Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica
Abstract The Prydz Bay coast, including the Larsemann Hills, features relatively extensive bedrock exposures of interest because of the proximity to a hypothesized suture associated with Gondwana assembly. Critical units are the basement Søstrene Orthogneiss (1,126 ± 11 Ma protolith) and cover Bratt...
Published in: | Journal of Metamorphic Geology |
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Language: | English |
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2021
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Online Access: | http://dx.doi.org/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12607 |
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crwiley:10.1111/jmg.12607 2024-06-23T07:47:58+00:00 Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica Spreitzer, Steven K. Walters, Jesse B. Cruz‐Uribe, Alicia Williams, Michael L. Yates, Martin G. Jercinovic, Michael J. Grew, Edward S. Carson, Christopher J. Baldwin, Julia Office of Polar Programs Australian Antarctic Division 2021 http://dx.doi.org/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12607 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#am http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Metamorphic Geology volume 39, issue 9, page 1205-1228 ISSN 0263-4929 1525-1314 journal-article 2021 crwiley https://doi.org/10.1111/jmg.12607 2024-06-11T04:41:02Z Abstract The Prydz Bay coast, including the Larsemann Hills, features relatively extensive bedrock exposures of interest because of the proximity to a hypothesized suture associated with Gondwana assembly. Critical units are the basement Søstrene Orthogneiss (1,126 ± 11 Ma protolith) and cover Brattstrand Paragneiss (maximum depositional age 1,023 ± 19 Ma). The two units share a polymetamorphic history with events at ~900 Ma (D 1 ) and ~530 Ma (D 2‐4 ). Here we present electron microprobe dates of monazite growth zones and Perple_X pseudosection models of granulite‐facies rocks from the Søstrene Orthogneiss, Brattstrand Paragneiss, and D 2‐4 pegmatites of the Larsemann Hills. We propose a scenario for Cambrian metamorphism involving a peak stage at 6–7.5 kbar and 800–860°C (D 2 convergence), melt crystallization and garnet breakdown during decompression to early retrograde conditions of 3–4.5 kbar and 700–750°C (D 2 convergence, D 3 extension), and a late retrograde stage with decompression and cooling to 3–3.5 kbar and 550–650°C (D 4 ). We combine monazite chemistry with phase assemblages predicted by pseudosection modelling to link specific monazite growth domains to individual tectonic stages. Monazite domains containing moderate Th and low to moderate Y are interpreted to be preserved from the prograde path when garnet was stable, and constrain the timing of prograde metamorphism at 536 ± 4 Ma. High‐Th, low‐Y domains, dated at 527 ± 2 Ma, represent the earliest stages of post‐peak melt crystallization. Monazite domains with elevated Y and low‐moderate Th are interpreted to represent monazite growth during garnet breakdown at 514 ± 2 Ma. Our monazite ages, combined with published biotite Ar–Ar cooling ages, yield a two‐stage history of cooling at 3–8°C/Myr from ~530 Ma to ~510 Ma followed by cooling at 18–25°C/Myr from ~510 Ma to ~490 Ma, corresponding to 0.2–0.6 mm/yr of exhumation. This duration of granulite‐facies metamorphism in the Larsemann Hills is consistent with estimates for Precambrian granulite ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Prydz Bay Wiley Online Library East Antarctica Larsemann Hills ENVELOPE(76.217,76.217,-69.400,-69.400) Prydz Bay Søstrene ENVELOPE(75.503,75.503,-69.588,-69.588) Journal of Metamorphic Geology |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Abstract The Prydz Bay coast, including the Larsemann Hills, features relatively extensive bedrock exposures of interest because of the proximity to a hypothesized suture associated with Gondwana