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Reidite
Reidite is a rare polymorph of ZrSiO4 created when zircon experiences high pressure and temperature. Reidite is denser than zircon and has the same crystal structure as scheelite. All natural occurrences of reidite are associated with meteorite impact events. On Earth, reidite has been reported from ten impact structures: the Chesapeake Bay Crater in Virginia; Ries Crater in Germany; Xiuyan Crater in China; Woodleigh Crater in Western Australia; Rock Elm Crater in Wisconsin; Dhala Crater in India; Stac Fada in Scotland; Haughton in Canada; Steen River in Canada, and Rochechouart in France. Reidite has also been found in one lunar meteorite. Name origin and discovery Reidite is named after Alan F. Reid, the scientist who first synthesized it during high-pressure experiments in the laboratory in 1969. Reidite was first discovered in natural samples by B.P. Glass and Shaobin Liu in 2001. Occurrence Reidite is formed from zircon above ~30GPa in shock recovery experiments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Elm Disturbance
The Rock Elm Disturbance is an impact crater in Pierce County, Wisconsin, United States, roughly southwest of Menomonie. The disturbance is named for Rock Elm, Wisconsin, a nearby town. Description The meteorite that caused the impact crater is estimated to have been in diameter with a mass of and impact velocity of . The crater is in diameter, and fossils found in the rock filling the crater suggest it dates to the Middle Ordovician Period, about 455 to 430 million years ago. It may be one of several Middle Ordovician meteors that fell roughly simultaneously 469 million years ago, part of a proposed Ordovician meteor event within the continental United States that includes the Decorah crater in Iowa, the Slate Islands crater in Lake Superior, and the Ames crater in Oklahoma. Crater characteristics A raised area at the center of the crater 0.8 km (0.5 mi) wide by 2.4 km (1.5 mi) long suggests that the impact caused a major upheaval of lower-lyin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woodleigh Crater
Woodleigh is a large meteorite impact crater (astrobleme) in Western Australia, centred on Woodleigh Station east of Shark Bay, Gascoyne region. A team of four scientists at the Geological Survey of Western Australia and the Australian National University, led by Arthur J. Mory, announced the discovery in the 15 April 2000 issue of ''Earth and Planetary Science Letters''. Description The crater is not exposed at the surface and therefore its size is uncertain. The original discovery team stated in 2000 that it may be up to in diameter, but others argue it may be much smaller, with one 2003 study suggesting a diameter closer to . The larger estimate of 120 km, if correct, would make this crater tied for the fourth largest confirmed impact structure in the world, and imply a bolide (asteroid or comet) about in diameter.PDF [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stac Fada Member
The Stac Fada Member is a distinctive layer towards the top of the Mesoproterozoic Bay of Stoer Formation, part of the Stoer Group (lowermost Torridonian Supergroup) in northwest Scotland. This rock unit is generally thick and is made of sandstone that contains accretionary lapilli and many dark green glassy fragments of mafic composition. Evidence for a meteorite impact in the area of the Minch or near Lairg has been published and refined in a series of studies from 2008 to 2019. The unit dates to approximately 1.2 billion years ago. The name comes from a small promontory to the west of the village of Stoer, in Assynt, Sutherland (at ). Extent The Stac Fada Member is exposed at a series of localities on or near the coast of Wester Ross, extending for about from the western side of Loch Ewe in the south to the Stoer peninsula in the north. Description The Stac Fada Member is an impactite consisting of a mixture of suevite and clast poor impact melt rocks. At the Stoer penins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. The name derives from the Persian ''zargun'', meaning "gold-hued". This word is corrupted into "jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from ''Zirkon'', which is the German adaptation of this word. Yellow, orange, and red zircon is also known as "hyacinth", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. The name derives from the Persian ''zargun'', meaning "gold-hued". This word is corrupted into "jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from ''Zirkon'', which is the German adaptation of this word. Yellow, orange, and red zircon is also known as "hyacinth", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steen River Crater
Steen River is an impact structure in Alberta, Canada. It is in diameter and the age is estimated to be 91 ± 7 million years (Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...). The crater is not exposed at the surface. The crater was partially eroded prior to burial, and lies under of sediments. References External linksExploration of the Steen River crater Further reading Niccoli, M., Hildebrand, A.R. and Lawton D.C. (2005) "Seismic Velocity Study of the Rim Uplift of the Steen River Impact Crater" Lunar and Planetary Science XXXVI. Impact craters of Alberta Cretaceous impact craters Cretaceous Canada Mackenzie County {{Canada-geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rochechouart Impact Structure
