From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation
A genetic model for the Motzfeldt Tantalum-Niobium-rich syenite in south-west Greenland, considered to be one of the world’s largest Ta prospects, is presented. The Motzfeldt primary magma formed early in regional Gardar (1273 ± 6 Ma) rifting. Isotope signatures indicate that the Hf had multiple sou...
Published in: | Ore Geology Reviews |
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2019
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Online Access: | https://research-portal.st-andrews.ac.uk/en/researchoutput/from-mantle-to-motzfeldt(1c0c9c45-c0f6-4e77-bf5c-d61fd8794870).html https://doi.org/10.1016/j.oregeorev.2019.02.032 https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/1/Finch_et_al_2019_Ore_Geology_Reviews_Submitted_Version_Jan_2019.pdf https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/2/Finch_2019_OGR_Mantle2Motzfeldt_AAM.pdf https://adrianfinchcouk.wordpress.com/2019/03/12/motzfeldt-genetic-model-published/ |
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ftunstandrewcris:oai:research-portal.st-andrews.ac.uk:publications/1c0c9c45-c0f6-4e77-bf5c-d61fd8794870 2024-06-23T07:53:20+00:00 From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation Finch, Adrian A. McCreath, Jamie A Reekie, Callum D.J. Hutchison, William Ismaila, Abdulmalik Armour-Brown, Ashlyn Andersen, Tom Simonsen, Siri L. 2019-04 application/pdf https://research-portal.st-andrews.ac.uk/en/researchoutput/from-mantle-to-motzfeldt(1c0c9c45-c0f6-4e77-bf5c-d61fd8794870).html https://doi.org/10.1016/j.oregeorev.2019.02.032 https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/1/Finch_et_al_2019_Ore_Geology_Reviews_Submitted_Version_Jan_2019.pdf https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/2/Finch_2019_OGR_Mantle2Motzfeldt_AAM.pdf https://adrianfinchcouk.wordpress.com/2019/03/12/motzfeldt-genetic-model-published/ eng eng https://research-portal.st-andrews.ac.uk/en/researchoutput/from-mantle-to-motzfeldt(1c0c9c45-c0f6-4e77-bf5c-d61fd8794870).html info:eu-repo/semantics/openAccess Finch , A A , McCreath , J A , Reekie , C D J , Hutchison , W , Ismaila , A , Armour-Brown , A , Andersen , T & Simonsen , S L 2019 , ' From Mantle to Motzfeldt : a genetic model for syenite-hosted Ta,Nb-mineralisation ' , Ore Geology Reviews , vol. 107 , pp. 402-416 . https://doi.org/10.1016/j.oregeorev.2019.02.032 Pyrochlore Tantalum Alkaline Gardar Province Hydrothermal alteration Greenland article 2019 ftunstandrewcris https://doi.org/10.1016/j.oregeorev.2019.02.032 2024-06-13T01:05:10Z A genetic model for the Motzfeldt Tantalum-Niobium-rich syenite in south-west Greenland, considered to be one of the world’s largest Ta prospects, is presented. The Motzfeldt primary magma formed early in regional Gardar (1273 ± 6 Ma) rifting. Isotope signatures indicate that the Hf had multiple sources involving juvenile Gardar Hf mixed with older (Palaeoproterozoic or Archaean) Hf. We infer that other High Field Strength Elements (HFSE) similarly had multiple sources. The magma differentiated in the crust and ascended before emplacement at the regional unconformity between Ketilidian basement and Eriksfjord supracrustals. The HFSE-rich magmas crystallised Ta-rich pyrochlore which formed pyrochlore-rich crystal mushes, and it is these pyrochlore-rich horizons, rich in Ta and Nb, that are the focus of exploration. The roof zone chilled and repeated sheeting at the roof provided a complex suite of cross-cutting syenite variants, including pyrochlore microsyenite, in a ‘Hot Sheeted Roof’ model. The area was subject to hydrothermal alteration which recrystallized alkali feldspar to coarse perthite and modified the mafic minerals to hematite, creating the friable and striking pink-nature of the Motzfeldt Sø Centre. Carbon and oxygen isotope investigation of carbonate constrains fluid evolution and shows that carbonate is primarily mantle-derived but late-stage hydrothermal alteration moved the oxygen isotopes towards more positive values (up to 21‰). The hydrothermal fluid was exceptionally fluorine-rich and mobilised many elements including U and Pb but did not transport HFSE such as Ta, Hf and Nb. Although the U and Pb content of the pyrochlore was enhanced by the fluid, the HFSE contents remained unchanged and therefore Hf isotopes were unaffected by fluid interaction. While the effect on hydrothermal alteration on the visual appearance of the rock is striking, magmatic processes concentrated HFSE including Ta and the hydrothermal phase has not altered the grade. Exploration for HFSE mineralisation commonly ... Article in Journal/Newspaper Greenland University of St Andrews: Research Portal Greenland Ore Geology Reviews 107 402 416 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
