Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway
This is the peer reviewed version of the following article: Fournier, H. W., Lee, J. K. W., & Camacho, A. (2019). Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway. Journal of Metamorphic Geology. doi:10.1111/jmg.12485, which...
Published in: | Journal of Metamorphic Geology |
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Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
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Wiley
2019
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Subjects: | |
Online Access: | http://hdl.handle.net/1974/26295 https://doi.org/10.1111/jmg.12485 |
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ftqueensuniv:oai:qspace.library.queensu.ca:1974/26295 |
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Open Polar |
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Queen's University, Ontario: QSpace |
op_collection_id |
ftqueensuniv |
language |
unknown |
topic |
Ar isotopes Caledonian orogeny Leknes Group muscovite thermal modelling short-lived fluid migration |
spellingShingle |
Ar isotopes Caledonian orogeny Leknes Group muscovite thermal modelling short-lived fluid migration Fournier, Herbert W. Lee, James K. W. Camacho, Alfredo Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
topic_facet |
Ar isotopes Caledonian orogeny Leknes Group muscovite thermal modelling short-lived fluid migration |
description |
This is the peer reviewed version of the following article: Fournier, H. W., Lee, J. K. W., & Camacho, A. (2019). Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway. Journal of Metamorphic Geology. doi:10.1111/jmg.12485, which has been published in final form at http://dx.doi.org/10.1111/jmg.12485. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. The determination of the thermal (temperature–time) histories of high-P metamorphic terranes has been commonly based on the concepts of slow cooling and closure temperatures. In this paper, we find that this approach cannot reconcile a geochronological data set obtained from the amphibolite-facies allochthonous Leknes Group of the Lofoten islands, Norway, which reveals an extremely complex thermal history. Using detailed results from several different geochronometers such as 40Ar/39Ar, Rb–Sr and U–Pb, we show that a model invoking multiple, short-lived thermal pulses related to hot-fluid infiltration channelized by shear zones can reconcile this complicated data set. This model suggests that hot fluids infiltrated throughout basement shear zones and affected the overlying cold allochthon, partially resetting U/Pb rutile and titanite ages, crystallizing new zircon and produced identical 40Ar/39Ar and Rb/Sr ages in muscovite, biotite and amphibole in various rocks throughout the region. This paper shows the enormous potential of coupling laser Ar-spot data with thermal modelling to identify and constrain the duration of short-lived events. An optimal P–T–t history has been derived by modelling the age data from a previously dated large muscovite crystal (Hames & Andresen, 1996, Geology, 24:1005) and using Zr-in-rutile thermometry which is consistent with all geochronological data and geological constraints from the basement zones and allochthon cover. This tectonothermal model history suggests that there have been three episodic hot-fluid and 40Ar-free infiltration events, resulting in the total resetting of Ar ages during the Scandian (425 Ma) for 1 Ma at 650°C and two reheating events at 415 Ma for 400 ka at 650°C and at 365 Ma for 50 ka at 600°C, which are modelled as thermal spikes above an ambient temperature of 300°C. Independent confirmation of these parameters was provided by Pb-diffusion modelling in rutile and titanite. The model suggests that the amphibolite facies rocks of the Leknes Group probably remained cold before being exhumed for at least 60 Ma (425–365 Ma) and successfully explains the presence of different minerals that crystallized or were totally/partially reset in the allochthon and in the basement. The migration of hot fluids for short periods of times within conduits extending through the basement and allochthon rock units is likely associated with episodic seismic activity during the Caledonian orogeny. Natural Sciences and Engineering Research Council of Canada Sigma Xi Geological Society of America: 9449‐10 |
format |
Article in Journal/Newspaper |
author |
Fournier, Herbert W. Lee, James K. W. Camacho, Alfredo |
author_facet |
Fournier, Herbert W. Lee, James K. W. Camacho, Alfredo |
author_sort |
Fournier, Herbert W. |
title |
Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
title_short |
Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
title_full |
Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
title_fullStr |
Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
title_full_unstemmed |
Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway |
title_sort |
slow cooling versus episodic fluid injections: deciphering the caledonian orogeny in vestvågøy, lofoten islands, norway |
publisher |
Wiley |
publishDate |
2019 |
url |
