Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle
The Napier Complex comprises some of the oldest rocks on earth (~3.8 billion years old), overprinted by an ultra-high temperature (UHT) metamorphic event near the Archean−Proterozoic boundary. Garnet, orthopyroxene, sapphirine, osumilite, rutile and a whole rock representing an equilibrated assembla...
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ftunivnebraskali:oai:digitalcommons.unl.edu:andrillaffiliates-1014 2023-11-12T04:05:29+01:00 Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle Mukasa, S. B. Choi, S. H. Andronikov, A. V. Osanai, Y. Harley, S. L. Kelly, N. M. 2007-01-01T08:00:00Z application/pdf https://digitalcommons.unl.edu/andrillaffiliates/15 https://digitalcommons.unl.edu/context/andrillaffiliates/article/1014/viewcontent/Mukasa_AAKCW_2007_Lu_Hf_systematics.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/andrillaffiliates/15 https://digitalcommons.unl.edu/context/andrillaffiliates/article/1014/viewcontent/Mukasa_AAKCW_2007_Lu_Hf_systematics.pdf Related Publications from ANDRILL Affiliates Environmental Indicators and Impact Assessment text 2007 ftunivnebraskali 2023-10-30T10:48:58Z The Napier Complex comprises some of the oldest rocks on earth (~3.8 billion years old), overprinted by an ultra-high temperature (UHT) metamorphic event near the Archean−Proterozoic boundary. Garnet, orthopyroxene, sapphirine, osumilite, rutile and a whole rock representing an equilibrated assemblage from this belt yield a Lu−Hf isochron age of 2,403 ± 43 Ma. Preservation of the UHT mineral assemblage in the rock analyzed suggests rapid cooling with closure likely to have occurred for the Lu−Hf system at post-peak UHT conditions near a temperature of ~800°C. Zircon εHf values measured “see through” the UHT metamorphism and show that the source of magmas that formed the Napier Complex was extremely depleted (> +5.6 εHf at 3.85 Ga) relative to the chondritic uniform reservoir (CHUR). These results suggest significant depletion of the early Archean mantle, in agreement with the early differentiation of the earth that the latest core formation models require. Text Antarc* Antarctica East Antarctica University of Nebraska-Lincoln: DigitalCommons@UNL East Antarctica Napier ENVELOPE(-58.440,-58.440,-62.167,-62.167) |
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University of Nebraska-Lincoln: DigitalCommons@UNL |
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Environmental Indicators and Impact Assessment |
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Environmental Indicators and Impact Assessment Mukasa, S. B. Choi, S. H. Andronikov, A. V. Osanai, Y. Harley, S. L. Kelly, N. M. Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
topic_facet |
Environmental Indicators and Impact Assessment |
description |
The Napier Complex comprises some of the oldest rocks on earth (~3.8 billion years old), overprinted by an ultra-high temperature (UHT) metamorphic event near the Archean−Proterozoic boundary. Garnet, orthopyroxene, sapphirine, osumilite, rutile and a whole rock representing an equilibrated assemblage from this belt yield a Lu−Hf isochron age of 2,403 ± 43 Ma. Preservation of the UHT mineral assemblage in the rock analyzed suggests rapid cooling with closure likely to have occurred for the Lu−Hf system at post-peak UHT conditions near a temperature of ~800°C. Zircon εHf values measured “see through” the UHT metamorphism and show that the source of magmas that formed the Napier Complex was extremely depleted (> +5.6 εHf at 3.85 Ga) relative to the chondritic uniform reservoir (CHUR). These results suggest significant depletion of the early Archean mantle, in agreement with the early differentiation of the earth that the latest core formation models require. |
format |
Text |
author |
Mukasa, S. B. Choi, S. H. Andronikov, A. V. Osanai, Y. Harley, S. L. Kelly, N. M. |
author_facet |
Mukasa, S. B. Choi, S. H. Andronikov, A. V. Osanai, Y. Harley, S. L. Kelly, N. M. |
author_sort |
Mukasa, S. B. |
title |
Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
title_short |
Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
title_full |
Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
title_fullStr |
Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
title_full_unstemmed |
Lu−Hf systematics of the ultra-high temperature Napier Complex, East Antarctica: Evidence for the early Archean differentiation of Earth’s mantle |
title_sort |
lu−hf systematics of the ultra-high temperature napier complex, east antarctica: evidence for the early archean differentiation of earth’s mantle |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
2007 |
url |
https://digitalcommons.unl.edu/andrillaffiliates/15 https://digitalcommons.unl.edu/context/andrillaffiliates/article/1014/viewcontent/Mukasa_AAKCW_2007_Lu_Hf_systematics.pdf |
long_lat |
ENVELOPE(-58.440,-58.440,-62.167,-62.167) |
geographic |
East Antarctica Napier |
geographic_facet |
East Antarctica Napier |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
Related Publications from ANDRILL Affiliates |
op_relation |
https://digitalcommons.unl.edu/andrillaffiliates/15 https://digitalcommons.unl.edu/context/andrillaffiliates/article/1014/viewcontent/Mukasa_AAKCW_2007_Lu_Hf_systematics.pdf |
_version_ |
1782342007588388864 |