Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland
Fine-grained sediments deposited by retreating glaciers weather faster than the global average and this weathering can impact the global carbon cycle and oceanic fluxes of nutrients and radiogenic isotopes. Much work has focused on subglacial and proglacial weathering of continental ice sheets, but...
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ftuninebromaha:oai:digitalcommons.unomaha.edu:geoggeolfacpub-1096 2024-02-04T10:00:47+01:00 Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland Scribner, Cecilia A. Martin, Ellen E. Martin, Jonathan B. Deuerling, Kelly M. Collazo, D. F. Marshall, A. T. 2015-09-21T07:00:00Z application/pdf https://digitalcommons.unomaha.edu/geoggeolfacpub/99 https://digitalcommons.unomaha.edu/context/geoggeolfacpub/article/1096/viewcontent/exposure_age_and_climate_control_on_weathering_in_deglaciated_waterheds_of_western_Greenland.pdf unknown DigitalCommons@UNO https://digitalcommons.unomaha.edu/geoggeolfacpub/99 https://digitalcommons.unomaha.edu/context/geoggeolfacpub/article/1096/viewcontent/exposure_age_and_climate_control_on_weathering_in_deglaciated_waterheds_of_western_Greenland.pdf http://creativecommons.org/licenses/by-nc-nd/4.0/ Geography and Geology Faculty Publications text 2015 ftuninebromaha 2024-01-07T17:40:53Z Fine-grained sediments deposited by retreating glaciers weather faster than the global average and this weathering can impact the global carbon cycle and oceanic fluxes of nutrients and radiogenic isotopes. Much work has focused on subglacial and proglacial weathering of continental ice sheets, but little is known about weathering and resulting fluxes from deglacial watersheds, which are disconnected from the ice sheets and discharge only annual precipitation and permafrost melt. We investigate the effects of exposure age and precipitation on weathering intensity in four deglacial watersheds on Greenland that form a transect from the coast near Sisimiut toward the Greenland Ice Sheet (GrIS) near Kangerlussuaq based on evaluations of major ion compositions, Sr isotope ratios, and mineral saturation states of waters and sediments. The transect is underlain by Archean orthogneiss and is characterized by gradients in moraine ages (∼7.5–8.0 ky inland to ∼10 ky at the coast) and water balance (−150 mm/yr inland to +150 mm/yr at the coast). Anion compositions are generally dominated by HCO3, but SO4 becomes increasingly important toward the coast, reflecting a switch from trace carbonate dissolution to sulfide mineral oxidation. Coastal watersheds have a higher proportion of dissolved silica, higher Na/Cl, Si/Ca, and lower Ca/Sr ratios than inland watersheds, indicating an increase in the relative proportion of silicate weathering and an increase in the extent of weathering toward the coast. More extensive weathering near the coast is also apparent in differences in the 87Sr/86Sr ratios of stream water and bedload (Δ87Sr/86Sr), which decreases from 0.017 inland to 0.005 at the coast, and in increased saturation states relative to amorphous SiO2 and quartz. The steep weathering gradient from inland to coastal watersheds reflects enhanced weathering compared to that expected from the 2 to 3 ky difference in exposure age caused by elevated coastal precipitation. The gradient of weathering with exposure age, water budget ... Text Greenland Ice Ice Sheet Kangerlussuaq permafrost Sisimiut University of Nebraska Omaha: DigitalCommons@UNO Greenland Kangerlussuaq ENVELOPE(-55.633,-55.633,72.633,72.633) Sisimiut ENVELOPE(-53.674,-53.674,66.939,66.939) |
institution |
Open Polar |
collection |
University of Nebraska Omaha: DigitalCommons@UNO |
op_collection_id |
ftuninebromaha |
language |
unknown |
description |
