A batholith () is a large mass of intrusive

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

(also called

plutonic Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...

rock), larger than in area, that forms from cooled

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such as

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

, quartz monzonite, or

diorite Diorite ( ) is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-sili ...

(see also '' granite dome''). Intrusion types

Formation

Although they may appear uniform, batholiths are in fact structures with complex histories and compositions. They are composed of multiple masses, or '' plutons'', bodies of igneous rock of irregular dimensions (typically at least several kilometers) that can be distinguished from adjacent igneous rock by some combination of criteria including age, composition, texture, or mappable structures. Individual plutons are solidified from magma that traveled toward the surface from a zone of

partial melting Partial melting occurs when only a portion of a solid is melted. For mixed substances, such as a rock containing several different minerals or a mineral that displays solid solution, this melt can be different from the bulk composition of the soli ...

near the base of the Earth's crust. Vitosha platoto

Traditionally, these plutons have been considered to form by ascent of relatively

buoyant Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...

magma in large masses called ''plutonic diapirs''. Because the diapirs are liquified and very hot, they tend to rise through the surrounding native country rock, pushing it aside and partially melting it. Most diapirs do not reach the surface to form

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

es, but instead they slow down, cool, and usually solidify 5 to 30 kilometers underground as plutons (hence the use of the word ''pluton''; in reference to the Roman god of the underworld

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest ...

). An alternate view is that plutons commonly are formed not by ascent of large magma diapirs, but rather by aggregation of smaller volumes of magma that ascend as dikes. A batholith is formed when many plutons converge to form a huge expanse of granitic rock. Some batholiths are mammoth, paralleling past and present subduction zones and other heat sources for hundreds of kilometers in

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' be ...

. One such batholith is the Sierra Nevada Batholith, which is a continuous granitic formation that makes up much of the Sierra Nevada in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. An even larger batholith, the

Coast Plutonic Complex The Coast Range Arc was a large volcanic arc system, extending from northern Washington through British Columbia and the Alaska Panhandle to southwestern Yukon. The Coast Range Arc lies along the western margin of the North American Plate in the ...

, is found predominantly in the Coast Mountains of western

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

; it extends for 1,800 kilometers and reaches into southeastern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

Surface expression and erosion

A batholith is an exposed area of (mostly) continuous plutonic rock that covers an area larger than 100 square kilometers (40 square miles). Areas smaller than 100 square kilometers are called '' stocks''. However, the majority of batholiths visible at the surface (via outcroppings) have areas far greater than 100 square kilometers. These areas are exposed to the surface through the process of

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

accelerated by continental uplift acting over many tens of millions to hundreds of millions of years. This process has removed several tens of square kilometers of overlying rock in many areas, exposing the once deeply buried batholiths. Batholiths exposed at the surface are subjected to huge pressure differences between their former location deep in the earth and their new location at or near the surface. As a result, their

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...

expands slightly over time. This manifests itself by a form of

mass wasting Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in ...

called exfoliation. This form of weathering causes convex and relatively thin sheets of rock to slough off the exposed surfaces of batholiths (a process accelerated by frost wedging). The result is fairly clean and rounded rock faces. A well-known result of this process is

Half Dome Half Dome is a granite dome at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three sides are smoo ...

Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about long and deep, surrounded by high granite summits such as Hal ...

Examples

Africa

*Aswan Granite Batholith *Cape Coast Batholith, Ghana *Heerenveen Batholith, South Africa *Paarl Rock, South Africa *Darling Batholith, South Africa *

Hook granite massif The Hook granite massif is a large formation in central Zambia formed around 550 million years ago during the Pan-African orogeny. It lies in the inner part of the Lufilian arc. Today, the south-western extension of the massif lies under the Kafue ...

, Zambia *Mubende Batholith, Uganda

Antarctica

*Antarctic Peninsula Batholith *Queen Maud Batholith

Asia

* Angara-Vitim batholith, Siberia * Bhongir Fort Batholith,

Telangana Telangana (; , ) is a state in India situated on the south-central stretch of the Indian peninsula on the high Deccan Plateau. It is the eleventh-largest state and the twelfth-most populated state in India with a geographical area of and 3 ...

, India * Chibagalakh batholith, Siberia *Mount Abu, India * Gangdese batholith, Himalaya *Trans-Himalayan Batholith, Himalaya * Kalba-Narym batholith, Kazakhstan *Karakorum Batholith, Himalaya *Tak batholith, Thailand *Tien Shan batholith, Central Asia *Ranchi batholith, India

Europe

*Bindal Batholith, Norway *

Cornubian batholith The Cornubian batholith is a large mass of granite rock, formed about 280 million years ago, which lies beneath much of Devon and Cornwall, the south-western peninsula of Great Britain. The main exposed masses of granite are seen at Dartmoor, Bo ...

