Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada
This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by granitic and gneissic rocks of the Precambrian Canadian Shield. Strontium isotope ratios ( 87 Sr/ 86 Sr...
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crcansciencepubl:10.1139/e06-088 2024-06-23T07:51:29+00:00 Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada Lacelle, Denis Lauriol, Bernard Clark, Ian D 2007 http://dx.doi.org/10.1139/e06-088 http://www.nrcresearchpress.com/doi/pdf/10.1139/e06-088 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 44, issue 1, page 61-79 ISSN 0008-4077 1480-3313 journal-article 2007 crcansciencepubl https://doi.org/10.1139/e06-088 2024-05-24T13:05:49Z This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by granitic and gneissic rocks of the Precambrian Canadian Shield. Strontium isotope ratios ( 87 Sr/ 86 Sr) indicate that the major source of calcium is derived from the local dissolution of fracture-filling calcite and a minor source is derived from silicate weathering. The calcite crusts have δ 13 C values between 1.6 and 12.0 and δ 18 O values in the –13.0 and –7.9 range. These values are highly enriched over the predicted isotopic values based on the δ 13 C DIC and δ 18 O of the local water and temperature at which calcite precipitation occurred. The isotopic enrichments are attributed to a combination of both equilibrium and kinetic evaporation and were verified experimentally. The series of evaporative experiments indicate that kinetic evaporation produces a far-from-equilibrium isotope effect on both the δ 13 C and δ 18 O composition of the precipitating calcite ( 13 C KIE CaCO 3 –CO 2 between 20.2 and 40.5 VPDB; 18 O KIE averaging 34.9% ± 3.7% VSMOW). Based on these results, the formation of the calcite crusts is ascribed to the evaporation of stagnating ephemeral lakes and streams following the retreat of valley glaciers. Given the >1500 m difference in heights between the highland and the valley, the katabatic winds originating from the Penny Ice Cap can act as a catalyst to increase the rate of evaporation. In addition, radiocarbon dating of ten of these crusts yielded Holocene ages (7640 cal (calibrated) BP to modern). These results suggest that the maximum expansion of Holocene valley glacier in Akshayuk Pass, previously thought to have occurred during the Little Ice Age, is probably much older. Article in Journal/Newspaper Baffin Island Baffin Cumberland Peninsula glacier* Ice cap Penny Ice Cap Canadian Science Publishing Baffin Island Canada Cumberland Peninsula ENVELOPE(-64.497,-64.497,66.501,66.501) Penny Ice Cap ENVELOPE(-66.214,-66.214,67.284,67.284) Akshayuk Pass ENVELOPE(-65.131,-65.131,66.667,66.667) Canadian Journal of Earth Sciences 44 1 61 79 |
institution |
Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by granitic and gneissic rocks of the Precambrian Canadian Shield. Strontium isotope ratios ( 87 Sr/ 86 Sr) indicate that the major source of calcium is derived from the local dissolution of fracture-filling calcite and a minor source is derived from silicate weathering. The calcite crusts have δ 13 C values between 1.6 and 12.0 and δ 18 O values in the –13.0 and –7.9 range. These values are highly enriched over the predicted isotopic values based on the δ 13 C DIC and δ 18 O of the local water and temperature at which calcite precipitation occurred. The isotopic enrichments are attributed to a combination of both equilibrium and kinetic evaporation and were verified experimentally. The series of evaporative experiments indicate that kinetic evaporation produces a far-from-equilibrium isotope effect on both the δ 13 C and δ 18 O composition of the precipitating calcite ( 13 C KIE CaCO 3 –CO 2 between 20.2 and 40.5 VPDB; 18 O KIE averaging 34.9% ± 3.7% VSMOW). Based on these results, the formation of the calcite crusts is ascribed to the evaporation of stagnating ephemeral lakes and streams following the retreat of valley glaciers. Given the >1500 m difference in heights between the highland and the valley, the katabatic winds originating from the Penny Ice Cap can act as a catalyst to increase the rate of evaporation. In addition, radiocarbon dating of ten of these crusts yielded Holocene ages (7640 cal (calibrated) BP to modern). These results suggest that the maximum expansion of Holocene valley glacier in Akshayuk Pass, previously thought to have occurred during the Little Ice Age, is probably much older. |
format |
Article in Journal/Newspaper |
author |
Lacelle, Denis Lauriol, Bernard Clark, Ian D |
spellingShingle |
Lacelle, Denis Lauriol, Bernard Clark, Ian D Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
author_facet |
Lacelle, Denis Lauriol, Bernard Clark, Ian D |
author_sort |
Lacelle, Denis |
title |
Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
title_short |
Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
title_full |
Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
title_fullStr |
Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
title_full_unstemmed |
Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada |
title_sort |
origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, akshayuk pass, southern baffin island, canada |
publisher |
Canadian Science Publishing |
publishDate |
2007 |
url |
http://dx.doi.org/10.1139/e06-088 http://www.nrcresearchpress.com/doi/pdf/10.1139/e06-088 |
long_lat |
ENVELOPE(-64.497,-64.497,66.501,66.501) ENVELOPE(-66.214,-66.214,67.284,67.284) ENVELOPE(-65.131,-65.131,66.667,66.667) |
geographic |
Baffin Island Canada Cumberland Peninsula Penny Ice Cap Akshayuk Pass |
geographic_facet |
Baffin Island Canada Cumberland Peninsula Penny Ice Cap Akshayuk Pass |
genre |
Baffin Island Baffin Cumberland Peninsula glacier* Ice cap Penny Ice Cap |
genre_facet |
Baffin Island Baffin Cumberland Peninsula glacier* Ice cap Penny Ice Cap |
op_source |
Canadian Journal of Earth Sciences volume 44, issue 1, page 61-79 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e06-088 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
44 |
container_issue |
1 |
container_start_page |
61 |
op_container_end_page |
79 |
_version_ |
1802642597006540800 |