Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland

Understanding patterns of geothermal and volcanic activity at many of Iceland's most active volcanic systems is hampered by thick overlying ice, which prevents direct observation and complicates interpretation of geophysical signals. Katla is a prime example, being a large and restless volcanic...

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Published in:Chemical Geology
Main Authors: Wynn, Peter M., Morrell, David J., Tuffen, Hugh, Barker, Philip, TWEED, Fiona, Burns, Rebecca
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2015
Subjects:
Online Access:http://eprints.staffs.ac.uk/2533/
https://eprints.staffs.ac.uk/2533/1/Wynn%20et%20al.,%202015.pdf
https://eprints.staffs.ac.uk/2533/7/Manuscript%20R2.docx
https://doi.org/10.1016/j.chemgeo.2014.12.026
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spelling ftustaffordshire:oai:eprints.staffs.ac.uk:2533 2023-05-15T15:13:04+02:00 Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland Wynn, Peter M. Morrell, David J. Tuffen, Hugh Barker, Philip TWEED, Fiona Burns, Rebecca 2015-03-09 text http://eprints.staffs.ac.uk/2533/ https://eprints.staffs.ac.uk/2533/1/Wynn%20et%20al.,%202015.pdf https://eprints.staffs.ac.uk/2533/7/Manuscript%20R2.docx https://doi.org/10.1016/j.chemgeo.2014.12.026 en eng Elsevier https://eprints.staffs.ac.uk/2533/1/Wynn%20et%20al.,%202015.pdf https://eprints.staffs.ac.uk/2533/7/Manuscript%20R2.docx Wynn, Peter M., Morrell, David J., Tuffen, Hugh, Barker, Philip, TWEED, Fiona and Burns, Rebecca (2015) Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland. Chemical Geology, 396. pp. 228-238. ISSN 00092541 cc_by cc_by_nc_nd CC-BY CC-BY-NC-ND Article PeerReviewed 2015 ftustaffordshire https://doi.org/10.1016/j.chemgeo.2014.12.026 2023-03-02T23:14:51Z Understanding patterns of geothermal and volcanic activity at many of Iceland's most active volcanic systems is hampered by thick overlying ice, which prevents direct observation and complicates interpretation of geophysical signals. Katla is a prime example, being a large and restless volcanic system covered by the 740 m thick Mýrdalsjökull ice cap, whose eruptions have triggered some of the most powerful known meltwater floods in historical times. To shed new light on geothermal and subglacial hydrological processes at Katla, we have determined the sulphate isotopic composition of a series of glacial meltwater samples discharged fromSólheimajökull, a valley glacier of Mýrdalsjökull, between 2009 and 2012. Dual isotopic analysis of δ34S and δ18O in dissolved sulphate allows identification of source mixing processes and chemical evolution during subglacial meltwater transport. Strikingly, meltwater δ18OSO4 signatures indicate redox conditions at the glacier bed, which are inverse to those normally encountered at Arctic and Alpine glaciers. Discharge of reduced, anoxic meltwater in summer, rather thanwinter, points towards seasonal release of geothermally derived volatile gases. Weattribute this to headward expansion of the channelized subglacial drainage system during the summer melt season, accessing key areas of geothermal activity within the Katla caldera. Volatile release may be further enhanced by unloading of overburden pressure due to snowpack melting in the summer season. In winter, restriction of subglacial channels to lower elevations effectively seals geothermal fluids and dissolved gases beneath the ice cap, with only sporadic release permitted by periodic increases in subglacialwater pressure.When the subglacial drainage configuration permits access to key geothermal areas, sulphate isotopic signatures thereby form sensitive indicators of geothermal activity occurring deep beneath the Mýrdalsjökull ice cap. Article in Journal/Newspaper Arctic glacier Ice cap Iceland Katla Mýrdalsjökull Staffordshire University: STORE - Staffordshire Online Repository Arctic Katla ENVELOPE(-19.062,-19.062,63.631,63.631) Mýrdalsjökull ENVELOPE(-19.174,-19.174,63.643,63.643) Sólheimajökull ENVELOPE(-19.303,-19.303,63.557,63.557) Chemical Geology 396 228 238
institution Open Polar
collection Staffordshire University: STORE - Staffordshire Online Repository
