, a vesicle is a small enclosed cavity found in some volcanic rock--such as basalt--formed by the entrapment of gas bubbles as the material solidifies. ... It has been suggested that crystallization processes be merged into this article or section. ... Zeolite Zeolites (Greek, zein,to boil;lithos,a stone) are minerals that have a porous structure. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... SAM WAS HERE!!!!!!!!!! Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... A geological joint is a generally planar fracture formed in a rock from extensional stress. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... The boundary of the Mandelbrot set is a famous example of a fractal. ...


Submarine eruptions

Pillow basalts on the south Pacific seafloor
Pillow basalts on the south Pacific seafloor

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. 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. Size of individual pillows vary from 10 cm up to several metres. Image File history File links Pillow basalts on the south Pacific seafloor: Courtesy of NOAA. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Pillow basalts on the south Pacific seafloor: Courtesy of NOAA. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...


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 is a basalt volcano which breached the ocean surface in 1963. 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. Surtsey, sixteen days after the onset of the eruption Surtsey (Icelandic: Surturs island) is a volcanic island off the southern coast of Iceland. ... The Atlantic Ocean is Earths second-largest ocean, covering approximately one_fifth of its surface. ...


Glass or obsidian may be present, particularly as rinds on rapidly chilled surfaces of lava flows, and is commonly (but not exclusively) associated with underwater eruptions. The material definition of glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly to below its glass transition temperature, thereby not giving enough time for a regular crystal lattice to form. ... Obsidian from Lake County, Oregon Top stone is obsidian, below that is pumice and in lower right hand is rhyolite (light color) Obsidian is a type of naturally occurring glass, produced from volcanoes when a fluid felsic lava cools rapidly and freezes without sufficient time for crystal growth, for example...


Distribution

The lava flows of the Deccan Traps in India, the Siberian Traps in Russia, the Columbia River Plateau of Washington and Oregon states in the United States, as well as the Triassic lavas of eastern North America are basalts. Other famous accumulations of basalts include Iceland and the islands of the Hawaii volcanic chain, forming above a mantle plume. Look up lava, Aa, and pahoehoe in Wiktionary, the free dictionary. ... The Deccan Traps is a large igneous province located in west-central India and is one of the largest volcanic features on Earth. ... The Siberian Traps form a large igneous province in Siberia. ... The Washington towns of Spokane, Vantage, Yakima and Pasco, and the Oregon town of Pendleton, lie on the Columbia River Plateau. ... Official language(s) None Capital Olympia Largest city Seattle Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 18th 184,824 km² 385 km 580 km 6. ... Official language(s) None Capital Salem Largest city Portland Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 9th 255,026 km² 420 km 580 km 2. ... The Triassic is a geologic period that extends from about 245 to 202 Ma (million years ago). ... World map showing North America A satellite composite image of North America. ... Official language(s) Hawaiian and English Capital Largest city Honolulu Honolulu Area  - Total   - Width   - Length    - % water  - Latitude  - Longitude Ranked 43rd 10,941 sq mi  28,337 km² n/a miles  n/a km 1,522 miles  2,450 km 41. ... A mantle plume is a manifestation of a type of geological phenomenon originally proposed by W. Jason Morgan in 1971. ...


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. Basalt columns The Giants Causeway is an area of 40,000 tightly packed basalt columns resulting from a volcanic eruption 60 million years ago. ... A regular hexagon A hexagon (also known as sexagon) is a polygon with six edges and six vertices. ...


Ancient precambrian basalts are usually only found in fold and thrust belts, and are often heavily metamorphosed. These are known as greenstone belts. Jade or nephrite is a gem mineral found in metamorphosed basalts. The Precambrian is an informal name for the eons of the geologic timescale that came before the current Phanerozoic eon. ... New Zealand greenstone is formed by the metamorphism of basalt. ... A selection of antique, hand-crafted Chinese jadeite jade buttons Jade An ornamental stone, jade is a name applied to two different silicate minerals. ... There is also a community named Actinolite,_Ontario in Canada. ...

Pliny used the word basalt and it is said to have had an Ethiopian origin, meaning a black stone. Basalt columns The Giants Causeway is an area of 40,000 tightly packed basalt columns resulting from a volcanic eruption 60 million years ago. ... The longer fragments of basalt at the base of the cliff can be larger than a person. ... The Uniting Church at Narooma from 1914 The parsonage associated with Naroomas Uniting Church Bridge at Narooma on the Princes Highway Narooma is a town in the Australian state of New South Wales on the far south coast. ... Holyrood Park is a royal park in central Edinburgh, Scotland. ... Pliny the Elder: an imaginative 19c portrait. ...


Lunar basalt

The dark areas visible on Earth's moon, the lunar maria, are plains of basalt and gabbro, and basalt Moon samples were brought to Earth by the astronauts of the Apollo program. Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... A map showing the location of Mare Imbrium The Lunar maria (singular: mare, pronounced MAH-ray) are large, dark, basaltic plains on Earths Moon, formed by ancient basaltic flood eruptions caused by extremely large meteoroid impacts. ... Gabbro specimen. ... U.S. Space Shuttle astronaut Bruce McCandless II using a manned maneuvering unit. ... Description Role: Earth and Lunar Orbit Crew: 3; CDR, CM pilot, LM pilot Dimensions Height: 36. ...


Lunar basalts occur in two forms;

  • High titanium (Ti) basalts, with 9-13% TiO2, generally confined to the period 3.85 to 3.55 Giga-annum (Ga)
  • Low-Ti lavas (1 to 5% TiO2) are most common in the period 3.45-3.15 Ga (Meyer, 1987).

