Editing Shocked quartz (section)

==Occurrence==
Shocked quartz is found worldwide, and occurs in the thin [[Cretaceous–Paleogene boundary]] layer, which occurs at the contact between [[Cretaceous]] and [[Paleogene]] rocks. This is further evidence (in addition to [[iridium]] enrichment) that the transition between the two geologic periods was caused by a large impact.<ref>{{cite conference|last=Bohor|first=BF|title=Shocked Quartz and More: Impact Signatures in K-T Boundary Clays and Claystones|conference=Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality|year = 1988|series=LPI Contributions|volume=673|page=17|bibcode=1988LPICo.673...17B}}</ref>

Lightning also generates [[planar deformation features]] in quartz and is capable of propagating appropriate pressure/temperature gradients in rocks and sediments alike.<ref>{{cite journal |last1=Gieré |first1=Reto |last2=Wimmenauer |first2=Wolfhard |last3=Müller-Sigmund |first3=Hiltrud |last4=Wirth |first4=Richard |last5=Lumpkin |first5=Gregory R. |last6=Smith |first6=Katherine L. |title=Lightning-induced shock lamellae in quartz |url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/100/7/1645/40585/Lightning-induced-shock-lamellae-in-quartz |journal=American Mineralogist |year=2015 |volume=100 |issue=7 |pages=1645–1648 |doi=10.2138/am-2015-5218 |bibcode=2015AmMin.100.1645G |s2cid=130973907 |url-access=subscription }}</ref> This very common mechanism may significantly contribute to the accumulation of shocked quartz in the geologic record. Mantle xenoliths and sediments derived from them may contain coesite or stishovite.<ref>{{cite journal|first1=JG|last1=Liou|first2=WG|last2=Ernst|first3=RY|last3=Zhang|first4=T|last4=Tsujimori|first5=BM|last5=Jahn|title=Ultrahigh-pressure minerals and metamorphic terranes – The view from China|journal=Journal of Asian Earth Sciences|volume=35|issue=3–4|year=2009|pages=199–231|doi=10.1016/j.jseaes.2008.10.012|bibcode=2009JAESc..35..199L}}</ref>

Though shocked quartz is only recently recognized, [[Eugene Shoemaker]] discovered it prior to its crystallographic description in building stones in the [[Bavaria]]n town of [[Nördlingen]], derived from [[shock metamorphism|shock-metamorphic]] rocks, such as [[breccia]] and [[pseudotachylite]], of [[Nördlinger Ries|Ries crater]].<ref name=Shoemaker_1961>{{cite journal|first1=EM|last1=Shoemaker|first2=ECT|last2=Chao|year=1961|title=New Evidence for the Impact Origin of the Ries Basin, Bavaria, Germany|journal=J. Geophys. Res.|volume=66|issue=10|pages=3371–3378|doi=10.1029/JZ066i010p03371|bibcode=1961JGR....66.3371S}}</ref><ref name=Cokinos_2009>{{cite book|title=The Fallen Sky|last=Cokinos|first=C|date=2009|publisher=Penguin|url=https://books.google.com/books?id=1uFRVyFxA04C&q=coesite&pg=PT246|isbn=978-1-101-13322-4}}</ref>