iPedia Free Information Center

Information about Xenolith

This article concerns the geologic term, for other uses see: Xenolith (disambiguation)
Enlarge picture
A xenolith
A xenolith (Greek: 'foreign rock') is a rock fragment which becomes enveloped in a larger rock during the latter's development and hardening. In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement and eruption. 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 lava on Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes.

Although the term xenolith is most commonly associated with igneous inclusions, a broad definition could include rock fragments which have become encased in sedimentary rock. Xenoliths are sometimes found in recovered meteorites.

Enlarge picture
A xenolith in Larchmont, New York
To be considered a true xenolith, the included rock must be identifiably different from the rock in which it is enveloped; an included rock of similar type is called an autolith or a cognate inclusion.

Xenoliths and xenocrysts provide important information about the composition of the otherwise innacessible mantle. Basalts, kimberlites, lamproites and lamprophyres, which have their source in the upper mantle, often contain fragments and crystals assumed to be a part of the originating mantle mineralogy. Xenoliths of dunite, peridotite and spinel lherzolite in basaltic lava flows are one example. Kimberlites contain, in addition to diamond xenocrysts, fragments of lherzolites of varying composition. The aluminium-bearing minerals of these fragments provide clues to the depth of origin. Calcic plagioclase is stable to 25 km depth. Between 25 km and about 60 km, spinel is the stable aluminium phase. At depths greater than about 60 km, dense garnet becomes the aluminium-bearing mineral. Some kimberlites contain xenoliths of eclogite, which is considered to be the high-pressure metamorphic product of oceanic basaltic crust, as it descends into the mantle along subduction zones. (Blatt, 1996)

References

  • Blatt, Harvey, and Robert J. Tracy (1996) Petrology, W. H. Freeman, 2nd ed. ISBN 0-7167-2438-3
Xenolith may refer to:
  • Xenolith is a geologic term for foreign rock fragment within a host rock.
  • Xenolith is the name of a Microsoft Windows Trojan identified in January, 1998.
  • Xenolith is a role-playing game for the PC introduced in 2001.

..... Click the link for more information.
Ancient Greek refers to the second stage in the history of the Greek language[1] as it existed during the Archaic (9th–6th centuries BC) and Classical (5th–4th centuries BC) periods in Greece.
..... Click the link for more information.
Balanced Rock stands in Garden of the Gods park in Colorado Springs, CO]] A rock is a naturally occurring aggregate of minerals and/or mineraloids. The Earth's lithosphere is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic.
..... Click the link for more information.
Oceanic crust      0-20 Ma
..... Click the link for more information.
Igneous rocks (etymology from latin ignis, fire) are rocks formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.
..... Click the link for more information.
Magma (Plurals: magmas and magmata) is molten rock located beneath the surface of the Earth (or any other terrestrial planet) that often collects in a magma chamber. Magma may contain suspended crystals and gas bubbles.
..... Click the link for more information.
Magma (Plurals: magmas and magmata) is molten rock located beneath the surface of the Earth (or any other terrestrial planet) that often collects in a magma chamber. Magma may contain suspended crystals and gas bubbles.
..... Click the link for more information.
Lava is molten rock expelled by a volcano during an eruption. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F).
..... Click the link for more information.
A diatreme is a breccia filled volcanic pipe that was formed by a gaseous explosion. Diatremes often breach the surface and produce a tuff cone or a filled relatively shallow crater known as a maar or other volcanic pipes.
..... Click the link for more information.
Quartz (from German Quarz   (help info ) [1]) is the second most common mineral in the Earth's continental crust, feldspar being the first.
..... Click the link for more information.
Diamond is an allotrope of carbon. It is the hardest known natural material and the third-hardest known material after aggregated diamond nanorods and ultrahard fullerite. Its hardness and high dispersion of light make it useful for industrial applications and jewelry.
..... Click the link for more information.
Kimberlite is a type of rock best known for sometimes containing diamonds. It is named after the town of Kimberley in South Africa, where the finding of a large kimberlite pipe in the 1870s spawned a diamond rush.
..... Click the link for more information.
A diatreme is a breccia filled volcanic pipe that was formed by a gaseous explosion. Diatremes often breach the surface and produce a tuff cone or a filled relatively shallow crater known as a maar or other volcanic pipes.
..... Click the link for more information.
Sedimentary rock is one of the three main rock groups (the others being igneous and metamorphic rock). Rock formed from sediments covers 75-80% of the Earth's land area, and includes common types such as chalk, limestone, dolomite, sandstone, conglomerate and shale.
..... Click the link for more information.
A meteorite is a natural object originating in outer space that survives an impact with the Earth's surface without being destroyed. While in space it is called a meteoroid.
..... Click the link for more information.
mantle is a ~2,900 km thick rocky shell comprising approximately 70% of Earth's volume. It is predominantly solid and overlies the Earth's iron-rich core, which occupies about 30% of Earth's volume.
..... Click the link for more information.
Basalt (IPA: /ˈbæsɒlt, bəˈsɒlt/) is a common gray to black extrusive volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface.
..... Click the link for more information.
Kimberlite is a type of rock best known for sometimes containing diamonds. It is named after the town of Kimberley in South Africa, where the finding of a large kimberlite pipe in the 1870s spawned a diamond rush.
..... Click the link for more information.
Lamproites are ultrapotassic mantle-derived volcanic rocks. They have low CaO, Al2O3, Na2O, high K2O/Al2O3, a relatively high MgO content and extreme enrichment in incompatible elements.
..... Click the link for more information.
Lamprophyres (Greek Lampros, "bright", and the terminal part of the word "porphyry", meaning "rocks containing bright porphyritic crystals")

Lamprophyres are uncommon, small volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths,
..... Click the link for more information.
Not to be confused with Dunnite.


Dunite (IPA: /ˈduːnʌɪt, ˈdʌnʌɪt/
..... Click the link for more information.
Peridotite is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic and ultrabasic, as the rock contains less than 45% silica.
..... Click the link for more information.
The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. The general formula is as (X)(Y)2O4, with X representing cations occupying tetrahedral sites and Y cations occupying octahedral sites.
..... Click the link for more information.
Lherzolite is a type of ultramafic igneous rock. It is a coarse grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser calcic chromium rich clinopyroxene. Minor minerals include chromium and aluminium spinels and garnets.
..... Click the link for more information.
Basalt (IPA: /ˈbæsɒlt, bəˈsɒlt/) is a common gray to black extrusive volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface.
..... Click the link for more information.
Lherzolite is a type of ultramafic igneous rock. It is a coarse grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser calcic chromium rich clinopyroxene. Minor minerals include chromium and aluminium spinels and garnets.
..... Click the link for more information.
Aluminium (IPA: /ˌæljʊˈmɪniəm/, /ˌæljəˈmɪniəm/) or aluminum (IPA: /əˈluːmɪnəm/
..... Click the link for more information.
Plagioclase is a very important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar
..... Click the link for more information.
The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. The general formula is as (X)(Y)2O4, with X representing cations occupying tetrahedral sites and Y cations occupying octahedral sites.
..... Click the link for more information.
Garnet is a group of minerals that have been used since the Bronze Age as gemstones and abrasives. Garnets are most often seen in red, but are available in a wide variety of colors spanning the entire spectrum.
..... Click the link for more information.


This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus


page counter