Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. The radionuclides ²³¹Pa and ²³⁰Th, produced in the water column and re...
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ftmit:oai:dspace.mit.edu:1721.1/55329 2023-06-11T04:08:52+02:00 Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean Hoffmann, Sharon Susanna Jerry F. McManus. Woods Hole Oceanographic Institution. Joint Program in Oceanography Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences 2009 207, [1] p., 4 leaves application/pdf http://hdl.handle.net/1721.1/55329 eng eng Massachusetts Institute of Technology http://hdl.handle.net/1721.1/55329 430034794 M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Earth Atmospheric and Planetary Sciences Joint Program in Oceanography Woods Hole Oceanographic Institution Thesis 2009 ftmit 2023-05-29T08:29:25Z Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. The radionuclides ²³¹Pa and ²³⁰Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance exists between ²³⁰Th production and burial in the Central Arctic basins, based on measured sedimentary ²³⁰Th, inventories in box cores, establishing this nuclide's utility as a paleoceanographic indicator of sedimentary processes and as a normalization tool. I present the first ²³⁰Th-normalized particle fluxes calculated for the central Arctic: vertical particle fluxes were extremely low during the late glacial, rose during the deglaciation due to particle inputs from shelf inundation, increased productivity and ice-rafted debris, and fell again following the establishment of interglacial conditions. A major event of lateral sediment redistribution, inferred from surplus ²³⁰Th, inventories, occurred in the Makarov Basin during the deglaciation and may have been due to destabilization of slope and shelf sediments as sea level rose. I present the first high-resolution, radiocarbon-dated downcore records of sedimentary ²³¹Pa/²³⁰Th from the Arctic Ocean. Low ratios indicate that ²³¹Pa was exported from all sites during the late glacial period, with export decreasing during the deglaciation and Holocene. 231Pa/²³⁰Th measurements in cores from three continental slope sites show no evidence for a ²³¹Pa sink related to boundary scavenging on the continental slopes. Holocene ²³¹Pa/²³⁰Th ratios show a very significant variation by depth, with strong export of ²³¹Pa at deep sites but little or no export at shallow sites, a result which echoes findings for the South Atlantic and the Pacific. (cont.) ... Thesis Arctic Arctic Ocean makarov basin DSpace@MIT (Massachusetts Institute of Technology) Arctic Arctic Ocean Pacific Makarov Basin ENVELOPE(170.000,170.000,87.000,87.000) |
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Open Polar |
collection |
DSpace@MIT (Massachusetts Institute of Technology) |
op_collection_id |
ftmit |
language |
English |
topic |
Earth Atmospheric and Planetary Sciences Joint Program in Oceanography Woods Hole Oceanographic Institution |
spellingShingle |
Earth Atmospheric and Planetary Sciences Joint Program in Oceanography Woods Hole Oceanographic Institution Hoffmann, Sharon Susanna Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
topic_facet |
Earth Atmospheric and Planetary Sciences Joint Program in Oceanography Woods Hole Oceanographic Institution |
description |
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. The radionuclides ²³¹Pa and ²³⁰Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance exists between ²³⁰Th production and burial in the Central Arctic basins, based on measured sedimentary ²³⁰Th, inventories in box cores, establishing this nuclide's utility as a paleoceanographic indicator of sedimentary processes and as a normalization tool. I present the first ²³⁰Th-normalized particle fluxes calculated for the central Arctic: vertical particle fluxes were extremely low during the late glacial, rose during the deglaciation due to particle inputs from shelf inundation, increased productivity and ice-rafted debris, and fell again following the establishment of interglacial conditions. A major event of lateral sediment redistribution, inferred from surplus ²³⁰Th, inventories, occurred in the Makarov Basin during the deglaciation and may have been due to destabilization of slope and shelf sediments as sea level rose. I present the first high-resolution, radiocarbon-dated downcore records of sedimentary ²³¹Pa/²³⁰Th from the Arctic Ocean. Low ratios indicate that ²³¹Pa was exported from all sites during the late glacial period, with export decreasing during the deglaciation and Holocene. 231Pa/²³⁰Th measurements in cores from three continental slope sites show no evidence for a ²³¹Pa sink related to boundary scavenging on the continental slopes. Holocene ²³¹Pa/²³⁰Th ratios show a very significant variation by depth, with strong export of ²³¹Pa at deep sites but little or no export at shallow sites, a result which echoes findings for the South Atlantic and the Pacific. (cont.) ... |
author2 |
Jerry F. McManus. Woods Hole Oceanographic Institution. Joint Program in Oceanography Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
format |
Thesis |
author |
Hoffmann, Sharon Susanna |
author_facet |
Hoffmann, Sharon Susanna |
author_sort |
Hoffmann, Sharon Susanna |
title |
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
title_short |
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
title_full |
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
title_fullStr |
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
title_full_unstemmed |
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean |
title_sort |
uranium-series radionuclide records of paleoceanographic and sedimentary changes in the arctic ocean |
publisher |
Massachusetts Institute of Technology |
publishDate |
2009 |
url |
http://hdl.handle.net/1721.1/55329 |
long_lat |
ENVELOPE(170.000,170.000,87.000,87.000) |
geographic |
Arctic Arctic Ocean Pacific Makarov Basin |
geographic_facet |
Arctic Arctic Ocean Pacific Makarov Basin |
genre |
Arctic Arctic Ocean makarov basin |
genre_facet |
Arctic Arctic Ocean makarov basin |
op_relation |
http://hdl.handle.net/1721.1/55329 430034794 |
op_rights |
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 |
_version_ |
1768382491727495168 |