Occurrence and implications of secondary olivine veinlets in lunar highland breccia Northwest Africa 11273

Xiaojia Zeng, Shijie Li, Katherine Joy, Xiongyao Li, Jianzhong Liu, Yang Li, Rui Li, Shijie Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Lunar breccias preserve the records of geologic processes on the Moon. In this study, we report the occurrence, petrography, mineralogy, and geological significance of the observed secondary olivine veinlets in lunar feldspathic breccia meteorite Northwest Africa (NWA) 11273. Bulk-rock composition measurements shown that this meteorite is geochemically similar to other lunar highland meteorites. In NWA 11273, five clasts are observed to host veinlets that are dominated by interconnecting olivine mineral grains. The host clasts mainly composed of mafic minerals (i.e., pyroxene and olivine) and probably sourced from a basaltic lithology. The studied olivine veinlets (~5 to 30 μm in width) are distributed within the mafic-mineral host, but do not extend into the adjacent plagioclase. Chemically, these olivine veinlets are Fe-richer (Fo41.4–51.9), compared with other olivine grains (Fo54.3–83.1) in lithic clasts and matrix of NWA 11273. By analogy with the secondary olivine veinlets observed in meteorites from asteroid Vesta (HED-group samples) and lunar mare samples, our study suggests that the newly observed olivine veinlets in NWA 11273 are likely formed by secondary deposition from a lunar fluid, rather than by crystallization from a high-temperature silicate melt. Such fluid could be sulfur- and phosphorous-poor and likely had an endogenic origin on the Moon. The new occurrence of secondary olivine veinlets in breccia NWA 11273 reveals that the fluid mobility and deposition could be a previously underappreciated geological process on the Moon.
Original languageEnglish
Pages (from-to)36-55
Number of pages20
JournalMetoritics and Planetary Science
Volume55
Issue number1
Early online date15 Dec 2019
DOIs
Publication statusPublished - 2020

Keywords

  • secondary olivine veinlets
  • fluid deposition
  • Moon
  • NWA 11273

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