Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments
Iceberg influence on diatom productivity has been observed for the present and suggested for the past, but direct seeding of the Southern Ocean during times of ice sheet collapse has never been directly demonstrated. Here we demonstrate enhanced diatom production and accumulation in the Amundsen Sea...
Published in: | Journal of Micropalaeontology |
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ftcopernicus:oai:publications.copernicus.org:jm115666 2024-09-09T18:59:49+00:00 Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments Furlong, Heather Scherer, Reed Paul 2024-08-01 application/pdf https://doi.org/10.5194/jm-43-269-2024 https://jm.copernicus.org/articles/43/269/2024/ eng eng doi:10.5194/jm-43-269-2024 https://jm.copernicus.org/articles/43/269/2024/ eISSN: 2041-4978 Text 2024 ftcopernicus https://doi.org/10.5194/jm-43-269-2024 2024-08-05T14:04:48Z Iceberg influence on diatom productivity has been observed for the present and suggested for the past, but direct seeding of the Southern Ocean during times of ice sheet collapse has never been directly demonstrated. Here we demonstrate enhanced diatom production and accumulation in the Amundsen Sea during a Mid-Pliocene interglacial that precisely coincides with pulses of ice-rafted debris (IRD) accumulation, and we infer a causal relation. International Ocean Discovery Program (IODP) Expedition 379 obtained continuous sediment records from the Amundsen Sea continental rise to document West Antarctic Ice Sheet (WAIS) history in an area currently experiencing the largest ice loss in Antarctica. Scanning electron microscopy (SEM) imagery of Mid-Pliocene interglacial sediments of Marine Isotope Stage (MIS) (GI-17, ∼ 3.9 Ma) documents distinct intervals of IRD-rich diatomite, whereas the overall diatom abundance and concentration of bloom species is relatively low in the absence of visible IRD. Sand- and granule-sized IRD grains are documented fully encased within diatomite laminae, with some displaying soft-sediment micro-deformation formed by grains falling into soft diatom ooze. IRD-rich diatomite layers are often characterized by nearly monospecific assemblages of the pelagic diatom Thalassiothrix antarctica , indicating very high primary productivity as IRD grains fell. Diatom-filled fecal pellets with clusters of barite grains are also documented within some of these laminae, further indicating direct mass sinking of diatom mats. Melting icebergs release soluble nutrients along with IRD; thus the coincidence of IRD and bloom species in Amundsen Sea sediments provides compelling evidence that iceberg discharge and melting directly initiates enhanced diatom productivity in the Southern Ocean. These results may contribute to interpreting past WAIS history by providing another proxy for potential collapse events. Furthermore, we suggest that ice sheet collapse may more broadly enhance Southern Ocean diatom ... Text Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* Southern Ocean Copernicus Publications: E-Journals Amundsen Sea Antarctic Southern Ocean West Antarctic Ice Sheet Journal of Micropalaeontology 43 2 269 282 |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Iceberg influence on diatom productivity has been observed for the present and suggested for the past, but direct seeding of the Southern Ocean during times of ice sheet collapse has never been directly demonstrated. Here we demonstrate enhanced diatom production and accumulation in the Amundsen Sea during a Mid-Pliocene interglacial that precisely coincides with pulses of ice-rafted debris (IRD) accumulation, and we infer a causal relation. International Ocean Discovery Program (IODP) Expedition 379 obtained continuous sediment records from the Amundsen Sea continental rise to document West Antarctic Ice Sheet (WAIS) history in an area currently experiencing the largest ice loss in Antarctica. Scanning electron microscopy (SEM) imagery of Mid-Pliocene interglacial sediments of Marine Isotope Stage (MIS) (GI-17, ∼ 3.9 Ma) documents distinct intervals of IRD-rich diatomite, whereas the overall diatom abundance and concentration of bloom species is relatively low in the absence of visible IRD. Sand- and granule-sized IRD grains are documented fully encased within diatomite laminae, with some displaying soft-sediment micro-deformation formed by grains falling into soft diatom ooze. IRD-rich diatomite layers are often characterized by nearly monospecific assemblages of the pelagic diatom Thalassiothrix antarctica , indicating very high primary productivity as IRD grains fell. Diatom-filled fecal pellets with clusters of barite grains are also documented within some of these laminae, further indicating direct mass sinking of diatom mats. Melting icebergs release soluble nutrients along with IRD; thus the coincidence of IRD and bloom species in Amundsen Sea sediments provides compelling evidence that iceberg discharge and melting directly initiates enhanced diatom productivity in the Southern Ocean. These results may contribute to interpreting past WAIS history by providing another proxy for potential collapse events. Furthermore, we suggest that ice sheet collapse may more broadly enhance Southern Ocean diatom ... |
format |
Text |
author |
Furlong, Heather Scherer, Reed Paul |
spellingShingle |
Furlong, Heather Scherer, Reed Paul Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
author_facet |
Furlong, Heather Scherer, Reed Paul |
author_sort |
Furlong, Heather |
title |
Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
title_short |
Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
title_full |
Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
title_fullStr |
Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
title_full_unstemmed |
Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments |
title_sort |
direct link between iceberg melt and diatom productivity demonstrated in mid-pliocene amundsen sea interglacial sediments |
publishDate |
2024 |
url |
https://doi.org/10.5194/jm-43-269-2024 https://jm.copernicus.org/articles/43/269/2024/ |
geographic |
Amundsen Sea Antarctic Southern Ocean West Antarctic Ice Sheet |
geographic_facet |
Amundsen Sea Antarctic Southern Ocean West Antarctic Ice Sheet |
genre |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* Southern Ocean |
genre_facet |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Iceberg* Southern Ocean |
op_source |
eISSN: 2041-4978 |
op_relation |
doi:10.5194/jm-43-269-2024 https://jm.copernicus.org/articles/43/269/2024/ |
op_doi |
https://doi.org/10.5194/jm-43-269-2024 |
container_title |
Journal of Micropalaeontology |
container_volume |
43 |
container_issue |
2 |
container_start_page |
269 |
op_container_end_page |
282 |
_version_ |
1809935626545397760 |