Magnesium stable isotope composition of Earth's upper mantle
The mantle is Earth's largest reservoir of Mg containing > 99% of Earth's Mg inventory. However, no consensus exists on the stable Mg isotope composition of the Earth's mantle or how variable it is and, in particular, whether the mantle has the same stable Mg isotope composition as...
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ftanucanberra:oai:digitalcollections.anu.edu.au:1885/38621 2023-05-15T13:57:36+02:00 Magnesium stable isotope composition of Earth's upper mantle Handler, Monica R. Baker, Joel A. Schiller, Martin Bennett, Victoria Yaxley, Gregory 2015-12-10T21:53:43Z http://hdl.handle.net/1885/38621 unknown Elsevier 0012-821X http://hdl.handle.net/1885/38621 Earth and Planetary Science Letters Journal article 2015 ftanucanberra 2015-12-28T23:26:11Z The mantle is Earth's largest reservoir of Mg containing > 99% of Earth's Mg inventory. However, no consensus exists on the stable Mg isotope composition of the Earth's mantle or how variable it is and, in particular, whether the mantle has the same stable Mg isotope composition as chondrite meteorites. We have determined the Mg isotope composition of olivine from 22 mantle peridotites from eastern Australia, west Antarctica, Jordan, Yemen and southwest Greenland by pseudo-high-resolution MC-ICP-MS on Mg purified to > 99%. The samples include fertile lherzolites, depleted harzburgites and dunites, cryptically metasomatised ('dry') peridotites and modally metasomatised apatite ± amphibole-bearing harzburgites and wehrlites. Olivine from these samples of early Archaean through to Permian lithospheric mantle have δ25MgDSM-3 = - 0.22 to - 0.08‰. These data indicate the bulk upper mantle as represented by peridotite olivine is homogeneous within current analytical uncertainties (external reproducibility ≤ ± 0.07‰ [2 sd]). We find no systematic δ25Mg variations with location, lithospheric age, peridotite fertility, or degree or nature of mantle metasomatism. Although pyroxene may have slightly heavier δ25Mg than coexisting olivine, any fractionation between mantle pyroxene and olivine is also within current analytical uncertainties with a mean Δ25Mgpyr-ol = +0.06 ± 0.10‰ (2 sd; n = 5). Our average mantle olivine δ25MgDSM-3 = - 0.14 ± 0.07‰ and δ26MgDSM-3 = - 0.27 ± 0.14‰ (2 sd) are indistinguishable from the average of data previously reported for terrestrial basalts, confirming that basalts have stable Mg isotope compositions representative of the mantle. Olivine from five pallasite meteorites have δ25MgDSM-3 = - 0.16 to - 0.11‰ that are identical to terrestrial olivine and indistinguishable from the average δ25Mg previously reported for chondrites. These data provide no evidence for measurable heterogeneity in the stable Mg isotope composition of the source material in the proto-planetary disc from which Earth and chondrite and pallasite parent bodies accreted. Article in Journal/Newspaper Antarc* Antarctica Greenland West Antarctica Australian National University: ANU Digital Collections Greenland West Antarctica |
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Australian National University: ANU Digital Collections |
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The mantle is Earth's largest reservoir of Mg containing > 99% of Earth's Mg inventory. However, no consensus exists on the stable Mg isotope composition of the Earth's mantle or how variable it is and, in particular, whether the mantle has the same stable Mg isotope composition as chondrite meteorites. We have determined the Mg isotope composition of olivine from 22 mantle peridotites from eastern Australia, west Antarctica, Jordan, Yemen and southwest Greenland by pseudo-high-resolution MC-ICP-MS on Mg purified to > 99%. The samples include fertile lherzolites, depleted harzburgites and dunites, cryptically metasomatised ('dry') peridotites and modally metasomatised apatite ± amphibole-bearing harzburgites and wehrlites. Olivine from these samples of early Archaean through to Permian lithospheric mantle have δ25MgDSM-3 = - 0.22 to - 0.08‰. These data indicate the bulk upper mantle as represented by peridotite olivine is homogeneous within current analytical uncertainties (external reproducibility ≤ ± 0.07‰ [2 sd]). We find no systematic δ25Mg variations with location, lithospheric age, peridotite fertility, or degree or nature of mantle metasomatism. Although pyroxene may have slightly heavier δ25Mg than coexisting olivine, any fractionation between mantle pyroxene and olivine is also within current analytical uncertainties with a mean Δ25Mgpyr-ol = +0.06 ± 0.10‰ (2 sd; n = 5). Our average mantle olivine δ25MgDSM-3 = - 0.14 ± 0.07‰ and δ26MgDSM-3 = - 0.27 ± 0.14‰ (2 sd) are indistinguishable from the average of data previously reported for terrestrial basalts, confirming that basalts have stable Mg isotope compositions representative of the mantle. Olivine from five pallasite meteorites have δ25MgDSM-3 = - 0.16 to - 0.11‰ that are identical to terrestrial olivine and indistinguishable from the average δ25Mg previously reported for chondrites. These data provide no evidence for measurable heterogeneity in the stable Mg isotope composition of the source material in the proto-planetary disc from which Earth and chondrite and pallasite parent bodies accreted. |
format |
Article in Journal/Newspaper |
author |
Handler, Monica R. Baker, Joel A. Schiller, Martin Bennett, Victoria Yaxley, Gregory |
spellingShingle |
Handler, Monica R. Baker, Joel A. Schiller, Martin Bennett, Victoria Yaxley, Gregory Magnesium stable isotope composition of Earth's upper mantle |
author_facet |
Handler, Monica R. Baker, Joel A. Schiller, Martin Bennett, Victoria Yaxley, Gregory |
author_sort |
Handler, Monica R. |
title |
Magnesium stable isotope composition of Earth's upper mantle |
title_short |
Magnesium stable isotope composition of Earth's upper mantle |
title_full |
Magnesium stable isotope composition of Earth's upper mantle |
title_fullStr |
Magnesium stable isotope composition of Earth's upper mantle |
title_full_unstemmed |
Magnesium stable isotope composition of Earth's upper mantle |
title_sort |
magnesium stable isotope composition of earth's upper mantle |
publisher |
Elsevier |
publishDate |
2015 |
url |
http://hdl.handle.net/1885/38621 |
geographic |
Greenland West Antarctica |
geographic_facet |
Greenland West Antarctica |
genre |
Antarc* Antarctica Greenland West Antarctica |
genre_facet |
Antarc* Antarctica Greenland West Antarctica |
op_source |
Earth and Planetary Science Letters |
op_relation |
0012-821X http://hdl.handle.net/1885/38621 |
_version_ |
1766265308834693120 |