Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages
Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36Cl dates of primarily glacial and volcanic events on Jan Mayen. Calcu...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/508229 2023-05-15T16:52:34+02:00 Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages Anjar, Johanna Akçar, Naki Larsen, Eiliv A. Lysa, Astrid Marrero, Shasta Mozafari, Nasim Vockenhuber, Christof 2021-09 application/application/pdf https://hdl.handle.net/20.500.11850/508229 https://doi.org/10.3929/ethz-b-000508229 en eng MDPI info:eu-repo/semantics/altIdentifier/doi/10.3390/geosciences11090390 info:eu-repo/semantics/altIdentifier/wos/000700784300001 http://hdl.handle.net/20.500.11850/508229 doi:10.3929/ethz-b-000508229 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Geosciences, 11 (9) cosmogenic surface exposure dating 36Cl background production info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2021 ftethz https://doi.org/20.500.11850/508229 https://doi.org/10.3929/ethz-b-000508229 https://doi.org/10.3390/geosciences11090390 2022-04-25T14:35:01Z Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36Cl dates of primarily glacial and volcanic events on Jan Mayen. Calculations of sample exposure ages were complicated by young exposure ages, young rock formation age, and high native Cl contents, leading to updates in CRONUScalc to enable accurate exposure age calculations. The samples provide good evidence against an equilibrium assumption when subtracting background production (e.g., 36Cl produced by neutron capture from fission of U or Th) for samples on young bedrock, with younger exposure ages most significantly affected. Exposure ages were calculated with a range of assumptions of bedrock formation ages appropriate for Jan Mayen, including the assumption that the rock formation age equaled the exposure age (i.e., the youngest age it could possibly have), and we found that although the effect on most of the ages was small, the calculated ages of 25 of the samples increased by more than 1 standard deviation from the age calculated assuming equilibrium background production, with a maximum deviation of 6.1 ka. Due to the very young bedrock on Jan Mayen, we consider the nonequilibrium ages to be the most reliable ages from the island and conclude that large-scale deglaciation on the south and central, lower-lying, parts of the island, started around 20 ka and lasted until ~7 ka. On northern Jan Mayen, the slopes of the 2277 m high stratovolcano Beerenberg are currently partly glaciated; however, outside of the Little Ice Age moraines, all but two samples give ages between 14 and 5.7 ka. ISSN:2076-3263 Article in Journal/Newspaper Iceland Jan Mayen North Atlantic ETH Zürich Research Collection Jan Mayen Beerenberg ENVELOPE(-8.167,-8.167,71.083,71.083) |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
cosmogenic surface exposure dating 36Cl background production |
spellingShingle |
cosmogenic surface exposure dating 36Cl background production Anjar, Johanna Akçar, Naki Larsen, Eiliv A. Lysa, Astrid Marrero, Shasta Mozafari, Nasim Vockenhuber, Christof Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
topic_facet |
cosmogenic surface exposure dating 36Cl background production |
description |
Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36Cl dates of primarily glacial and volcanic events on Jan Mayen. Calculations of sample exposure ages were complicated by young exposure ages, young rock formation age, and high native Cl contents, leading to updates in CRONUScalc to enable accurate exposure age calculations. The samples provide good evidence against an equilibrium assumption when subtracting background production (e.g., 36Cl produced by neutron capture from fission of U or Th) for samples on young bedrock, with younger exposure ages most significantly affected. Exposure ages were calculated with a range of assumptions of bedrock formation ages appropriate for Jan Mayen, including the assumption that the rock formation age equaled the exposure age (i.e., the youngest age it could possibly have), and we found that although the effect on most of the ages was small, the calculated ages of 25 of the samples increased by more than 1 standard deviation from the age calculated assuming equilibrium background production, with a maximum deviation of 6.1 ka. Due to the very young bedrock on Jan Mayen, we consider the nonequilibrium ages to be the most reliable ages from the island and conclude that large-scale deglaciation on the south and central, lower-lying, parts of the island, started around 20 ka and lasted until ~7 ka. On northern Jan Mayen, the slopes of the 2277 m high stratovolcano Beerenberg are currently partly glaciated; however, outside of the Little Ice Age moraines, all but two samples give ages between 14 and 5.7 ka. ISSN:2076-3263 |
format |
Article in Journal/Newspaper |
author |
Anjar, Johanna Akçar, Naki Larsen, Eiliv A. Lysa, Astrid Marrero, Shasta Mozafari, Nasim Vockenhuber, Christof |
author_facet |
Anjar, Johanna Akçar, Naki Larsen, Eiliv A. Lysa, Astrid Marrero, Shasta Mozafari, Nasim Vockenhuber, Christof |
author_sort |
Anjar, Johanna |
title |
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
title_short |
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
title_full |
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
title_fullStr |
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
title_full_unstemmed |
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages |
title_sort |
cosmogenic exposure dating (36cl) of landforms on jan mayen, north atlantic, and the effects of bedrock formation age assumptions on 36cl ages |
publisher |
MDPI |
publishDate |
2021 |
url |
https://hdl.handle.net/20.500.11850/508229 https://doi.org/10.3929/ethz-b-000508229 |
long_lat |
ENVELOPE(-8.167,-8.167,71.083,71.083) |
geographic |
Jan Mayen Beerenberg |
geographic_facet |
Jan Mayen Beerenberg |
genre |
Iceland Jan Mayen North Atlantic |
genre_facet |
Iceland Jan Mayen North Atlantic |
op_source |
Geosciences, 11 (9) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.3390/geosciences11090390 info:eu-repo/semantics/altIdentifier/wos/000700784300001 http://hdl.handle.net/20.500.11850/508229 doi:10.3929/ethz-b-000508229 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/508229 https://doi.org/10.3929/ethz-b-000508229 https://doi.org/10.3390/geosciences11090390 |
_version_ |
1766042941413916672 |