PETROGENESIS OF SILICATE INCLUSIONS IN THE WEEKEROO STATION IIE IRON METEORITE: DIFFERENTIATION, REMELTING, AND DYNAMIC MIXING - PART II: CHEMICAL COMPOSITION OF AGGLUTINATE GLASS AS A TEST OF THE undefinedFUSION OF THE FINEST FRACTIONundefined (F3) MODEL
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dc.contributor.author | Ruzicka A. | |
dc.contributor.author | Fowler G.W. | |
dc.contributor.author | Snyder G.A. | |
dc.contributor.author | Prinz M. | |
dc.contributor.author | Papike J.J. | |
dc.contributor.author | Taylor L.A. | |
dc.date.accessioned | 2021-01-09T04:56:48Z | |
dc.date.available | 2021-01-09T04:56:48Z | |
dc.date.issued | 1999 | |
dc.identifier | https://elibrary.ru/item.asp?id=149024 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 1999, , 13, 2123-2143 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/22445 | |
dc.description.abstract | The Weekeroo Station IIE iron meteorite contains a variety of felsic and mafic inclusions enclosed in an FeNi-metal host. Petrographic, EMP, and SIMS data suggest that the petrogenesis of the silicates was complex, and included differentiation, remelting, FeO-reduction, and dynamic mixing of phases.Differentiation produced a variety of olivine-free inclusion assemblages, ranging from pyroxene + plagioclase + tridymite with peritectic compositions, to coarse orthopyroxene, to plagioclase + tridymite and its glassy equivalent. Individual phases have similar trace-element abundances and patterns, despite large variations in inclusion textures, modes, and bulk compositions, probably as a result of mechanical separation of pre-existing phases in an impact event that dynamically mixed silicates with the metallic host. Trace-element data imply that augite and plagioclase grains in different inclusions crystallized from the same precursor melt, characterized by relatively unfractionated REE abundances of ~20-30 x CI-chondrites except for a negative Eu anomaly. Such a precursor melt could have been produced by ~2-5% equilibrium partial melting of an H-chondrite silicate protolith, or by higher degrees of partial melting involving subsequent fractional crystallization. Glass appears to have formed by the remelting of pre-existing plagioclase and orthopyroxene, in a process that involved either disequilibrium or substantial melting of these phases. During remelting, silicate melt reacted with the FeNi-metal host, and FeO was reduced to Fe-metal. Following remelting and metal-silicate mixing, inclusions apparently cooled at different rates in a near-surface setting on the parent body; glass- or pigeonite-bearing inclusions cooled more rapidly (=<2.5°C/hr between 1000-850°C) than pigeonite-free, largely crystalline inclusions.The results of this study point to two likely models for forming IIE iron meteorites, both involving collision between an FeNi-metal impactor and either a differentiated or undifferentiated silicate-rich target of H-chondrite affinity. Each model has difficulties and it is possible that both are required to explain the diverse IIE group. | |
dc.title | PETROGENESIS OF SILICATE INCLUSIONS IN THE WEEKEROO STATION IIE IRON METEORITE: DIFFERENTIATION, REMELTING, AND DYNAMIC MIXING - PART II: CHEMICAL COMPOSITION OF AGGLUTINATE GLASS AS A TEST OF THE undefinedFUSION OF THE FINEST FRACTIONundefined (F3) MODEL | |
dc.type | Статья |
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