Difference between revisions of "Petrology" - New World Encyclopedia

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'''Petrology''' is a field of [[geology]] which focuses on the study of [[Rock (geology)|rock]]s and the conditions by which they form. There are three branches of petrology, corresponding to the three types of rocks: [[igneous]], [[metamorphic rocks|metamorphic]], and [[sedimentary]]. The word petrology itself comes from the Greek word "petra", meaning rock. The word "lithology" once was approximately synonymous with [[petrography]], but today lithology is essentially a subdivision of petrology focusing on macroscopic hand-sample or outcrop-scale description of rocks.
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[[Image:Igneous rock Santoroni Greece.jpg|thumb|right|200px|A sample of igneous rock. The light-colored tracks show the direction of lava flow.]]
  
Petrology utilizes the classical fields of [[mineralogy]], [[petrography]], [[optical mineralogy]], and chemical analyses to describe the composition and texture of rocks. Modern petrologists also include the principles of [[geochemistry]] and [[geophysics]] through the studies of geochemical trends and cycles and the use of [[thermodynamic]] data and experiments to better understand the origins of rocks.
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'''Petrology''' is a field of [[geology]] that focuses on the study of [[Rock (geology)|rock]]s and the conditions under which they are formed. It utilizes the classical fields of [[mineralogy]], [[petrography]],<ref>"Petrography" is a branch of petrology involving the study of the mineral content and textural relationships within rocks. The term "lithology" was once roughly synonymous with petrography, but today lithology is essentially a subdivision of petrology focusing on macroscopic hand-sample or outcrop-scale description of rocks.</ref> and chemical analyses to describe the structure and composition of rocks. In addition, modern petrologists include the principles of [[geochemistry]] and [[geophysics]] to better understand the origins of rocks. There are three branches of petrology, corresponding to the three main types of rocks: [[igneous]], [[metamorphic]], and [[sedimentary]].
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The study of rocks provides us with important information about the nature of the [[Earth]]'s crust and mantle. In addition, it enables us to gain a sense of the Earth's history, including tectonic processes that occurred over the long course of geological time. On a practical level, the field of petrology helps us gain an understanding of many of the raw materials we rely on for our sustenance and technological development.
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[[Image:Quartzite.jpg|thumb|200px|right|caption|A sample of [[quartzite]], a form of metamorphic rock, from the collection at the Museum of Geology, [[University of Tartu]].]]
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== Etymology ==
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The word petrology is derived from a combination of the [[greek language|Greek]] words ''petra'' (πέτρα), meaning "rock," and ''logos'' (λόγος), meaning "knowledge."
  
 
== Branches of petrology ==
 
== Branches of petrology ==
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*Igneous petrology focuses on the composition and texture of [[igneous rock]]s (rocks such as [[granite]] or [[basalt]] which have crystallized from molten rock or [[magma]]). Igneous rocks include [[volcanic]] and [[intrusion|plutonic]] rocks.  
 
*Igneous petrology focuses on the composition and texture of [[igneous rock]]s (rocks such as [[granite]] or [[basalt]] which have crystallized from molten rock or [[magma]]). Igneous rocks include [[volcanic]] and [[intrusion|plutonic]] rocks.  
 
*Sedimentary petrology focuses on the composition and texture of [[sedimentary rock]]s (rocks such as [[sandstone]], [[shale]], or [[limestone]] which consist of pieces or particles derived from other rocks or biological or chemical deposits, and are usually bound together in a [[Matrix (geology)|matrix]] of finer material).
 
