Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions
Abstract We employed a commercial wireline drill rig to investigate the subglacial conditions of Black Rapids Glacier, a well-studied surge-type glacier in the central Alaska Range. The four main goals were: to assess the capabilities of the commercial drilling industry for sampling subglacial mater...
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Cambridge University Press (CUP)
1999
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Online Access: | http://dx.doi.org/10.1017/s0022143000001350 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001350 |
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crcambridgeupr:10.1017/s0022143000001350 2024-06-23T07:45:03+00:00 Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions Truffer, M. Motyka, R.J. Harrison, W.D. Echelmeyer, K. A. Fisk, B. Tulaczyk, S. 1999 http://dx.doi.org/10.1017/s0022143000001350 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001350 en eng Cambridge University Press (CUP) Journal of Glaciology volume 45, issue 151, page 495-505 ISSN 0022-1430 1727-5652 journal-article 1999 crcambridgeupr https://doi.org/10.1017/s0022143000001350 2024-06-05T04:04:38Z Abstract We employed a commercial wireline drill rig to investigate the subglacial conditions of Black Rapids Glacier, a well-studied surge-type glacier in the central Alaska Range. The four main goals were: to assess the capabilities of the commercial drilling industry for sampling subglacial material, to investigate the basal morphology, to determine the subglacial geology and to emplace borehole instruments. The drilling was done in an area where seasonal and secular variations in speed are large, and where seismic studies suggested the presence of a till layer. Four holes were drilled at three locations to a maximum depth of 620 m. Three holes yielded samples of basal ice and till, although recovery of the latter was generally poor. Bedrock was sampled in one or possibly two of the holes. In the area sampled, t he glacier is underlain by a till layer some 4–7 m thick, confirming the seismic interpretation. It consists of a sandy matrix at least 20–30% of which comprises larger clasts. Limited samples of the matrix indicate that near the top of the till the porosity is 40%, and t hat some of the pore water is frozen. Geologic studies suggest that the drilling area lies to the north of the Denali Fault, a major tectonic boundary followed by the glacier, and that most of the till is locally derived with transport distances of <2 km. Article in Journal/Newspaper alaska range glacier Journal of Glaciology Alaska Cambridge University Press Journal of Glaciology 45 151 495 505 |
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Open Polar |
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Cambridge University Press |
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English |
description |
Abstract We employed a commercial wireline drill rig to investigate the subglacial conditions of Black Rapids Glacier, a well-studied surge-type glacier in the central Alaska Range. The four main goals were: to assess the capabilities of the commercial drilling industry for sampling subglacial material, to investigate the basal morphology, to determine the subglacial geology and to emplace borehole instruments. The drilling was done in an area where seasonal and secular variations in speed are large, and where seismic studies suggested the presence of a till layer. Four holes were drilled at three locations to a maximum depth of 620 m. Three holes yielded samples of basal ice and till, although recovery of the latter was generally poor. Bedrock was sampled in one or possibly two of the holes. In the area sampled, t he glacier is underlain by a till layer some 4–7 m thick, confirming the seismic interpretation. It consists of a sandy matrix at least 20–30% of which comprises larger clasts. Limited samples of the matrix indicate that near the top of the till the porosity is 40%, and t hat some of the pore water is frozen. Geologic studies suggest that the drilling area lies to the north of the Denali Fault, a major tectonic boundary followed by the glacier, and that most of the till is locally derived with transport distances of <2 km. |
format |
Article in Journal/Newspaper |
author |
Truffer, M. Motyka, R.J. Harrison, W.D. Echelmeyer, K. A. Fisk, B. Tulaczyk, S. |
spellingShingle |
Truffer, M. Motyka, R.J. Harrison, W.D. Echelmeyer, K. A. Fisk, B. Tulaczyk, S. Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
author_facet |
Truffer, M. Motyka, R.J. Harrison, W.D. Echelmeyer, K. A. Fisk, B. Tulaczyk, S. |
author_sort |
Truffer, M. |
title |
Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
title_short |
Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
title_full |
Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
title_fullStr |
Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
title_full_unstemmed |
Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions |
title_sort |
subglacial drilling at black rapids glacier, alaska, u.s.a.: drilling method and sample descriptions |
publisher |
Cambridge University Press (CUP) |
publishDate |
1999 |
url |
http://dx.doi.org/10.1017/s0022143000001350 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001350 |
genre |
alaska range glacier Journal of Glaciology Alaska |
genre_facet |
alaska range glacier Journal of Glaciology Alaska |
op_source |
Journal of Glaciology volume 45, issue 151, page 495-505 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000001350 |
container_title |
Journal of Glaciology |
container_volume |
45 |
container_issue |
151 |
container_start_page |
495 |
op_container_end_page |
505 |
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1802650439834927104 |