INVESTIGADORES
VARELA Maria Eugenia
artículos
Título:
THE TUCSON UNGROUPED IRON METEORITE AND ITS RELATIONSHIP TO CHONDRITES
Autor/es:
KURAT GERO,; VARELA M.E.; ZINNER E; BRANDSTAETTER F.
Revista:
METEORITICS & PLANETARY SCIENCE
Editorial:
METEORITICAL SOC
Referencias:
Año: 2010 vol. 45 p. 1982 - 2006
ISSN:
1086-9379
Resumen:
Abstract?Tucson is an enigmatic ataxitic iron meteorite, an assemblage of reduced silicatesembedded in Fe-Ni metal with dissolved Si and Cr. Both, silicates and metal, contain arecord of formation at high temperature (1800 K) and fast cooling. The latter resulted inthe preservation of abundant glasses, Al-rich pyroxenes, brezinaite, and fine-grained metal.Our chemical and petrographic studies of all phases (minerals and glasses) indicate that theyhave a nebular rather than an igneous origin and give support to a chondritic connection assuggested by Prinz et al. (1987). All silicate phases in Tucson apparently grew from a liquidthat had refractory trace elements at approximately 6?20 · CI abundances withnonfractionated (solar) pattern, except for Sc, which was depleted (1 · CI). Metal seemsto have precipitated before and throughout silicate aggregate formation, allowingpreservation of all evolutionary steps of the silicates by separating them from theenvironment. In contrast to most chondrites, Tucson documents coprecipitation of metaland silicates from the solar nebula gas and precipitation of metal before silicates?inaccordance with theoretical condensation calculations for high-pressure solar nebula gas.We suggest that Tucson is the most metal-rich and volatile-element-poor member of the CRchondrite clan.