*Sedimentary petrology focuses on the composition and texture of [[sedimentary rock]]s (rocks such as [[sandstone]], [[shale]], or [[limestone]] which consist of pieces or particles derived from other rocks or biological or chemical deposits, and are usually bound together in a [[Matrix (geology)|matrix]] of finer material).
*Metamorphic petrology focuses on the composition and texture of [[metamorphic rock]]s (rocks such as [[slate]], [[marble]], [[gneiss]], or [[schist]] which started out as sedimentary or igneous rocks but which have undergone chemical, mineralogical or textural changes due to extremes of pressure, temperature or both)
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*Metamorphic petrology focuses on the composition and texture of [[metamorphic rock]]s (rocks such as [[slate]], [[marble]], [[gneiss]], or [[schist]] which started out as sedimentary or igneous rocks but which have undergone chemical, mineralogical or textural changes due to extremes of pressure, temperature or both).
*Experimental petrology employs high-pressure, high-temperature apparatus to investigate the geochemistry and [[Phase (matter)|phase relations]] of natural or synthetic materials at elevated pressures and temperatures. Experiments are particularly useful for investigating rocks of the lower [[Crust (geology)|crust]] and upper [[Mantle (geology)|mantle]] that rarely survive the journey to the surface in pristine condition. The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built.
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*Experimental petrology employs high-[[pressure]], high-[[temperature]] apparatus to investigate the geochemistry and [[Phase (matter)|phase relations]] of natural or synthetic materials at elevated pressures and temperatures. Experiments are particularly useful for investigating rocks of the lower [[Crust (geology)|crust]] and upper [[Mantle (geology)|mantle]] that rarely survive the journey to the surface in pristine condition. The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built.
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[[Image:Limestoneshale7342.jpg|frame|200px|right|Two types of sedimentary rock, limey [[shale]] overlaid by [[limestone]], observed at [[Cumberland Plateau]], [[Tennessee]].]]
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== Significance of studying rocks ==
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The study of rocks is important for several reasons:
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* Their [[mineral]]s and global chemistry provide information about the composition of the [[Earth]]'s crust and mantle.
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* Their ages can be calculated by various methods of [[radiometric dating]], and a time sequence of geological events can be put together.
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* Their features are usually characteristic of a specific [[plate tectonics|tectonic]] environment, allowing scientists to reconstitute tectonic processes.
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* Many rocks host important [[ore]]s that provide valuable raw materials that we rely on for our sustenance and technological development.
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==See also==
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* [[Igneous rock]]
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* [[Metamorphic rock]]
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* [[Mineral]]
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* [[Rock (geology)]]
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* [[Sedimentary rock]]
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== Notes ==
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<references/>
  
 
==References==
 
==References==
* Bayly, M. Brian (1968) ''Introduction to petrology'' Prentice-Hall, Englewood Cliffs, NJ;
 
* Blatt, Harvey and Tracy, Robert J. (1996) ''Petrology: igneous, sedimentary, and metamorphic'' W.H. Freeman, New York, ISBN 0716724383 ;
 
* Dietrich, Richard Vincent and Skinner, Brian J. (1979) ''Rocks and rock minerals'' Wiley, New York, ISBN 0471029343 ;
 
* Fei, Yingwei; Bertka, Constance M. and Mysen, Bjorn O. (eds.) (1999) ''Mantle petrology: field observations and high-pressure experimentation'' The Geochemical Society, Houston, TX, ISBN 0941809056 ;
 
*  Stanton, R. L. (1972) ''Ore petrology'' McGraw-Hill, New York, ISBN 0070608431 ;
 
 
==See also==
 
* [[List of publications in geology#Petrology| Important publications in petrology]]
 
  
==External links==
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* Best, Myron G. ''Igneous and Metamorphic Petrology''. 2nd ed. Oxford, UK: Blackwell, 2003. ISBN 1405105887
* [http://www.geolab.unc.edu/Petunia/IgMetAtlas/mainmenu.html ''Atlas of Igneous and metamorphic rocks, minerals, and textures'' Geology Department, University of North Carolina];
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* Blatt, Harvey, and Robert J. Tracy. ''Petrology: Igneous, Sedimentary, and Metamorphic''. 2nd ed. New York: W.H. Freeman, 1995. ISBN 0716724383
* [http://www.geol.lsu.edu/metpetdb/index.html ''Metamorphic Petrology Database (MetPetDB)'' Department of Geology and Geophysics, Louisiana State University];
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* Pellant, Chris. ''Rocks and Minerals''. Smithsonian Handbooks. New York: Dorling Kindersley, 2002. ISBN 0789491060
* [http://www.petdb.org/ ''Petrological Database of the Ocean Floor (PETDB)'' Center for International Earth Science Information Network (CIESIN), Columbia University];
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* Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. ''Rocks, Gems and Minerals''. Rev. ed. New York: St. Martin's Press, 2001. ISBN 1582381321
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* Skinner, Brian J., Stephen C. Porter, and Jeffrey Park. ''Dynamic Earth: An Introduction to Physical Geology''. 5th ed. Hoboken, NJ: John Wiley, 2004. ISBN 0471152285
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* Winter, John D. ''An Introduction to Igneous and Metamorphic Petrology''. Upper Saddle River, NJ: Prentice Hall, 2001. ISBN 0132403420
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[[Category:Petrology| ]]
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[[Category:Physical sciences]]
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[[Category:Earth sciences]]
 
[[Category:Geology]]
 
[[Category:Geology]]
  
[[ca:Litologia]]
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[[cs:Petrologie]]
 
[[de:Petrologie]]
 
[[et:Petroloogia]]
 
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[[eu:Petrologia]]
 
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[[fr:Pétrologie]]
 
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[[he:פטרולוגיה]]
 
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[[zh:岩石学]]
 

Latest revision as of 02:53, 24 November 2022

A sample of igneous rock. The light-colored tracks show the direction of lava flow.

