Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes.
The Paleocene lava succession of the Faroe Islands Basalt Group (FIBG), which is a part of the North Atlantic Igneous Province (NAIP), is intruded by numerous basaltic sills. These can be grouped into three main categories according to their geochemical characteristics: A low-TiO2 sill category (TiO...
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Online Access: | http://dro.dur.ac.uk/29381/ http://dro.dur.ac.uk/29381/1/29381.pdf https://doi.org/10.11648/j.earth.20190805.11 |
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:29381 2023-05-15T16:10:50+02:00 Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. Hansen, Jógvan Davidson, Jon Jerram, Dougal Ottley, Christopher Widdowson, Mike 2019-10-31 application/pdf http://dro.dur.ac.uk/29381/ http://dro.dur.ac.uk/29381/1/29381.pdf https://doi.org/10.11648/j.earth.20190805.11 unknown Science Publishing Group dro:29381 issn:2328-5974 doi:10.11648/j.earth.20190805.11 http://dro.dur.ac.uk/29381/ https://doi.org/10.11648/j.earth.20190805.11 http://dro.dur.ac.uk/29381/1/29381.pdf Copyright © 2019 Authors retain the copyright of this article. This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. CC-BY Earth sciences, 2019, Vol.8(5), pp.235-267 [Peer Reviewed Journal] Article PeerReviewed 2019 ftunivdurham https://doi.org/10.11648/j.earth.20190805.11 2020-06-11T22:25:19Z The Paleocene lava succession of the Faroe Islands Basalt Group (FIBG), which is a part of the North Atlantic Igneous Province (NAIP), is intruded by numerous basaltic sills. These can be grouped into three main categories according to their geochemical characteristics: A low-TiO2 sill category (TiO2 = 0.7-0.9), a relatively high-TiO2 sill category (TiO2 = 1.95-2.6) and an intermediate-TiO2 sill that displays major element compositions lying between the other two categories. Mantle normalised plots for the high-TiO2 and low-TiO2 sills display relatively uniform flat LREE trends and slightly steeper HREE slopes for high-TiO2 relative to low-TiO2 sills. The intermediate-TiO2 Morskranes Sill is LREE depleted. Mantle normalised trace elements of low-TiO2 sill samples define positive Eu and Sr anomalies, whereas high-TiO2 sill samples display negative anomalies for these same lements. Different Nb and Ta anomalies (positive versus negative) in many high-TiO2 versus low-TiO2 sill samples suggest various metasomatism of their sources prior to partial melting. The intermediate-TiO2 sill displays noticeably lower 87Sr/86Sr, 206Pb/204Pb and 208Pb/204Pb ratios relative to both the high-TiO2 and the low-TiO2 sill samples. Pb isotope compositions displayed by local contaminated basaltic lavas imply that some of these assimilated distinct crustal material from E Greenland or basement from NW Britain, while others probably assimilated only distinct E Greenland type of crustal material. A third crustal source of E Greenland or Rockall-type basement could be required in order to explain some of the range in lead isotopes displayed by the intermediate-TiO2 Morskranes Sill. Geochemical modelling suggest that Faroese high-TiO2 sills, could have formed by ~4 to 7.5% batch melting of moderately fertile lherzolites, while 16 to 21% batch melting fertile mantle sources could explain geochemical compositions of Faroese low-TiO2 sills. The intermediate-TiO2 sill samples could have formed by a range of 6 to 7% batch melting of a depleted mantle source, probably with a composition comparable to sources that gave rise to local low-TiO2 and intermediate-TiO2 host-rocks. Most Faroese sill samples probably developed outside the garnet stabilitry field and probably formed by batch melting of mantle materials comparable in composition to those reported for the sub-continental lithospheric mantle (SCLM) previously at depths of ≤ 85 km. Relative enrichments in LREE (and LILE in general), and their varying Nb and Ta anomalies point to sources affected by metasomatism. Article in Journal/Newspaper Faroe Islands Greenland North Atlantic Durham University: Durham Research Online Faroe Islands Greenland Morskranes ENVELOPE(-6.841,-6.841,62.132,62.132) Earth Sciences 8 5 235 |
institution |
Open Polar |
collection |
Durham University: Durham Research Online |
op_collection_id |
ftunivdurham |
language |
unknown |
description |