Fine-grained sediments deposited by retreating glaciers weather faster than the global average and this weathering can impact the global carbon cycle and oceanic fluxes of nutrients and radiogenic isotopes. Much work has focused on subglacial and proglacial weathering of continental ice sheets, but little is known about weathering and resulting fluxes from deglacial watersheds, which are disconnected from the ice sheets and discharge only annual precipitation and permafrost melt. We investigate the effects of exposure age and precipitation on weathering intensity in four deglacial watersheds on Greenland that form a transect from the coast near Sisimiut toward the Greenland Ice Sheet (GrIS) near Kangerlussuaq based on evaluations of major ion compositions, Sr isotope ratios, and mineral saturation states of waters and sediments. The transect is underlain by Archean orthogneiss and is characterized by gradients in moraine ages (∼7.5–8.0 ky inland to ∼10 ky at the coast) and water balance (−150 mm/yr inland to +150 mm/yr at the coast). Anion compositions are generally dominated by HCO3, but SO4 becomes increasingly important toward the coast, reflecting a switch from trace carbonate dissolution to sulfide mineral oxidation. Coastal watersheds have a higher proportion of dissolved silica, higher Na/Cl, Si/Ca, and lower Ca/Sr ratios than inland watersheds, indicating an increase in the relative proportion of silicate weathering and an increase in the extent of weathering toward the coast. More extensive weathering near the coast is also apparent in differences in the 87Sr/86Sr ratios of stream water and bedload (Δ87Sr/86Sr), which decreases from 0.017 inland to 0.005 at the coast, and in increased saturation states relative to amorphous SiO2 and quartz. The steep weathering gradient from inland to coastal watersheds reflects enhanced weathering compared to that expected from the 2 to 3 ky difference in exposure age caused by elevated coastal precipitation. The gradient of weathering with exposure age, water budget ... |
format |
Text |
author |
Scribner, Cecilia A. Martin, Ellen E. Martin, Jonathan B. Deuerling, Kelly M. Collazo, D. F. Marshall, A. T. |
spellingShingle |
Scribner, Cecilia A. Martin, Ellen E. Martin, Jonathan B. Deuerling, Kelly M. Collazo, D. F. Marshall, A. T. Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
author_facet |
Scribner, Cecilia A. Martin, Ellen E. Martin, Jonathan B. Deuerling, Kelly M. Collazo, D. F. Marshall, A. T. |
author_sort |
Scribner, Cecilia A. |
title |
Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
title_short |
Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
title_full |
Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
title_fullStr |
Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
title_full_unstemmed |
Exposure age and climate controls on weathering in deglaciated watersheds of western Greenland |
title_sort |
exposure age and climate controls on weathering in deglaciated watersheds of western greenland |
publisher |
DigitalCommons@UNO |
publishDate |
2015 |
url |
https://digitalcommons.unomaha.edu/geoggeolfacpub/99 https://digitalcommons.unomaha.edu/context/geoggeolfacpub/article/1096/viewcontent/exposure_age_and_climate_control_on_weathering_in_deglaciated_waterheds_of_western_Greenland.pdf |
long_lat |
ENVELOPE(-55.633,-55.633,72.633,72.633) ENVELOPE(-53.674,-53.674,66.939,66.939) |
geographic |
Greenland Kangerlussuaq Sisimiut |
geographic_facet |
Greenland Kangerlussuaq Sisimiut |
genre |
Greenland Ice Ice Sheet Kangerlussuaq permafrost Sisimiut |
genre_facet |
Greenland Ice Ice Sheet Kangerlussuaq permafrost Sisimiut |
op_source |
Geography and Geology Faculty Publications |
op_relation |
https://digitalcommons.unomaha.edu/geoggeolfacpub/99 https://digitalcommons.unomaha.edu/context/geoggeolfacpub/article/1096/viewcontent/exposure_age_and_climate_control_on_weathering_in_deglaciated_waterheds_of_western_Greenland.pdf |
op_rights |
http://creativecommons.org/licenses/by-nc-nd/4.0/ |
_version_ |
1789966248874868736 |