Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007. / Includes bibliographical references. / This thesis employs compound-specific stable carbon and radiocarbon isotopic analysis of organic biomarkers to (a) resolve petrogenic from pre-aged vascular plant organic carbon (OC) in continental margin sediments, (b) investigate the underlying mechanisms controlling the anomalously old ages that are often observed for the terrestrial component of sedimentary OC, and (c) address the associated consequences for biomarker-based climate reconstructions. In Chapters 2 and 3, coupled molecular isotope mass balances demonstrate that the amount of petrogenic OC residing on the Beaufort Shelf (Arctic Ocean) and the Eel River Margin (coastal California) has been previously overestimated due to the presence of significantly 'pre-aged' terrestrial OC. However, even though the contribution of organic matter emanating from sedimentary rocks may be smaller, these results reinforce the emerging notion that it is not completely oxidized during weathering and subsequent seaward transport. In Chapter 4, comparison of the down-core radiocarbon profiles for certain vascular plant biomarkers extracted from Cariaco Basin (Caribbean Sea) and Saanich Inlet (coastal British Columbia) sediments with the radiocarbon evolution of atmospheric carbon dioxide reveals that the vast majority of the terrestrial OC experiences multi-millennial residence times on land prior to entering the sea. Most of the remaining inventory is deposited in sediments within one or two decades, providing direct evidence that very little terrestrial organic matter is rapidly transferred to the marine environment. / (cont.) With this in mind, the striking modulation in the signal amplitude of a biomarker-based tropical paleoaridity record presented in Chapter 5 was instead used to evaluate the role of low versus high latitude forcing in abrupt paleoclimate oscillations during the last full glacial cycle. Seasonal variations in the position of the Intertropical Convergence Zone were interpreted to be a response to both high latitude adjustments in meridional overturning circulation and precessionally-driven modifications in local insolation. Finally, Chapter 6 addresses the broader implications of multi-millennial terrestrial residence times for paleoclimate records based on vascular plant biomarkers. / by Nicholas J. Drenzek. / Ph.D.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/40965 |
| Date | January 2007 |
| Creators | Drenzek, Nicholas J |
| Contributors | Timothy I. Eglinton., Woods Hole Oceanographic Institution., Joint Program in Oceanography/Applied Ocean Science and Engineering, Woods Hole Oceanographic Institution, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 223 p., application/pdf |
| 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 |
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