Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks
Elevated δ18O is used as a marker for the presence of continents and surficial alteration in the Eoarchean and Hadean. This study establishes a timeline for δ18O enrichment in Eoarchean metasedimentary rocks of the Isua supracrustal belt in Greenland. The source-rocks for the protolith of these meta...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/218988 2024-01-14T10:07:23+01:00 Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks Gauthiez Putallaz, Laure Nutman, Allen P. Bennett, Vickie Rubatto, Daniela application/pdf http://hdl.handle.net/1885/218988 https://doi.org/10.1016/j.chemgeo.2020.119474 https://openresearch-repository.anu.edu.au/bitstream/1885/218988/3/01_Gauthiez-Putallaz_Origins_of_high_2020.pdf.jpg en_AU eng Elsevier http://purl.org/au-research/grants/arc/DP120100273 http://purl.org/au-research/grants/arc/DP170100715 http://purl.org/au-research/grants/arc/DP110101599 0009-2541 http://hdl.handle.net/1885/218988 doi:10.1016/j.chemgeo.2020.119474 https://openresearch-repository.anu.edu.au/bitstream/1885/218988/3/01_Gauthiez-Putallaz_Origins_of_high_2020.pdf.jpg © 2020 Elsevier B.V Chemical Geology https://dx.doi.org/ Eoarchean Weathering Oxygen Isotopes SHRIMP Isua Metasediments Journal article ftanucanberra https://doi.org/10.1016/j.chemgeo.2020.119474 2023-12-15T09:33:39Z Elevated δ18O is used as a marker for the presence of continents and surficial alteration in the Eoarchean and Hadean. This study establishes a timeline for δ18O enrichment in Eoarchean metasedimentary rocks of the Isua supracrustal belt in Greenland. The source-rocks for the protolith of these metasedimentary rocks are mafic to intermediate magmatic rocks of ≥3709 ± 4 Ma, based on the age of zircons found in volcanogenic layers. The δ18O of +5.4 ± 0.4‰ of the zircon crystals indicate that the sources had a primary mantle-derived signature. However, garnet in two metasediments yields higher δ18O values of +8.7 to +9.7‰, in equilibrium with a whole-rock of +11 to +12‰ at 500-600 °C. This requires that the mafic protolith was weathered at surficial conditions, in agreement with previous conclusions based on major element geochemistry. The garnet grains with high δ18O record four growth zones, assigned to I) arc-building thermal metamorphism, II-III) terrane assembly at medium to high-pressure conditions, estimated to occur at 3660-3690 Ma and IV) late-Archaean overprint likely at ca. 2690 Ma. This shows that material with originally mantle-like δ18O was altered at low temperature (near-surface) to generate elevated oxygen isotope signatures and then recycled to middle-crustal conditions within 10-50 million years of crystallization in the Eoarchean. We propose that melting of such rocks could produce the zircon crystals with high δ18O that are found in the detrital and magmatic record in the Archean. This work was funded by Australian Research Council projects DP120100273 and DP170100715. DR acknowledges the support of ARC grant DP110101599 and Swiss National Science Foundation grant 200021-166280. Article in Journal/Newspaper Greenland Australian National University: ANU Digital Collections Greenland Chemical Geology 537 119474 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
English |
topic |
Eoarchean Weathering Oxygen Isotopes SHRIMP Isua Metasediments |
spellingShingle |
Eoarchean Weathering Oxygen Isotopes SHRIMP Isua Metasediments Gauthiez Putallaz, Laure Nutman, Allen P. Bennett, Vickie Rubatto, Daniela Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
topic_facet |
Eoarchean Weathering Oxygen Isotopes SHRIMP Isua Metasediments |
description |
Elevated δ18O is used as a marker for the presence of continents and surficial alteration in the Eoarchean and Hadean. This study establishes a timeline for δ18O enrichment in Eoarchean metasedimentary rocks of the Isua supracrustal belt in Greenland. The source-rocks for the protolith of these metasedimentary rocks are mafic to intermediate magmatic rocks of ≥3709 ± 4 Ma, based on the age of zircons found in volcanogenic layers. The δ18O of +5.4 ± 0.4‰ of the zircon crystals indicate that the sources had a primary mantle-derived signature. However, garnet in two metasediments yields higher δ18O values of +8.7 to +9.7‰, in equilibrium with a whole-rock of +11 to +12‰ at 500-600 °C. This requires that the mafic protolith was weathered at surficial conditions, in agreement with previous conclusions based on major element geochemistry. The garnet grains with high δ18O record four growth zones, assigned to I) arc-building thermal metamorphism, II-III) terrane assembly at medium to high-pressure conditions, estimated to occur at 3660-3690 Ma and IV) late-Archaean overprint likely at ca. 2690 Ma. This shows that material with originally mantle-like δ18O was altered at low temperature (near-surface) to generate elevated oxygen isotope signatures and then recycled to middle-crustal conditions within 10-50 million years of crystallization in the Eoarchean. We propose that melting of such rocks could produce the zircon crystals with high δ18O that are found in the detrital and magmatic record in the Archean. This work was funded by Australian Research Council projects DP120100273 and DP170100715. DR acknowledges the support of ARC grant DP110101599 and Swiss National Science Foundation grant 200021-166280. |
format |
Article in Journal/Newspaper |
author |
Gauthiez Putallaz, Laure Nutman, Allen P. Bennett, Vickie Rubatto, Daniela |
author_facet |
Gauthiez Putallaz, Laure Nutman, Allen P. Bennett, Vickie Rubatto, Daniela |
author_sort |
Gauthiez Putallaz, Laure |
title |
Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
title_short |
Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
title_full |
Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
title_fullStr |
Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
title_full_unstemmed |
Origins of high δ 18 O in 3.7-3.6 Ga crust: A zircon and garnet record in Isua clastic metasedimentary rocks |
title_sort |
origins of high δ 18 o in 3.7-3.6 ga crust: a zircon and garnet record in isua clastic metasedimentary rocks |
publisher |
Elsevier |
url |
http://hdl.handle.net/1885/218988 https://doi.org/10.1016/j.chemgeo.2020.119474 https://openresearch-repository.anu.edu.au/bitstream/1885/218988/3/01_Gauthiez-Putallaz_Origins_of_high_2020.pdf.jpg |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Chemical Geology https://dx.doi.org/ |
op_relation |
http://purl.org/au-research/grants/arc/DP120100273 http://purl.org/au-research/grants/arc/DP170100715 http://purl.org/au-research/grants/arc/DP110101599 0009-2541 http://hdl.handle.net/1885/218988 doi:10.1016/j.chemgeo.2020.119474 https://openresearch-repository.anu.edu.au/bitstream/1885/218988/3/01_Gauthiez-Putallaz_Origins_of_high_2020.pdf.jpg |
op_rights |
© 2020 Elsevier B.V |
op_doi |
https://doi.org/10.1016/j.chemgeo.2020.119474 |
container_title |
Chemical Geology |
container_volume |
537 |
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119474 |
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1788061783256203264 |