Pyrochlore Tantalum Alkaline Gardar Province Hydrothermal alteration Greenland |
spellingShingle |
Pyrochlore Tantalum Alkaline Gardar Province Hydrothermal alteration Greenland Finch, Adrian A. McCreath, Jamie A Reekie, Callum D.J. Hutchison, William Ismaila, Abdulmalik Armour-Brown, Ashlyn Andersen, Tom Simonsen, Siri L. From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
topic_facet |
Pyrochlore Tantalum Alkaline Gardar Province Hydrothermal alteration Greenland |
description |
A genetic model for the Motzfeldt Tantalum-Niobium-rich syenite in south-west Greenland, considered to be one of the world’s largest Ta prospects, is presented. The Motzfeldt primary magma formed early in regional Gardar (1273 ± 6 Ma) rifting. Isotope signatures indicate that the Hf had multiple sources involving juvenile Gardar Hf mixed with older (Palaeoproterozoic or Archaean) Hf. We infer that other High Field Strength Elements (HFSE) similarly had multiple sources. The magma differentiated in the crust and ascended before emplacement at the regional unconformity between Ketilidian basement and Eriksfjord supracrustals. The HFSE-rich magmas crystallised Ta-rich pyrochlore which formed pyrochlore-rich crystal mushes, and it is these pyrochlore-rich horizons, rich in Ta and Nb, that are the focus of exploration. The roof zone chilled and repeated sheeting at the roof provided a complex suite of cross-cutting syenite variants, including pyrochlore microsyenite, in a ‘Hot Sheeted Roof’ model. The area was subject to hydrothermal alteration which recrystallized alkali feldspar to coarse perthite and modified the mafic minerals to hematite, creating the friable and striking pink-nature of the Motzfeldt Sø Centre. Carbon and oxygen isotope investigation of carbonate constrains fluid evolution and shows that carbonate is primarily mantle-derived but late-stage hydrothermal alteration moved the oxygen isotopes towards more positive values (up to 21‰). The hydrothermal fluid was exceptionally fluorine-rich and mobilised many elements including U and Pb but did not transport HFSE such as Ta, Hf and Nb. Although the U and Pb content of the pyrochlore was enhanced by the fluid, the HFSE contents remained unchanged and therefore Hf isotopes were unaffected by fluid interaction. While the effect on hydrothermal alteration on the visual appearance of the rock is striking, magmatic processes concentrated HFSE including Ta and the hydrothermal phase has not altered the grade. Exploration for HFSE mineralisation commonly ... |
format |
Article in Journal/Newspaper |
author |
Finch, Adrian A. McCreath, Jamie A Reekie, Callum D.J. Hutchison, William Ismaila, Abdulmalik Armour-Brown, Ashlyn Andersen, Tom Simonsen, Siri L. |
author_facet |
Finch, Adrian A. McCreath, Jamie A Reekie, Callum D.J. Hutchison, William Ismaila, Abdulmalik Armour-Brown, Ashlyn Andersen, Tom Simonsen, Siri L. |
author_sort |
Finch, Adrian A. |
title |
From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
title_short |
From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
title_full |
From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
title_fullStr |
From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
title_full_unstemmed |
From Mantle to Motzfeldt:a genetic model for syenite-hosted Ta,Nb-mineralisation |
title_sort |
from mantle to motzfeldt:a genetic model for syenite-hosted ta,nb-mineralisation |
publishDate |
2019 |
url |
https://research-portal.st-andrews.ac.uk/en/researchoutput/from-mantle-to-motzfeldt(1c0c9c45-c0f6-4e77-bf5c-d61fd8794870).html https://doi.org/10.1016/j.oregeorev.2019.02.032 https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/1/Finch_et_al_2019_Ore_Geology_Reviews_Submitted_Version_Jan_2019.pdf https://research-repository.st-andrews.ac.uk/bitstream/10023/17329/2/Finch_2019_OGR_Mantle2Motzfeldt_AAM.pdf https://adrianfinchcouk.wordpress.com/2019/03/12/motzfeldt-genetic-model-published/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Finch , A A , McCreath , J A , Reekie , C D J , Hutchison , W , Ismaila , A , Armour-Brown , A , Andersen , T & Simonsen , S L 2019 , ' From Mantle to Motzfeldt : a genetic model for syenite-hosted Ta,Nb-mineralisation ' , Ore Geology Reviews , vol. 107 , pp. 402-416 . https://doi.org/10.1016/j.oregeorev.2019.02.032 |
op_relation |
https://research-portal.st-andrews.ac.uk/en/researchoutput/from-mantle-to-motzfeldt(1c0c9c45-c0f6-4e77-bf5c-d61fd8794870).html |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.oregeorev.2019.02.032 |
container_title |
Ore Geology Reviews |
container_volume |
107 |
container_start_page |
402 |
op_container_end_page |
416 |
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1802644914957189120 |