The origin of alteration “orangettes” in Dhofar 019: Implications for the age and aqueous history of the shergottites

L. J. Hallis*, L. Kemppinen, M. R. Lee, L. A. Taylor

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
303 Downloads (Pure)

Abstract

The shergottites are the largest group of Martian meteorites, and the only group that has not been found to contain definitive evidence of Martian aqueous alteration. Given recent reports of current liquid water at the surface of Mars, this study aimed to investigate in detail the possibility of Martian phyllosilicate within shergottite Dhofar 019. Optical and scanning electron microscopy, followed by transmission electron microscopy, confirmed the presence of alteration orangettes, with a layered structure consisting of poorly ordered Mg-phyllosilicate and calcite. These investigations identified maskelynite dissolution, followed by Mg-phyllosilicate and calcite deposition within the dissolution pits, as the method of orangette production. The presence of celestine within the orangette layers, the absence of shock dislocation features within calcite, and the Mg-rich nature of the phyllosilicate, all indicate a terrestrial origin for these features on Dhofar 019.

Original languageEnglish
Pages (from-to)2695-2706
Number of pages12
JournalMeteoritics and Planetary Science
Volume52
Issue number12
Early online date3 Nov 2017
DOIs
Publication statusPublished - 1 Dec 2017

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