op_collection_id ftustaffordshire
language English
description Understanding patterns of geothermal and volcanic activity at many of Iceland's most active volcanic systems is hampered by thick overlying ice, which prevents direct observation and complicates interpretation of geophysical signals. Katla is a prime example, being a large and restless volcanic system covered by the 740 m thick Mýrdalsjökull ice cap, whose eruptions have triggered some of the most powerful known meltwater floods in historical times. To shed new light on geothermal and subglacial hydrological processes at Katla, we have determined the sulphate isotopic composition of a series of glacial meltwater samples discharged fromSólheimajökull, a valley glacier of Mýrdalsjökull, between 2009 and 2012. Dual isotopic analysis of δ34S and δ18O in dissolved sulphate allows identification of source mixing processes and chemical evolution during subglacial meltwater transport. Strikingly, meltwater δ18OSO4 signatures indicate redox conditions at the glacier bed, which are inverse to those normally encountered at Arctic and Alpine glaciers. Discharge of reduced, anoxic meltwater in summer, rather thanwinter, points towards seasonal release of geothermally derived volatile gases. Weattribute this to headward expansion of the channelized subglacial drainage system during the summer melt season, accessing key areas of geothermal activity within the Katla caldera. Volatile release may be further enhanced by unloading of overburden pressure due to snowpack melting in the summer season. In winter, restriction of subglacial channels to lower elevations effectively seals geothermal fluids and dissolved gases beneath the ice cap, with only sporadic release permitted by periodic increases in subglacialwater pressure.When the subglacial drainage configuration permits access to key geothermal areas, sulphate isotopic signatures thereby form sensitive indicators of geothermal activity occurring deep beneath the Mýrdalsjökull ice cap.
format Article in Journal/Newspaper
author Wynn, Peter M.
Morrell, David J.
Tuffen, Hugh
Barker, Philip
TWEED, Fiona
Burns, Rebecca
spellingShingle Wynn, Peter M.
Morrell, David J.
Tuffen, Hugh
Barker, Philip
TWEED, Fiona
Burns, Rebecca
Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
author_facet Wynn, Peter M.
Morrell, David J.
Tuffen, Hugh
Barker, Philip
TWEED, Fiona
Burns, Rebecca
author_sort Wynn, Peter M.
title Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
title_short Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
title_full Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
title_fullStr Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
title_full_unstemmed Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland
title_sort seasonal release of anoxic geothermal meltwater from the katla volcanic system at sólheimajökull, iceland
publisher Elsevier
publishDate 2015
url http://eprints.staffs.ac.uk/2533/
https://eprints.staffs.ac.uk/2533/1/Wynn%20et%20al.,%202015.pdf
https://eprints.staffs.ac.uk/2533/7/Manuscript%20R2.docx
https://doi.org/10.1016/j.chemgeo.2014.12.026
long_lat ENVELOPE(-19.062,-19.062,63.631,63.631)
ENVELOPE(-19.174,-19.174,63.643,63.643)
ENVELOPE(-19.303,-19.303,63.557,63.557)
geographic Arctic
Katla
Mýrdalsjökull
Sólheimajökull
geographic_facet Arctic
Katla
Mýrdalsjökull
Sólheimajökull
genre Arctic
glacier
Ice cap
Iceland
Katla
Mýrdalsjökull
genre_facet Arctic
glacier
Ice cap
Iceland
Katla
Mýrdalsjökull
op_relation https://eprints.staffs.ac.uk/2533/1/Wynn%20et%20al.,%202015.pdf
https://eprints.staffs.ac.uk/2533/7/Manuscript%20R2.docx
Wynn, Peter M., Morrell, David J., Tuffen, Hugh, Barker, Philip, TWEED, Fiona and Burns, Rebecca (2015) Seasonal release of anoxic geothermal meltwater from the Katla volcanic system at Sólheimajökull, Iceland. Chemical Geology, 396. pp. 228-238. ISSN 00092541
op_rights cc_by
cc_by_nc_nd
op_rightsnorm CC-BY
CC-BY-NC-ND
op_doi https://doi.org/10.1016/j.chemgeo.2014.12.026
container_title Chemical Geology
container_volume 396
container_start_page 228
op_container_end_page 238
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