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Titolo:
Oxygen isotopes and the early Solar System
Autore:
Franchi, IA; Baker, L; Bridges, JC; Wright, IP; Pillinger, CT;
Indirizzi:
Open Univ, Planetary & Space Sci Res Inst, Milton Keynes MK7 6AA, Bucks, England Open Univ Milton Keynes Bucks England MK7 6AA nes MK7 6AA, Bucks, England Nat Hist Museum, Dept Mineral, London SW7 5BD, England Nat Hist Museum London England SW7 5BD Mineral, London SW7 5BD, England
Titolo Testata:
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
fascicolo: 1787, volume: 359, anno: 2001,
pagine: 2019 - 2034
SICI:
1364-503X(20011015)359:1787<2019:OIATES>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
ORDINARY CHONDRITES; CARBONACEOUS CHONDRITES; METEORITES; CHONDRULES; NEBULA; EARTH; COMPONENTS; SILICATES; EVOLUTION; ALLENDE;
Keywords:
meteorites; oxygen isotopes; hydrothermal alteration; chondrites; mass-independent fractionation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Franchi, IA Open Univ, Planetary & Space Sci Res Inst, Walton Hall, MiltonKeynes MK7 6AA, Bucks, England Open Univ Walton Hall Milton Keynes Bucks England MK7 6AA land
Citazione:
I.A. Franchi et al., "Oxygen isotopes and the early Solar System", PHI T ROY A, 359(1787), 2001, pp. 2019-2034

Abstract

Meteorites preserve a wide range of oxygen isotopic signatures from the time of the Solar System's formation. Most of these rocks record complex histories, each phase of which has the potential for overwriting initial oxygensignatures. The unequilibrated ordinary chondrites reveal evidence of hydrothermal alteration through isotopic disequilibrium within chondrules and in secondary magnetites, which we can now constrain to temperatures of 140-180 degreesC. The effects of this alteration are progressively obliterated by later thermal metamorphism. Further heating leads to melting (shown in achondritic meteorites), producing well-defined mass-fractionation lines using high-precision analyses. The oxygen from low-temperature minerals in carbonaceous chondrites reveals high levels of isotopic uniformity, suggesting that the aqueous alteration occurred under open-system conditions. The initial isotopic composition of the water from the ordinary chondrites is quite distinct from that in thecarbonaceous chondrites, but both fall on a single line of slope 1.0, as do the initial anhydrous silicate compositions. This is taken to show that aprocess generating a mass-independent fractionation was responsible for most of the oxygen-isotopic variation seen in meteorites. Subsequent aqueous alteration of the meteorite parent-bodies involving these components is then capable of producing the full observed variation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/11/17 alle ore 03:43:37