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...
Published in: | Chemical Geology |
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Language: | English |
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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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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 |
_version_ |
1766343667041173504 |