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{{Short description|Form of the mineral quartz, found in nuclear test sites and meteor impact zones}}
⚫
[[File:Suvasvesi shocked quartz.jpg|thumb|right|upright=1,2|photomicrograph of shocked quartz]]
{{Distinguish|Fused quartz}}
⚫
'''Shocked quartz''' is a form of [[quartz]] that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal. These planes, which show up as lines under a microscope, are called [[planar deformation features]] (PDFs), or shock lamellae.
⚫
[[File:Suvasvesi shocked quartz.jpg|thumb|right|upright=1.2|[[Photomicrograph]] of shocked quartz]]
⚫
'''Shocked quartz''' is a form of [[quartz]] that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the [[crystalline structure]] of quartz is deformed along planes inside the crystal. These planes, which show up as lines under a microscope, are called [[planar deformation features]] (PDFs), or shock lamellae.


==Discovery==
==Discovery==
Shocked quartz was discovered following underground [[Nuclear weapon|nuclear bomb]] testing, which generated the intense pressures required to alter the quartz lattice. [[Eugene Shoemaker]] showed that shocked quartz is also found inside [[Impact crater|craters]] created by [[Meteoroid|meteor]] impact, such as the [[Barringer Crater]] and [[Chicxulub crater]].<ref>{{cite paper|author=[[Eugene Merle Shoemaker]]|title=Impact mechanics at Meteor crater, Arizona|publisher=U.S. Atomic Energy Commission Open File Report|date=1959}}</ref> The presence of shocked quartz supports that such craters were formed by impact, because a volcanic eruption would not generate the required pressure.
Shocked quartz was discovered following [[underground nuclear weapons testing]], which generated the intense pressures required to alter the quartz lattice. [[Eugene Shoemaker]] showed that shocked quartz is also found inside [[Impact crater|craters]] created by [[Meteoroid|meteor]] impact, such as the [[Barringer Crater]] and [[Chicxulub crater]].<ref>{{cite report |author=Eugene Merle Shoemaker|author-link=Eugene Merle Shoemaker|title=Impact mechanics at Meteor crater, Arizona |website=US Geological Survey |doi=10.3133/ofr59108 |doi-access=free |date=1959}}</ref> The presence of shocked quartz supports that such craters were formed by impact, because a volcanic eruption would not generate the required pressure.<ref>{{cite conference|last1=de Silva|first1=SL|last2=Sharpton|first2=VL|title = Explosive Volcanism, Shock Metamorphism and the K-T Boundary|conference = Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality|year = 1988|series = LPI Contributions|volume = 673|page = 38|bibcode=1988LPICo.673...38D}}</ref>


Lightning is now known to contribute to the surface record of shocked quartz grains, complicating identification of [[hypervelocity impact]] features.<ref name="ammin.geoscienceworld.org">{{cite web|url=http://ammin.geoscienceworld.org/content/100/7/1645.abstract |title=Lightning-induced shock lamellae in quartz |publisher=Ammin.geoscienceworld.org |date=2015-07-01 |accessdate=2018-08-07}}</ref>
Lightning is now known to contribute to the surface record of shocked quartz grains, complicating identification of [[hypervelocity impact]] features.<ref name="ammin.geoscienceworld.org">{{cite journal|url=http://ammin.geoscienceworld.org/content/100/7/1645.abstract |title=Lightning-induced shock lamellae in quartz |publisher=Ammin.geoscienceworld.org |date=2015-07-01 |doi=10.2138/am-2015-5218 |access-date=2018-08-07|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. |journal=American Mineralogist |volume=100 |issue=7 |pages=1645–1648 |bibcode=2015AmMin.100.1645G |s2cid=130973907 }}</ref>


==Formation==
==Formation==
⚫
[[File:820qtz.jpg|thumb|right|Photomicrograph of a shocked quartz grain (0.13&nbsp;mm across) from the [[Chesapeake Bay impact crater]], showing shock lamellae]]
Shocked quartz is usually associated in nature with two high-pressure [[polymorphism (materials science)|polymorphs]] of [[silicon dioxide]]: [[coesite]] and [[stishovite]]. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 [[Pascal (unit)|gigapascals]]), but at moderate temperatures. Coesite and stishovite are usually viewed as indicative of [[impact event]]s, [[eclogite facies]] metamorphism, (or [[thermonuclear explosion]]), but are also found in sediments prone to [[lightning]] strikes and in [[fulgurite]]s.<ref>{{cite journal |last=Melosh |first=H.J. |title=Impact geologists, beware! |journal=Geophysical Research Letters |volume=44 |issue=17 |pages=8873–8874 |doi=10.1002/2017GL074840 |year=2017 |bibcode=2017GeoRL..44.8873M }}</ref><ref name="ammin.geoscienceworld.org">{{cite web|url=http://ammin.geoscienceworld.org/content/100/7/1645.abstract |title=Lightning-induced shock lamellae in quartz |publisher=Ammin.geoscienceworld.org |date=2015-07-01 |accessdate=2018-08-07}}</ref>
Shocked quartz is usually associated in nature with two high-pressure [[polymorphism (materials science)|polymorphs]] of [[silicon dioxide]]: [[coesite]] and [[stishovite]]. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 [[Pascal (unit)|gigapascals]]), but at moderate temperatures. Coesite and stishovite are usually viewed as indicative of [[impact event]]s or [[eclogite facies]] metamorphism (or [[nuclear explosion]]), but are also found in sediments prone to [[lightning]] strikes and in [[fulgurite]]s.<ref>{{cite journal |last=Melosh |first=H.J. |title=Impact geologists, beware! |journal=Geophysical Research Letters |volume=44 |issue=17 |pages=8873–8874 |doi=10.1002/2017GL074840 |year=2017 |bibcode=2017GeoRL..44.8873M |s2cid=134575031 }}</ref><ref name="ammin.geoscienceworld.org"/>


