On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation
We present whole-rock and zircon rare earth element (REE) data from two early Archaean gneisses (3.81 Ga and 3.64 Ga) from the Itsaq gneiss complex, south-west Greenland. Both gneisses represent extremely rare examples of unaltered, fresh and relatively undeformed igneous rocks of such antiquity. Ca...
Published in: | Earth and Planetary Science Letters |
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ftqueensland:oai:eprints.qut.edu.au:126286 2024-04-28T08:21:26+00:00 On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation Whitehouse, M. J. Kamber, B. S. 2002 https://eprints.qut.edu.au/126286/ unknown Elsevier BV doi:10.1016/s0012-821x(02)01000-2 Whitehouse, M. J. & Kamber, B. S. (2002) On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation. Earth and Planetary Science Letters, 204(3-4), pp. 333-346. https://eprints.qut.edu.au/126286/ Science & Engineering Faculty; Australian Research Centre for Aerospace Automation Consult author(s) regarding copyright matters This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the document is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recognise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au Earth and Planetary Science Letters lanthanides zircon distribution coefficients Archaean Hadean Greenland southern west greenland crystal x-ray continental-crust synthetic detrital zircons amitsoq gneiss isotope saturation chemistry evolution Geochemistry & Geophysics Contribution to Journal 2002 ftqueensland https://doi.org/10.1016/s0012-821x(02)01000-2 2024-04-10T00:02:51Z We present whole-rock and zircon rare earth element (REE) data from two early Archaean gneisses (3.81 Ga and 3.64 Ga) from the Itsaq gneiss complex, south-west Greenland. Both gneisses represent extremely rare examples of unaltered, fresh and relatively undeformed igneous rocks of such antiquity. Cathodoluminescence imaging of their zircons indicates a single crystallisation episode with no evidence for either later metamorphic and/or anatectic reworking or inheritance of earlier grains. Uniform, single-population U/Pb age data confirm the structural simplicity of these zircons. One sample, a 3.64 Ga granodioritic gneiss from the Gothabsfjord, yields a chondrite-normalised REE pattern with a positive slope from La to Lu as well as substantial positive Ce and slight negative Eu anomalies, features generally considered to be typical of igneous zircon. In contrast, the second sample, a 3.81 Ga tonalite from south of the Isua Greenstone Belt, has variable but generally much higher light REE abundances, with similar middle to heavy REE. Calculation of zircon/melt distribution coefficients (D-REE(zircon/melt)) from each sample yields markedly different values for the trivalent REE (i.e. Ce and Eu omitted) and simple application of one set of D-REE(zircon/melt) to model the melt composition for the other sample yields concentrations that are in error by up to two orders of magnitude for the light REE (La-Nd). The observed light REE overabundance in the 3.81 Ga tonalite is a commonly observed feature in terrestrial zircons for which a number of explanations ranging from lattice strain to disequilibrium crystallisation have been proposed and are further investigated herein. Regardless of the cause of light REE overabundance, our study shows that simple application of zircon/melt distribution coefficients is not an unambiguous method for ascertaining original melt composition. In this context, recent studies that use REE data to claim that > 4.3 Ga Hadean detrital zircons originally crystallised from an evolved magma, ... Article in Journal/Newspaper Greenland Queensland University of Technology: QUT ePrints Earth and Planetary Science Letters 204 3-4 333 346 |
institution |
Open Polar |
collection |
Queensland University of Technology: QUT ePrints |
op_collection_id |
ftqueensland |
language |
unknown |
topic |
lanthanides zircon distribution coefficients Archaean Hadean Greenland southern west greenland crystal x-ray continental-crust synthetic detrital zircons amitsoq gneiss isotope saturation chemistry evolution Geochemistry & Geophysics |
spellingShingle |
lanthanides zircon distribution coefficients Archaean Hadean Greenland southern west greenland crystal x-ray continental-crust synthetic detrital zircons amitsoq gneiss isotope saturation chemistry evolution Geochemistry & Geophysics Whitehouse, M. J. Kamber, B. S. On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
topic_facet |
lanthanides zircon distribution coefficients Archaean Hadean Greenland southern west greenland crystal x-ray continental-crust synthetic detrital zircons amitsoq gneiss isotope saturation chemistry evolution Geochemistry & Geophysics |
description |
We present whole-rock and zircon rare earth element (REE) data from two early Archaean gneisses (3.81 Ga and 3.64 Ga) from the Itsaq gneiss complex, south-west Greenland. Both gneisses represent extremely rare examples of unaltered, fresh and relatively undeformed igneous rocks of such antiquity. Cathodoluminescence imaging of their zircons indicates a single crystallisation episode with no evidence for either later metamorphic and/or anatectic reworking or inheritance of earlier grains. Uniform, single-population U/Pb age data confirm the structural simplicity of these zircons. One sample, a 3.64 Ga granodioritic gneiss from the Gothabsfjord, yields a chondrite-normalised REE pattern with a positive slope from La to Lu as well as substantial positive Ce and slight negative Eu anomalies, features generally considered to be typical of igneous zircon. In contrast, the second sample, a 3.81 Ga tonalite from south of the Isua Greenstone Belt, has variable but generally much higher light REE abundances, with similar middle to heavy REE. Calculation of zircon/melt distribution coefficients (D-REE(zircon/melt)) from each sample yields markedly different values for the trivalent REE (i.e. Ce and Eu omitted) and simple application of one set of D-REE(zircon/melt) to model the melt composition for the other sample yields concentrations that are in error by up to two orders of magnitude for the light REE (La-Nd). The observed light REE overabundance in the 3.81 Ga tonalite is a commonly observed feature in terrestrial zircons for which a number of explanations ranging from lattice strain to disequilibrium crystallisation have been proposed and are further investigated herein. Regardless of the cause of light REE overabundance, our study shows that simple application of zircon/melt distribution coefficients is not an unambiguous method for ascertaining original melt composition. In this context, recent studies that use REE data to claim that > 4.3 Ga Hadean detrital zircons originally crystallised from an evolved magma, ... |
format |
Article in Journal/Newspaper |
author |
Whitehouse, M. J. Kamber, B. S. |
author_facet |
Whitehouse, M. J. Kamber, B. S. |
author_sort |
Whitehouse, M. J. |
title |
On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
title_short |
On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
title_full |
On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
title_fullStr |
On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
title_full_unstemmed |
On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation |
title_sort |
on the overabundance of light rare earth elements in terrestrial zircons and its implication for earth's earliest magmatic differentiation |
publisher |
Elsevier BV |
publishDate |
2002 |
url |
https://eprints.qut.edu.au/126286/ |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Earth and Planetary Science Letters |
op_relation |
doi:10.1016/s0012-821x(02)01000-2 Whitehouse, M. J. & Kamber, B. S. (2002) On the overabundance of light rare earth elements in terrestrial zircons and its implication for Earth's earliest magmatic differentiation. Earth and Planetary Science Letters, 204(3-4), pp. 333-346. https://eprints.qut.edu.au/126286/ Science & Engineering Faculty; Australian Research Centre for Aerospace Automation |
op_rights |
Consult author(s) regarding copyright matters This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the document is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recognise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au |
op_doi |
https://doi.org/10.1016/s0012-821x(02)01000-2 |
container_title |
Earth and Planetary Science Letters |
container_volume |
204 |
container_issue |
3-4 |
container_start_page |
333 |
op_container_end_page |
346 |
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1797583779070476288 |