Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica
We present textural evidence of spinel (low-Zn) and quartz from two samples of quartzofeldspathic rocks from the Larsemann Hills, East Antarctica. The present occurrence is unusual for the fact that the direct grain contact is preserved unlike most other occurrences where these two phases are separa...
Published in: | Polar Science |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2020
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ftnipr:oai:nipr.repo.nii.ac.jp:00016344 2023-05-15T13:49:00+02:00 Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica 2020-12 https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16344 http://id.nii.ac.jp/1291/00016223/ en eng https://doi.org/10.1016/j.polar.2020.100588 https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16344 http://id.nii.ac.jp/1291/00016223/ Polar Science, 26, 100588(2020-12) 18739652 Larsemann hills Spinel + quartz Monazite Metastable contact Journal Article 2020 ftnipr https://doi.org/10.1016/j.polar.2020.100588 2022-12-03T19:43:16Z We present textural evidence of spinel (low-Zn) and quartz from two samples of quartzofeldspathic rocks from the Larsemann Hills, East Antarctica. The present occurrence is unusual for the fact that the direct grain contact is preserved unlike most other occurrences where these two phases are separated by reaction products during retrograde and/or prograde metamorphic stages. Textural features further indicate that Ti-biotite was part of the prograde assemblage that underwent partial melting to produce spinel. The maximum temperature estimated from the rock is 870 °C. Monazite grains are abundant in the rock and these are mostly homogeneous in terms of U, Th and Pb distribution. In situ U–Th-total Pb EPMA data of these monazite yield a group age of 527 ± 8 Ma. Textural and geochronological data match with the second (M2) stage of metamorphism of the Larsemann Hills region as evident from the existing geological record. Although spinel and quartz was considered to be a part of peak M2 assemblage in earlier studies, preservation of their grain contact is enigmatic. We consider the grain contact metastable and its preservation possibly resulted from significant overstepping of cooling reaction due to fast reaction kinetics. Article in Journal/Newspaper Antarc* Antarctica East Antarctica Polar Science Polar Science National Institute of Polar Research Repository, Japan East Antarctica Larsemann Hills ENVELOPE(76.217,76.217,-69.400,-69.400) Polar Science 26 100588 |
institution |
Open Polar |
collection |
National Institute of Polar Research Repository, Japan |
op_collection_id |
ftnipr |
language |
English |
topic |
Larsemann hills Spinel + quartz Monazite Metastable contact |
spellingShingle |
Larsemann hills Spinel + quartz Monazite Metastable contact Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
topic_facet |
Larsemann hills Spinel + quartz Monazite Metastable contact |
description |
We present textural evidence of spinel (low-Zn) and quartz from two samples of quartzofeldspathic rocks from the Larsemann Hills, East Antarctica. The present occurrence is unusual for the fact that the direct grain contact is preserved unlike most other occurrences where these two phases are separated by reaction products during retrograde and/or prograde metamorphic stages. Textural features further indicate that Ti-biotite was part of the prograde assemblage that underwent partial melting to produce spinel. The maximum temperature estimated from the rock is 870 °C. Monazite grains are abundant in the rock and these are mostly homogeneous in terms of U, Th and Pb distribution. In situ U–Th-total Pb EPMA data of these monazite yield a group age of 527 ± 8 Ma. Textural and geochronological data match with the second (M2) stage of metamorphism of the Larsemann Hills region as evident from the existing geological record. Although spinel and quartz was considered to be a part of peak M2 assemblage in earlier studies, preservation of their grain contact is enigmatic. We consider the grain contact metastable and its preservation possibly resulted from significant overstepping of cooling reaction due to fast reaction kinetics. |
format |
Article in Journal/Newspaper |
title |
Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
title_short |
Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
title_full |
Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
title_fullStr |
Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
title_full_unstemmed |
Petrogenetic re-examination of spinel + quartz assemblage in the Larsemann Hills, East Antarctica |
title_sort |
petrogenetic re-examination of spinel + quartz assemblage in the larsemann hills, east antarctica |
publishDate |
2020 |
url |
https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16344 http://id.nii.ac.jp/1291/00016223/ |
long_lat |
ENVELOPE(76.217,76.217,-69.400,-69.400) |
geographic |
East Antarctica Larsemann Hills |
geographic_facet |
East Antarctica Larsemann Hills |
genre |
Antarc* Antarctica East Antarctica Polar Science Polar Science |
genre_facet |
Antarc* Antarctica East Antarctica Polar Science Polar Science |
op_relation |
https://doi.org/10.1016/j.polar.2020.100588 https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16344 http://id.nii.ac.jp/1291/00016223/ Polar Science, 26, 100588(2020-12) 18739652 |
op_doi |
https://doi.org/10.1016/j.polar.2020.100588 |
container_title |
Polar Science |
container_volume |
26 |
container_start_page |
100588 |
_version_ |
1766250392384962560 |