Crustal partial melting on Vesta: Evidence from highly metamorphosed eucrites

A. Yamaguchi, J. A. Barrat, R. C. Greenwood, N. Shirai, C. Okamoto, T. Setoyanagi, M. Ebihara, I. A. Franchi, M. Bohn

研究成果: Article査読

64 被引用数 (Scopus)

抄録

We have performed a mineralogical and geochemical study of eight metamorphosed basaltic eucrites. These are classified into granulitic eucrites and type 4-7 eucrites on the basis of their textures and pyroxene mineralogy, and display mineralogical evidence for high temperature metamorphism, including partial melting. In particular, rare earth element (REE) patterns of a number of the eucrites studied show varying degrees of light REE depletion due to partial melting, with subsequent melt extraction. A simple correlation between metamorphic grade, as deduced from pyroxene mineralogy, and the degree of light REE depletion was not detected. This can be explained by the fact that homogenization, exsolution and inversion of pigeonite would have required prolonged heating at moderate temperatures (∼800-1000 °C), whereas partial melting would have taken place over a short time interval where temperatures exceeded that of the solidus. The eucrites studied therefore record a two stage thermal regime consisting of short, high temperature reheating events superimposed on long duration global crustal metamorphism. The short reheating events may have been caused by impact events and/or intrusions of hot magmas. The results of this study demonstrate that the thermal history of eucritic crust was more complex than can be explained by a simple burial model alone. In particular, the origin of Stannern trend eucrites requires contamination of Main-Group magmas by partial melts extracted from residual eucrites.

本文言語English
ページ(範囲)7162-7182
ページ数21
ジャーナルGeochimica et Cosmochimica Acta
73
23
DOI
出版ステータスPublished - 2009 12 1
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ASJC Scopus subject areas

  • 地球化学および岩石学

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