New eucrite Dar al Gani 872: Petrography, chemical composition, and evolution

Andrea Patzer, Dolores H. Hill, William V. Boynton

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Dar al Gani 872 (DaG 872) is a new meteorite from Libya that we classified by means of Instrumental Neutron Activation Analysis (INAA), electron microprobe, and optical microscopy. According to our results, DaG 872 is a Mg-rich main group eucrite, i.e., a monomict noncumulate basaltic eucrite displaying a predominant coarse-grained relict subophitic and a fine-grained granulitic texture. The meteorite also shows pockets of late-stage mesostasis and is penetrated by several calcite veins due to terrestrial weathering. Finally, it exhibits shock phenomena of stage 1-2 including heavily fractured mineral components, undulose extinction of plagioclase, kinked lamellae, and mosaicism in pyroxenes corresponding to peak pressures of ∼20 GPa. In view of petrographic criteria as well as compositional and exsolution characteristics of its pyroxenes, the sample represents a metamorphic type 5 eucrite. Assuming the metamorphic type to be a function of burial depth on the parent body and taking into account the relatively high shock stage, the excavation of DaG 872 was likely induced by a major impact event. Prior to this point, DaG 872 apparently underwent a 4-stage geological evolution that is reflected by intricate textural and mineralogical features.

Original languageEnglish (US)
Pages (from-to)783-794
Number of pages12
JournalMeteoritics and Planetary Science
Volume38
Issue number5
DOIs
StatePublished - May 2003

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ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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