Reconstructing Dust Fluxes and Sediment Focusing in the Equatorial Pacific Over Glacial and Interglacial Time-scales Using Grain Size Analysis

Abstract

Understanding paleo-dust fluxes can provide insights into the dust cycle and its interaction with other components of the Earth’s system. In high nutrient low chlorophyll regions like the equatorial Pacific, dust mediates the biogeochemical exchange of carbon between the atmosphere and ocean. However, the interpretation of sediments in this region has been controversial. This thesis presents new disaggregated inorganic grain size (DIGS) distributions of several marine sediment cores from this region, focusing on the last 30,000 yrs. DIGS data are used to derive dust fluxes and to investigate sediment redistribution on the sea floor. Dust fluxes in the eastern equatorial Pacific (EEP) were highest in the deglaciation (15,000 - 18,000 yrs B.P.), rather than during the full glacial period, as previously observed. Furthermore, grain size sorting coefficients show that sediments in the EEP are moderately to well sorted, thus supporting geochemical evidence for sediment reworking in this region.