The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway
Abstract We quantify the magnitude of millennial-scale glacial erosion at Engabreen, a temperate glacier in coastal northern Norway, using the in situ cosmogenic nuclides carbon-14 ( 14 C) and beryllium-10 ( 10 Be) in bedrock exposed recently by glacial retreat. Nuclide concentrations show no depend...
Published in: | Annals of Glaciology |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
2019
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/aog.2019.42 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000429 |
id |
crcambridgeupr:10.1017/aog.2019.42 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/aog.2019.42 2024-06-09T07:38:29+00:00 The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway Rand, Cari Goehring, Brent M. 2019 http://dx.doi.org/10.1017/aog.2019.42 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000429 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Annals of Glaciology volume 60, issue 80, page 73-81 ISSN 0260-3055 1727-5644 journal-article 2019 crcambridgeupr https://doi.org/10.1017/aog.2019.42 2024-05-15T13:04:13Z Abstract We quantify the magnitude of millennial-scale glacial erosion at Engabreen, a temperate glacier in coastal northern Norway, using the in situ cosmogenic nuclides carbon-14 ( 14 C) and beryllium-10 ( 10 Be) in bedrock exposed recently by glacial retreat. Nuclide concentrations show no dependence on distance down or across the valley. As such, resulting Holocene erosion depths along two transects perpendicular to glacier flow are highly variable with no systematic distribution, ranging from 0.10 to 2.95 m. We observed 14 C– 10 Be ratios elevated above the production ratio in samples of abraded bedrock, which is counter to the expectation for surfaces covered during the Holocene and exposed only recently. Muon reactions produce nuclides at greater depths than do spallation reactions and 14 C at production rates at higher than those of 10 Be, resulting in 14 C– 10 Be ratios that increase with depth. Therefore, elevated 14 C– 10 Be ratios indicate that sampled sites were deeply plucked during recent cover, the Little Ice Age in this case, and then rapidly abraded prior to retreat. Our results suggest that, while glacial erosion can generate a u-shaped valley profile over long periods of time (e.g., 10 5 –10 7 years), the discontinuous nature of glacial plucking produces spatially variable patterns of erosion over shorter millennial timescales. Article in Journal/Newspaper Annals of Glaciology glacier Northern Norway Cambridge University Press Engabreen ENVELOPE(13.771,13.771,66.682,66.682) Norway Annals of Glaciology 60 80 73 81 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract We quantify the magnitude of millennial-scale glacial erosion at Engabreen, a temperate glacier in coastal northern Norway, using the in situ cosmogenic nuclides carbon-14 ( 14 C) and beryllium-10 ( 10 Be) in bedrock exposed recently by glacial retreat. Nuclide concentrations show no dependence on distance down or across the valley. As such, resulting Holocene erosion depths along two transects perpendicular to glacier flow are highly variable with no systematic distribution, ranging from 0.10 to 2.95 m. We observed 14 C– 10 Be ratios elevated above the production ratio in samples of abraded bedrock, which is counter to the expectation for surfaces covered during the Holocene and exposed only recently. Muon reactions produce nuclides at greater depths than do spallation reactions and 14 C at production rates at higher than those of 10 Be, resulting in 14 C– 10 Be ratios that increase with depth. Therefore, elevated 14 C– 10 Be ratios indicate that sampled sites were deeply plucked during recent cover, the Little Ice Age in this case, and then rapidly abraded prior to retreat. Our results suggest that, while glacial erosion can generate a u-shaped valley profile over long periods of time (e.g., 10 5 –10 7 years), the discontinuous nature of glacial plucking produces spatially variable patterns of erosion over shorter millennial timescales. |
format |
Article in Journal/Newspaper |
author |
Rand, Cari Goehring, Brent M. |
spellingShingle |
Rand, Cari Goehring, Brent M. The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
author_facet |
Rand, Cari Goehring, Brent M. |
author_sort |
Rand, Cari |
title |
The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
title_short |
The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
title_full |
The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
title_fullStr |
The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
title_full_unstemmed |
The distribution and magnitude of subglacial erosion on millennial timescales at Engabreen, Norway |
title_sort |
distribution and magnitude of subglacial erosion on millennial timescales at engabreen, norway |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/aog.2019.42 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000429 |
long_lat |
ENVELOPE(13.771,13.771,66.682,66.682) |
geographic |
Engabreen Norway |
geographic_facet |
Engabreen Norway |
genre |
Annals of Glaciology glacier Northern Norway |
genre_facet |
Annals of Glaciology glacier Northern Norway |
op_source |
Annals of Glaciology volume 60, issue 80, page 73-81 ISSN 0260-3055 1727-5644 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/aog.2019.42 |
container_title |
Annals of Glaciology |
container_volume |
60 |
container_issue |
80 |
container_start_page |
73 |
op_container_end_page |
81 |
_version_ |
1801373200415719424 |