The Paleocene lava succession of the Faroe Islands Basalt Group (FIBG), which is a part of the North Atlantic Igneous Province (NAIP), is intruded by numerous basaltic sills. These can be grouped into three main categories according to their geochemical characteristics: A low-TiO2 sill category (TiO2 = 0.7-0.9), a relatively high-TiO2 sill category (TiO2 = 1.95-2.6) and an intermediate-TiO2 sill that displays major element compositions lying between the other two categories. Mantle normalised plots for the high-TiO2 and low-TiO2 sills display relatively uniform flat LREE trends and slightly steeper HREE slopes for high-TiO2 relative to low-TiO2 sills. The intermediate-TiO2 Morskranes Sill is LREE depleted. Mantle normalised trace elements of low-TiO2 sill samples define positive Eu and Sr anomalies, whereas high-TiO2 sill samples display negative anomalies for these same lements. Different Nb and Ta anomalies (positive versus negative) in many high-TiO2 versus low-TiO2 sill samples suggest various metasomatism of their sources prior to partial melting. The intermediate-TiO2 sill displays noticeably lower 87Sr/86Sr, 206Pb/204Pb and 208Pb/204Pb ratios relative to both the high-TiO2 and the low-TiO2 sill samples. Pb isotope compositions displayed by local contaminated basaltic lavas imply that some of these assimilated distinct crustal material from E Greenland or basement from NW Britain, while others probably assimilated only distinct E Greenland type of crustal material. A third crustal source of E Greenland or Rockall-type basement could be required in order to explain some of the range in lead isotopes displayed by the intermediate-TiO2 Morskranes Sill. Geochemical modelling suggest that Faroese high-TiO2 sills, could have formed by ~4 to 7.5% batch melting of moderately fertile lherzolites, while 16 to 21% batch melting fertile mantle sources could explain geochemical compositions of Faroese low-TiO2 sills. The intermediate-TiO2 sill samples could have formed by a range of 6 to 7% batch melting of a depleted mantle source, probably with a composition comparable to sources that gave rise to local low-TiO2 and intermediate-TiO2 host-rocks. Most Faroese sill samples probably developed outside the garnet stabilitry field and probably formed by batch melting of mantle materials comparable in composition to those reported for the sub-continental lithospheric mantle (SCLM) previously at depths of ≤ 85 km. Relative enrichments in LREE (and LILE in general), and their varying Nb and Ta anomalies point to sources affected by metasomatism. |
format |
Article in Journal/Newspaper |
author |
Hansen, Jógvan Davidson, Jon Jerram, Dougal Ottley, Christopher Widdowson, Mike |
spellingShingle |
Hansen, Jógvan Davidson, Jon Jerram, Dougal Ottley, Christopher Widdowson, Mike Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
author_facet |
Hansen, Jógvan Davidson, Jon Jerram, Dougal Ottley, Christopher Widdowson, Mike |
author_sort |
Hansen, Jógvan |
title |
Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
title_short |
Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
title_full |
Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
title_fullStr |
Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
title_full_unstemmed |
Contrasting TiO2 compositions in early cenozoic mafic sills of the Faroe Islands : an example of basalt formation from distinct melting regimes. |
title_sort |
contrasting tio2 compositions in early cenozoic mafic sills of the faroe islands : an example of basalt formation from distinct melting regimes. |
publisher |
Science Publishing Group |
publishDate |
2019 |
url |
http://dro.dur.ac.uk/29381/ http://dro.dur.ac.uk/29381/1/29381.pdf https://doi.org/10.11648/j.earth.20190805.11 |
long_lat |
ENVELOPE(-6.841,-6.841,62.132,62.132) |
geographic |
Faroe Islands Greenland Morskranes |
geographic_facet |
Faroe Islands Greenland Morskranes |
genre |
Faroe Islands Greenland North Atlantic |
genre_facet |
Faroe Islands Greenland North Atlantic |
op_source |
Earth sciences, 2019, Vol.8(5), pp.235-267 [Peer Reviewed Journal] |
op_relation |
dro:29381 issn:2328-5974 doi:10.11648/j.earth.20190805.11 http://dro.dur.ac.uk/29381/ https://doi.org/10.11648/j.earth.20190805.11 http://dro.dur.ac.uk/29381/1/29381.pdf |
op_rights |
Copyright © 2019 Authors retain the copyright of this article. This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.11648/j.earth.20190805.11 |
container_title |
Earth Sciences |
container_volume |
8 |
container_issue |
5 |
container_start_page |
235 |
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1765995973981503488 |