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Topic: Shocked quartz

	Shocked quartz - Wikipedia, the free encyclopedia
		Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz.
		Shocked quartz was discovered after underground nuclear bomb testing, which caused the intense pressures required to form shocked quartz.
		Shocked quartz is associated with two pressure polymorphs of silicon dioxide: coesite and stishovite.
	en.wikipedia.org /wiki/Shocked_quartz (236 words)

	Shocked quartz -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-22)
		Shocked quartz is a form of (A hard glossy mineral consisting of silicon dioxide in crystal form; present in most rocks (especially sandstone and granite); yellow sand is quartz with iron oxide impurities) quartz that has a microscopic structure that is different from normal quartz.
		Shocked quartz was discovered after underground (Click link for more info and facts about nuclear bomb) nuclear bomb testing, which caused the intense pressures required to form shocked quartz.
		Shocked quartz is also found worldwide, in a thin layer at the boundary between (From 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants) Cretaceous and (From 63 million to 2 million years ago) Tertiary rocks.
	www.absoluteastronomy.com /encyclopedia/s/sh/shocked_quartz.htm (335 words)

	Shocked quartz (Site not responding. Last check: 2007-10-22)
		Shocked quartz is a form of quartz that has a microscopic structurethat is different from normal quartz.
		Shocked quartz was discovered after underground nuclear bomb testing,which caused the intense pressures required to form shocked quartz.
		Shocked quartz is associated with two pressure polymorphs of silicon dioxide : coesite and stishovite.
	www.therfcc.org /shocked-quartz-132466.html (220 words)

	Shocked quartz (Site not responding. Last check: 2007-10-22)
		Bunch,TE & Cohen, AJ, 1963, Coesite and shocked* quartz from Holleford crater,...
		Shocked quartz grains are produced by the force of an impact on sandstone rocks.This impact occurred during the Devonian Period of geologic time,...
		Shocked quartz is a form of quartz that has a microscopic structure that isdifferent from normal quartz.
	www.uniqueaerobics.com /shocked+quartz.html (1110 words)

	World and I Magazine - Massive Meteorites in Geological History
		Common quartz is an abundant mineral found occasionally in the form of large distinctive crystals, but also widespread as sand and as a component of many rocks.
		Quartz acquires this pattern only under conditions of extreme shock such as is produced by meteorite impact or nuclear explosion.
		Thus the "shocked" quartz in the boundary layer proves beyond any reasonable doubt that an enormous explosion did indeed rock the earth 65 million years ago.
	www.worldandi.com /public/1990/august/ns3.cfm (3180 words)

	Shocked Minerals
		The types of shock features and their associations allow estimates of the pressure that was applied to the grain.
		Shocked minerals are now commonly found in association with the KT boundary event.
		Shocked zircons are therefore one of the key arguments used to rule out the Manson crater as the source of the KT boundary ejecta.
	www.agu.org /revgeophys/claeys00/node3.html (351 words)

	Becker's Australia - Bedout: A Possible End-Permian Impact Crater Offshore Northwestern Australia (Site not responding. Last check: 2007-10-22)
		Recently, large shocked quartz grains (S-1) were found in the Fraser Park, Australia and Graphite Peak Antarctica, Permian-Triassic boundary layer (yellow dot).
		Shock melted plagioclase grains set in a matrix of albite, Fe-Ti Oxides and glass that is altering to chlorite 3044 m (9986 ft.).
		Shown is the distribution of the maximum grain size of shocked quartz with distance from the two proposed source craters (Chicxulub for K/T and Bedout for P/Tr).
	beckeraustralia.crustal.ucsb.edu /paper_10.html (979 words)