==Occurrence==
==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.
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. 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.
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 }}</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>{{cite web|url=http://sortingoutscience.net/2008/02/05/the-scientific-tourist-6-nothing-but-rim/|title=The scientific tourist #6 — nothing but rim!|author=Sam Wise|date=2008-02-05|accessdate=2017-10-19|deadurl=bot: unknown|archiveurl=https://web.archive.org/web/20170112014704/http://sortingoutscience.net/2008/02/05/the-scientific-tourist-6-nothing-but-rim/|archivedate=2017-01-12|df=}}</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>


== See also ==
== See also ==
⚫
[[File:820qtz.jpg|thumb|right|[[Photomicrograph]] of a shocked quartz grain (0.13 mm across) from the [[Chesapeake Bay impact crater]], showing shock lamellae]]
* [[Breccia]]
* [[Fulgurite]]
* [[Lechatelierite]]
* [[Lechatelierite]]
* [[Seifertite]]
* [[Seifertite]]
Line 27: Line 27:


==References==
==References==
{{Reflist|colwidth=33em}}
{{reflist}}


==External links==
==External links==

Latest revision as of 00:11, 4 June 2023

Not to be confused with Fused quartz.
Photomicrograph of shocked quartz

Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal. These planes, which show up as lines under a microscope, are called planar deformation features (PDFs), or shock lamellae.

Discovery[edit]

Shocked quartz was discovered following underground nuclear weapons testing, which generated the intense pressures required to alter the quartz lattice. Eugene Shoemaker showed that shocked quartz is also found inside craters created by meteor impact, such as the Barringer Crater and Chicxulub crater.[1] The presence of shocked quartz supports that such craters were formed by impact, because a volcanic eruption would not generate the required pressure.[2]

Lightning is now known to contribute to the surface record of shocked quartz grains, complicating identification of hypervelocity impact features.[3]

Formation[edit]

Photomicrograph of a shocked quartz grain (0.13 mm across) from the Chesapeake Bay impact crater, showing shock lamellae

Shocked quartz is usually associated in nature with two high-pressure polymorphs of silicon dioxide: coesite and stishovite. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 gigapascals), but at moderate temperatures. Coesite and stishovite are usually viewed as indicative of impact events or eclogite facies metamorphism (or nuclear explosion), but are also found in sediments prone to lightning strikes and in fulgurites.[4][3]

Occurrence[edit]

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.[5]

Lightning also generates planar deformation features in quartz and is capable of propagating appropriate pressure/temperature gradients in rocks and sediments alike.[6] 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.[7]

Though shocked quartz is only recently recognized, Eugene Shoemaker discovered it prior to its crystallographic description in building stones in the Bavarian town of Nördlingen, derived from shock-metamorphic rocks, such as breccia and pseudotachylite, of Ries crater.[8][9]

See also[edit]

References[edit]

  1. ^ Eugene Merle Shoemaker (1959). Impact mechanics at Meteor crater, Arizona. US Geological Survey (Report). doi:10.3133/ofr59108.
  2. ^ de Silva, SL; Sharpton, VL (1988). Explosive Volcanism, Shock Metamorphism and the K-T Boundary. Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality. LPI Contributions. Vol. 673. p. 38. Bibcode:1988LPICo.673...38D.
  3. ^ a b Gieré, Reto; Wimmenauer, Wolfhard; Müller-Sigmund, Hiltrud; Wirth, Richard; Lumpkin, Gregory R.; Smith, Katherine L. (2015-07-01). "Lightning-induced shock lamellae in quartz". American Mineralogist. 100 (7). Ammin.geoscienceworld.org: 1645–1648. Bibcode:2015AmMin.100.1645G. doi:10.2138/am-2015-5218. S2CID 130973907. Retrieved 2018-08-07.
  4. ^ Melosh, H.J. (2017). "Impact geologists, beware!". Geophysical Research Letters. 44 (17): 8873–8874. Bibcode:2017GeoRL..44.8873M. doi:10.1002/2017GL074840. S2CID 134575031.
  5. ^ Bohor, BF (1988). Shocked Quartz and More: Impact Signatures in K-T Boundary Clays and Claystones. Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality. LPI Contributions. Vol. 673. p. 17. Bibcode:1988LPICo.673...17B.
  6. ^ Gieré, Reto; Wimmenauer, Wolfhard; Müller-Sigmund, Hiltrud; Wirth, Richard; Lumpkin, Gregory R.; Smith, Katherine L. (2015). "Lightning-induced shock lamellae in quartz". American Mineralogist. 100 (7): 1645–1648. Bibcode:2015AmMin.100.1645G. doi:10.2138/am-2015-5218. S2CID 130973907.
  7. ^ Liou, JG; Ernst, WG; Zhang, RY; Tsujimori, T; Jahn, BM (2009). "Ultrahigh-pressure minerals and metamorphic terranes – The view from China". Journal of Asian Earth Sciences. 35 (3–4): 199–231. Bibcode:2009JAESc..35..199L. doi:10.1016/j.jseaes.2008.10.012.
  8. ^ Shoemaker, EM; Chao, ECT (1961). "New Evidence for the Impact Origin of the Ries Basin, Bavaria, Germany". J. Geophys. Res. 66 (10): 3371–3378. Bibcode:1961JGR....66.3371S. doi:10.1029/JZ066i010p03371.
  9. ^ Cokinos, C (2009). The Fallen Sky. Penguin. ISBN 978-1-101-13322-4.

External links[edit]

Retrieved from "https://en.chped.com/w/index.php?title=Shocked_quartz&oldid=1158419323"