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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