Petrology
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Petrology (from
Ancient Greek πέτρος (pétros) 'rock', and -λογία (-logía) 'study of') is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology.[1] Igneous and metamorphic petrology are commonly taught together because both make heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock.[2]
Modern sedimentary petrology is making increasing use of chemistry.
Background
Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of rocks while petrography is the speciality that deals with microscopic details.
In the petroleum industry, lithology, or more specifically mud logging, is the graphic representation of geological formations being drilled through and drawn on a log called a mud log. As the cuttings are circulated out of the borehole, they are sampled, examined (typically under a 10× microscope) and tested chemically when needed.
Methodology
Petrology utilizes the fields of
thermodynamic
data and experiments in order to better understand the origins of rocks.
Branches
There are three branches of petrology, corresponding to the three types of rocks:
sedimentary
, and another dealing with experimental techniques:
- 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.[3]
- 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 have undergone chemical, mineralogical or textural changes due to the effects of pressure, temperature, or both). The original rock, prior to change (called the protolith), may be of any sort.[3]
- terrestrial planets and the Moon. The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built.
See also
References
Citations
- ISBN 978-0-7167-3743-8.
- ^ Frost, B. R.; Frost, C. D. (2014). Essentials of Igneous and Metamorphic Petrology. Cambridge University Press.
- ^ ISBN 978-0-321-59257-6.
Sources
- Best, Myron G. (2002), ISBN 1-4051-0588-7.
- Blatt, Harvey; Tracy, Robert J.; Owens, Brent (2005), ISBN 978-0-7167-3743-8.
- Boggs, S. Jr. (2009), Petrology of Sedimentary Rocks, Cambridge University Press
- Dietrich, Richard Vincent; Skinner, Brian J. (2009), Gems, Granites, and Gravels: knowing and using rocks and minerals (ISBN 978-0-521-10722-8
- Fei, Yingwei; Bertka, Constance M.; Mysen, Bjorn O. (eds.) (1999), Mantle Petrology: field observations and high-pressure experimentation (Houston TX: ISBN 0-941809-05-6.
- Philpotts, Anthony; Ague, Jay (2009), Principles of Igneous and Metamorphic Petrology (ISBN 978-0-521-88006-0
- Robb, L. (2005). Introduction to Ore-Forming Processes (ISBN 978-0-632-06378-9
- Blackwell Science
- Yardley, B. W. D.; OCLC 1226719524.)
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External links
Wikimedia Commons has media related to Petrology.
Wikisource has original works on the topic: Petrology
- Atlas of Igneous and metamorphic rocks, minerals, and textures – Geology Department, University of North Carolina
- Metamorphic Petrology Database (MetPetDB) – Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute
- Petrological Database of the Ocean Floor (PetDB) - Center for International Earth Science Information Network, Columbia University