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Quaternary Arctic Ocean sea ice variations and deep water isolation times
Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
Lund University, Department of Geology.
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2010 (English)In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, no 25-26, 3430-3441 p.Article in journal (Refereed) Published
Abstract [en]

A short sediment core retrieved from a local depression forming an intra basin on the Lomonosov Ridge during the Healy-Oden Trans-Arctic Expedition 2005 (HOTRAX) contains a record of the Marine Isotope Stages (MIS) 1-3 showing exceptionally high abundances of calcareous microfossils during parts of MIS 3. Based on radiocarbon dating, linear sedimentation rates of 7-9 cm/ka persist during the last deglaciation. Last Glacial Maximum (LGM) is partly characterized by a hiatus. Planktic foraminiferal abundance variations of Neogloboquadrina pachyderma sinistral and calcareous nannofossils reflect changes in Arctic Ocean summer sea ice coverage and probably inflow of subpolar North Atlantic water. Marine reservoir ages of 1400 years or more, at least during the last deglaciation, seem plausible from calibration of the radiocarbon ages using modeled reservoir corrections from previous studies in combination with the microfossil abundance record of the studied core. Paired benthic-planktic radiocarbon dated foraminiferal samples indicate a slow decrease in age difference between surface and bottom waters from the Late Glacial to the Holocene, suggesting circulation and ventilation changes.

Place, publisher, year, edition, pages
2010. Vol. 29, no 25-26, 3430-3441 p.
National Category
Earth and Related Environmental Sciences
Research subject
Geology
Identifiers
URN: urn:nbn:se:su:diva-30891DOI: 10.1016/j.quascirev.2010.06.011ISI: 000284724400007OAI: oai:DiVA.org:su-30891DiVA: diva2:274694
Available from: 2009-10-30 Created: 2009-10-30 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Quaternary paleoceanography of the Arctic Ocean: A study of sediment stratigraphy and physical properties
Open this publication in new window or tab >>Quaternary paleoceanography of the Arctic Ocean: A study of sediment stratigraphy and physical properties
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A Quaternary perspective on the paleoceanographic evolution of the central Arctic Ocean has been obtained in this PhD thesis by studying sediment cores from all of the Arctic’s major submarine ridges and plateaus. The included cores were mainly recovered during the Healy-Oden Trans-Arctic expedition in 2005 and the Lomonosov Ridge off Greenland expedition in 2007. One of the main thesis objectives is to establish whether different sediment depositional regimes prevailed in different parts of the central Arctic Ocean during the Quaternary and, if so, establish general sedimentation rates for these regimes. This was approached by dating key cores using the decay of the cosmogenic isotopes 10Be and 14C, and through stratigraphic core-to-core correlation using sediment physical properties. However, the Arctic Ocean sea ice complicated the use of 10Be for dating because a solid sea ice cover prevents the 10Be isotopes from reaching the seafloor, resulting in too old ages. Dating using 14C is also complicated due to uncertain marine reservoir age corrections in the central Arctic Ocean. The core-to-core correlations show five areas with different depositional regimes; the northern Mendeleev Ridge and Alpha Ridge, southern Mendeleev Ridge, Morris Jesup Rise, Lomonosov Ridge and Yermak Plateau, listed in the order of increasing sedimentation rates from ~0.5cm/ka to ~4.8 cm/ka. A detailed study of the relationship between sediment bulk density and grain sizes suggests a strong link between variations in clay abundance and bulk density. Grain size analysis of a Lomonosov Ridge core show that fine silt and clay dominates the interglacials, possibly due to increased suspension freezing of these size fractions into sea ice and/or nepheloid transport. Sediments younger than the marine isotope stage (MIS) 7 generally contain more coarse silt, attributed to a regime shift during the Quaternary with increased iceberg transport into the central Arctic Ocean from MIS 6 and onwards.

Place, publisher, year, edition, pages
Stockholm: Department of Geology and Geochemistry, Stockholm University, 2009. 37 p.
Series
Meddelanden från Stockholms universitets institution för geologi och geokemi, ISSN 1101-1599 ; 337
Keyword
Arctic Ocean, sedimentology, Quaternary, stratigraphy, physical properties
National Category
Earth and Related Environmental Sciences Geology Geology
Research subject
Marine Geoscience
Identifiers
urn:nbn:se:su:diva-30895 (URN)978-91-7155-968-5 (ISBN)
Public defence
2009-11-27, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In progress. Paper 4: In progress. Paper 5: In progress. Paper 6: In progress. Available from: 2009-11-05 Created: 2009-10-30 Last updated: 2009-10-30Bibliographically approved
2. Late Quaternary Biostratigraphy and Paleoceanography of the central Arctic Ocean
Open this publication in new window or tab >>Late Quaternary Biostratigraphy and Paleoceanography of the central Arctic Ocean
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The central Arctic Ocean is one of the least explored deep sea regions and long biostratigraphic sediment records are sparse. The main focus of this thesis is the Arctic Ocean foraminiferal record and its application to reconstruct paleoceanographic variations and summer sea ice cover changes between late Quaternary interglacial periods. One of the studied cores was retrieved from the central Lomonosov Ridge Intra Basin. This core contains a relatively high-resolution biostratigraphic record spanning Marine Isotope Stages (MIS) 1–3, although with a hiatus encompassing the Last Glacial Maximum. Radiocarbon age calibrations in this core show a decreasing trend of high marine reservoir ages of about 1400 years during the last deglaciation to 700 years in the late Holocene. The cores from the Lomonosov Ridge off Greenland and the Morris Jesup Rise contain preserved calcareous microfossils further back in time than most previously studied central Arctic Ocean cores. The calcium content estimated by X-ray fluorescence scanning of these cores shows a distinct pattern of calcium rich intervals coinciding with peaks in foraminiferal abundance in the sediment record of MIS 1–7. The calcium peaks originate from material accumulated during interglacials, primarily through detrital carbonate and dolomite input from the decaying North American ice sheet and secondarily from biogenic material. Intervals of calcareous benthic foraminifera are found in pre MIS 7 sediments on both the southern Lomonosov Ridge and Morris Jesup Rise. Their assemblage composition and stable carbon isotope data suggest increased primary production and decreased summer sea ice cover compared to the Holocene central Arctic Ocean. This is also suggested for an interval of high abundance of the subpolar planktic foraminifera Turborotalita quinqueloba on the southern Lomonosov Ridge with a proposed MIS 11 age.

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, Stockholm University, 2011. 32 p.
Series
Meddelanden från Stockholms universitets institution för geologiska vetenskaper, 345
Keyword
Arctic Ocean, Quaternary, biostratigraphy, foraminifera, paleoceanography
National Category
Other Earth and Related Environmental Sciences
Research subject
Marine Geoscience
Identifiers
urn:nbn:se:su:diva-57245 (URN)978-91-7447-311-7 (ISBN)
Public defence
2011-06-10, Ahlmansalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted.

Available from: 2011-05-12 Created: 2011-05-04 Last updated: 2014-03-28Bibliographically approved

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