Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly
Despite extensive investigation, the tectono-thermal evolution of the Archean crust in the Lewisian Gneiss Complex in NW Scotland (LGC) is debated. Most U–Pb zircon geochronological and metamorphic studies have focused on rocks from the central region of the mainland LGC, where granulite facies asse...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/640054 2024-02-11T10:06:47+01:00 Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly Volante, Silvia Dziggel, Annika Walters, Jesse B. Evans, Noreen J. Herbst, Maximilian Roper, Richard Albert 2023 application/application/pdf https://hdl.handle.net/20.500.11850/640054 https://doi.org/10.3929/ethz-b-000640054 en eng Wiley-Blackwell info:eu-repo/semantics/altIdentifier/doi/10.1111/jmg.12748 info:eu-repo/semantics/altIdentifier/wos/001085895700001 http://hdl.handle.net/20.500.11850/640054 doi:10.3929/ethz-b-000640054 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International Journal of Metamorphic Geology in situ titanite petrochronology Laxfordian metamorphism North Atlantic Craton strain partitioning supercontinent assembly info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2023 ftethz https://doi.org/20.500.11850/64005410.3929/ethz-b-00064005410.1111/jmg.12748 2024-01-22T00:52:43Z Despite extensive investigation, the tectono-thermal evolution of the Archean crust in the Lewisian Gneiss Complex in NW Scotland (LGC) is debated. Most U–Pb zircon geochronological and metamorphic studies have focused on rocks from the central region of the mainland LGC, where granulite facies assemblages associated with the oldest (Badcallian) tectono-metamorphic event at c. 2.75 Ga are overprinted by younger amphibolite facies assemblages related to the Inverian (c. 2.5 Ga) and subsequent Laxfordian (c. 1.9–1.65 Ga) tectono-thermal events. In the southern and northern regions of the mainland LGC, deformation and metamorphism associated with the Laxfordian event are pervasive, although the timing and conditions are poorly constrained. Here, we present new field, petrographic and structural data, U–Pb zircon and titanite geochronology and phase equilibrium modelling of amphibolite samples from the northern and southern regions. Our field observations show that in both regions, pre-Laxfordian structures are significantly reworked by steep NW-striking fabrics that are themselves pervasively overprinted by co-axial deformation and amphibolite facies metamorphism related to the Laxfordian event. In situ U–Pb titanite geochronology yields Laxfordian ages of 1853 ± 20 Ma in the southern region (P = 6–8 kbar and T = 640–690°C) and 1750 ± 20 Ma and 1776 ± 10 Ma in the northern region (P = 6–7.5 kbar and T = 740–760°C). While U–Pb dating of zircon rims from felsic gneisses in the central region shows a dominant Inverian metamorphic overprint at c. 2500 Ma, zircon rims in felsic gneisses from the northern and southern regions commonly yield Laxfordian dates as young as c. 1800 Ma. Combined, the results support the idea that, during the Palaeoproterozoic, the central region of the LGC acted as low-strain domain, in which intense deformation and metamorphism were restricted to crustal-scale shear zones. By contrast, in the southern and northern regions, early (c. 1.85 Ga) and late (c. 1.75 Ga) Laxfordian deformation and ... Article in Journal/Newspaper North Atlantic ETH Zürich Research Collection |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
in situ titanite petrochronology Laxfordian metamorphism North Atlantic Craton strain partitioning supercontinent assembly |
spellingShingle |
in situ titanite petrochronology Laxfordian metamorphism North Atlantic Craton strain partitioning supercontinent assembly Volante, Silvia Dziggel, Annika Walters, Jesse B. Evans, Noreen J. Herbst, Maximilian Roper, Richard Albert Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
topic_facet |
in situ titanite petrochronology Laxfordian metamorphism North Atlantic Craton strain partitioning supercontinent assembly |
description |
Despite extensive investigation, the tectono-thermal evolution of the Archean crust in the Lewisian Gneiss Complex in NW Scotland (LGC) is debated. Most U–Pb zircon geochronological and metamorphic studies have focused on rocks from the central region of the mainland LGC, where granulite facies assemblages associated with the oldest (Badcallian) tectono-metamorphic event at c. 2.75 Ga are overprinted by younger amphibolite facies assemblages related to the Inverian (c. 2.5 Ga) and subsequent Laxfordian (c. 1.9–1.65 Ga) tectono-thermal events. In the southern and northern regions of the mainland LGC, deformation and metamorphism associated with the Laxfordian event are pervasive, although the timing and conditions are poorly constrained. Here, we present new field, petrographic and structural data, U–Pb zircon and titanite geochronology and phase equilibrium modelling of amphibolite samples from the northern and southern regions. Our field observations show that in both regions, pre-Laxfordian structures are significantly reworked by steep NW-striking fabrics that are themselves pervasively overprinted by co-axial deformation and amphibolite facies metamorphism related to the Laxfordian event. In situ U–Pb titanite geochronology yields Laxfordian ages of 1853 ± 20 Ma in the southern region (P = 6–8 kbar and T = 640–690°C) and 1750 ± 20 Ma and 1776 ± 10 Ma in the northern region (P = 6–7.5 kbar and T = 740–760°C). While U–Pb dating of zircon rims from felsic gneisses in the central region shows a dominant Inverian metamorphic overprint at c. 2500 Ma, zircon rims in felsic gneisses from the northern and southern regions commonly yield Laxfordian dates as young as c. 1800 Ma. Combined, the results support the idea that, during the Palaeoproterozoic, the central region of the LGC acted as low-strain domain, in which intense deformation and metamorphism were restricted to crustal-scale shear zones. By contrast, in the southern and northern regions, early (c. 1.85 Ga) and late (c. 1.75 Ga) Laxfordian deformation and ... |
format |
Article in Journal/Newspaper |
author |
Volante, Silvia Dziggel, Annika Walters, Jesse B. Evans, Noreen J. Herbst, Maximilian Roper, Richard Albert |
author_facet |
Volante, Silvia Dziggel, Annika Walters, Jesse B. Evans, Noreen J. Herbst, Maximilian Roper, Richard Albert |
author_sort |
Volante, Silvia |
title |
Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
title_short |
Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
title_full |
Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
title_fullStr |
Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
title_full_unstemmed |
Constraints on the Palaeoproterozoic tectono-metamorphic evolution of the Lewisian Gneiss Complex, NW Scotland: Implications for Nuna assembly |
title_sort |
constraints on the palaeoproterozoic tectono-metamorphic evolution of the lewisian gneiss complex, nw scotland: implications for nuna assembly |
publisher |
Wiley-Blackwell |
publishDate |
2023 |
url |
https://hdl.handle.net/20.500.11850/640054 https://doi.org/10.3929/ethz-b-000640054 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Journal of Metamorphic Geology |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1111/jmg.12748 info:eu-repo/semantics/altIdentifier/wos/001085895700001 http://hdl.handle.net/20.500.11850/640054 doi:10.3929/ethz-b-000640054 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_doi |
https://doi.org/20.500.11850/64005410.3929/ethz-b-00064005410.1111/jmg.12748 |
_version_ |
1790604736684097536 |