	Becker's Australia - Bedout: A Possible End-Permian Impact Crater Offshore Northwestern Australia (Site not responding. Last check: 2007-10-22)
		Shown is the distribution of the maximum grain size of shocked quartz with distance from the proposed source crater.
		When the maximum grain size of shocked quartz from Fraser Park and Graphite Peak are plotted with respect to distance from Bedout, they match well with the maximum sizes for shocked quartz in the K/T boundary and their distance from Chicxulub (Fig.
		Pope (42) demonstrated that the global shocked quartz distribution in the K/T boundary is best explained by dispersal by stratospheric winds and settling of the particles through the atmosphere.
	beckeraustralia.crustal.ucsb.edu /paper_7.html (720 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		For example, the widths of shock waves in gas are limited to about 10 micrometers, which is roughly equal to one molecular mean free path, but shock waves in solids are wider, up to a few meters in rocks, depending on their porosities.
		The measurement error for the shock pressure is indicated by the bar at the bottom of the diagram, while the error for the density is smaller than the symbols.
		Pre-shock temperature of quartz 20ºC. The lower curve is given for the ordinary ray, and the upper curve marks the extraordinary ray in quartz.
	www.univie.ac.at /geochemistry/impp.html (10429 words)

	Piecing Together a Permian Impact :: Astrobiology Magazine :: Search for Life in the Universe
		Shocked quartz is fractured in several directions and is therefore believed to be a good indication of a meteor impact.
		Shocked quartz associated with the Chicxulub crater shows that the grain size drops the further you get from the crater.
		The grain size of the shocked quartz associated with the Bedout crater follows the same distribution pattern as Chicxulub.
	www.astrobio.net /news/article969.html (1190 words)

	Shock metamorphism of minerals
		It is caused by the passage of strong shock waves, which occur exclusively in the context of natural impact events, nuclear or chemical explosions, and laboratory-scale shock experiments.
		A shock wave is a degenerated, short-living compression wave, which is accompanied by high pressures and temperatures and a material transport behind the shock front.
		Both the shocked primary minerals and the newly formed (high-pressure) phases are not only unequivocal indicators of impact events but also serve for shock barometry and thermometry.
	ecf.hq.eso.org /~ralbrech/amico/intabs/langenhorstf.html (895 words)

	Summer Field Work (Site not responding. Last check: 2007-10-22)
		Sand-sized quartz grain (0.13 mm) from the USGS-NASA Langley core showing two well-developed, intersecting sets of shock lamellae produced by the late Eocene Chesapeake Bay bolide impact.
		This shocked quartz grain is from the upper part of the crater-fill deposits at a depth of 820.6 ft in the core.
		USGS field investigations of the Chesapeake Bay impact crater during year 2000 are conducted in cooperation with the NASA Langley Research Center, the Hampton Roads Planning District Commission, the Virginia Department of Environmental Quality, the Virginia Division of Mineral Resources, and the Geology Department, College of William and Mary.
	geology.er.usgs.gov /eespteam/crater/shockquartz.html (210 words)

	Fashion Newsrat: Your Source for Fashion News on Quartz (Site not responding. Last check: 2007-10-22)
		Quartz and what it means to CUB Dec 6, 2003 City Union Bank (CUB) has voted for Quartz banking solution of Tata Consultancy Services.
		A Sparkling Globe, Reflecting the Power Of the Universe Dec 19, 2003 Carved from a block of quartz, and coated with misted-on metal, this gleaming sphere is as big as a Ping-Pong ball and as bright as a mirror.
		Dec 3, 2003 The Main Zone, a broad zone of strong quartz tourmaline veining, is close to surface between sections 4950E and 4912E and was tested by holes TG03-23 to TG03-29...
	newsrat.com /fashion/designers/Quartz.html (3139 words)

	Bayerisches Geoinstitut - Annual Report 2001 Planar microstructures in quartz grains from the submarine Mjølnir ...
		Quartz grains from the 40 km diameter Mjølnir Crater (Barents Sea), one of the few known submarine impact craters, were investigated by TEM.
		Our observations indicate that the shock response of quartz in loose, submarine sediments is rather different to that in compact rocks.
		While shocked quartz in compact rocks develops amorphous PDFs, the major deformation reaction of quartz grains from the Mjølnir impact crater is strong internal fragmentation and, to a lesser extent, twinning.
	www.bgi.uni-bayreuth.de /annual_report/2001/c_28.phtml (509 words)

