Editing Geology (section)

===Petrology===
{{Main|Petrology}}

In addition to identifying rocks in the field ([[lithology]]), petrologists identify rock samples in the laboratory. Two of the primary methods for identifying rocks in the laboratory are through [[optical microscopy]] and by using an [[electron microprobe]]. In an [[optical mineralogy]] analysis, petrologists analyze [[thin section]]s of rock samples using a [[petrographic microscope]], where the minerals can be identified through their different properties in plane-polarized and cross-polarized light, including their [[birefringence]], [[pleochroism]], [[Crystal twinning|twinning]], and interference properties with a [[Conoscopy|conoscopic lens]].<ref>{{Cite book |isbn= 978-0-19-506024-9 |author= Nesse, William D. |year= 1991 |publisher= Oxford University Press |location= New York |title= Introduction to optical mineralogy}}</ref> In the electron microprobe, individual locations are analyzed for their exact chemical compositions and variation in composition within individual crystals.<ref>{{Cite journal |author=Morton |first=A. C. |year=1985 |title=A new approach to provenance studies: electron microprobe analysis of detrital garnets from Middle Jurassic sandstones of the northern North Sea |journal=Sedimentology |volume=32 |issue=4 |pages=553–566 |bibcode=1985Sedim..32..553M |doi=10.1111/j.1365-3091.1985.tb00470.x}}</ref> [[Stable isotope|Stable]]<ref>{{Cite journal |doi= 10.1016/S0012-8252(02)00133-2 |title= Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie–Sulu orogen in China: implications for geodynamics and fluid regime |year= 2003 |author= Zheng, Y |journal= Earth-Science Reviews |volume= 62 |issue= 1 |pages= 105–161 |bibcode= 2003ESRv...62..105Z |last2= Fu |first2= Bin |last3= Gong |first3= Bing |last4= Li |first4= Long}}</ref> and [[radioactive isotope]]<ref>{{Cite journal |author=Condomines |first1=M. |last2=Tanguy |first2=J. |last3=Michaud |first3=V. |year=1995 |title=Magma dynamics at Mt Etna: Constraints from U-Th-Ra-Pb radioactive disequilibria and Sr isotopes in historical lavas |journal=Earth and Planetary Science Letters |volume=132 |issue=1 |pages=25–41 |bibcode=1995E&PSL.132...25C |doi=10.1016/0012-821X(95)00052-E}}</ref> studies provide insight into the [[geochemical]] evolution of rock units.

Petrologists can also use [[fluid inclusion]] data<ref>{{Cite book |last1=Shepherd |first1=T. J. |title=A practical guide to fluid inclusion studies |last2=Rankin |first2=A. H. |last3=Alderton |first3=D. H. M. |journal=Mineralogical Magazine |publisher=Blackie |year=1985 |volume=50 |issue=356 |page=352 |isbn=978-0-412-00601-2 |location=Glasgow |doi=10.1180/minmag.1986.050.356.32 |bibcode=1986MinM...50..352P | url=https://books.google.com/books?id=CVSGAAAAIAAJ }}</ref> and perform high temperature and pressure physical experiments<ref>{{Cite journal |doi= 10.1007/BF00375521 |title= Experimental petrology of alkalic lavas: constraints on cotectics of multiple saturation in natural basic liquids |year= 1987 |author= Sack, Richard O. |journal= Contributions to Mineralogy and Petrology |volume= 96 |issue= 1 |pages= 1–23 |last2= Walker |first2= David |last3= Carmichael |first3= Ian S.E. |bibcode= 1987CoMP...96....1S|s2cid= 129193823 }}</ref> to understand the temperatures and pressures at which different mineral phases appear, and how they change through igneous<ref>{{Cite book |isbn= 978-0-7637-3448-0 |author= McBirney, Alexander R. |year= 2007 |publisher= Jones and Bartlett Publishers |location= Boston |title= Igneous petrology}}</ref> and metamorphic processes. This research can be extrapolated to the field to understand metamorphic processes and the conditions of crystallization of igneous rocks.<ref>{{Cite book
 | isbn = 978-0-939950-34-8
 | author = Spear, Frank S.
 | year = 1995
 | publisher = Mineralogical Soc. of America
 | location = Washington, DC
 | title = Metamorphic phase equilibria and pressure-temperature-time paths}}</ref> This work can also help to explain processes that occur within the Earth, such as [[subduction]] and [[magma chamber]] evolution.<ref>{{Cite journal|last1=Deegan|first1=F. M.|last2=Troll|first2=V. R.|last3=Freda|first3=C.|last4=Misiti|first4=V.|last5=Chadwick|first5=J. P.|last6=McLeod|first6=C. L.|last7=Davidson|first7=J. P.|date=May 2010|title=Magma–Carbonate Interaction Processes and Associated CO2 Release at Merapi Volcano, Indonesia: Insights from Experimental Petrology|url=https://doi.org/10.1093/petrology/egq010|journal=Journal of Petrology|volume=51|issue=5|pages=1027–1051|doi=10.1093/petrology/egq010|issn=1460-2415}}</ref>
[[File:Agiospavlos DM 2004 IMG003 Felsenformation nahe.JPG|thumb|Folded [[rock (geology)|rock]] strata]]