Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl 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 36 Cl dates of primarily glacial and volcanic events on Jan Mayen. Calc...
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ftdoajarticles:oai:doaj.org/article:77999da66f1243c8b80ce4963f4144e9 2023-05-15T16:52:20+02:00 Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages Johanna Anjar Naki Akҫar Eiliv A. Larsen Astrid Lyså Shasta Marrero Nasim Mozafari Christof Vockenhuber 2021-09-01T00:00:00Z https://doi.org/10.3390/geosciences11090390 https://doaj.org/article/77999da66f1243c8b80ce4963f4144e9 EN eng MDPI AG https://www.mdpi.com/2076-3263/11/9/390 https://doaj.org/toc/2076-3263 doi:10.3390/geosciences11090390 2076-3263 https://doaj.org/article/77999da66f1243c8b80ce4963f4144e9 Geosciences, Vol 11, Iss 390, p 390 (2021) cosmogenic surface exposure dating 36 Cl Jan Mayen background production Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.3390/geosciences11090390 2022-12-31T04:23:16Z 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 36 Cl 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., 36 Cl 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. Article in Journal/Newspaper Iceland Jan Mayen North Atlantic Directory of Open Access Journals: DOAJ Articles Jan Mayen Beerenberg ENVELOPE(-8.167,-8.167,71.083,71.083) Geosciences 11 9 390 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
cosmogenic surface exposure dating 36 Cl Jan Mayen background production Geology QE1-996.5 |
spellingShingle |
cosmogenic surface exposure dating 36 Cl Jan Mayen background production Geology QE1-996.5 Johanna Anjar Naki Akҫar Eiliv A. Larsen Astrid Lyså Shasta Marrero Nasim Mozafari Christof Vockenhuber Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
topic_facet |
cosmogenic surface exposure dating 36 Cl Jan Mayen background production Geology QE1-996.5 |
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 36 Cl 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., 36 Cl 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. |
format |
Article in Journal/Newspaper |
author |
Johanna Anjar Naki Akҫar Eiliv A. Larsen Astrid Lyså Shasta Marrero Nasim Mozafari Christof Vockenhuber |
author_facet |
Johanna Anjar Naki Akҫar Eiliv A. Larsen Astrid Lyså Shasta Marrero Nasim Mozafari Christof Vockenhuber |
author_sort |
Johanna Anjar |
title |
Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
title_short |
Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
title_full |
Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
title_fullStr |
Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
title_full_unstemmed |
Cosmogenic Exposure Dating ( 36 Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36 Cl Ages |
title_sort |
cosmogenic exposure dating ( 36 cl) of landforms on jan mayen, north atlantic, and the effects of bedrock formation age assumptions on 36 cl ages |
publisher |
MDPI AG |
publishDate |
2021 |
url |
https://doi.org/10.3390/geosciences11090390 https://doaj.org/article/77999da66f1243c8b80ce4963f4144e9 |
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, Vol 11, Iss 390, p 390 (2021) |
op_relation |
https://www.mdpi.com/2076-3263/11/9/390 https://doaj.org/toc/2076-3263 doi:10.3390/geosciences11090390 2076-3263 https://doaj.org/article/77999da66f1243c8b80ce4963f4144e9 |
op_doi |
https://doi.org/10.3390/geosciences11090390 |
container_title |
Geosciences |
container_volume |
11 |
container_issue |
9 |
container_start_page |
390 |
_version_ |
1766042466516992000 |