Date of Award

1-1-2013

Document Type

Open Access Thesis

Department

Marine Science

First Advisor

Howie Scher

Abstract

Previous studies of sediment from southern Kerguelen Plateau have provided insight about Antarctica's climate activity during the Bartonian/Priabonian boundary (ca. 37 Ma). Detrital and fossil fish tooth neodymium (Nd) isotope records, along with foraminiferal δ18O values, suggest a change in the source of terrigenous sediment coincident with global cooling and/or ice sheet growth on Antarctica. My thesis work has corroborated the initial findings and has provided additional insight into the Antarctic weathering regime during this climate event. Nd and hafnium (Hf) isotope values of terrigenous sediment at ODP Site 748B (58°26.45'S, 78°58.89'E, 1290m) were cross-plotted along with the seawater and terrestrial array in Nd-Hf diagrams to constrain changes in the weathering style on Antarctica. The coupled Nd-Hf data suggests that the delivery of radiogenic isotope fingerprints to Kerguelen Plateau during the Bartonian/Priabonian boundary was a function of the style of weathering on Antarctica as well as modification of the terrigenous fraction during transport. An increased erosional flux of an older source is inferred from a decrease to more unradiogenic εNd values 37 Ma. At the same time, there is a small shift in εHf, to less radiogenic values, indicating a small change from chemical to mechanical style weathering. The findings support the conclusion that there was a change in the Antarctic weathering flux, along with a change in weathering style approximately 37 Ma.

Rights

© 2013, Brian Smith

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