Annealing history of zircons from Apollo 14083 and 14303 impact breccias

· by · in ,

R. T. Pidgeon, R. E. Merle, M. L. Grange, A. A. Nemchin

Meteoritics & Planetary Science
First published: 13 August 2018

LINK

“Breccia boulders scattered around the 25 Ma Cone Crater near the Apollo 14 landing site provide a potential source of material ejected from the underlying Fra Mauro formation, which is interpreted to form from the ejecta blanket of the ~3.9 Ga Imbrium impact. However, questions remain as to whether all or some of the rocks collected are from the Fra Mauro Formation. In this contribution, we present new Raman measurements on zircons from impact breccias 14083 and 14303 that indicate a zircon radiation damage age of the breccias of 3900 ± 120 (2σ) Ma. These ages are compatible with a history of thermal shock during their emplacement as part of the Imbrium impact ejecta blanket. In contrast, previously published Raman analyses of zircons from a sample of breccia 14311 have a younger radiation damage age of 3410 ± 80 (2σ) Ma, confirming that this breccia had a different thermal history and was possibly unrelated to the Fra Mauro Formation. The radiation damage ages of breccias 14083 and 14303, in combination with previously published apatite U‐Pb ages, place constraints on the thermal conditions within the Imbrium ejecta blanket. “

Related posts (automatically generated):

  1. Annealing of radiation damage in zircons from Apollo 14 impact breccia 14311: Implications for the thermal history of the breccia.
  2. A protracted timeline for lunar bombardment from mineral chemistry, Ti thermometry and U–Pb geochronology of Apollo 14 melt breccia zircons
  3. Radiogenic Pb mobilization induced by shock metamorphism of zircons in the Apollo 72255 Civet Cat norite clast
  4. Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U–Pb SIMS analyses
  5. Xenon systematics of individual lunar zircons, a new window on the history of the lunar surface
  6. High resolution U-Pb ages of Ca-phosphates in Apollo 14 breccias: Implications for the age of the Imbrium impact
  7. Ages of lunar impact breccias: limits for timing of the Imbrium impact
  8. Pb-Pb ages of feldspathic clasts in two Apollo 14 breccia samples
  9. Evidence for multiple 4.0–3.7 Ga impact events within the Apollo 16 collection
  10. U‐Pb SIMS ages of Apollo 14 zircon: Identifying distinct magmatic episodes
Tags: , , ,