Kish, S. Lamont-Doherty Earth Observatory REU, WPVJVXA@grove.iup.edu
WEST AFRICAN COASTAL SEDIMENT SOURCES INFERRED FROM STRONTIUM ISOTOPE RECORDS
The Sr isotope record from RC11-83, a high resolution core off the southern coast of Africa, displays an alternating climatic record linked to glacial cyclicity. The Sr record extends to Stage 4 with Sr ratio highs during interglacial episodes and Sr ratios lows during glacial episodes, specifically a Sr ratio high of 0.722 during the Holocene and a Sr ratio low of 0.718 during the Last Galcial Maximum. The drastic difference in Sr ratios in the record raises the question of how the source of sediment to this region has changed over time. The first step in this analysis was designed to determine the source of sediment to RC11-83 during the Holocene. A swath of cores between 15-50 South latitude were analyzed and four possible modes of transport were considered.
Twenty samples were processed through a series of leaches to isolate the detrital clay fraction and analyzed on a mass spectrometer to determine the Sr 87/86 ratios. The results favor the mixing of source areas with a greater component of high Sr ratio detritus carried by the Agulhas Current and a lesser component of low Sr ratio detritus transported by the Antarctic Circumpolar Current at RC11-83 during the Holocene.
Day: Wednesday, Feb. 3
Location: Sweeney Center