Micro-Fourier Transform Infrared (FT-IR) and ?D value investigation of hydrothermal vein quartz: interpretation of fluid inclusion ?D values in hydrothermal systems
Micro-Fourier Transform Infrared (FT-IR) and ?D value investigation of hydrothermal vein quartz: interpretation of fluid inclusion ?D values in hydrothermal systems
Some recent studies have suggested that the hydrogen isotopic composition (?D) of hydrothermal fluids, released in vacuo by thermal decrepitation of quartz, are not always accurately revealed. We report the results of a step-heating ?D value study of vein quartz, hosted by Lower Palaeozoic rocks in SW England, which was analyzed by micro-FT-IR for hydrogen speciation, before and after fluid extraction at temperatures between 750 and 1500 °C. The ?D values of individual aliquots of released water vary between ?3‰ and ?208‰, with the lowest values generally corresponding to the highest temperature fractions and samples of relatively low yield. The data show significant departures from geologically reasonable ?D. Micro-FT-IR analyses show that a variety of OH species are present within the vein quartz, with significant intra and inter sample variation. Typically a broad absorption due to molecular water, in the region 3400 cm?1 is observed, along with bands attributed to Li–OH and Al–OH. On heating, the broad absorption due to molecular water is reduced, accompanied by a measurable loss of Li–OH species. The latter becomes more pronounced in the higher temperature fractions (>750 °C). These data support earlier studies which indicated that contributions from the contrasting OH reservoirs in quartz can significantly influence the reported ?D values. These new data also suggest that the incorporation of OH released from Li–OH sites in the quartz may be the most important factor in the generation of the anomalous values for these samples.
4595-4606
Gleeson, S.A.
e88ff5fe-291e-4687-9065-302484db9a88
Roberts, S.
f095c7ab-a37b-4064-8a41-ae4820832856
Fallick, A.E.
5b1b907f-57fc-43cc-9a9f-5b9fa80c313b
Boyce, A.J.
4c7d549e-ca7d-4bed-89b6-a7364513d130
15 September 2008
Gleeson, S.A.
e88ff5fe-291e-4687-9065-302484db9a88
Roberts, S.
f095c7ab-a37b-4064-8a41-ae4820832856
Fallick, A.E.
5b1b907f-57fc-43cc-9a9f-5b9fa80c313b
Boyce, A.J.
4c7d549e-ca7d-4bed-89b6-a7364513d130
Gleeson, S.A., Roberts, S., Fallick, A.E. and Boyce, A.J.
(2008)
Micro-Fourier Transform Infrared (FT-IR) and ?D value investigation of hydrothermal vein quartz: interpretation of fluid inclusion ?D values in hydrothermal systems.
Geochimica et Cosmochimica Acta, 72 (18), .
(doi:10.1016/j.gca.2008.06.014).
Abstract
Some recent studies have suggested that the hydrogen isotopic composition (?D) of hydrothermal fluids, released in vacuo by thermal decrepitation of quartz, are not always accurately revealed. We report the results of a step-heating ?D value study of vein quartz, hosted by Lower Palaeozoic rocks in SW England, which was analyzed by micro-FT-IR for hydrogen speciation, before and after fluid extraction at temperatures between 750 and 1500 °C. The ?D values of individual aliquots of released water vary between ?3‰ and ?208‰, with the lowest values generally corresponding to the highest temperature fractions and samples of relatively low yield. The data show significant departures from geologically reasonable ?D. Micro-FT-IR analyses show that a variety of OH species are present within the vein quartz, with significant intra and inter sample variation. Typically a broad absorption due to molecular water, in the region 3400 cm?1 is observed, along with bands attributed to Li–OH and Al–OH. On heating, the broad absorption due to molecular water is reduced, accompanied by a measurable loss of Li–OH species. The latter becomes more pronounced in the higher temperature fractions (>750 °C). These data support earlier studies which indicated that contributions from the contrasting OH reservoirs in quartz can significantly influence the reported ?D values. These new data also suggest that the incorporation of OH released from Li–OH sites in the quartz may be the most important factor in the generation of the anomalous values for these samples.
This record has no associated files available for download.
More information
Published date: 15 September 2008
Identifiers
Local EPrints ID: 63239
URI: http://eprints.soton.ac.uk/id/eprint/63239
ISSN: 0016-7037
PURE UUID: ac82529d-e262-4701-85d1-70b88a76850c
Catalogue record
Date deposited: 22 Sep 2008
Last modified: 16 Mar 2024 02:37
Export record
Altmetrics
Contributors
Author:
S.A. Gleeson
Author:
A.E. Fallick
Author:
A.J. Boyce
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
