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Reconstruction of Quaternary Paleo-circulation in the Western Arctic Ocean Based on a Neodymium Isotope Record from the Northwind Ridge

Gray, Rachael E.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1332458739

Abstract Details

2012, Master of Science, Ohio State University, Geological Sciences.
An understanding of past ocean circulation in the Arctic is critical for interpretations of past global ocean and atmospheric circulation, as well as predictions of future conditions. The Arctic Ocean plays a major role in global climate, due to its contributions to both the North Atlantic Deep Water (and subsequently the Atlantic Meridional Overturning Circulation) and the planet's albedo (due to sea ice cover). A sediment core from the Northwind Ridge in the western Arctic Ocean, ~800 km north of Alaska, has been sampled for measurement of radiogenic isotope ratios of neodymium and strontium. Sediment grain coatings were leached from the bulk sediment and measured for 87/86Sr and εNd, a proxy for seawater source. Two leaching solutions, one using buffered acetic acid and the second using hydroxylamine hydrochloride, were applied to sediments. Strontium data suggests that acetic acid best captures the seawater signal, while hydroxylamine hydrochloride leaching likely caused clay contamination of the hydrogenous data. εNd ratios were compared with independent lithologic proxies measured on the core and with results of earlier radiogenic-isotope studies in the Arctic Ocean. Data obtained suggest that radiogenic waters dominated the western Arctic Ocean during the estimated Early Pleistocene, probably due to increased Pacific water inputs and/or enhanced brine exclusion from sea ice formation on the Siberian shelves. These conditions likely indicate relatively warm climatic environments with predominantly seasonal sea ice, and thus can be potentially used as a paleo-analog for the projected near-future state of the Arctic. Further upcore, in the estimated Middle to Late Pleistocene, εNd values decrease overall, with high-amplitude fluctuations corresponding to glacial-interglacial cyclicity. Strongly non-radiogenic values in glacial intervals suggest the predominance of inputs from the Canadian Shield eroded by the Laurentide ice sheet. More radiogenic but gradually decreasing interglacial values indicate a change from Pacific to Atlantic water influence during the Middle to Late Pleistocene. Further isotope work on other cores may clarify the mechanisms and extent of this shift in circulation patterns.
Lawrence Krissek, PhD (Advisor)
Leonid Polyak, PhD (Committee Member)
W. Berry Lyons, PhD (Committee Member)
58 p.
Geology; Marine Geology; Oceanography
Arctic Ocean; neodymium; radiogenic isotopes; Northwind Ridge; paleoceanography; circulation; Quaternary

Recommended Citations

Citations

  • Gray, R. E. (2012). Reconstruction of Quaternary Paleo-circulation in the Western Arctic Ocean Based on a Neodymium Isotope Record from the Northwind Ridge [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332458739

    APA Style (7th edition)

  • Gray, Rachael. Reconstruction of Quaternary Paleo-circulation in the Western Arctic Ocean Based on a Neodymium Isotope Record from the Northwind Ridge. 2012. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1332458739.

    MLA Style (8th edition)

  • Gray, Rachael. "Reconstruction of Quaternary Paleo-circulation in the Western Arctic Ocean Based on a Neodymium Isotope Record from the Northwind Ridge." Master's thesis, Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332458739

    Chicago Manual of Style (17th edition)

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© 2012, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.