Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact?
Abstract Zircon in five samples of variably comminuted, melted, and hydrothermally altered orthogneiss from the Maniitsoq structure of southern West Greenland yield a weighted mean 207 Pb/ 206 Pb age of 3000.9 ± 1.9 Ma (ion probe data, n = 37). The age data constitute a rare example of pervasive and...
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crwiley:10.1111/maps.12169 2023-12-03T10:23:28+01:00 Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? Scherstén, Anders Garde, Adam A. 2013 http://dx.doi.org/10.1111/maps.12169 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmaps.12169 https://onlinelibrary.wiley.com/doi/pdf/10.1111/maps.12169 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Meteoritics & Planetary Science volume 48, issue 8, page 1472-1498 ISSN 1086-9379 1945-5100 Space and Planetary Science Geophysics journal-article 2013 crwiley https://doi.org/10.1111/maps.12169 2023-11-09T14:09:36Z Abstract Zircon in five samples of variably comminuted, melted, and hydrothermally altered orthogneiss from the Maniitsoq structure of southern West Greenland yield a weighted mean 207 Pb/ 206 Pb age of 3000.9 ± 1.9 Ma (ion probe data, n = 37). The age data constitute a rare example of pervasive and nearly complete isotopic resetting of zircon during a regional hydrothermal event. Many zircon grains are homogeneous or display weak flame‐like patterns in backscattered electron images. Other grains show complex internal textures, where homogeneous, high‐U fronts commonly cut across relict igneous‐type oscillatory zonation. Inclusions of quartz, plagioclase, mica, and other Al ± Na ± Ca ± Fe‐bearing silicates are very common. In two samples, selective replacement of zircon with baddeleyite occurs along concentric zones with relict igneous zonation, and as specks a few microns large within recrystallized, high‐U areas. We interpret the 3000.9 ± 1.9 Ma date as the minimum age of the recently proposed impact structure at Maniitsoq. The great geographical extent and intensity of the hydrothermal event suggest massive invasion of water into the currently exposed crust, implying that the age of the hydrothermal alteration would closely approximate the age of the proposed impact at Maniitsoq. At the western margin of the Taserssuaq tonalite complex, which postdates the Maniitsoq event, a 207 Pb/ 206 Pb mean age of 2994.6 ± 3.4 Ma obtained from zircon has mostly retained igneous‐type oscillatory zonation. A subsequent thermal event at approximately 2975 Ma is recorded in several samples by zircon with baddeleyite replacement textures. Article in Journal/Newspaper Greenland Maniitsoq Wiley Online Library (via Crossref) Greenland Maniitsoq ENVELOPE(-55.217,-55.217,72.967,72.967) Meteoritics & Planetary Science 48 8 1472 1498 |
institution |
Open Polar |
collection |
Wiley Online Library (via Crossref) |
op_collection_id |
crwiley |
language |
English |
topic |
Space and Planetary Science Geophysics |
spellingShingle |
Space and Planetary Science Geophysics Scherstén, Anders Garde, Adam A. Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
topic_facet |
Space and Planetary Science Geophysics |
description |
Abstract Zircon in five samples of variably comminuted, melted, and hydrothermally altered orthogneiss from the Maniitsoq structure of southern West Greenland yield a weighted mean 207 Pb/ 206 Pb age of 3000.9 ± 1.9 Ma (ion probe data, n = 37). The age data constitute a rare example of pervasive and nearly complete isotopic resetting of zircon during a regional hydrothermal event. Many zircon grains are homogeneous or display weak flame‐like patterns in backscattered electron images. Other grains show complex internal textures, where homogeneous, high‐U fronts commonly cut across relict igneous‐type oscillatory zonation. Inclusions of quartz, plagioclase, mica, and other Al ± Na ± Ca ± Fe‐bearing silicates are very common. In two samples, selective replacement of zircon with baddeleyite occurs along concentric zones with relict igneous zonation, and as specks a few microns large within recrystallized, high‐U areas. We interpret the 3000.9 ± 1.9 Ma date as the minimum age of the recently proposed impact structure at Maniitsoq. The great geographical extent and intensity of the hydrothermal event suggest massive invasion of water into the currently exposed crust, implying that the age of the hydrothermal alteration would closely approximate the age of the proposed impact at Maniitsoq. At the western margin of the Taserssuaq tonalite complex, which postdates the Maniitsoq event, a 207 Pb/ 206 Pb mean age of 2994.6 ± 3.4 Ma obtained from zircon has mostly retained igneous‐type oscillatory zonation. A subsequent thermal event at approximately 2975 Ma is recorded in several samples by zircon with baddeleyite replacement textures. |
format |
Article in Journal/Newspaper |
author |
Scherstén, Anders Garde, Adam A. |
author_facet |
Scherstén, Anders Garde, Adam A. |
author_sort |
Scherstén, Anders |
title |
Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
title_short |
Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
title_full |
Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
title_fullStr |
Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
title_full_unstemmed |
Complete hydrothermal re‐equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001 Ma minimum age of impact? |
title_sort |
complete hydrothermal re‐equilibration of zircon in the maniitsoq structure, west greenland: a 3001 ma minimum age of impact? |
publisher |
Wiley |
publishDate |
2013 |
url |
http://dx.doi.org/10.1111/maps.12169 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmaps.12169 https://onlinelibrary.wiley.com/doi/pdf/10.1111/maps.12169 |
long_lat |
ENVELOPE(-55.217,-55.217,72.967,72.967) |
geographic |
Greenland Maniitsoq |
geographic_facet |
Greenland Maniitsoq |
genre |
Greenland Maniitsoq |
genre_facet |
Greenland Maniitsoq |
op_source |
Meteoritics & Planetary Science volume 48, issue 8, page 1472-1498 ISSN 1086-9379 1945-5100 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/maps.12169 |
container_title |
Meteoritics & Planetary Science |
container_volume |
48 |
container_issue |
8 |
container_start_page |
1472 |
op_container_end_page |
1498 |
_version_ |
1784271610225623040 |