Origin of 182W Anomalies in Ocean Island Basalts
Journal Article
·
· Geochemistry, Geophysics, Geosystems
- University of Münster (Germany)
- University of Münster (Germany); Brown Univ., Providence, RI (United States)
- University of Münster (Germany); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Univ. of California, Santa Barbara, CA (United States)
- University of Münster (Germany); Max Planck Institute for Solar System Research (Germany)
Ocean island basalts (OIB) show variable 182W deficits that have been attributed to either early differentiation of the mantle or core-mantle interaction. However, 182W variations may also reflect nucleosynthetic isotope heterogeneity inherited from Earth's building material, which would be evident from correlated 182W and 183W anomalies. Some datasets for OIB indeed show hints for such correlated variations, meaning that a nucleosynthetic origin of W isotope anomalies in OIB cannot be excluded. We report high-precision W isotope data for OIB from Samoa and Hawaii, which confirm previously reported 182W deficits for these samples, but also demonstrate that none of these samples have resolvable 183W anomalies. These data therefore rule out a nucleosynthetic origin of the 182W deficits in OIB, which most likely reflect the entrainment of either core material or an overabundance of late-accreted materials within OIB mantle sources. If these processes occurred over Earth's history, they may have also been responsible for shifting the 182W composition of the bulk mantle to its modern-day value. We also report Mo isotope data for some Hawaiian OIB, which reveal no resolved nucleosynthetic Mo isotopic anomalies. This is consistent with inheritance of 182W deficits in OIB from the addition of either core or late-accreted material, but only if these materials have a non-carbonaceous (NC) meteorite-like heritage. As such, these data rule out significant contributions of carbonaceous chondrite (CC)-like materials to either Earth's core or late accretion.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 2006736
- Report Number(s):
- LLNL--JRNL-844238; 1067452
- Journal Information:
- Geochemistry, Geophysics, Geosystems, Journal Name: Geochemistry, Geophysics, Geosystems Journal Issue: 2 Vol. 24; ISSN 1525-2027
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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