Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin
We have analysed the alkenone unsaturation ratio (UK'37) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured UK'37 ratios were converted into temperature using t...
Published in: | Deep Sea Research Part I: Oceanographic Research Papers |
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ftawi:oai:epic.awi.de:4970 2024-09-15T18:19:01+00:00 Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin Benthien, Albert Müller, P. 2000 https://epic.awi.de/id/eprint/4970/ https://doi.org/10.1016/S0967-0637(00)00030-3 https://hdl.handle.net/10013/epic.15539 unknown Benthien, A. orcid:0000-0002-9159-3109 and Müller, P. (2000) Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin , Deep-Sea Research I, 47 (12), pp. 2369-2393 . doi:10.1016/S0967-0637(00)00030-3 <https://doi.org/10.1016/S0967-0637%2800%2900030-3> , hdl:10013/epic.15539 EPIC3Deep-Sea Research I, 47(12), pp. 2369-2393 Article isiRev 2000 ftawi https://doi.org/10.1016/S0967-0637(00)00030-3 2024-06-24T03:54:51Z We have analysed the alkenone unsaturation ratio (UK'37) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured UK'37 ratios were converted into temperature using the global core-top calibration of Müller et al. (1998) and compared with annual mean atlas sea-surface temperatures (SSTs) of overlying surface waters. The results reveal a close correspondence (<1.5°C) between atlas and alkenone temperatures for the Western Tropical Atlantic and the Brazil Current region north of 32°S, but deviating low alkenone temperatures by -2° to -6°C are found in the regions of the Brazil-Malvinas Confluence (35-39°S) and the Malvinas Current (41-48°S). From the oceanographic evidence these low UK'37 values cannot be explained by preferential alkenone production below the mixed layer or during the cold season. Higher nutrient availability and algal growth rates are also unlikely causes. Instead, our results imply that lateral displacement of suspended particles and sediments, caused by strong surface and bottom currents, benthic storms, and downslope processes is responsible for the deviating temperatures. In this way, particles and sediments carrying a cold water UK'37 signal of coastal and/or southern origin are transported northward and offshore into areas with warmer surface waters. In the northern Argentine Basin the depth between displaced and unaffected sediments appears to coincide with the boundary between the northward flowing Lower Circumpolar Deep Water (LCDW) and the southward flowing North Atlantic Deep Water (NADW) at about 4000 m. Article in Journal/Newspaper NADW North Atlantic Deep Water North Atlantic Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Deep Sea Research Part I: Oceanographic Research Papers 47 12 2369 2393 |
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Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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ftawi |
language |
unknown |
description |
We have analysed the alkenone unsaturation ratio (UK'37) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured UK'37 ratios were converted into temperature using the global core-top calibration of Müller et al. (1998) and compared with annual mean atlas sea-surface temperatures (SSTs) of overlying surface waters. The results reveal a close correspondence (<1.5°C) between atlas and alkenone temperatures for the Western Tropical Atlantic and the Brazil Current region north of 32°S, but deviating low alkenone temperatures by -2° to -6°C are found in the regions of the Brazil-Malvinas Confluence (35-39°S) and the Malvinas Current (41-48°S). From the oceanographic evidence these low UK'37 values cannot be explained by preferential alkenone production below the mixed layer or during the cold season. Higher nutrient availability and algal growth rates are also unlikely causes. Instead, our results imply that lateral displacement of suspended particles and sediments, caused by strong surface and bottom currents, benthic storms, and downslope processes is responsible for the deviating temperatures. In this way, particles and sediments carrying a cold water UK'37 signal of coastal and/or southern origin are transported northward and offshore into areas with warmer surface waters. In the northern Argentine Basin the depth between displaced and unaffected sediments appears to coincide with the boundary between the northward flowing Lower Circumpolar Deep Water (LCDW) and the southward flowing North Atlantic Deep Water (NADW) at about 4000 m. |
format |
Article in Journal/Newspaper |
author |
Benthien, Albert Müller, P. |
spellingShingle |
Benthien, Albert Müller, P. Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
author_facet |
Benthien, Albert Müller, P. |
author_sort |
Benthien, Albert |
title |
Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
title_short |
Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
title_full |
Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
title_fullStr |
Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
title_full_unstemmed |
Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin |
title_sort |
anomalously low alkenone temperatures caused by lateral particle and sediment transport in the malvinas current region, western argentine basin |
publishDate |
2000 |
url |
https://epic.awi.de/id/eprint/4970/ https://doi.org/10.1016/S0967-0637(00)00030-3 https://hdl.handle.net/10013/epic.15539 |
genre |
NADW North Atlantic Deep Water North Atlantic |
genre_facet |
NADW North Atlantic Deep Water North Atlantic |
op_source |
EPIC3Deep-Sea Research I, 47(12), pp. 2369-2393 |
op_relation |
Benthien, A. orcid:0000-0002-9159-3109 and Müller, P. (2000) Anomalously low alkenone temperatures caused by lateral particle and sediment transport in the Malvinas Current region, western Argentine Basin , Deep-Sea Research I, 47 (12), pp. 2369-2393 . doi:10.1016/S0967-0637(00)00030-3 <https://doi.org/10.1016/S0967-0637%2800%2900030-3> , hdl:10013/epic.15539 |
op_doi |
https://doi.org/10.1016/S0967-0637(00)00030-3 |
container_title |
Deep Sea Research Part I: Oceanographic Research Papers |
container_volume |
47 |
container_issue |
12 |
container_start_page |
2369 |
op_container_end_page |
2393 |
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