Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica
Monazites in high-grade metapelites from the Lutzow-Holm Complex and Napier Complex have been examined in terms of U, Th, Pb and rare earth element (REE) chemistry using an electron microprobe. The studied samples include four granulite-facies garnet-biotite-bearing metapelites from Skallen within t...
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National Institute of Polar Research/National Institute of Polar Research
2006
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ftnipr:oai:nipr.repo.nii.ac.jp:00003167 2023-05-15T13:49:00+02:00 Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica Tomokazu Hokada Yoichi Motoyoshi 2006-10 https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3167 http://id.nii.ac.jp/1291/00003167/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3167&item_no=1&attribute_id=18&file_no=1 en eng National Institute of Polar Research/National Institute of Polar Research National Institute of Polar Research https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3167 http://id.nii.ac.jp/1291/00003167/ AA1130866X Polar geoscience, 19, 118-151(2006-10) https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3167&item_no=1&attribute_id=18&file_no=1 Lutzow-Holm Complex monazite Napier Complex rare earth element/REE U-Th-Pb age Departmental Bulletin Paper P(論文) 2006 ftnipr 2022-12-03T19:43:04Z Monazites in high-grade metapelites from the Lutzow-Holm Complex and Napier Complex have been examined in terms of U, Th, Pb and rare earth element (REE) chemistry using an electron microprobe. The studied samples include four granulite-facies garnet-biotite-bearing metapelites from Skallen within the Lutzow-Holm Complex, and a re-hydrated garnet-sillimanite gneiss from the Mt. Riiser-Larsen area within the UHT zone of the Napier Complex. Two out of four garnet-bearing metapelitic samples from Skallen gave simple 560-500Ma monazite U-Th-Pb ages, whereas the other two samples yielded two age populations, i.e., 560-500Ma and 650-580Ma. The younger age group is consistent with the 550-520Ma metamorphic ages reported by SHRIMP. The older>580Ma monazites are relatively enriched in Nd, Sm, Gd, Dy (MREE) and depleted in Si (Ca and Th) compared with the younger (560-500Ma) ones. These older monazites possibly formed through M-HREE-enriched conditions such as garnet-free conditions, suggesting that the growth of these monazites pre-dated the peak metamorphism. Garnet-sillimanite gneiss from the Mt. Riiser-Larsen area shows various post-UHT re-hydration textures such as biotite-sillimanite aggregates, and fine-grained biotite flakes around or intracrystalline fractures within garnet porphyroblasts. Monazites enclosed within garnet cores have 2480-2440Ma U-Th-Pb ages consistent with the reported zircon and monazite SHRIMP dates. On the other hand, those associated with re-hydrated zones gave fluctuating 2200-700Ma ages. These younger ages are thought to reflect the incomplete chemical disturbance during the post-UHT crustal processes. Report Antarc* Antarctica East Antarctica Polar geoscience National Institute of Polar Research Repository, Japan East Antarctica Riiser-Larsen ENVELOPE(50.667,50.667,-66.783,-66.783) Dy ENVELOPE(11.369,11.369,64.834,64.834) Napier ENVELOPE(-58.440,-58.440,-62.167,-62.167) Skallen ENVELOPE(39.467,39.467,-69.650,-69.650) |
institution |
Open Polar |
collection |
National Institute of Polar Research Repository, Japan |
op_collection_id |
ftnipr |
language |
English |
topic |
Lutzow-Holm Complex monazite Napier Complex rare earth element/REE U-Th-Pb age |
spellingShingle |
Lutzow-Holm Complex monazite Napier Complex rare earth element/REE U-Th-Pb age Tomokazu Hokada Yoichi Motoyoshi Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
topic_facet |
Lutzow-Holm Complex monazite Napier Complex rare earth element/REE U-Th-Pb age |
description |
Monazites in high-grade metapelites from the Lutzow-Holm Complex and Napier Complex have been examined in terms of U, Th, Pb and rare earth element (REE) chemistry using an electron microprobe. The studied samples include four granulite-facies garnet-biotite-bearing metapelites from Skallen within the Lutzow-Holm Complex, and a re-hydrated garnet-sillimanite gneiss from the Mt. Riiser-Larsen area within the UHT zone of the Napier Complex. Two out of four garnet-bearing metapelitic samples from Skallen gave simple 560-500Ma monazite U-Th-Pb ages, whereas the other two samples yielded two age populations, i.e., 560-500Ma and 650-580Ma. The younger age group is consistent with the 550-520Ma metamorphic ages reported by SHRIMP. The older>580Ma monazites are relatively enriched in Nd, Sm, Gd, Dy (MREE) and depleted in Si (Ca and Th) compared with the younger (560-500Ma) ones. These older monazites possibly formed through M-HREE-enriched conditions such as garnet-free conditions, suggesting that the growth of these monazites pre-dated the peak metamorphism. Garnet-sillimanite gneiss from the Mt. Riiser-Larsen area shows various post-UHT re-hydration textures such as biotite-sillimanite aggregates, and fine-grained biotite flakes around or intracrystalline fractures within garnet porphyroblasts. Monazites enclosed within garnet cores have 2480-2440Ma U-Th-Pb ages consistent with the reported zircon and monazite SHRIMP dates. On the other hand, those associated with re-hydrated zones gave fluctuating 2200-700Ma ages. These younger ages are thought to reflect the incomplete chemical disturbance during the post-UHT crustal processes. |
format |
Report |
author |
Tomokazu Hokada Yoichi Motoyoshi |
author_facet |
Tomokazu Hokada Yoichi Motoyoshi |
author_sort |
Tomokazu Hokada |
title |
Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
title_short |
Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
title_full |
Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
title_fullStr |
Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
title_full_unstemmed |
Electron microprobe technique for U-Th-Pb and REE chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the Lutzow-Holm Complex and the Napier Complex, East Antarctica |
title_sort |
electron microprobe technique for u-th-pb and ree chemistry of monazite, and its implications for pre-, peak- and post- metamorphic events of the lutzow-holm complex and the napier complex, east antarctica |
publisher |
National Institute of Polar Research/National Institute of Polar Research |
publishDate |
2006 |
url |
https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3167 http://id.nii.ac.jp/1291/00003167/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3167&item_no=1&attribute_id=18&file_no=1 |
long_lat |
ENVELOPE(50.667,50.667,-66.783,-66.783) ENVELOPE(11.369,11.369,64.834,64.834) ENVELOPE(-58.440,-58.440,-62.167,-62.167) ENVELOPE(39.467,39.467,-69.650,-69.650) |
geographic |
East Antarctica Riiser-Larsen Dy Napier Skallen |
geographic_facet |
East Antarctica Riiser-Larsen Dy Napier Skallen |
genre |
Antarc* Antarctica East Antarctica Polar geoscience |
genre_facet |
Antarc* Antarctica East Antarctica Polar geoscience |
op_relation |
https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3167 http://id.nii.ac.jp/1291/00003167/ AA1130866X Polar geoscience, 19, 118-151(2006-10) https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3167&item_no=1&attribute_id=18&file_no=1 |
_version_ |
1766250369546977280 |