Date of Award

12-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Stefanie Brachfeld

Committee Member

Michael Kruge

Committee Member

Yang Deng

Subject(s)

Analytical geochemistry--Antarctica--East Antarctica, Marine sediments--Antarctica--East Antarctica, Marine sediments--Antarctica--Antarctic Peninsula, Stratigraphic Geology--Holocene

Abstract

Marine sediment geochemistry targeting both organic and inorganic compounds can be used for the reconstruction of paleoenvironmental conditions. Part 1 of this study was a qualitative organic geochemical analysis implemented on sediment cores from the Antarctic Peninsula (AP) and East Antarctic Margin (EAM). Intervals of organic or diatomaceous rich sediment were analyzed by Pyrolysis-Gas Chromatography/Mass Spectroscopy (Py-GC/MS) with the goal of identifying soft-bodied algae responsible for elevated wt% carbon levels in horizons where diatoms are absent, and identifying the presence of methanogens in basins where cold seeps are likely to be present. The identification of biomarkers in Antarctic sediment was challenging due to low wt% carbon in the sediment and small samples sizes used in Py-GC/MS, however, one persistent diatom source biomarker was identified. Samples from the Perseverance Drift, northern AP, presented evidence of early diagenesis under anoxic conditions. Continuation of this work necessitates a change in sample collection protocols to minimize contact between the sediment and plastic sampling tools and storage containers.

Part 2 of this study examined the geochemistry of a complete Holocene record, retrieved from a sediment core in Nielsen Basin on the EAM. Major and trace element geochemistry of the Nielsen Basin diamict and open marine sediment matches the composition of local source rocks, indicating locally-derived material throughout the Holocene. Intervals of low Fe or low wt% carbon were observed, which likely limits the pyritization process and preserves ferromagnetic greigite. This is likely responsible for the strongly magnetic zones observed by Kacperowski, 2009. A sequence of paleoenvironmental intervals similar to those documented on the AP, were identified in JPC40, suggesting that Holocene environmental change observed on the AP were not isolated, but continent wide. However, the timing of the transitions between these intervals is not the same as observed on the AP. This may be a function of the challenges inherent in radiocarbon dating of acid insoluble organic matter, or to genuine time transgressive behavior of these climate events on the AP vs. the EAM.

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