	PowerPoint Presentation - Astrophysical Apocalypse Scenarios (Site not responding. Last check: 2007-10-22)
		A 0.32 mm shocked quartz grain from intracrater breccia sample Y6 N14 of the Chicxulub crater.
		This quartz grain shows at least 8 sets of planar deformation features when rotated; two strong sets (and part of a third set) of shock lamellae are visible in this orientation.
		Impact is the only natural process known to produce shock waves of sufficient strength to cause deformation of this type.
	physics.elon.edu /~acrider/presentations/fellowsday/FD2004_files/slide0106.htm (134 words)

	Evidence For Meteor Impact, 1980-1990 (Site not responding. Last check: 2007-10-22)
		Quartz is a mineral made from Silica (pure sand) and has a structure that can be deformed if it undergoes high pressures.
		The type of pressure applied by an impact causes what is known as shock metamorphism, this deforms the structure of the quartz and creates parallel laminar ripples.
		The major 'antithesis' to the meteor hypothesis is for massive volcanic activity, this can create shocked quartz (and many other features of the K-T boundary) from explosive eruptions, but the form of the quartz is different from that observed.
	palaeo.gly.bris.ac.uk /Communication/Lee/page1.html (820 words)

	The KT extinction
		Shocked quartz is formed when quartz crystals undergo a sudden pulse of great pressure.
		On top of the igneous rock lies a mass of broken rock, probably the largest surviving debris particles that fell back on to the crater without melting, and on top of that are normal sediments that formed slowly to fill the crater in the shallow tropical seas that covered the impact area.
		At the same time, smaller fragments, including shocked quartz, were blown upward between the hot fireball and the larger fragments, and were deposited second and regionally (about 30 minutes to reach Colorado).
	www.ucmp.berkeley.edu /education/events/cowen1b.html (2564 words)

	ODP/Leg 165 Post-cruise Press Release (Site not responding. Last check: 2007-10-22)
		The quartz is referred to as "shocked" because the structure in these crystals can only be formed by the enormous pressures generated by the high velocity impact of a meteorite with the Earth.
		The quartz and other mineral fragments in the upper layer are thus from material ejected from the Chicxulub crater in Mexico.
		The shocked quartz grains were a part of a huge, dark dust cloud that enveloped the Earth for some time after the impact.
	owen.nhm.ac.uk /odp/public/pressrel_html/leg165postpr.html (1259 words)

	shocked quartz (Site not responding. Last check: 2007-10-22)
		Shocked quartz is a form of quartz that has a microscopic structure that is different from...
		Shocked quartz was discovered after underground nuclear bomb...
		Shocked quartz are abundant within the KT boundary clay layer in...
	www.jewelry-4me.com /gemstones/shocked-quartz.htm (323 words)

	Saarijarvi impact structure
		Those Vendian sediments in the bottom of the structure (~138 m - ~156 m inc. shocked quartz) may be sediments which were present while the impact happens.
		This top section of sediment layers is formed after impact from a material which were contaminated by shocked quartz from material drifted from outside of the crater by wind, water or glaciers.
		Between sediments including shocked quartz are a thick layers of clay and silt sediments (~138 m - ~58 m, mainly Vendian) including "red bed" -type layers which does not have shocked quartz.
	www.somerikko.net /old/geo/imp/saari_e.htm (878 words)

	SPACE.com -- Did Triassic Asteroid Impact Spare the Dinosaurs?
		Another vital clue is known as shocked quartz -- distinctive crystals of the rock quartz containing fractures caused by a huge amount of pressure exerted over a small period of time.
		The only places where shocked quartz has been found are at known extraterrestrial impact sites, nuclear test sites and in high-pressure laboratory experiments.
		"Shocked quartz is evidence of an impact,'' said Smithsonian Institution paleontologist Michael Brett-Surman.
	www.space.com /scienceastronomy/solarsystem/asteroid_triassic_wg_010813.html (1325 words)

	Science News: Extinction upon impact? - evidence that meteorite struck earth 66 million years ago and caused mass ...
		Pieces of shocked quartz, foundaround the world, present strong evidence that a large meteorite or asteroid struck the earth 66 million years ago and generated a globe-girdling dust cloud that caused a round of mass extinctions and ultimately the demise of the dinosaurs, report researchers in the May 8 SCIENCE.
		This resemblance indicates that the quartz was shocked, or fractured, by the impact of a large body, and that it was then lofted into the stratosphere and deposited around the world, says Bohor.
		The shocked quartz findings representthe latest volley in a series of debates over the cause of the extinctions that ended the Cretaceous period (SN: 4/18/87, p.248).
	www.findarticles.com /p/articles/mi_m1200/is_v131/ai_4970905 (663 words)

