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Weathering processes, catchment geology and river management impacts on radiogenic ( 87 Sr/ 86 Sr) and stable (δ 88/86 Sr) strontium isotope compositions of Canadian boreal rivers

Weathering processes, catchment geology and river management impacts on radiogenic ( 87 Sr/ 86 Sr) and stable (δ 88/86 Sr) strontium isotope compositions of Canadian boreal rivers
Weathering processes, catchment geology and river management impacts on radiogenic ( 87 Sr/ 86 Sr) and stable (δ 88/86 Sr) strontium isotope compositions of Canadian boreal rivers
Radiogenic (87Sr/86Sr) and stable (δ88/86Sr) strontium isotope compositions spanning a calendar year are reported for rivers from across subarctic Canada that drain contrasting lithologies ranging from Precambrian bedrock (Koksoak, Great Whale and La Grande rivers of Northern Quebec) to carbonate and clastic Phanerozoic sedimentary rocks of the Western Interior Platform (Nelson River, of central and western Canada). The 87Sr/86Sr isotopic compositions of the river waters reflect the underlying geology, with rivers draining the Precambrian Shield having higher 87Sr/86Sr ratios (0.727–0.734) than the Phanerozoic dominated Nelson River (0.713). The stable strontium isotope values (δ88/86Sr) range from 0.26 to 0.39‰, with the values for the Nelson River overlapping those of the other three. Rivers that have not been developed for hydroelectric power show a seasonal variation in the 87Sr/86Sr ratios, whereas those that have been diverted or dammed show little or no seasonal variation due to increased residence time of their water in hydroelectric reservoirs. The three rivers from Northern Quebec show discrete ranges in their 87Sr/86Sr and δ88/86Sr isotope compositions that correlate with the Ca/Sr and Na/Sr ratios of the river water. These correlations are interpreted to reflect differential chemical weathering of felsic versus mafic source rocks and/or of surficial sediment vs bedrock sources.
0009-2541
50-60
Stevenson, Ross
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Pearce, Christopher R.
c83b6228-0b64-4f5a-a8ad-e5cd33a11de3
Rosa, Eric
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Hélie, Jean-françois
cebb284d-8469-46e0-ac7b-27355005b580
Hillaire-marcel, Claude
9d5b7d2a-efa3-4f18-9387-f9e40208acab
Stevenson, Ross
ff043493-81af-4a8a-ad3c-c62d5ce32192
Pearce, Christopher R.
c83b6228-0b64-4f5a-a8ad-e5cd33a11de3
Rosa, Eric
3b100d43-4f4b-4dcc-bd91-1c1a0c3e3001
Hélie, Jean-françois
cebb284d-8469-46e0-ac7b-27355005b580
Hillaire-marcel, Claude
9d5b7d2a-efa3-4f18-9387-f9e40208acab

Stevenson, Ross, Pearce, Christopher R., Rosa, Eric, Hélie, Jean-françois and Hillaire-marcel, Claude (2018) Weathering processes, catchment geology and river management impacts on radiogenic ( 87 Sr/ 86 Sr) and stable (δ 88/86 Sr) strontium isotope compositions of Canadian boreal rivers. Chemical Geology, 486, 50-60. (doi:10.1016/j.chemgeo.2018.03.039).

Record type: Article

Abstract

Radiogenic (87Sr/86Sr) and stable (δ88/86Sr) strontium isotope compositions spanning a calendar year are reported for rivers from across subarctic Canada that drain contrasting lithologies ranging from Precambrian bedrock (Koksoak, Great Whale and La Grande rivers of Northern Quebec) to carbonate and clastic Phanerozoic sedimentary rocks of the Western Interior Platform (Nelson River, of central and western Canada). The 87Sr/86Sr isotopic compositions of the river waters reflect the underlying geology, with rivers draining the Precambrian Shield having higher 87Sr/86Sr ratios (0.727–0.734) than the Phanerozoic dominated Nelson River (0.713). The stable strontium isotope values (δ88/86Sr) range from 0.26 to 0.39‰, with the values for the Nelson River overlapping those of the other three. Rivers that have not been developed for hydroelectric power show a seasonal variation in the 87Sr/86Sr ratios, whereas those that have been diverted or dammed show little or no seasonal variation due to increased residence time of their water in hydroelectric reservoirs. The three rivers from Northern Quebec show discrete ranges in their 87Sr/86Sr and δ88/86Sr isotope compositions that correlate with the Ca/Sr and Na/Sr ratios of the river water. These correlations are interpreted to reflect differential chemical weathering of felsic versus mafic source rocks and/or of surficial sediment vs bedrock sources.

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Stevenson et al (Accepted) - Accepted Manuscript
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Accepted/In Press date: 26 March 2018
e-pub ahead of print date: 5 April 2018
Published date: 15 May 2018

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Local EPrints ID: 420017
URI: http://eprints.soton.ac.uk/id/eprint/420017
ISSN: 0009-2541
PURE UUID: b96f041c-7777-47f0-8823-e4cb81330589

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Date deposited: 25 Apr 2018 16:30
Last modified: 10 Jan 2022 05:59

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Contributors

Author: Ross Stevenson
Author: Christopher R. Pearce
Author: Eric Rosa
Author: Jean-françois Hélie
Author: Claude Hillaire-marcel

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