The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks
Initial 187Os/188Os isotopic compositions for geochronologically and geologically well -constrained 3.8-Ga spinel peridotites from the Itsaq Gneiss Complex of southern West Greenland and chromite separates from 3.46-Ga komatiites from the Pilbara region of Western Australia have been determined to i...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/71962 2024-01-14T10:07:19+01:00 The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks Bennett, Victoria Nutman, Allen Esat, Tezer http://hdl.handle.net/1885/71962 https://doi.org/10.1016/S0016-7037(02)00862-1 https://openresearch-repository.anu.edu.au/bitstream/1885/71962/5/MigratedxPub2976_RSD_2002.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/71962/7/01_Bennett_The_Osmium_Mantle_Evolution_2002.pdf.jpg unknown Pergamon-Elsevier Ltd 1872-9533 http://hdl.handle.net/1885/71962 doi:10.1016/S0016-7037(02)00862-1 https://openresearch-repository.anu.edu.au/bitstream/1885/71962/5/MigratedxPub2976_RSD_2002.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/71962/7/01_Bennett_The_Osmium_Mantle_Evolution_2002.pdf.jpg Geochimica et Cosmochimica Acta Keywords: Archean crustal evolution isotopic composition mantle chemistry osmium isotope Australia Greenland Journal article ftanucanberra https://doi.org/10.1016/S0016-7037(02)00862-1 2023-12-15T09:33:39Z Initial 187Os/188Os isotopic compositions for geochronologically and geologically well -constrained 3.8-Ga spinel peridotites from the Itsaq Gneiss Complex of southern West Greenland and chromite separates from 3.46-Ga komatiites from the Pilbara region of Western Australia have been determined to investigate the osmium isotopic evolution of the early terrestial mantle. The measured compositions of 187Os/188Os(0) = 0.10262 ± 2, from an olivine separate, and 0.10329 ± 3, for a spinel separate from ∼3.8-Ga peridotite G93/42, are the lowest yet reported from any terrestrial sample. The corrections for in situ decay over 3.8 Ga for these low Re/Os phases are minimal and change the isotopic compositions by only 0.5 and 2.2% for the spinel and the olivine, respectively, resulting in 187Os/188Os(3.8Ga) = 0.1021 ± 0.0002 and 0.1009 ± 0.0002, respectively. These data extend direct measurement of Os isotopic compositions to much earlier periods of Earth history than previously documented and provide the best constraints on the Os isotopic composition of the early Archean terrestrial mantle. Analyses of Pilbara chromites yield 3.46-Ga mantle compositions of 0.1042 ± 0.0002 and 0.1051 ± 0.0002. These new data, combined with published initial Os isotopic compositions from late Archean and early Proterozoic samples, are compatible with the mantle, or at least portions of it, evolving from a solar system initially defined by meteorites to a modern composition of 187Os/188Os(0) = 0.1296 ± 0.0008 as previously suggested from peridotite xenolith data (Meisel et al., 2001); the associated 187Re/188Os(0) = 0.435 ± 0.005. Thus, chondritic 187Os/188Os compositions were a feature of the upper mantle for at least 3.8 billion years, requiring chondritic Re/Os ratios to have been a characteristic of the very early terrestrial mantle. In contrast, nonchondritic initial compositions of some Archean komatiites demonstrate that Os isotopic heterogeneity is an ancient feature of plume materials, reflecting the development of variable Re/Os ... Article in Journal/Newspaper Greenland Australian National University: ANU Digital Collections Greenland Geochimica et Cosmochimica Acta 66 14 2615 2630 |
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ftanucanberra |
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Keywords: Archean crustal evolution isotopic composition mantle chemistry osmium isotope Australia Greenland |
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Keywords: Archean crustal evolution isotopic composition mantle chemistry osmium isotope Australia Greenland Bennett, Victoria Nutman, Allen Esat, Tezer The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
topic_facet |
Keywords: Archean crustal evolution isotopic composition mantle chemistry osmium isotope Australia Greenland |
description |
Initial 187Os/188Os isotopic compositions for geochronologically and geologically well -constrained 3.8-Ga spinel peridotites from the Itsaq Gneiss Complex of southern West Greenland and chromite separates from 3.46-Ga komatiites from the Pilbara region of Western Australia have been determined to investigate the osmium isotopic evolution of the early terrestial mantle. The measured compositions of 187Os/188Os(0) = 0.10262 ± 2, from an olivine separate, and 0.10329 ± 3, for a spinel separate from ∼3.8-Ga peridotite G93/42, are the lowest yet reported from any terrestrial sample. The corrections for in situ decay over 3.8 Ga for these low Re/Os phases are minimal and change the isotopic compositions by only 0.5 and 2.2% for the spinel and the olivine, respectively, resulting in 187Os/188Os(3.8Ga) = 0.1021 ± 0.0002 and 0.1009 ± 0.0002, respectively. These data extend direct measurement of Os isotopic compositions to much earlier periods of Earth history than previously documented and provide the best constraints on the Os isotopic composition of the early Archean terrestrial mantle. Analyses of Pilbara chromites yield 3.46-Ga mantle compositions of 0.1042 ± 0.0002 and 0.1051 ± 0.0002. These new data, combined with published initial Os isotopic compositions from late Archean and early Proterozoic samples, are compatible with the mantle, or at least portions of it, evolving from a solar system initially defined by meteorites to a modern composition of 187Os/188Os(0) = 0.1296 ± 0.0008 as previously suggested from peridotite xenolith data (Meisel et al., 2001); the associated 187Re/188Os(0) = 0.435 ± 0.005. Thus, chondritic 187Os/188Os compositions were a feature of the upper mantle for at least 3.8 billion years, requiring chondritic Re/Os ratios to have been a characteristic of the very early terrestrial mantle. In contrast, nonchondritic initial compositions of some Archean komatiites demonstrate that Os isotopic heterogeneity is an ancient feature of plume materials, reflecting the development of variable Re/Os ... |
format |
Article in Journal/Newspaper |
author |
Bennett, Victoria Nutman, Allen Esat, Tezer |
author_facet |
Bennett, Victoria Nutman, Allen Esat, Tezer |
author_sort |
Bennett, Victoria |
title |
The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
title_short |
The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
title_full |
The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
title_fullStr |
The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
title_full_unstemmed |
The Osmium Mantle Evolution Curve and Limits on Accretion and Differentiation of the Earth from Archean (3.4 - 3.8 Ga) Ultramafic Rocks |
title_sort |
osmium mantle evolution curve and limits on accretion and differentiation of the earth from archean (3.4 - 3.8 ga) ultramafic rocks |
publisher |
Pergamon-Elsevier Ltd |
url |
http://hdl.handle.net/1885/71962 https://doi.org/10.1016/S0016-7037(02)00862-1 https://openresearch-repository.anu.edu.au/bitstream/1885/71962/5/MigratedxPub2976_RSD_2002.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/71962/7/01_Bennett_The_Osmium_Mantle_Evolution_2002.pdf.jpg |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Geochimica et Cosmochimica Acta |
op_relation |
1872-9533 http://hdl.handle.net/1885/71962 doi:10.1016/S0016-7037(02)00862-1 https://openresearch-repository.anu.edu.au/bitstream/1885/71962/5/MigratedxPub2976_RSD_2002.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/71962/7/01_Bennett_The_Osmium_Mantle_Evolution_2002.pdf.jpg |
op_doi |
https://doi.org/10.1016/S0016-7037(02)00862-1 |
container_title |
Geochimica et Cosmochimica Acta |
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66 |
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14 |
container_start_page |
2615 |
op_container_end_page |
2630 |
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1788061729881587712 |