Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite
We determined the bromine isotope compositions of magmatic and hydrothermal sodalite (Na8Al6Si6O24Cl2) and tugtupite (Na8Al2Be2Si8O24Cl2) from the Ilímaussaq intrusion in South Greenland, in order to constrain the Br isotope composition of the melt and hydrothermal fluids from which these minerals w...
Published in: | Minerals |
---|---|
Main Authors: | , , , |
Format: | Text |
Language: | English |
Published: |
Multidisciplinary Digital Publishing Institute
2021
|
Subjects: | |
Online Access: | https://doi.org/10.3390/min11040370 |
id |
ftmdpi:oai:mdpi.com:/2075-163X/11/4/370/ |
---|---|
record_format |
openpolar |
spelling |
ftmdpi:oai:mdpi.com:/2075-163X/11/4/370/ 2023-08-20T04:06:59+02:00 Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite Hans G. M. Eggenkamp Michael A. W. Marks Pascale Louvat Gregor Markl agris 2021-03-31 application/pdf https://doi.org/10.3390/min11040370 EN eng Multidisciplinary Digital Publishing Institute Mineral Geochemistry and Geochronology https://dx.doi.org/10.3390/min11040370 https://creativecommons.org/licenses/by/4.0/ Minerals; Volume 11; Issue 4; Pages: 370 bromine isotopes sodalite tugtupite isotope fractionation Text 2021 ftmdpi https://doi.org/10.3390/min11040370 2023-08-01T01:24:17Z We determined the bromine isotope compositions of magmatic and hydrothermal sodalite (Na8Al6Si6O24Cl2) and tugtupite (Na8Al2Be2Si8O24Cl2) from the Ilímaussaq intrusion in South Greenland, in order to constrain the Br isotope composition of the melt and hydrothermal fluids from which these minerals were formed. Early formed magmatic sodalite has high Br contents (138 ± 10 µg/g, n = 5) and low δ81Br values (+0.23 ± 0.07‰). Late stage hydrothermal sodalite has lower Br contents (53±10 µg/g, n = 5) and higher δ81Br values (+0.36 ± 0.08‰). Tugtupite that forms at even later stages shows the lowest Br contents (26 ± 2 µg/g, n = 2) and the highest δ81Br values (+0.71 ± 0.17‰). One hydrothermal sodalite has a Br concentration of 48 ± 9 µg/g and an exceptionally high δ81Br of 0.82 ± 0.12‰, very similar to the δ81Br of tugtupites. We suggest that this may be a very late stage sodalite that possibly formed under Be deficient conditions. The data set suggests that sodalite crystallises with a negative Br isotope fractionation factor, which means that the sodalite has a more negative δ81Br than the melt, of −0.3 to −0.4‰ from the melt. This leads to a value of +0.5 to +0.6‰ relative to SMOB for the melt from which sodalite crystallises. This value is similar to a recently published δ81Br value of +0.7‰ for very deep geothermal fluids with very high R/Ra He isotope ratios, presumably derived from the mantle. During crystallisation of later stage hydrothermal sodalite and the Be mineral tugtupite, δ81Br of the residual fluids (both melt and hydrothermal fluid) increases as light 79Br crystallises in the sodalite and tugtupite. This results in increasing δ81Br values of later stage minerals that crystallise with comparable fractionation factors from a fluid with increasingly higher δ81Br values. Text Greenland MDPI Open Access Publishing Greenland Minerals 11 4 370 |
institution |
Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
language |
English |
topic |
bromine isotopes sodalite tugtupite isotope fractionation |
spellingShingle |
bromine isotopes sodalite tugtupite isotope fractionation Hans G. M. Eggenkamp Michael A. W. Marks Pascale Louvat Gregor Markl Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
topic_facet |
bromine isotopes sodalite tugtupite isotope fractionation |
description |
We determined the bromine isotope compositions of magmatic and hydrothermal sodalite (Na8Al6Si6O24Cl2) and tugtupite (Na8Al2Be2Si8O24Cl2) from the Ilímaussaq intrusion in South Greenland, in order to constrain the Br isotope composition of the melt and hydrothermal fluids from which these minerals were formed. Early formed magmatic sodalite has high Br contents (138 ± 10 µg/g, n = 5) and low δ81Br values (+0.23 ± 0.07‰). Late stage hydrothermal sodalite has lower Br contents (53±10 µg/g, n = 5) and higher δ81Br values (+0.36 ± 0.08‰). Tugtupite that forms at even later stages shows the lowest Br contents (26 ± 2 µg/g, n = 2) and the highest δ81Br values (+0.71 ± 0.17‰). One hydrothermal sodalite has a Br concentration of 48 ± 9 µg/g and an exceptionally high δ81Br of 0.82 ± 0.12‰, very similar to the δ81Br of tugtupites. We suggest that this may be a very late stage sodalite that possibly formed under Be deficient conditions. The data set suggests that sodalite crystallises with a negative Br isotope fractionation factor, which means that the sodalite has a more negative δ81Br than the melt, of −0.3 to −0.4‰ from the melt. This leads to a value of +0.5 to +0.6‰ relative to SMOB for the melt from which sodalite crystallises. This value is similar to a recently published δ81Br value of +0.7‰ for very deep geothermal fluids with very high R/Ra He isotope ratios, presumably derived from the mantle. During crystallisation of later stage hydrothermal sodalite and the Be mineral tugtupite, δ81Br of the residual fluids (both melt and hydrothermal fluid) increases as light 79Br crystallises in the sodalite and tugtupite. This results in increasing δ81Br values of later stage minerals that crystallise with comparable fractionation factors from a fluid with increasingly higher δ81Br values. |
format |
Text |
author |
Hans G. M. Eggenkamp Michael A. W. Marks Pascale Louvat Gregor Markl |
author_facet |
Hans G. M. Eggenkamp Michael A. W. Marks Pascale Louvat Gregor Markl |
author_sort |
Hans G. M. Eggenkamp |
title |
Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
title_short |
Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
title_full |
Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
title_fullStr |
Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
title_full_unstemmed |
Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite |
title_sort |
bromine isotope variations in magmatic and hydrothermal sodalite and tugtupite and the estimation of br isotope fractionation between melt and sodalite |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2021 |
url |
https://doi.org/10.3390/min11040370 |
op_coverage |
agris |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Minerals; Volume 11; Issue 4; Pages: 370 |
op_relation |
Mineral Geochemistry and Geochronology https://dx.doi.org/10.3390/min11040370 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/min11040370 |
container_title |
Minerals |
container_volume |
11 |
container_issue |
4 |
container_start_page |
370 |
_version_ |
1774718361813385216 |