Ni isotopes provide a glimpse of Earth's pre-late-veneer mantle
Moderately siderophile (e.g., Ni) and highly siderophile elements (HSEs) in the bulk silicate Earth (BSE) are believed to be partly or near-completely delivered by late accretion after the depletion caused by metallic core formation. However, the extent and rate of remixing of late-accreted material...
| Published in: | Science Advances |
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| Main Authors: | , , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://curis.ku.dk/portal/da/publications/ni-isotopes-provide-a-glimpse-of-earths-prelateveneer-mantle(70e100a6-e8e7-4cdc-8a12-679b4725d31a).html https://doi.org/10.1126/sciadv.adj2170 https://curis.ku.dk/ws/files/378756965/Ni_isotopes_provide_a_glimpse_of_Earth_s_pre_late_veneer_mantle.pdf |
| Summary: | Moderately siderophile (e.g., Ni) and highly siderophile elements (HSEs) in the bulk silicate Earth (BSE) are believed to be partly or near-completely delivered by late accretion after the depletion caused by metallic core formation. However, the extent and rate of remixing of late-accreted materials that equilibrated with Earth's pre-late-veneer mantle have long been debated. Observing evidence of this siderophile element-depleted pre-late-veneer mantle would provide powerful confirmation of this model of early mantle evolution. We find that the mantle source of the ~3.8-billion-year-old (Ga) Narssaq ultramafic cumulates from Southwest Greenland exhibits a subtle 60Ni/58Ni excess of ~0.05 per mil and contains a clear HSE deficiency of ~60% relative to the BSE. The intermediate Ni isotopic composition and HSE abundances of the ~3.8-Ga Narssaq mantle mark a transitional Eoarchean snapshot as the poorly mixed 3.8-Ga mantle containing elements of pre-late-veneer mantle material transitions to modern Earth's mantle. |
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