http://hdl.handle.net/1974/26295 https://doi.org/10.1111/jmg.12485 |
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ENVELOPE(-66.733,-66.733,-66.983,-66.983) ENVELOPE(-63.150,-63.150,-64.533,-64.533) ENVELOPE(13.611,13.611,68.148,68.148) |
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Andresen Canada Fournier Lofoten Norway Vestvågøy |
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Andresen Canada Fournier Lofoten Norway Vestvågøy |
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Leknes Lofoten Vestvågøy |
genre_facet |
Leknes Lofoten Vestvågøy |
op_relation |
Fournier, H. W., Lee, J. K. W., & Camacho, A. (2019). Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway. Journal of Metamorphic Geology. doi:10.1111/jmg.12485 http://hdl.handle.net/1974/26295 https://dx.doi.org/10.1111/jmg.12485 |
op_doi |
https://doi.org/10.1111/jmg.12485 |
container_title |
Journal of Metamorphic Geology |
container_volume |
37 |
container_issue |
6 |
container_start_page |
769 |
op_container_end_page |
793 |
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1766062849388445696 |
spelling |
ftqueensuniv:oai:qspace.library.queensu.ca:1974/26295 2023-05-15T17:07:26+02:00 Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway Fournier, Herbert W. Lee, James K. W. Camacho, Alfredo 2019-06-07T15:39:01Z http://hdl.handle.net/1974/26295 https://doi.org/10.1111/jmg.12485 unknown Wiley Fournier, H. W., Lee, J. K. W., & Camacho, A. (2019). Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway. Journal of Metamorphic Geology. doi:10.1111/jmg.12485 http://hdl.handle.net/1974/26295 https://dx.doi.org/10.1111/jmg.12485 Ar isotopes Caledonian orogeny Leknes Group muscovite thermal modelling short-lived fluid migration journal article 2019 ftqueensuniv https://doi.org/10.1111/jmg.12485 2020-12-29T09:09:52Z This is the peer reviewed version of the following article: Fournier, H. W., Lee, J. K. W., & Camacho, A. (2019). Slow cooling versus episodic fluid injections: Deciphering the Caledonian orogeny in Vestvågøy, Lofoten islands, Norway. Journal of Metamorphic Geology. doi:10.1111/jmg.12485, which has been published in final form at http://dx.doi.org/10.1111/jmg.12485. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. The determination of the thermal (temperature–time) histories of high-P metamorphic terranes has been commonly based on the concepts of slow cooling and closure temperatures. In this paper, we find that this approach cannot reconcile a geochronological data set obtained from the amphibolite-facies allochthonous Leknes Group of the Lofoten islands, Norway, which reveals an extremely complex thermal history. Using detailed results from several different geochronometers such as 40Ar/39Ar, Rb–Sr and U–Pb, we show that a model invoking multiple, short-lived thermal pulses related to hot-fluid infiltration channelized by shear zones can reconcile this complicated data set. This model suggests that hot fluids infiltrated throughout basement shear zones and affected the overlying cold allochthon, partially resetting U/Pb rutile and titanite ages, crystallizing new zircon and produced identical 40Ar/39Ar and Rb/Sr ages in muscovite, biotite and amphibole in various rocks throughout the region. This paper shows the enormous potential of coupling laser Ar-spot data with thermal modelling to identify and constrain the duration of short-lived events. An optimal P–T–t history has been derived by modelling the age data from a previously dated large muscovite crystal (Hames & Andresen, 1996, Geology, 24:1005) and using Zr-in-rutile thermometry which is consistent with all geochronological data and geological constraints from the basement zones and allochthon cover. This tectonothermal model history suggests that there have been three episodic hot-fluid and 40Ar-free infiltration events, resulting in the total resetting of Ar ages during the Scandian (425 Ma) for 1 Ma at 650°C and two reheating events at 415 Ma for 400 ka at 650°C and at 365 Ma for 50 ka at 600°C, which are modelled as thermal spikes above an ambient temperature of 300°C. Independent confirmation of these parameters was provided by Pb-diffusion modelling in rutile and titanite. The model suggests that the amphibolite facies rocks of the Leknes Group probably remained cold before being exhumed for at least 60 Ma (425–365 Ma) and successfully explains the presence of different minerals that crystallized or were totally/partially reset in the allochthon and in the basement. The migration of hot fluids for short periods of times within conduits extending through the basement and allochthon rock units is likely associated with episodic seismic activity during the Caledonian orogeny. Natural Sciences and Engineering Research Council of Canada Sigma Xi Geological Society of America: 9449‐10 Article in Journal/Newspaper Leknes Lofoten Vestvågøy Queen's University, Ontario: QSpace Andresen ENVELOPE(-66.733,-66.733,-66.983,-66.983) Canada Fournier ENVELOPE(-63.150,-63.150,-64.533,-64.533) Lofoten Norway Vestvågøy ENVELOPE(13.611,13.611,68.148,68.148) Journal of Metamorphic Geology 37 6 769 793 |