Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden

Scapolites from barren regional Na-Cl metasomatic assemblages (RM), iron oxide-copper-gold deposits (IOCG), scapolite altered metabasic rocks (IOCG-M), and from IOCG-proximal alteration/Na-skarns (IOCG-PS) from Norrbotten County in Northern Sweden have been analysed for halogen content and Cl stable...

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Published in:Chemical Geology
Main Authors: Bernal, Nelson, Gleeson, Sarah, Smith, Martin, Barnes, Jamie, Pan, Yanuming
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
Online Access:https://research.brighton.ac.uk/en/publications/d743ca1f-a642-41d0-bd5c-222bf1e78b6f
https://doi.org/10.1016/j.chemgeo.2017.01.005
https://cris.brighton.ac.uk/ws/files/434833/Bernal%20et%20al%202016.pdf
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spelling ftunbrightoncris:oai:pure.atira.dk:publications/d743ca1f-a642-41d0-bd5c-222bf1e78b6f 2023-05-15T17:45:07+02:00 Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden Bernal, Nelson Gleeson, Sarah Smith, Martin Barnes, Jamie Pan, Yanuming 2017-01-13 application/pdf https://research.brighton.ac.uk/en/publications/d743ca1f-a642-41d0-bd5c-222bf1e78b6f https://doi.org/10.1016/j.chemgeo.2017.01.005 https://cris.brighton.ac.uk/ws/files/434833/Bernal%20et%20al%202016.pdf eng eng info:eu-repo/semantics/openAccess Bernal , N , Gleeson , S , Smith , M , Barnes , J & Pan , Y 2017 , ' Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden ' , Chemical Geology , vol. 451 , pp. 90-103 . https://doi.org/10.1016/j.chemgeo.2017.01.005 Halogens Chlorine isotopes Isotope fractionation Scapolite IOCG article 2017 ftunbrightoncris https://doi.org/10.1016/j.chemgeo.2017.01.005 2022-01-01T08:45:58Z Scapolites from barren regional Na-Cl metasomatic assemblages (RM), iron oxide-copper-gold deposits (IOCG), scapolite altered metabasic rocks (IOCG-M), and from IOCG-proximal alteration/Na-skarns (IOCG-PS) from Norrbotten County in Northern Sweden have been analysed for halogen content and Cl stable isotope composition. The aim of the study was to constrain the source of halogens within alteration assemblages, and to investigate the possible fractionation of Cl isotopes between scapolite and the hydrothermal fluid. Scapolite separates were analyzed for Cl, Br, and major oxide concentrations using electron probe micro-analysis (EPMA) and micro-X-ray fluorescence (XRFM) spectrometry. Chlorine was extracted from the scapolite separates via pyrohydrolysis and then analysed for their stable Cl isotope compositions by isotope ratio mass spectrometry (IRMS). All samples of scapolite investigated in this study are marialitic in composition. One of the scapolites from the Gruvberget deposit (IOCG-PS) had a Cl/Br molar ratio of 2,363, which is the highest amongst all scapolites reported in the literature to date. Cl/Br molar ratios lower than seawater (650), were identified in two IOCG-PS scapolite samples (Cl/Br=554 and 271), as well as in two IOCG-M scapolites (Cl/Br=393 and 565). Three RM scapolites had Cl/Br molar ratios very close to, or slightly higher than, seawater values (639 to 770). Samples with Cl/Br molar ratios less than seawater are inferred to have halogens derived from evaporative residual brines; whereas samples with molar ratios higher than seawater may have halogens derived from fluids that have dissolved halite and/or are from magmatic systems. Considering the wide variation of the Cl/Br molar ratios in the IOCG-PS and IOCG-M scapolites compared to the restricted composition of the regional alteration (RM), it is proposed that the hydrothermal fluids interacted with several different protoliths to generate the IOCG alteration. Article in Journal/Newspaper Northern Sweden Norrbotten The University of Brighton Research Portal Gruvberget ENVELOPE(21.767,21.767,65.785,65.785) Chemical Geology 451 90 103
institution Open Polar
collection The University of Brighton Research Portal
op_collection_id ftunbrightoncris
language English
