ISSN:
1573-0794
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract Fossil track analyses of a ∼ 3 cm section of boulder fragment 72255, collected at the base of the South Massif, yield a surface exposure age for this boulder in its present location of ∼ 40 m.y. This age is in good agreement with the81Kr-Kr exposure age (Leichet al., 1975), suggesting that the boulder was either never exposed to cosmic radiation prior to its emplacement at the foot of the South Massif or that it was heavily shielded during any previous irradiation. High-voltage electron microscope observations reveal no evidence of solar flare irradiation prior to breccia compaction, indicating that the breccia components were never part of a pre-Serenitatis near-surface regolith. The fission track record of a whitlockite crystal from 72255 yields a fission track age of 3.96 −0.07 +0.04 g.y. Comparison with the40Ar-39 Ar age of 4.00±0.03 g.y. suggests that this age represents the compaction age of the parent boulder.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00569673
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