Expression of Global Stadial Events Captured in a High Deposition Rate Marine Sedimentary Sequence off the Zambezi River Delta

• Main Author: Mamikunian, Gregory Vartan
• Other Authors: Charles, Christopher D
• Format: Thesis
• Language: English
• Published: eScholarship, University of California 2019
• Subjects: Geology; Geochemistry; Geophysics; Heinrich Events; hydroclimate variability; Mozambique; paleoclimate; sea level change; Zambezi river; Antarc*; Antarctic; Planktonic foraminifera
• Online Access: https://escholarship.org/uc/item/7zd6h5c2; https://escholarship.org/content/qt7zd6h5c2/qt7zd6h5c2.pdf

The progression of a geographically specific hydroclimate system over the course of global climatic anomalies and shifts like the Last Glacial Maximum (LGM) and Heinrich Stadial (HS) events gives rise to the strength and impact of these paleoclimate events on the worlds oceans and atmospheric conditions. The interplay of the Intertropical Convergence Zone (ITCZ) location in response to positive feedback loops derived from high latitude hemispheric specific aberrations (HS events) causes shifts in the intensity and spatial variability of global precipitation belts. Here, we show the implications of HS1, HS4, and the LGM on the hydroclimate variability of South Central Africa using barium ratios and the δ18O of individual planktonic foraminifera captured in an ultra-high deposition sequence drilled off the Mozambique Margin at the output of the Zambezi River. In addition to sea surface measurements, a high resolution benthic δ18O record was constructed to locate and observe the expression of these events in the Southern Hemisphere. We find abrupt excursions to low δ18O values in line with HS events indicating these events are characterized by a warming of sub-Antarctic surface waters. In addition, we find that during HS events and the LGM there is evidence for southern shifts in the ITCZ documented by increased precipitation and freshwater discharge into the Mozambique Channel captured by elevated barium levels and negative shifts in δ18O of planktonic foraminifera.