assembly. Critical units are the basement Søstrene Orthogneiss (1,126 ± 11 Ma protolith) and cover Brattstrand Paragneiss (maximum depositional age 1,023 ± 19 Ma). The two units share a polymetamorphic history with events at ~900 Ma (D 1 ) and ~530 Ma (D 2‐4 ). Here we present electron microprobe dates of monazite growth zones and Perple_X pseudosection models of granulite‐facies rocks from the Søstrene Orthogneiss, Brattstrand Paragneiss, and D 2‐4 pegmatites of the Larsemann Hills. We propose a scenario for Cambrian metamorphism involving a peak stage at 6–7.5 kbar and 800–860°C (D 2 convergence), melt crystallization and garnet breakdown during decompression to early retrograde conditions of 3–4.5 kbar and 700–750°C (D 2 convergence, D 3 extension), and a late retrograde stage with decompression and cooling to 3–3.5 kbar and 550–650°C (D 4 ). We combine monazite chemistry with phase assemblages predicted by pseudosection modelling to link specific monazite growth domains to individual tectonic stages. Monazite domains containing moderate Th and low to moderate Y are interpreted to be preserved from the prograde path when garnet was stable, and constrain the timing of prograde metamorphism at 536 ± 4 Ma. High‐Th, low‐Y domains, dated at 527 ± 2 Ma, represent the earliest stages of post‐peak melt crystallization. Monazite domains with elevated Y and low‐moderate Th are interpreted to represent monazite growth during garnet breakdown at 514 ± 2 Ma. Our monazite ages, combined with published biotite Ar–Ar cooling ages, yield a two‐stage history of cooling at 3–8°C/Myr from ~530 Ma to ~510 Ma followed by cooling at 18–25°C/Myr from ~510 Ma to ~490 Ma, corresponding to 0.2–0.6 mm/yr of exhumation. This duration of granulite‐facies metamorphism in the Larsemann Hills is consistent with estimates for Precambrian granulite ... |
author2 |
Baldwin, Julia Office of Polar Programs Australian Antarctic Division |
format |
Article in Journal/Newspaper |
author |
Spreitzer, Steven K. Walters, Jesse B. Cruz‐Uribe, Alicia Williams, Michael L. Yates, Martin G. Jercinovic, Michael J. Grew, Edward S. Carson, Christopher J. |
spellingShingle |
Spreitzer, Steven K. Walters, Jesse B. Cruz‐Uribe, Alicia Williams, Michael L. Yates, Martin G. Jercinovic, Michael J. Grew, Edward S. Carson, Christopher J. Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
author_facet |
Spreitzer, Steven K. Walters, Jesse B. Cruz‐Uribe, Alicia Williams, Michael L. Yates, Martin G. Jercinovic, Michael J. Grew, Edward S. Carson, Christopher J. |
author_sort |
Spreitzer, Steven K. |
title |
Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
title_short |
Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
title_full |
Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
title_fullStr |
Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
title_full_unstemmed |
Monazite petrochronology of polymetamorphic granulite‐facies rocks of the Larsemann Hills, Prydz Bay, East Antarctica |
title_sort |
monazite petrochronology of polymetamorphic granulite‐facies rocks of the larsemann hills, prydz bay, east antarctica |
publisher |
Wiley |
publishDate |
2021 |
url |
http://dx.doi.org/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12607 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12607 |
long_lat |
ENVELOPE(76.217,76.217,-69.400,-69.400) ENVELOPE(75.503,75.503,-69.588,-69.588) |
geographic |
East Antarctica Larsemann Hills Prydz Bay Søstrene |
geographic_facet |
East Antarctica Larsemann Hills Prydz Bay Søstrene |
genre |
Antarc* Antarctica East Antarctica Prydz Bay |
genre_facet |
Antarc* Antarctica East Antarctica Prydz Bay |
op_source |
Journal of Metamorphic Geology volume 39, issue 9, page 1205-1228 ISSN 0263-4929 1525-1314 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#am http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/jmg.12607 |
container_title |
Journal of Metamorphic Geology |
_version_ |
1802638301063020544 |