An achondrite[1] is a stony meteorite that does not contain chondrules.[2][3] It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies.[4][5] As a result, achondrites have distinct textures and mineralogies indicative of igneous processes.[6]
Achondrites account for about 8% of meteorites overall, and the majority (about two-thirds) of them are HED meteorites, possibly originating from the crust of asteroid 4 Vesta. Other types include Martian, Lunar, and several types thought to originate from as-yet unidentified asteroids. These groups have been determined on the basis of e.g. the Fe/Mn chemical ratio and the 17O/18O oxygenisotope ratios, thought to be characteristic "fingerprints" for each parent body.[7]
Primitive achondrites, also called PAC group, are so-called because their chemical composition is primitive in the sense that it is similar to the composition of chondrites, but their texture is igneous, indicative of melting processes. To this group belong:[8]
Acapulcoites (after the meteorite Acapulco, Mexico)
Asteroidal achondrites, also called evolved achondrites, are so-called because they have been differentiated on a parent body. This means that their mineralogical and chemical composition was changed by melting and crystallization processes. They are divided into several groups:[8]
HED meteorites (Vesta). They may have originated on the asteroid 4 Vesta, because their reflection spectra are very similar.[9] They are named after the initial letters of the three subgroups:
^Sahijpal, S.; Soni, P.; Gagan, G. (2007). "Numerical simulations of the differentiation of accreting planetesimals with 26Al and 60Fe as the heat sources". Meteoritics & Planetary Science. 42 (9): 1529–1548. Bibcode:2007M&PS...42.1529S. doi:10.1111/j.1945-5100.2007.tb00589.x.
^Gupta, G.; Sahijpal, S. (2010). "Differentiation of Vesta and the parent bodies of other achondrites". J. Geophys. Res. Planets. 115 (E8). Bibcode:2010JGRE..115.8001G. doi:10.1029/2009JE003525. S2CID 129905814.
^Mason, B. (1962). Meteorites. New York: John Wiley.
^Mittlefehldt, David W.; McCoy, Timothy J.; Goodrich, Cyrena Anne; Kracher, Alfred (1998). "Non-chondritic Meteorites from Asteroidal Bodies". Reviews in Mineralogy and Geochemistry. 36 (1): 4.1–4.195.
^ abcO. Richard Norton. The Cambridge encyclopedia of meteorites. UK, Cambridge University Press, 2002. ISBN0-521-62143-7.
^Drake, M. J. (2001). "The eucrite/Vesta story". Meteoritics and Planetary Science. 36 (4): 501–513. Bibcode:2001M&PS...36..501D. doi:10.1111/j.1945-5100.2001.tb01892.x. S2CID 128394153.
^Treiman, A. H. (2000). "The SNC meteorites are from Mars". Planetary and Space Science. 48 (12–14): 1213–1230. Bibcode:2000P&SS...48.1213T. doi:10.1016/S0032-0633(00)00105-7.
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Achondrite Images from Meteorites Australia
November 23, 2023
achondrite, achondrite, stony, meteorite, that, does, contain, chondrules, consists, material, similar, terrestrial, basalts, plutonic, rocks, been, differentiated, reprocessed, lesser, greater, degree, melting, recrystallization, within, meteorite, parent, bo. An achondrite 1 is a stony meteorite that does not contain chondrules 2 3 It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies 4 5 As a result achondrites have distinct textures and mineralogies indicative of igneous processes 6 Achondrite Type Cumberland Falls achondrite aubrite Compositional typeStonyA eucrite achondrite from the Millbillillie meteorite shower Achondrites account for about 8 of meteorites overall and the majority about two thirds of them are HED meteorites possibly originating from the crust of asteroid 4 Vesta Other types include Martian Lunar and several types thought to originate from as yet unidentified asteroids These groups have been determined on the basis of e g the Fe Mn chemical ratio and the 17O 18O oxygen isotope ratios thought to be characteristic fingerprints for each parent body 7 Contents 1 Classification 1 1 Primitive achondrites 1 2 Asteroidal achondrites 1 3 Lunar meteorites 1 4 Martian meteorite 2 See also 3 References 4 External linksClassification editAchondrites are classified into the following groups 8 Primitive achondrites Asteroidal achondrites Lunar meteorites Martian meteoritesPrimitive achondrites edit Primitive achondrites also called PAC group are so called because their chemical composition is primitive in the sense that it is similar to the composition of chondrites but their texture is igneous indicative of melting processes To this group belong 8 Acapulcoites after the meteorite Acapulco Mexico Lodranites after the meteorite Lodran Winonaites after the meteorite Winona Ureilites after the meteorite Novy Ureii Russia Brachinites after the meteorite Brachina Asteroidal achondrites edit Asteroidal achondrites also called evolved achondrites are so called because they have been differentiated on a parent body This means that their mineralogical and chemical composition was changed by melting and crystallization processes They are divided into several groups 8 HED meteorites Vesta They may have originated on the asteroid 4 Vesta because their reflection spectra are very similar 9 They are named after the initial letters of the three subgroups Howardites Eucrites Diogenites Angrites AubritesLunar meteorites edit Lunar meteorites are meteorites that originated from the Moon Martian meteorite edit Martian meteorites 10 are meteorites that originated from Mars They are divided into three main groups with two exceptions see last two entries Shergottites Nakhlites Chassignites OPX martian meteorites ALH 84001 Regolith Soil samples NWA 7034 and pairings See also editGlossary of meteoriticsReferences edit Etymology from the prefix a privative a and the word chondrite Recommended classifications Eucrite pmict Achondrite Encyclopaedia Britannica Sahijpal S Soni P Gagan G 2007 Numerical simulations of the differentiation of accreting planetesimals with 26Al and 60Fe as the heat sources Meteoritics amp Planetary Science 42 9 1529 1548 Bibcode 2007M amp PS 42 1529S doi 10 1111 j 1945 5100 2007 tb00589 x Gupta G Sahijpal S 2010 Differentiation of Vesta and the parent bodies of other achondrites J Geophys Res Planets 115 E8 Bibcode 2010JGRE 115 8001G doi 10 1029 2009JE003525 S2CID 129905814 Mason B 1962 Meteorites New York John Wiley Mittlefehldt David W McCoy Timothy J Goodrich Cyrena Anne Kracher Alfred 1998 Non chondritic Meteorites from Asteroidal Bodies Reviews in Mineralogy and Geochemistry 36 1 4 1 4 195 a b c O Richard Norton The Cambridge encyclopedia of meteorites UK Cambridge University Press 2002 ISBN 0 521 62143 7 Drake M J 2001 The eucrite Vesta story Meteoritics and Planetary Science 36 4 501 513 Bibcode 2001M amp PS 36 501D doi 10 1111 j 1945 5100 2001 tb01892 x S2CID 128394153 Treiman A H 2000 The SNC meteorites are from Mars Planetary and Space Science 48 12 14 1213 1230 Bibcode 2000P amp SS 48 1213T doi 10 1016 S0032 0633 00 00105 7 External links edit nbsp Wikimedia Commons has media related to Achondrite meteorites Achondrite Images from Meteorites Australia Retrieved from https en wikipedia org w index php title Achondrite amp oldid 1177660051, wikipedia, wiki, book, books, library,
