An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface expression of an impact structure. In many cases, on Earth, the impact crater has been destroyed by erosion, leaving only the deformed rock or sediment of the impact structure behind.[1] This is the fate of almost all old impact craters on Earth, unlike the ancient pristine craters preserved on the Moon and other geologically inactive rocky bodies with old surfaces[2] in the Solar System. Impact structure is synonymous with the less commonly used term astrobleme meaning "star wound".[3]
Impact crater structure
In an impact structure, the typical visible and topographic expressions of an impact crater are no longer obvious. Any meteorite fragments that may once have been present would be long since eroded away. Possible impact structures may be initially recognized by their anomalous geological character or geophysical expression. These may still be confirmed as impact structures by the presence of shocked minerals (particularly shocked quartz), shatter cones, geochemical evidence of extraterrestrial material or other methods.
^Moore, Jeffrey M.; Black, Greg; Buratti, Bonnie; Phillips, Cynthia B.; Spencer, John; Sullivan, Robert (2009). "Surface Properties, Regolith, and Landscape Degradation". In Pappalardo, Robert T. (ed.). Europa. The University of Arizona space science series. McKinnon, William B.; Khurana, Krishan. Tucson: The University of Arizona Press. p. 341. ISBN978-0-8165-2844-8. Bodies with current geological activity such as Io and Earth have very few recognizable impact craters—Io, in fact, is so volcanically active that not a single impact crater, of any size, has been found on its surface to date. The Earth has about 150 recognized craters, but many have been geologically modified and would be difficult to recognize from orbit. On the other hand, geologically inactive bodies with old surfaces, such as Earth's Moon or Callisto, are covered with impact craters of all sizes.
^French, Bevan M (1998). Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures. Houston, Texas: Lunar and Planetary Institute. p. 120. LPI Contribution No. 954.
External linksEdit
Terrestrial Impact Craters at the Lunar and Planetary Institute
Earth Impact Database
October 15, 2023
impact, structure, impact, structure, generally, circular, craterlike, geologic, structure, deformed, bedrock, sediment, produced, impact, planetary, surface, whatever, stage, erosion, structure, contrast, impact, crater, surface, expression, impact, structure. An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface whatever the stage of erosion of the structure In contrast an impact crater is the surface expression of an impact structure In many cases on Earth the impact crater has been destroyed by erosion leaving only the deformed rock or sediment of the impact structure behind 1 This is the fate of almost all old impact craters on Earth unlike the ancient pristine craters preserved on the Moon and other geologically inactive rocky bodies with old surfaces 2 in the Solar System Impact structure is synonymous with the less commonly used term astrobleme meaning star wound 3 Impact crater structureIn an impact structure the typical visible and topographic expressions of an impact crater are no longer obvious Any meteorite fragments that may once have been present would be long since eroded away Possible impact structures may be initially recognized by their anomalous geological character or geophysical expression These may still be confirmed as impact structures by the presence of shocked minerals particularly shocked quartz shatter cones geochemical evidence of extraterrestrial material or other methods See also EditComplex crater Earth Impact Database Multi ringed basin Impact event List of impact craters on Earth List of possible impact structures on Earth Traces of Catastrophe book from Lunar and Planetary Institute comprehensive reference on impact crater science Peak ringReferences Edit Neuendorf K K E J P Mehl Jr and J A Jackson eds 2005 Glossary of Geology 5th ed Alexandria Virginia American Geological Institute 779 pp ISBN 0 922152 76 4 Moore Jeffrey M Black Greg Buratti Bonnie Phillips Cynthia B Spencer John Sullivan Robert 2009 Surface Properties Regolith and Landscape Degradation In Pappalardo Robert T ed Europa The University of Arizona space science series McKinnon William B Khurana Krishan Tucson The University of Arizona Press p 341 ISBN 978 0 8165 2844 8 Bodies with current geological activity such as Io and Earth have very few recognizable impact craters Io in fact is so volcanically active that not a single impact crater of any size has been found on its surface to date The Earth has about 150 recognized craters but many have been geologically modified and would be difficult to recognize from orbit On the other hand geologically inactive bodies with old surfaces such as Earth s Moon or Callisto are covered with impact craters of all sizes French Bevan M 1998 Traces of Catastrophe A Handbook of Shock Metamorphic Effects in Terrestrial Meteorite Impact Structures Houston Texas Lunar and Planetary Institute p 120 LPI Contribution No 954 External links EditTerrestrial Impact Craters at the Lunar and Planetary Institute Earth Impact Database Retrieved from https en wikipedia org w index php title Impact structure amp oldid 1171962263, wikipedia, wiki, book, books, library,
