Origin of excess 176Hf in meteorites

Kristine Thrane, James N. Connelly, Martin Bizzarro, Bradley S. Meyer, Lih-Sin The

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

26 Citationer (Scopus)


After considerable controversy regarding the 176Lu decay constant (λ176Lu), there is now widespread agreement that (1.867 ± 0.008) × 10-11 yr-1 as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the 176Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than ∼ 4.56 Ga meteorites unresolved. We attribute 176Hf excess in older meteorites to an accelerated decay of 176Lu caused by excitation of the long-lived 176Lu ground state to a short-lived 176mLu isomer. The energy needed to cause this transition is ascribed to a post-crystallization spray of cosmic rays accelerated by nearby supernova(e) that occurred after 4564.5 Ma. The majority of these cosmic rays are estimated to penetrate accreted material down to 10-20m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of 176Hf with depth of burial at the time of the irradiation event.

Sider (fra-til)861-867
Antal sider7
TidsskriftAstrophysical Journal
Udgave nummer2
StatusUdgivet - 2010
Udgivet eksterntJa


  • Programområde 4: Mineralske råstoffer


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