, England *Corsica-Sardinia Batholith * Donegal batholith, Ireland *Leinster Batholith, Ireland *Mancellian batholith, France * North Pennine Batholith, England * Ljusdal Batholith, Sweden * Mt-Louis-Andorra Batholith *Riga Batholith, Latvia *Salmi Batholith, Republic of Karelia, Russia *Sunnhordaland Batholith, Norway * Transscandinavian Igneous Belt, Sweden and Norway :*Revsund Massif :*Rätan Batholith :*Småland–Värmland Belt *

Vitosha Vitosha ( bg, Витоша ), the ancient ''Scomius'' or ''Scombrus'', is a mountain massif, on the outskirts of Sofia, the capital of Bulgaria. Vitosha is one of the symbols of Sofia and the closest site for hiking, alpinism and skiing. Conven ...

- Plana,

Sofia Sofia ( ; bg, София, Sofiya, ) is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain in the western parts of the country. The city is built west of the Iskar river, and h ...

, Bulgaria

North America

* Bald Rock Batholith * Boulder Batholith *

British Virgin Islands ) , anthem = "God Save the King" , song_type = Territorial song , song = " Oh, Beautiful Virgin Islands" , image_map = File:British Virgin Islands on the globe (Americas centered).svg , map_caption = , mapsize = 290px , image_map2 = Bri ...

Chambers-Strathy Batholith The Chambers-Strathy Batholith, also called the Strathy-Chambers Batholith, is a large granitoid batholith complex in the Temagami, Ontario, Temagami region of Northeastern Ontario, Canada. Named for the Chambers Township, Ontario, Chambers and Str ...

* Chilliwack batholith *Golden Horn Batholith * Idaho Batholith *Ilimaussaq Batholith,

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

* Kenosha Batholith * Mount Stewart Batholith,

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

* Wallowa Batholith,

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

* Peninsular Ranges, Baja and

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

* Pike's Peak Granite Batholith *

Ruby Mountains The Ruby Mountains are a mountain range, primarily located within Elko County with a small extension into White Pine County, in Nevada, United States. Most of the range is included within the Humboldt-Toiyabe National Forest. The range reache ...

*Rio Verde Batholith, Mexico * San Lorenzo Batholith,

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...

* Sierra Nevada Batholith * South Mountain Batholith, Nova Scotia * Town Mountain Granite batholith, Texas * Wyoming batholith

Oceania

*Cullen Batholith, Australia * Kosciuszko Batholith, Australia * Moruya Batholith, Australia * Scottsdale Batholith, Australia Stratigraphic revision and remapping of the Mathinna Supergroup between the River Tamar and the Scottsdale Batholith, northeast Tasmania
Department of Infrastructure, Energy and Resources. Mineral Resources Tasmania. June 2011 *Median Batholith, New Zealand *New England Batholith, Australia

South America

* Achala Batholith, Argentina * Antioquia Batholith, Colombia *Guanambi Batholith,

Bahia Bahia ( , , ; meaning "bay") is one of the 26 states of Brazil, located in the Northeast Region of the country. It is the fourth-largest Brazilian state by population (after São Paulo, Minas Gerais, and Rio de Janeiro) and the 5th-largest b ...

, Brazil * Parguaza rapakivi granite Batholith, Venezuela and Colombia * Cerro Aspero Batholith, Argentina * Coastal Batholith of Peru * Colangüil Batholith, Argentina * Cordillera Blanca Batholith, Peru * Vicuña Mackenna Batholith, Chile * Elqui-Limarí Batholith, Chile and Argentina * Futrono-Riñihue Batholith, Chile * Illescas Batholith, Uruguay * Coastal Batholith of central Chile * Panguipulli Batholith, Chile *Patagonian Batholith, Chile and Argentina ** North Patagonian Batholith ** South Patagonian Batholith

References

* Plummer, McGeary, Carlson, ''Physical Geology'', Eighth Edition (McGraw-Hill: Boston, 1999) pages 61–63 * Glazner, Bartley, Coleman, Gray, Taylor
Are plutons assembled over millions of years by amalgamation from small magma chambers?
GSA Today: Vol. 14, No. 4, pp. 4–11

External links

{{Authority control Volcanism