Origin and significance of cosmogenic signatures in vesicles of lunar basalt 15016OPEN ACCESS 

· by · in

Bekaert, D. V., Avice, G. and Marty, B.

Meteoritics & Planetary Science. doi: 10.1111/maps.13069

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“Lunar basalt 15016 (~3.3 Ga) is among the most vesicular (50% by volume) basalts recovered by the Apollo missions. We investigated the possible occurrence of indigenous lunar nitrogen and noble gases trapped in vesicles within basalt 15016, by crushing several cm-sized chips. Matrix/mineral gases were also extracted from crush residues by fusion with a CO2 laser. No magmatic/primordial component could be identified; all isotope compositions, including those of vesicles, pointed to a cosmogenic origin. We found that vesicles contained ~0.2%, ~0.02%, ~0.002%, and ~0.02% of the total amount of cosmogenic 21Ne, 38Ar, 83Kr, and 126Xe, respectively, produced over the basalt’s 300 Myr of exposure. Diffusion/recoil of cosmogenic isotopes from the basaltic matrix/minerals to intergrain joints and vesicles is discussed. The enhanced proportion of cosmogenic Xe isotopes relative to Kr detected in vesicles could be the result of kinetic fractionation, through which preferential retention of Xe isotopes over Kr within vesicles might have occurred during diffusion from the vesicle volume to the outer space through microleaks. This study suggests that cosmogenic loss, known to be significant for 3He and 21Ne, and to a lesser extent for 36Ar (Signer et al. ), also occurs to a negligible extent for the heaviest noble gases Kr and Xe.”

Related posts (automatically generated):

  1. Lunar meteorite Yamato-983885: Noble gases, nitrogen and cosmic ray exposure history
  2. The Lunar Breccia Dhofar 1442: Noble Gases, Nitrogen, and Carbon Released by Stepwise Combustion and CrushingOPEN ACCESS 
  3. A New Lunar High-Ti Basalt Type Defined from Clasts in Apollo 16 Breccia 60639
  4. Oldest high-Ti basalt and magnesian crustal materials in feldspathic lunar meteorite Dhofar 1428
  5. A revised shock history for the youngest unbrecciated lunar basalt—Northwest Africa 032 and paired meteorites
  6. Mare basalt meteorites, magnesian-suite rocks and KREEP reveal loss of zinc during and after lunar formation
  7. Origin and transportation history of lunar breccia 14311.
  8. Origin of native silicon and iron silicides in the Dhofar 280 lunar meteorite
  9. Enigmatic cathodoluminescent objects in the Dhofar 025 lunar meteorite: Origin and sources
  10. A South Pole–Aitken impact origin of the lunar compositional asymmetryOPEN ACCESS 
Tags: , ,