Large igneous rock intrusion
Half Dome
, a
quartz monzonite
monolith
in
Yosemite National Park
and part of the
Sierra Nevada Batholith
A
batholith
(from
Ancient Greek
bathos
'depth', and
lithos
'rock') is a large mass of
intrusive
igneous rock
(also called plutonic rock), larger than 100 km
2
(40 sq mi) in area,
[1]
that forms from cooled
magma
deep in the
Earth's crust
. Batholiths are almost always made mostly of
felsic
or
intermediate
rock types, such as
granite
,
quartz monzonite
, or
diorite
(see also
granite dome
).
Basic types of
igneous intrusions
:
1.
Laccolith
2. Small
dike
3.
Batholith
4.
Dike
5.
Sill
6.
Volcanic neck
and
pipe
7.
Lopolith
Note: As a general rule, in contrast to the active volcanic vent in the figure, these names refer to the fully cooled and usually millions-of-years-old rock formations, which are the result of the underground magmatic activity shown.
Formation
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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
near the base of the Earth's crust.
The eroded laccolith above the batholith system of
Vitosha
-
Plana
domed mountains, next to
Sofia
,
Bulgaria
Traditionally, these plutons have been considered to form by ascent of relatively buoyant 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
volcanoes
, 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
). An alternate view is that plutons are formed by aggregation of smaller volumes of magma that ascend as
dikes
.
[2]
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
. One such batholith is the
Sierra Nevada Batholith
, which is a continuous granitic formation that makes up much of the
Sierra Nevada
in California. An even larger batholith, the
Coast Plutonic Complex
, is found predominantly in the
Coast Mountains
of western Canada; it extends for 1,800 kilometers and reaches into southeastern Alaska.
Surface expression and erosion
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]
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
.
[3]
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
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
expands slightly over time. This manifests itself by a form of
mass wasting
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
in
Yosemite Valley
.
Examples
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]
Africa
[
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]
- Aswan Granite Batholith
- Cape Coast Batholith, Ghana
- Heerenveen Batholith, South Africa
[4]
- Paarl Rock, South Africa
- Darling Batholith, South Africa
- Hook granite massif
, Zambia
- Mubende Batholith, Uganda
Antarctica
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]
- Antarctic Peninsula Batholith
- Queen Maud Batholith
Asia
[
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]
- Angara-Vitim batholith
, Siberia
- Bhongir
Fort Batholith,
Telangana
, India
[5]
- Chibagalakh batholith
, Siberia
- Mount Abu, India
[6]
- 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
[
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]
- Bindal Batholith, Norway
- Cornubian batholith
, 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
- Ratan Batholith
- Smaland?Varmland Belt
|
North America
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]
Oceania
[
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]
- Cullen Batholith, Australia
- Kosciuszko
Batholith, Australia
- Moruya
Batholith, Australia
- Scottsdale
Batholith, Australia
[11]
- Median Batholith, New Zealand
- New England Batholith, Australia
South America
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]
- Achala Batholith
, Argentina
- Antioquia Batholith
, Colombia
- Guanambi Batholith,
Bahia
, Brazil
- Parguaza rapakivi granite Batholith
, Venezuela and Colombia
- Cerro Aspero Batholith
, Argentina
- Coastal Batholith of Peru
- Colanguil Batholith
, Argentina
- Cordillera Blanca Batholith
, Peru
- Vicuna Mackenna Batholith
, Chile
- Elqui-Limari Batholith
, Chile and Argentina
- Futrono-Rinihue Batholith
, Chile
- Illescas Batholith
, Uruguay
- Coastal Batholith of central Chile
- Panguipulli Batholith
, Chile
- Patagonian Batholith, Chile and Argentina
|
See also
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]
References
[
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]
- ^
Petersen, James F.; Sack, Dorothy; Gabler, Robert E. (2017).
Physical Geography
(11th ed.). Boston:
Cengage
Learning Inc. p. 614.
ISBN
978-1-305-65264-4
.
- ^
Hall, Clarence A. Jr. (2007).
Introduction to the geology of southern California and its native plants
. Berkeley: University of California Press. p. 22.
ISBN
9780520249325
.
- ^
GLENCOE SCIENCE | Earth Science Twelfth Grade High School Textbook (Georgia); pg. 115 paragraph 1, pg. 521 question 9
- ^
Clemens, J.D.; Belcher, R.W; Kisters, A.F.M. (2010).
"The Heerenveen Batholith, Barberton Mountain Land, South Africa: Mesoarchaean, Potassic, Felsic Magmas Formed by Melting of an Ancient Subduction Complex"
.
Journal of Petrology
.
51
(5): 1099?1120.
doi
:
10.1093/petrology/egq014
.
{{
cite journal
}}
: CS1 maint: multiple names: authors list (
link
)
- ^
"Bhongir fort's batholith marvel"
. June 2016.
- ^
"Rapid Uplift: Mount Abu Geology"
. 22 July 2018.
- ^
Erik H. Erikson Jr.
"Petrogenesis of the Mount Stuart Batholith Plutonic Equivalent of the High-Aluina Basalt Association"
(PDF)
.
The Mount Stuart batholith is a Late Cretaceous calc-alkaline pluton composed of intrusive phases ranging in composition from two-pyroxene gabbro to granite.
- ^
Myrl E. BeckJr.; Russell F. Burmester; Ruth Schoonover.
"Paleomagnetism and tectonics of the Cretaceous Mt. Stuart Batholith of Washington: translation or tilt?"
.
The Mt. Stuart Batholith is a composite pluton of Late Cretaceous age that intrudes the crystalline North Cascades terrane of northwestern Washington.
- ^
Morton, Douglas M.; Miller, Fred K. (2014).
Douglas M. Morton, Fred K. Miller, Peninsular Ranges Batholith, Baja and Southern California, Geological Society of America, 2014
.
ISBN
9780813712116
.
- ^
Davin A. Bagdonas; Carol D. Frost; C. Mark Fanning (2016).
"The origin of extensive Neoarchean high-silica batholiths and the nature of intrusive complements to silicic ignimbrites: Insights from the Wyoming batholith, U.S.A."
(PDF)
.
American Mineralogist
.
101
(6): 1332?1347.
Bibcode
:
2016AmMin.101.1332B
.
doi
:
10.2138/am-2016-5512
.
S2CID
131845599
. Retrieved
June 8,
2016
.
...Neoarchean granite batholith, herein named the Wyoming batholith, extends more than 200 km across central Wyoming in the Granite and the Laramie Mountains.
- ^
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
- Plummer, McGeary, Carlson,
Physical Geology
, Eighth Edition (McGraw-Hill: Boston, 1999) pages 61?63
ISBN
0-697-37404-1
- 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
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