Rochechouart impact structure or Rochechouart astrobleme is an impact structure in France. Erosion has over the millions of years has mostly destroyed its impact crater, the initial surface expression of the asteroid impact leaving highly deformed bedrock and fragments of the crater's floor as evidence of it. In 2008, the French State acknowledged the heritage value of the Rochechouart impact structure creating the “” on 12 sites representative of characteristics geological features of the impact structure. Location Named after the town of Rochechouart, the Rochechouart impact structure is located on the western margin of the French Massif Central near the city of Limoges, approximately south of Paris. Rochechouart (population about ) is built with rocks created or modified by the impact (impactites). Chassenon, a third of the size of Rochechouart, is also built of impactites. Impactite was used 2000 years ago for building Chassenon's monumental Roman baths of Cassinom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pacific and Indian Oceans. Its Metropolitan France, metropolitan area extends from the Rhine to the Atlantic Ocean and from the Mediterranean Sea to the English Channel and the North Sea; overseas territories include French Guiana in South America, Saint Pierre and Miquelon in the North Atlantic, the French West Indies, and many islands in Oceania and the Indian Ocean. Due to its several coastal territories, France has the largest exclusive economic zone in the world. France borders Belgium, Luxembourg, Germany, Switzerland, Monaco, Italy, Andorra, and Spain in continental Europe, as well as the Kingdom of the Netherlands, Netherlands, Suriname, and Brazil in the Americas via its overseas territories in French Guiana and Saint Martin (island), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Meteorite
A lunar meteorite is a meteorite that is known to have originated on the Moon. A meteorite hitting the Moon is normally classified as a transient lunar phenomenon. Discovery In January 1982, John Schutt, leading an expedition in Antarctica for the ANSMET program, found a meteorite that he recognized to be unusual. Shortly thereafter, the meteorite now called Allan Hills 81005 was sent to Washington, DC, where Smithsonian Institution geochemist Brian Mason recognized that the sample was unlike any other known meteorite and resembled some rocks brought back from the Moon by the Apollo program. Several years later, Japanese scientists recognized that they had also collected a lunar meteorite, Yamato 791197, during the 1979 field season in Antarctica. , 371 lunar meteorites have been discovered, perhaps representing more than 30 separate meteorite falls (i.e., many of the stones are "paired" fragments of the same meteoroid). The total mass is more than . All lunar meteorites ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uvarovite
Uvarovite is a chromium-bearing garnet group species with the formula: Ca3 Cr2( Si O4)3. It was discovered in 1832 by Germain Henri Hess who named it after Count Sergei Semenovitch Uvarov (1765–1855), a Russian statesman and amateur mineral collector. It is classified in the ugrandite group alongside the other calcium-bearing garnets andradite and grossular. Uvarovite is the rarest of the common members of the garnet group, and is the only consistently green garnet species, with an emerald-green color. It occurs as well-formed fine-sized crystals. Occurrence Uvarovite most commonly occurs in solid solution with grossular or andradite, and is generally found associated with serpentinite, chromite, metamorphic limestones, and skarn ore-bodies. The most significant source of uvarovite historically has been a now-closed copper mine at Outokumpu, Finland, from where most museum specimens have been collected. The uvarovite crystals found in the Outokumpu district are among a wide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libyan Desert Glass
Libyan Desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of square kilometers. Geologic origin The origin of desert glass is uncertain. Meteoritic origins have long been considered possible, and recent research links the glass to impact features, such as zircon breakdown, vaporized quartz and meteoritic metals, and to an impact crater. Some geologists associate the glass with radiative melting from meteoric large aerial bursts, making it analogous to trinitite created from sand exposed to the thermal radiation of a nuclear explosion. Libyan Desert glass has been dated as having formed about 29 million years ago. Like obsidian, it was knapped and used to make tools during the Pleistocene. The glass is nearly pure silica which requires temperatures above 1,600 °C to form – hotter than any i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haughton Impact Crater
Haughton impact crater is located on Devon Island, Nunavut in far Northern Canada. It is about in diameter and was formed 31-32 million years ago during the Early Oligocene. The impacting object is estimated to have been approximately in diameter. Devon Island itself is composed of Paleozoic shale and siltstone overlying gneissic bedrock. When the crater formed, the shale and siltstone were peeled back to expose the basement; material from as deep as has been identified. Description At 75° north latitude, it is one of the highest-latitude impact craters known. The temperature is below the freezing point of water for much of the year, and the limited vegetation is slow-growing, leading to very little weathering. For this reason Haughton retains many geological features that lower-latitude craters lose to erosion. Because Haughton's geology and climatology are as close to Mars-like as can be had on Earth, Haughton and its environs have been dubbed by scientists working ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
