Apatite : a U-Pb thermochronometer or geochronometer?
The Ministry of Mineral Resources (MMR) of the Greenland Government is acknowledged for supporting the field and analytical work in the Maniitsoq region, SW Greenland. Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally conside...
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ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/18484 2023-07-02T03:32:25+02:00 Apatite : a U-Pb thermochronometer or geochronometer? Kirkland, C. L. Yakymchuk, C. Szilas, K. Evans, N. Hollis, J. McDonald, B. Gardiner, N. J. University of St Andrews. School of Earth & Environmental Sciences 2019-09-17T10:30:02Z 15 application/pdf http://hdl.handle.net/10023/18484 https://doi.org/10.1016/j.lithos.2018.08.007 https://www.sciencedirect.com/science/article/pii/S0024493718302809?via%3Dihub#s0140 eng eng Lithos Kirkland , C L , Yakymchuk , C , Szilas , K , Evans , N , Hollis , J , McDonald , B & Gardiner , N J 2018 , ' Apatite : a U-Pb thermochronometer or geochronometer? ' , Lithos , vol. 318-319 , pp. 143-157 . https://doi.org/10.1016/j.lithos.2018.08.007 0024-4937 PURE: 261213902 PURE UUID: ce3525bc-c1d5-41be-b9ab-1b9df7078dd6 Scopus: 85051636362 ORCID: /0000-0003-3465-9295/work/62311899 http://hdl.handle.net/10023/18484 https://doi.org/10.1016/j.lithos.2018.08.007 https://www.sciencedirect.com/science/article/pii/S0024493718302809?via%3Dihub#s0140 Copyright ©2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Apatite Geochronology Greenland Metamorphism Pseudosection Themochronology U-Pb QE Geology Geochemistry and Petrology Geology DAS QE Journal article 2019 ftstandrewserep https://doi.org/10.1016/j.lithos.2018.08.007 2023-06-13T18:26:20Z The Ministry of Mineral Resources (MMR) of the Greenland Government is acknowledged for supporting the field and analytical work in the Maniitsoq region, SW Greenland. Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600 °C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a <600 °C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic ... Article in Journal/Newspaper Greenland Maniitsoq University of St Andrews: Digital Research Repository Greenland Maniitsoq ENVELOPE(-55.217,-55.217,72.967,72.967) Lithos 318-319 143 157 |
institution |
Open Polar |
collection |
University of St Andrews: Digital Research Repository |
op_collection_id |
ftstandrewserep |
language |
English |
topic |
Apatite Geochronology Greenland Metamorphism Pseudosection Themochronology U-Pb QE Geology Geochemistry and Petrology Geology DAS QE |
spellingShingle |
Apatite Geochronology Greenland Metamorphism Pseudosection Themochronology U-Pb QE Geology Geochemistry and Petrology Geology DAS QE Kirkland, C. L. Yakymchuk, C. Szilas, K. Evans, N. Hollis, J. McDonald, B. Gardiner, N. J. Apatite : a U-Pb thermochronometer or geochronometer? |
topic_facet |
Apatite Geochronology Greenland Metamorphism Pseudosection Themochronology U-Pb QE Geology Geochemistry and Petrology Geology DAS QE |
description |
The Ministry of Mineral Resources (MMR) of the Greenland Government is acknowledged for supporting the field and analytical work in the Maniitsoq region, SW Greenland. Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600 °C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a <600 °C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic ... |
author2 |
University of St Andrews. School of Earth & Environmental Sciences |
format |
Article in Journal/Newspaper |
author |
Kirkland, C. L. Yakymchuk, C. Szilas, K. Evans, N. Hollis, J. McDonald, B. Gardiner, N. J. |
author_facet |
Kirkland, C. L. Yakymchuk, C. Szilas, K. Evans, N. Hollis, J. McDonald, B. Gardiner, N. J. |
author_sort |
Kirkland, C. L. |
title |
Apatite : a U-Pb thermochronometer or geochronometer? |
title_short |
Apatite : a U-Pb thermochronometer or geochronometer? |
title_full |
Apatite : a U-Pb thermochronometer or geochronometer? |
title_fullStr |
Apatite : a U-Pb thermochronometer or geochronometer? |
title_full_unstemmed |
Apatite : a U-Pb thermochronometer or geochronometer? |
title_sort |
apatite : a u-pb thermochronometer or geochronometer? |
publishDate |
2019 |
url |
http://hdl.handle.net/10023/18484 https://doi.org/10.1016/j.lithos.2018.08.007 https://www.sciencedirect.com/science/article/pii/S0024493718302809?via%3Dihub#s0140 |
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_relation |
Lithos Kirkland , C L , Yakymchuk , C , Szilas , K , Evans , N , Hollis , J , McDonald , B & Gardiner , N J 2018 , ' Apatite : a U-Pb thermochronometer or geochronometer? ' , Lithos , vol. 318-319 , pp. 143-157 . https://doi.org/10.1016/j.lithos.2018.08.007 0024-4937 PURE: 261213902 PURE UUID: ce3525bc-c1d5-41be-b9ab-1b9df7078dd6 Scopus: 85051636362 ORCID: /0000-0003-3465-9295/work/62311899 http://hdl.handle.net/10023/18484 https://doi.org/10.1016/j.lithos.2018.08.007 https://www.sciencedirect.com/science/article/pii/S0024493718302809?via%3Dihub#s0140 |
op_rights |
Copyright ©2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
op_doi |
https://doi.org/10.1016/j.lithos.2018.08.007 |
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Lithos |
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318-319 |
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143 |
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