Paper No. 16-2
Presentation Time: 1:50 PM
A RECORD OF BIOGENIC SILICA VARIABILITY ACROSS THE PLIOCENE M2 GLACIAL EVENT IN THE SOUTHWESTERN INDIAN OCEAN, IODP SITE U1475
COENEN, Jason1, SCHERER, Reed P.2, LEVAY, Leah J.3, STANSELL, Nathan D.4, GOETZ, Peter1, HEMMING, Sidney5, HALL, Ian R.6 and EXPEDITION 361 SCIENTISTS, The7, (1)Department of Geology and Environmental Geosciences, Northern Illinois University, University Davis Hall 312, Normal Rd, DeKalb, IL 60115, (2)Geology and Environmental Geosciences, Northern Illinois University, University Davis Hall 312, Normal Rd, DeKalb, IL 60115, (3)International Ocean Discovery Program, Texas A&M University, 1000 Discovery Dr, College Station, TX 77845, (4)Geology and Environmental Geosciences, Northern Illinois University, Davis Hall 312, Normal Rd, DeKalb, IL 60115, (5)LDEO, Columbia University, Palisades, NY 10964, (6)Cardiff School of Earth and Ocean Sciences, Cardiff University, P.O. Box 914, Cardiff, CF10 3YE, Wales, (7)International Ocean Discovery Program, Texas A&M University, College Station, TX 77843
The Indian-Atlantic Ocean gateway is a significant area to study for palaeoceanography due to its pronounced ocean frontal system and links to high latitude climate dynamics. Distribution and changes in the frontal systems have the potential to influence global climate on millennial time scales. Ocean fronts are divided based on physical and chemical properties, productivity, and differences in microfossil assemblages. During glacial intervals, such as the Last Glacial Maximum (LGM), ocean fronts have been suggested to shift north, which has been suggested to intensify Northern Hemisphere Glaciation.
In the spring of 2016, International Ocean Discovery Program (IODP) Expedition 361 scientists recovered a series of sediment cores along the Agulhas Current system to understand the last ~6 million years of Agulhas Current history. Site U1475 on the Agulhas Plateau, provides an opportunity to understand long term fluctuations of the current and ocean fronts in the region via proxy records generated at this site.
We present data from sediments analyzed from Site U1475 (41°25.61’S; 25°15.64’E), located just south of the Agulhas Retroflection Current and the subtropical front today. Biogenic silica % for a 200,000-year interval based on the shipboard age model was selected from the interval between 3.26-3.46 Ma. This interval was selected to understand how the Pliocene ocean and frontal system was influenced by the poorly studied M2 glaciation, ~3.3 Ma ago. These preliminary results suggest changes in nutrient availability and a northward migration of the ocean frontal system, which is similar to those observed during the LGM at site MD02-2588 (41°S; 26°E).These ocean frontal migrations inferred from changes in biogenic silica % and other proxies will contribute to a better understanding of Pliocene paleoceanography.
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