A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland
We present high spatial resolution ion-microprobe rare earth element (REE) data for discrete growth phases of complex polyphase zircons from early Archaean Amitsoq gneisses, outer Godthabsfjord, SW Greenland. In Matsuda diagrams, the two major growth phases, >3.8 Ga cores and ca. 3.65 Ga rims, ha...
Published in: | Precambrian Research |
---|---|
Main Authors: | , |
Other Authors: | , , |
Format: | Conference Object |
Language: | English |
Published: |
Elsevier BV
2003
|
Subjects: | |
Online Access: | https://espace.library.uq.edu.au/view/UQ:66652 |
id |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:66652 |
---|---|
record_format |
openpolar |
spelling |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:66652 2023-05-15T16:22:46+02:00 A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland Whitehouse, M. J. Kamber, B. S. Peter W. U. Appel Stephen Moorbath Jacques L. R. Touret 2003-01-01 https://espace.library.uq.edu.au/view/UQ:66652 eng eng Elsevier BV doi:10.1016/S0301-9268(03)00105-0 issn:0301-9268 Geosciences Multidisciplinary Lanthanides Zircon Petrogenesis Archaean Greenland Godthabsfjord Combined Ion-microprobe High-grade Metamorphism Crustal Evolution Age Significance Pb Life Akilia Origin Th Isotope 260301 Geochronology and Isotope Geochemistry C1 780104 Earth sciences Conference Paper 2003 ftunivqespace https://doi.org/10.1016/S0301-9268(03)00105-0 2020-09-07T22:27:07Z We present high spatial resolution ion-microprobe rare earth element (REE) data for discrete growth phases of complex polyphase zircons from early Archaean Amitsoq gneisses, outer Godthabsfjord, SW Greenland. In Matsuda diagrams, the two major growth phases, >3.8 Ga cores and ca. 3.65 Ga rims, have steep positive slopes from La to Lu, prominent positive Ce anomalies and negative Eu anomalies that are consistent with growth in a melt. Exceptions to this are non-cathodolurnmescent zircon developed between the cores and rims, sometimes truncating zoning in the cores, and late Archaean prismatic tip overgrowths, both of which exhibit flatter light REE (LREE) patterns and have small or no Eu anomaly, which we interpret as the result of metamorphism and/or small-degree, isolated partial melting. Our data support previous interpretations that the ca. 3.65 Ga zircon phase was generated in a melt, with the >3.8 Ga phase representing either original protolith zircons in a large degree partial melt or inherited zircons in an introduced magma. Regardless which of these two interpretations is correct for these, and similar, rocks in the outer GodthAbsfjord, the 3.65 Ga event will have profoundly affected isotopic systems and obscured beyond recognition any earlier igneous features such as cross-cutting relationships, which may only be assigned a minimum 3.65 Ga age. (C) 2003 Elsevier Science B.V. All rights reserved. Conference Object Godthåbsfjord Greenland The University of Queensland: UQ eSpace Greenland Precambrian Research 126 3-4 363 377 |
institution |
Open Polar |
collection |
The University of Queensland: UQ eSpace |
op_collection_id |
ftunivqespace |
language |
English |
topic |
Geosciences Multidisciplinary Lanthanides Zircon Petrogenesis Archaean Greenland Godthabsfjord Combined Ion-microprobe High-grade Metamorphism Crustal Evolution Age Significance Pb Life Akilia Origin Th Isotope 260301 Geochronology and Isotope Geochemistry C1 780104 Earth sciences |
spellingShingle |
Geosciences Multidisciplinary Lanthanides Zircon Petrogenesis Archaean Greenland Godthabsfjord Combined Ion-microprobe High-grade Metamorphism Crustal Evolution Age Significance Pb Life Akilia Origin Th Isotope 260301 Geochronology and Isotope Geochemistry C1 780104 Earth sciences Whitehouse, M. J. Kamber, B. S. A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
topic_facet |
Geosciences Multidisciplinary Lanthanides Zircon Petrogenesis Archaean Greenland Godthabsfjord Combined Ion-microprobe High-grade Metamorphism Crustal Evolution Age Significance Pb Life Akilia Origin Th Isotope 260301 Geochronology and Isotope Geochemistry C1 780104 Earth sciences |
description |
We present high spatial resolution ion-microprobe rare earth element (REE) data for discrete growth phases of complex polyphase zircons from early Archaean Amitsoq gneisses, outer Godthabsfjord, SW Greenland. In Matsuda diagrams, the two major growth phases, >3.8 Ga cores and ca. 3.65 Ga rims, have steep positive slopes from La to Lu, prominent positive Ce anomalies and negative Eu anomalies that are consistent with growth in a melt. Exceptions to this are non-cathodolurnmescent zircon developed between the cores and rims, sometimes truncating zoning in the cores, and late Archaean prismatic tip overgrowths, both of which exhibit flatter light REE (LREE) patterns and have small or no Eu anomaly, which we interpret as the result of metamorphism and/or small-degree, isolated partial melting. Our data support previous interpretations that the ca. 3.65 Ga zircon phase was generated in a melt, with the >3.8 Ga phase representing either original protolith zircons in a large degree partial melt or inherited zircons in an introduced magma. Regardless which of these two interpretations is correct for these, and similar, rocks in the outer GodthAbsfjord, the 3.65 Ga event will have profoundly affected isotopic systems and obscured beyond recognition any earlier igneous features such as cross-cutting relationships, which may only be assigned a minimum 3.65 Ga age. (C) 2003 Elsevier Science B.V. All rights reserved. |
author2 |
Peter W. U. Appel Stephen Moorbath Jacques L. R. Touret |
format |
Conference Object |
author |
Whitehouse, M. J. Kamber, B. S. |
author_facet |
Whitehouse, M. J. Kamber, B. S. |
author_sort |
Whitehouse, M. J. |
title |
A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
title_short |
A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
title_full |
A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
title_fullStr |
A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
title_full_unstemmed |
A rare earth element study of complex zircons from early Archaean Amitsoq gneisses, Godthåbsfjord, south-west Greenland |
title_sort |
rare earth element study of complex zircons from early archaean amitsoq gneisses, godthåbsfjord, south-west greenland |
publisher |
Elsevier BV |
publishDate |
2003 |
url |
https://espace.library.uq.edu.au/view/UQ:66652 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Godthåbsfjord Greenland |
genre_facet |
Godthåbsfjord Greenland |
op_relation |
doi:10.1016/S0301-9268(03)00105-0 issn:0301-9268 |
op_doi |
https://doi.org/10.1016/S0301-9268(03)00105-0 |
container_title |
Precambrian Research |
container_volume |
126 |
container_issue |
3-4 |
container_start_page |
363 |
op_container_end_page |
377 |
_version_ |
1766010874816888832 |