Los Angeles: The most differentiated basaltic martian meteorite

A. E. Rubin, P. H. Warren, J. P. Greenwood, R. S. Verish, L. A. Leshin, R. L. Hervig, R. N. Clayton, T. K. Mayeda

Research output: Contribution to journalArticle

113 Scopus citations

Abstract

Los Angeles is a new martian meteorite that expands the compositional range of basaltic shergottites. Compared to Shergotty, Zagami, QUE94201, and EET79001-B, Los Angeles is more differentiated, with higher concentrations of incompatible elements (e.g., La) and a higher abundance of late-stage phases such as phosphates and K-rich feld-spathic glass. The pyroxene crystallization trend starts at compositions more ferroan than in other martian basalts. Trace elements indicate a greater similarity to Shergotty and Zagami than to QUE94201 or EET79001-B, but the Mg/Fe ratio is low even compared to postulated parent melts of Shergotty and Zagami. Pyroxene in Los Angeles has 0.7-4-μm-thick exsolution lamellae, ~10 times thicker than those in Shergotty and Zagami. Opaque oxide compositions suggest a low equilibration temperature at an oxygen fugacity near the fayalite-magnetite-quartz buffer. Los Angeles cooled more slowly than Shergotty and Zagami. Slow cooling, coupled with the ferroan bulk composition, produced abundant fine-grained intergrowths of fayalite, hedenbergite, and silica, by the breakdown of pyroxferroite. Shock effects in Los Angeles include maskelynitized plagioclase, pyroxene with mosaic extinction, and rare fault zones. One such fault ruptured a previously decomposed zone of pyroxferroite. Although highly differentiated, the bulk composition of Los Angeles is not close to the low-Ca/Si composition of the globally wind-stirred soil of Mars.

Original languageEnglish (US)
Pages (from-to)1011-1014
Number of pages4
JournalGeology
Volume28
Issue number11
DOIs
StatePublished - Jan 1 2000
Externally publishedYes

Keywords

  • Los Angeles meteorite
  • Mars
  • Martian meteorites
  • Pyroxferroite
  • Shergottite meteorites

ASJC Scopus subject areas

  • Geology

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    Rubin, A. E., Warren, P. H., Greenwood, J. P., Verish, R. S., Leshin, L. A., Hervig, R. L., Clayton, R. N., & Mayeda, T. K. (2000). Los Angeles: The most differentiated basaltic martian meteorite. Geology, 28(11), 1011-1014. https://doi.org/10.1130/0091-7613(2000)028<1011:LATMDB>2.3.CO;2