Lunar basalts show exotic textures and mineralogy, particularly shock metamorphism, lack of the oxidation typical of terrestrial basalts, lack of hydration and peculiar geochemistry. Their short period of eruption is considered to be related to the swift cooling of the Moon's magma ocean after the satellite formed from a theorised impact with a Mars-sized body. General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. ... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... For the Roman god, see Mars (mythology). ...


Types of basalt

  • Tholeiitic basalt is relatively rich in silica and poor in sodium. 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. Pyroxene (augite and orthopyroxene or pigeonite), calcium-rich plagioclase, and magnetite are common minerals. Contains interstitial quartz or tridymite plus minor olivine.
  • Olivine tholeiite has augite and orthopyroxene or pigeonite with abundant olivine. Olivine may have rims of pyroxene.
  • High alumina basalt has typically only augite with common olivine. Has greater than 17% alumina (Al2O3) and less titanium than tholeites.
  • Alkaline basalt is relatively poor in silica and rich in sodium. It has augite, olivine, feldspathoids, and may have alkali feldspar and phlogopite.

[1] [2] The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... [[Image:http://www. ... A flood basalt is a giant volcanic eruption that coats large stretches of land with basalt lava. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... Augite is a mafic mineral described chemically as (Ca, Na)(Mg, Fe, Al)(Al, Si)2O6 or calcium sodium magnesium iron aluminium silicate. ... This page meets Wikipedias criteria for speedy deletion. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... Magnetite is a ferromagnetic mineral form of iron(II,III) oxide, with chemical formula , one of several iron oxides and a member of the spinel group. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... Tridymite Tridymite is a high-temperature polymorph of quartz and usually occurs as minute tabular white or colorless pseudo-hexagonal triclinic crystals, or scales, in cavities in acidic volcanic rocks. ... Olivine The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 in which the ratio of magnesium and iron varies between the two endmembers of the series: forsterite (Mg-rich) and fayalite (Fe-rich). ... Aluminium oxide (or aluminum oxide) (Al2O3) is a chemical compound of aluminium and oxygen. ... 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) is a specific type of base, formed as a carbonate, hydroxide or other ionic salt of an alkali metal or alkali earth metal element. ... Feldspar is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earths crust. ... Phlogopite is a yellow, greenish or reddish brown member of the mica family of phyllosilicates. ...


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. These are; The term Metamorphic can be associated with a number of meanings:- Metamorphic rock The term for rocks that have been transformed by extreme heat and pressure. ... The term facies was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy (see Cross and Homewood 1997), which replaced the earlier notions of Neptunism. ...

Metamorphosed basalts are important hosts for a variety of hydrothermal ore deposits, including gold deposits, nickel deposits, volcanogenic massive sulfide ore deposits and others. Greenschist is a general field petrologic term applied to metamorphically altered mafic volcanic rock. ... Blueschist is a rock that forms by the metamorphism of sodium-rich basic rocks at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to 400 degrees Celsius (cool by metamorphic standards). ... Zeolite facies describes the mineral assemblage resulting from the pressure and temperature conditions of low-grade metamorphism. ... Modern petrology defnes a granulite sensuo stricto as a coarse grained, high-grade metamorphic rock composed primarily of pyroxene, plagioclase feldspar and accessory garnet, oxide and amphibole. ... Eclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. ... Iron ore (Banded iron formation) Manganese ore Lead ore Gold ore An ore is a volume of rock containing components or minerals in a mode of occurrence which renders it valuable for mining. ... General Name, Symbol, Number gold, Au, 79 Chemical series transition metals Group, Period, Block 11, 6, d Appearance metallic yellow Atomic mass 196. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic Atomic mass 58. ... Volcanogenic massive sulfide ore deposits or VMS are a type of metal sulfide ore deposit, mainly Cu-Zn, associated with certain types of volcanism. ...


See also

Wikimedia Commons has media related to:
Category:Basalt

Image File history File links Commons-logo. ... The Wikimedia Commons (also called Commons or Wikicommons) is a repository of free content images, sound and other multimedia files. ... Basalt fiber or fibre is a material made from extremely fine fibers of basalt, which is composed of the minerals plagioclase, pyroxene, and olivine. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... A volcano is a geological landform usually generated by the eruption through a planets surface of magma, molten rock welling up from the planets interior. ... Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ...

References

  1.   Hyndman, Donald W. (1985). Petrology of igneous and metamorphic rocks, 2nd ed., McGraw-Hill. ISBN 0-07-031658-9.
  2.   Blatt, Harvey and Robert Tracy (1996). Petrology, 2nd ed., Freeman. ISBN 0-7167-2438-3.

External links

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

  Results from FactBites:
 
Summer 2002 Conservation Perspectives: New and Ancient Treasures: the Traprock Mountains of New England - E. Farnsworth (3901 words)
Yellow corydalis is one of the earliest plants to flower on the traprock ridges of Connecticut, blooming in April when insects are few and frequently hampered by variable spring weather.
Traprock also provides a handy raw material for gravel and pavement; thus, quarries have exploited the Metacomet Range for decades.
Home to a controversial traprock quarry and vulnerable to further development, this property at the heart of Mt. Tom is critical to the ecological integrity of the mountain and its scenic and recreational pleasures.
traprock 여고생들의 춤 여고생들의 춤 엽기적인 중국 소녀 탁재훈 부인 백지영 싸움 마니아 (101 words)
traprock 여고생들의 춤 여고생들의 춤 엽기적인 중국 소녀 탁재훈 부인 백지영 싸움 마니아
터이니 traprock 그 분부에 복종하자 ---- 한명회는 이런 뜻을 말하였다.
하는 수가 있지만, 사회생활에서도 그렇게 한다면 타격을 traprock들이 받게 될 것입니다.
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