Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1999 Today, deep waters produced in the North Atlantic are exported through the western South Atlantic. Antarctic...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
1999
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/4677 2023-05-15T13:53:14+02:00 Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data Horowitz, Michael Western South Atlantic 1999-01 application/pdf https://hdl.handle.net/1912/4677 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/4677 doi:10.1575/1912/4677 doi:10.1575/1912/4677 Ocean circulation Oceanic mixing Thesis 1999 ftwhoas https://doi.org/10.1575/1912/4677 2022-05-28T22:58:25Z Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1999 Today, deep waters produced in the North Atlantic are exported through the western South Atlantic. Antarctic intermediate water AAJW also enters the Atlantic in this region. Circumpolar deep water (CDW) fills the depths below AAIW and above and below northern source waters. A depth transect of cores from 1567-3909 m water depth in the western South Atlantic are ideally located to monitor inter-ocean exchange of deep water, and variations in the relative strength of northern versus southern source water production. Last glacial maximum (LGM) Cd/Ca and δ13C data indicate a nutrient-depleted intermediate-depth water mass. In the mid-depth western South Atlantic, a simple conversion of LGM δ13C data suggests significantly less nutrient enrichment than LGM Cd/Ca ratios, but Cd/Ca and δ13C data can be reconciled when plotted in CdW/δ13C space. Paired LGM Cd/Ca and δ13C data from mid-depth cores suggest increasingly nutrient rich waters below 2000 m, but do not require an increase in Southern Ocean water contribution relative to today. Cd/Ca data suggest no glacial-interglacial change in the hydrography of the deepest waters ofthe region. To maintain relatively low Cd/Ca ratios low nutrients in the deepest western South Atlantic waters, and in CDW in general, during the LGM requires an increased supply ofnutrient-depleted glacial North Atlantic intermediate water (GNA1W) and/or nutrient-depleted glacial Subantarctic surface waters to CDW to balance reduced NADW contribution to CDW. LGM Cd/Ca and δ13C data suggest strong GNA1W influence in the western South Atlantic which in turn implies export of GNAIW from the Atlantic, and entrainment of GNA1W into the Antarctic Circumpolar current. Thesis Antarc* Antarctic NADW North Atlantic Southern Ocean Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Antarctic Southern Ocean The Antarctic Woods Hole, MA |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Ocean circulation Oceanic mixing |
spellingShingle |
Ocean circulation Oceanic mixing Horowitz, Michael Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
topic_facet |
Ocean circulation Oceanic mixing |
description |
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1999 Today, deep waters produced in the North Atlantic are exported through the western South Atlantic. Antarctic intermediate water AAJW also enters the Atlantic in this region. Circumpolar deep water (CDW) fills the depths below AAIW and above and below northern source waters. A depth transect of cores from 1567-3909 m water depth in the western South Atlantic are ideally located to monitor inter-ocean exchange of deep water, and variations in the relative strength of northern versus southern source water production. Last glacial maximum (LGM) Cd/Ca and δ13C data indicate a nutrient-depleted intermediate-depth water mass. In the mid-depth western South Atlantic, a simple conversion of LGM δ13C data suggests significantly less nutrient enrichment than LGM Cd/Ca ratios, but Cd/Ca and δ13C data can be reconciled when plotted in CdW/δ13C space. Paired LGM Cd/Ca and δ13C data from mid-depth cores suggest increasingly nutrient rich waters below 2000 m, but do not require an increase in Southern Ocean water contribution relative to today. Cd/Ca data suggest no glacial-interglacial change in the hydrography of the deepest waters ofthe region. To maintain relatively low Cd/Ca ratios low nutrients in the deepest western South Atlantic waters, and in CDW in general, during the LGM requires an increased supply ofnutrient-depleted glacial North Atlantic intermediate water (GNA1W) and/or nutrient-depleted glacial Subantarctic surface waters to CDW to balance reduced NADW contribution to CDW. LGM Cd/Ca and δ13C data suggest strong GNA1W influence in the western South Atlantic which in turn implies export of GNAIW from the Atlantic, and entrainment of GNA1W into the Antarctic Circumpolar current. |
format |
Thesis |
author |
Horowitz, Michael |
author_facet |
Horowitz, Michael |
author_sort |
Horowitz, Michael |
title |
Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
title_short |
Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
title_full |
Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
title_fullStr |
Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
title_full_unstemmed |
Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data |
title_sort |
western south atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal cd/ca and stable carbon isotope data |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
1999 |
url |
https://hdl.handle.net/1912/4677 |
op_coverage |
Western South Atlantic |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic NADW North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic NADW North Atlantic Southern Ocean |
op_source |
doi:10.1575/1912/4677 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/4677 doi:10.1575/1912/4677 |
op_doi |
https://doi.org/10.1575/1912/4677 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766258233961349120 |