	X-RAY DIFFRACTION EVIDENCE FOR SHOCKED QUARTZ IN AN UPPER EOCENE SAND DEPOSIT, WARREN COUNTY, GEORGIA, U.S.A (Site not responding. Last check: 2007-10-22)
		Quartz grains collected from a transgressive sand unit atop the sequence boundary at the kaolin-rich Huber Formation in the Georgia Coastal Plain were examined by X-ray powder diffraction (XRD) for evidence of crystal defect line broadening.
		We also analyzed alluvial quartz grains from crystalline rocks of the Georgia Piedmont and quartz grains from the Crow Creek Member of the Upper Cretaceous Pierre Shale (Nebraska) that display obvious sets of PDF’s.
		XRD peak shapes of alluvial quartz derived from the Georgia Piedmont indicate minimal defect density and crystal strain (i.e.
	gsa.confex.com /gsa/2002AM/finalprogram/abstract_38959.htm (415 words)

	Lecture 5 (Site not responding. Last check: 2007-10-22)
		Shocked quartz is known only from known asteroid impact sites and nuclear bomb test sites.
		Shocked quartz had previously only been produced in high-pressure experiments or found at nuclear explosion test sites and known asteroid impact sites.
		Shocked quartz has never been found in the deposits of even the most explosive volcanic eruptions, so this was very good evidence that the Ir layer was produced by a giant impact.
	www.ldeo.columbia.edu /dees/ees/life/lectures/lect08.html (3174 words)

	Shocked Quartz
		Shocked quartz is formed when quartz crystals undergo...
		I. Shock metamorphism of the Coconino sandstone at Meteor Crater, Arizona.
		Shocked quartz is fractured in several directions and is therefore...
	www.about-gemstones.com /quartz/Shocked-Quartz.shtml (675 words)

	Bayerisches Geoinstitut - Annual Report 2003 - Experimentally shock-loaded quartz: Comparison of two different ...
		Six quartz samples experimentally shock-loaded at JSC-NASA to peak shock pressures between 8 GPa and 33 GPa and a standard reference sample have been ion-thinned, carbon coated and observed in a transmission electron microscope (TEM).
		The integral intensity of the (10.1) diffraction line of quartz has been measured to calculate the absolute quartz content, with the remaining fraction reflecting the absolute diaplectic glass content.
		Thepowder XRD study confirmed the positive correlation between the glass content and peak shock pressure in experimentally shocked quartz.
	www.bgi.uni-bayreuth.de /annual_report/2003/c_68.phtml (664 words)

	Becker's Australia - Bedout: A Possible End-Permian Impact Crater Offshore Northwestern Australia (Site not responding. Last check: 2007-10-22)
		Acceptance that an impact accompanied the K/T extinction increased dramatically with the discovery of the Chicxulub crater (11,12).
		Recently, large quartz grains (S-1) were found in the Fraser Park, Australia (yellow dot) and Graphite Peak, Antarctica, Permian-Triassic boundary layers.
		Quartz grains are mounted in oil and photographed in plane polarized light.
	beckeraustralia.crustal.ucsb.edu /paper_3.html (529 words)

	PROBABLE SHOCKED QUARTZ AS EVIDENCE FOR AN UPPER EOCENE IMPACT HORIZON IN COASTAL PLAIN STRATA, WARREN COUNTY, GEORGIA, ... (Site not responding. Last check: 2007-10-22)
		The lamellae appear to be parallel to {10-12}, a common PDF orientation in strongly shocked quartz.
		Moreover, the features are invisible except when immersed in oils with refractive indices close to quartz, suggesting a structural or compositional difference between the lamellae and host grain.
		If these quartz grains are indeed shocked, the sandy lag at the base of the Twiggs Clay may record the Chesapeake Bay impact in the stratigraphy of Georgia and may be related to the parent stratum for georgiaites.
	gsa.confex.com /gsa/2002AM/finalprogram/abstract_41931.htm (498 words)

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