Petrology is a field of geology that focuses on the study of rocks and the conditions under which they are formed. It utilizes the classical fields of mineralogy, petrography,[1] and chemical analyses to describe the structure and composition of rocks. In addition, modern petrologists include the principles of geochemistry and geophysics to better understand the origins of rocks. There are three branches of petrology, corresponding to the three main types of rocks: igneous, metamorphic, and sedimentary.

The study of rocks provides us with important information about the nature of the Earth's crust and mantle. In addition, it enables us to gain a sense of the Earth's history, including tectonic processes that occurred over the long course of geological time. On a practical level, the field of petrology helps us gain an understanding of many of the raw materials we rely on for our sustenance and technological development.

A sample of quartzite, a form of metamorphic rock, from the collection at the Museum of Geology, University of Tartu.

Etymology

The word petrology is derived from a combination of the Greek words petra (πέτρα), meaning "rock," and logos (λόγος), meaning "knowledge."

Branches of petrology

  • Igneous petrology focuses on the composition and texture of igneous rocks (rocks such as granite or basalt which have crystallized from molten rock or magma). Igneous rocks include volcanic and plutonic rocks.
  • Sedimentary petrology focuses on the composition and texture of sedimentary rocks (rocks such as sandstone, shale, or limestone which consist of pieces or particles derived from other rocks or biological or chemical deposits, and are usually bound together in a matrix of finer material).
  • Metamorphic petrology focuses on the composition and texture of metamorphic rocks (rocks such as slate, marble, gneiss, or schist which started out as sedimentary or igneous rocks but which have undergone chemical, mineralogical or textural changes due to extremes of pressure, temperature or both).
  • Experimental petrology employs high-pressure, high-temperature apparatus to investigate the geochemistry and phase relations of natural or synthetic materials at elevated pressures and temperatures. Experiments are particularly useful for investigating rocks of the lower crust and upper mantle that rarely survive the journey to the surface in pristine condition. The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built.
Two types of sedimentary rock, limey shale overlaid by limestone, observed at Cumberland Plateau, Tennessee.

Significance of studying rocks

The study of rocks is important for several reasons:

  • Their minerals and global chemistry provide information about the composition of the Earth's crust and mantle.
  • Their ages can be calculated by various methods of radiometric dating, and a time sequence of geological events can be put together.
  • Their features are usually characteristic of a specific tectonic environment, allowing scientists to reconstitute tectonic processes.
  • Many rocks host important ores that provide valuable raw materials that we rely on for our sustenance and technological development.

See also

Notes

  1. "Petrography" is a branch of petrology involving the study of the mineral content and textural relationships within rocks. The term "lithology" was once roughly synonymous with petrography, but today lithology is essentially a subdivision of petrology focusing on macroscopic hand-sample or outcrop-scale description of rocks.

References
ISBN links support NWE through referral fees

  • Best, Myron G. Igneous and Metamorphic Petrology. 2nd ed. Oxford, UK: Blackwell, 2003. ISBN 1405105887
  • Blatt, Harvey, and Robert J. Tracy. Petrology: Igneous, Sedimentary, and Metamorphic. 2nd ed. New York: W.H. Freeman, 1995. ISBN 0716724383
  • Pellant, Chris. Rocks and Minerals. Smithsonian Handbooks. New York: Dorling Kindersley, 2002. ISBN 0789491060
  • Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. Rocks, Gems and Minerals. Rev. ed. New York: St. Martin's Press, 2001. ISBN 1582381321
  • Skinner, Brian J., Stephen C. Porter, and Jeffrey Park. Dynamic Earth: An Introduction to Physical Geology. 5th ed. Hoboken, NJ: John Wiley, 2004. ISBN 0471152285
  • Winter, John D. An Introduction to Igneous and Metamorphic Petrology. Upper Saddle River, NJ: Prentice Hall, 2001. ISBN 0132403420

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