Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland
Pressurised meltwater has a major impact on ice dynamics, as well as on sedimentary and deformational processes occurring below/in front of glaciers and ice sheets, but its role in glaciotectonic processes is yet to be fully understood. This study explores micro- and macroscale structures developed...
Published in: | Quaternary Research |
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Cambridge University Press
2020
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ftnerc:oai:nora.nerc.ac.uk:526051 2023-05-15T16:47:58+02:00 Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland Sigfúsdóttir, Thorbjörg Phillips, Emrys Benediktsson, Ívar Örn 2020-01 text http://nora.nerc.ac.uk/id/eprint/526051/ https://nora.nerc.ac.uk/id/eprint/526051/1/QR-S-19-00014%282%293.pdf https://doi.org/10.1017/qua.2019.48 en eng Cambridge University Press https://nora.nerc.ac.uk/id/eprint/526051/1/QR-S-19-00014%282%293.pdf Sigfúsdóttir, Thorbjörg; Phillips, Emrys; Benediktsson, Ívar Örn. 2020 Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland. Quaternary Research, 93 (1). 88-109. https://doi.org/10.1017/qua.2019.48 <https://doi.org/10.1017/qua.2019.48> Publication - Article PeerReviewed 2020 ftnerc https://doi.org/10.1017/qua.2019.48 2023-02-04T19:49:43Z Pressurised meltwater has a major impact on ice dynamics, as well as on sedimentary and deformational processes occurring below/in front of glaciers and ice sheets, but its role in glaciotectonic processes is yet to be fully understood. This study explores micro- and macroscale structures developed within décollements in two thrust-block moraines of Late Weichselian age in Melasveit, western Iceland. The aim is to investigate how pressurised subglacial meltwater can aid the dislocation and transport of large, unfrozen and unlithified sediment blocks by glaciers. A detailed model is constructed for the development of the thrust-block moraines and the microscale processes occurring along their detachments during thrusting. The detachments are characterized by relatively thin zones of crosscutting hydrofractures, which reflect fluctuating water pressures during glaciotectonism. Little evidence of shearing is observed along the leading edges of the thrusts in both moraines. This is supported by high water pressures along the detachments and indicates that the thrust blocks were initially decoupled from the underlying deposits. As the thrust moraines evolved, an increased amount of shear occurred in between events of sediment liquefaction, hydrofracturing, and fluid escape. This was followed by progressive locking up of the detachments and eventual cessation in the accretion of the thrust blocks. Article in Journal/Newspaper Iceland Natural Environment Research Council: NERC Open Research Archive Quaternary Research 93 88 109 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
Pressurised meltwater has a major impact on ice dynamics, as well as on sedimentary and deformational processes occurring below/in front of glaciers and ice sheets, but its role in glaciotectonic processes is yet to be fully understood. This study explores micro- and macroscale structures developed within décollements in two thrust-block moraines of Late Weichselian age in Melasveit, western Iceland. The aim is to investigate how pressurised subglacial meltwater can aid the dislocation and transport of large, unfrozen and unlithified sediment blocks by glaciers. A detailed model is constructed for the development of the thrust-block moraines and the microscale processes occurring along their detachments during thrusting. The detachments are characterized by relatively thin zones of crosscutting hydrofractures, which reflect fluctuating water pressures during glaciotectonism. Little evidence of shearing is observed along the leading edges of the thrusts in both moraines. This is supported by high water pressures along the detachments and indicates that the thrust blocks were initially decoupled from the underlying deposits. As the thrust moraines evolved, an increased amount of shear occurred in between events of sediment liquefaction, hydrofracturing, and fluid escape. This was followed by progressive locking up of the detachments and eventual cessation in the accretion of the thrust blocks. |
format |
Article in Journal/Newspaper |
author |
Sigfúsdóttir, Thorbjörg Phillips, Emrys Benediktsson, Ívar Örn |
spellingShingle |
Sigfúsdóttir, Thorbjörg Phillips, Emrys Benediktsson, Ívar Örn Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
author_facet |
Sigfúsdóttir, Thorbjörg Phillips, Emrys Benediktsson, Ívar Örn |
author_sort |
Sigfúsdóttir, Thorbjörg |
title |
Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
title_short |
Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
title_full |
Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
title_fullStr |
Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
title_full_unstemmed |
Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland |
title_sort |
micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in melasveit, western iceland |
publisher |
Cambridge University Press |
publishDate |
2020 |
url |
http://nora.nerc.ac.uk/id/eprint/526051/ https://nora.nerc.ac.uk/id/eprint/526051/1/QR-S-19-00014%282%293.pdf https://doi.org/10.1017/qua.2019.48 |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
https://nora.nerc.ac.uk/id/eprint/526051/1/QR-S-19-00014%282%293.pdf Sigfúsdóttir, Thorbjörg; Phillips, Emrys; Benediktsson, Ívar Örn. 2020 Micromorphological evidence for the role of pressurised water in the formation of large-scale thrust-block moraines in Melasveit, western Iceland. Quaternary Research, 93 (1). 88-109. https://doi.org/10.1017/qua.2019.48 <https://doi.org/10.1017/qua.2019.48> |
op_doi |
https://doi.org/10.1017/qua.2019.48 |
container_title |
Quaternary Research |
container_volume |
93 |
container_start_page |
88 |
op_container_end_page |
109 |
_version_ |
1766038064853942272 |