topic Halogens
Chlorine isotopes
Isotope fractionation
Scapolite
IOCG
spellingShingle Halogens
Chlorine isotopes
Isotope fractionation
Scapolite
IOCG
Bernal, Nelson
Gleeson, Sarah
Smith, Martin
Barnes, Jamie
Pan, Yanuming
Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
topic_facet Halogens
Chlorine isotopes
Isotope fractionation
Scapolite
IOCG
description Scapolites from barren regional Na-Cl metasomatic assemblages (RM), iron oxide-copper-gold deposits (IOCG), scapolite altered metabasic rocks (IOCG-M), and from IOCG-proximal alteration/Na-skarns (IOCG-PS) from Norrbotten County in Northern Sweden have been analysed for halogen content and Cl stable isotope composition. The aim of the study was to constrain the source of halogens within alteration assemblages, and to investigate the possible fractionation of Cl isotopes between scapolite and the hydrothermal fluid. Scapolite separates were analyzed for Cl, Br, and major oxide concentrations using electron probe micro-analysis (EPMA) and micro-X-ray fluorescence (XRFM) spectrometry. Chlorine was extracted from the scapolite separates via pyrohydrolysis and then analysed for their stable Cl isotope compositions by isotope ratio mass spectrometry (IRMS). All samples of scapolite investigated in this study are marialitic in composition. One of the scapolites from the Gruvberget deposit (IOCG-PS) had a Cl/Br molar ratio of 2,363, which is the highest amongst all scapolites reported in the literature to date. Cl/Br molar ratios lower than seawater (650), were identified in two IOCG-PS scapolite samples (Cl/Br=554 and 271), as well as in two IOCG-M scapolites (Cl/Br=393 and 565). Three RM scapolites had Cl/Br molar ratios very close to, or slightly higher than, seawater values (639 to 770). Samples with Cl/Br molar ratios less than seawater are inferred to have halogens derived from evaporative residual brines; whereas samples with molar ratios higher than seawater may have halogens derived from fluids that have dissolved halite and/or are from magmatic systems. Considering the wide variation of the Cl/Br molar ratios in the IOCG-PS and IOCG-M scapolites compared to the restricted composition of the regional alteration (RM), it is proposed that the hydrothermal fluids interacted with several different protoliths to generate the IOCG alteration.
format Article in Journal/Newspaper
author Bernal, Nelson
Gleeson, Sarah
Smith, Martin
Barnes, Jamie
Pan, Yanuming
author_facet Bernal, Nelson
Gleeson, Sarah
Smith, Martin
Barnes, Jamie
Pan, Yanuming
author_sort Bernal, Nelson
title Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
title_short Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
title_full Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
title_fullStr Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
title_full_unstemmed Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden
title_sort evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (iocg) deposits and regional na-cl metasomatic alteration, norrbotten county, sweden
publishDate 2017
url https://research.brighton.ac.uk/en/publications/d743ca1f-a642-41d0-bd5c-222bf1e78b6f
https://doi.org/10.1016/j.chemgeo.2017.01.005
https://cris.brighton.ac.uk/ws/files/434833/Bernal%20et%20al%202016.pdf
long_lat ENVELOPE(21.767,21.767,65.785,65.785)
geographic Gruvberget
geographic_facet Gruvberget
genre Northern Sweden
Norrbotten
genre_facet Northern Sweden
Norrbotten
op_source Bernal , N , Gleeson , S , Smith , M , Barnes , J & Pan , Y 2017 , ' Evidence of multiple halogen sources in scapolites from iron oxidecopper- gold (IOCG) deposits and regional Na-Cl metasomatic alteration, Norrbotten County, Sweden ' , Chemical Geology , vol. 451 , pp. 90-103 . https://doi.org/10.1016/j.chemgeo.2017.01.005
op_rights info:eu-repo/semantics/openAccess
op_doi https://doi.org/10.1016/j.chemgeo.2017.01.005
container_title Chemical Geology
container_volume 451
container_start_page 90
op_container_end_page 103
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