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A meta-analysis of geochronologically relevant half-lives: what's the best decay constant?
Ist Teil von
International geology review, 2014-05, Vol.56 (7), p.905-914
Ort / Verlag
Philadelphia: Taylor & Francis
Erscheinungsjahr
2014
Quelle
Taylor & Francis Journals Auto-Holdings Collection
Beschreibungen/Notizen
Twenty-first century advances in both the analytical procedures and instrumentation used in geochronology promise age accuracy better than ±1‰, but realizing this potential requires knowledge of decay constants (λ) that exceed this level. Given the paucity of improved recent measurements of λ, the community has experimented with hybrid methodologies utilizing data largely generated during the 1970s. In this article, we perform a systematic review of laboratory decay constant determinations relevant to geochronology (i.e.
87
Rb,
147
Sm,
176
Lu,
230
Th,
232
Th,
235
U, and
238
U), focusing on methodological consistency. For radioisotopes for which multiple studies are available, results are combined through a random effects model to yield the best available values and associated uncertainties. Unfortunately, despite its vital role in modern geochronology, only one experimental determination of
238
U decay met our criteria for consideration, significantly limiting the ability to assess its reliability. Thus, utilizing λ
238
as an anchor for establishing other decay constants (e.g.
40
K,
176
Lu, and spontaneous
238
U fission) places an unverified result at the core of geochronology. For geochronology to attain its greatest potential, more and better laboratory determinations of decay constants are required, along with a community methodology that permits us to continuously take advantage of new data.