Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean.
Calculations of the energetics of terrestrial accretion indicate that the Earth was extensively molten in its early history. Examination of early Archaean rocks from West Greenland (3.6-3.8 Gyr old) using short-lived 146Sm-142Nd chronometry indicates that an episode of mantle differentiation took pl...
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ftuloxford:oai:ora.ox.ac.uk:uuid:03057705-e3d0-4692-af04-83129d463af0 2023-05-15T16:27:58+02:00 Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. Caro, G Bourdon, B Wood, B Corgne, A 2016-07-28 https://doi.org/10.1038/nature03827 https://ora.ox.ac.uk/objects/uuid:03057705-e3d0-4692-af04-83129d463af0 eng eng doi:10.1038/nature03827 https://ora.ox.ac.uk/objects/uuid:03057705-e3d0-4692-af04-83129d463af0 https://doi.org/10.1038/nature03827 info:eu-repo/semantics/embargoedAccess Journal article 2016 ftuloxford https://doi.org/10.1038/nature03827 2022-06-28T20:04:50Z Calculations of the energetics of terrestrial accretion indicate that the Earth was extensively molten in its early history. Examination of early Archaean rocks from West Greenland (3.6-3.8 Gyr old) using short-lived 146Sm-142Nd chronometry indicates that an episode of mantle differentiation took place close to the end of accretion (4.46 +/- 0.11 Gyr ago). This has produced a chemically depleted mantle with an Sm/Nd ratio higher than the chondritic value. In contrast, application of 176Lu-176Hf systematics to 3.6-3.8-Gyr-old zircons from West Greenland indicates derivation from a mantle source with a chondritic Lu/Hf ratio. Although an early Sm/Nd fractionation could be explained by basaltic crust formation, magma ocean crystallization or formation of continental crust, the absence of coeval Lu/Hf fractionation is in sharp contrast with the well-known covariant behaviour of Sm/Nd and Lu/Hf ratios in crustal formation processes. Here we show using mineral-melt partitioning data for high-pressure mantle minerals that the observed Nd and Hf signatures could have been produced by segregation of melt from a crystallizing magma ocean at upper-mantle pressures early in Earth's history. This residual melt would have risen buoyantly and ultimately formed the earliest terrestrial protocrust. Article in Journal/Newspaper Greenland ORA - Oxford University Research Archive Greenland Nature 436 7048 246 249 |
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Open Polar |
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ORA - Oxford University Research Archive |
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ftuloxford |
language |
English |
description |
Calculations of the energetics of terrestrial accretion indicate that the Earth was extensively molten in its early history. Examination of early Archaean rocks from West Greenland (3.6-3.8 Gyr old) using short-lived 146Sm-142Nd chronometry indicates that an episode of mantle differentiation took place close to the end of accretion (4.46 +/- 0.11 Gyr ago). This has produced a chemically depleted mantle with an Sm/Nd ratio higher than the chondritic value. In contrast, application of 176Lu-176Hf systematics to 3.6-3.8-Gyr-old zircons from West Greenland indicates derivation from a mantle source with a chondritic Lu/Hf ratio. Although an early Sm/Nd fractionation could be explained by basaltic crust formation, magma ocean crystallization or formation of continental crust, the absence of coeval Lu/Hf fractionation is in sharp contrast with the well-known covariant behaviour of Sm/Nd and Lu/Hf ratios in crustal formation processes. Here we show using mineral-melt partitioning data for high-pressure mantle minerals that the observed Nd and Hf signatures could have been produced by segregation of melt from a crystallizing magma ocean at upper-mantle pressures early in Earth's history. This residual melt would have risen buoyantly and ultimately formed the earliest terrestrial protocrust. |
format |
Article in Journal/Newspaper |
author |
Caro, G Bourdon, B Wood, B Corgne, A |
spellingShingle |
Caro, G Bourdon, B Wood, B Corgne, A Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
author_facet |
Caro, G Bourdon, B Wood, B Corgne, A |
author_sort |
Caro, G |
title |
Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
title_short |
Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
title_full |
Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
title_fullStr |
Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
title_full_unstemmed |
Trace-element fractionation in Hadean mantle generated by melt segregation from a magma ocean. |
title_sort |
trace-element fractionation in hadean mantle generated by melt segregation from a magma ocean. |
publishDate |
2016 |
url |
https://doi.org/10.1038/nature03827 https://ora.ox.ac.uk/objects/uuid:03057705-e3d0-4692-af04-83129d463af0 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_relation |
doi:10.1038/nature03827 https://ora.ox.ac.uk/objects/uuid:03057705-e3d0-4692-af04-83129d463af0 https://doi.org/10.1038/nature03827 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1038/nature03827 |
container_title |
Nature |
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436 |
container_issue |
7048 |
container_start_page |
246 |
op_container_end_page |
249 |
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1766017584944119808 |