Publication Date


Document Type


First Advisor

Scherer, Reed P.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Earth, Atmosphere and Environment


The objective of this study was to assess the radiolarian assemblage of the Agulhas Current at International Ocean Discovery Program Expedition 361, Site U1479 (the most westward site), through the Mid-Pleistocene Transition (MPT). Samples between 1,000 to 777ka were utilized to (1) characterize the radiolarian assemblage, (2) observe whether the radiolarian assemblage is sufficiently distinctive to help discern the occurrence of the MPT in the Southern Ocean, and (3) determine whether changes in the radiolarian assemblage reflect a change or changes in ocean currents that may have occurred during the MPT.

Over 300 radiolarian species from 15 different families were identified in the relative abundance slides. Utilizing Tetrapyle octacantha, Lithomelissa thoracites, Phorticium clevei, Botryostrobus auritus/australis, and Cycladophora davisiana, the cyclicity of radiolarian assemblage peaks appeared to transition from obliquity- (~40ka) to eccentricity (100ka)- scaled cycles. Peaks in the abundance of these radiolarians were not tied directly to glacial/interglacial cycles as colder water taxa and subtropical taxa often had periods of overlap in spikes or drops in abundance. This suggests the mixing of the Agulhas Current with Atlantic and Antarctic waters, prominently the North Atlantic Deep Water and Antarctic Bottom Water, respectively, likely influenced relative abundances of radiolarians instead of purely glacial/interglacial intervals.


117 pages




Northern Illinois University

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