On Saharan dust and past climate

North Africa produces more than half of the world’s atmospheric dust load. Once entrained into the atmosphere, this dust plays an important role in Earth’s climate system, modifying the radiative budget regionally, and supplying nutrients that fuel primary productivity across the North Atlantic Ocean and as far afield as the Amazonian Basin. Dust also accumulates in deep sea sediments, providing continuous long-term archives of palaeo-hydroclimate. However, a solid understanding of the provenance of this terrigenous sediment is required to properly interpret these palaeoclimate proxy records. Radiogenic isotope tracers, most commonly Strontium (Sr) and Neodymium (Nd), are used to link the deposition of dust and riverine material preserved in the marine realm to its continental source. In this thesis, I use radiogenic isotopes to i) identify three geochemically distinct preferential dust source areas in North Africa ii) quantify contamination by marine phases, especially marine barite, on the terrigenous fraction of marine sediments and iii) study changes in northwest African hydroclimate through the last 20,000 years, identifying a decoupling between continental rainfall and trade wind strength at the termination of the most recent African Humid Period. Overall, the work presented in this thesis focuses on improving our ability to trace the provenance of windblown dust and riverine terrigenous material preserved in marine archives, which is indispensable for reconstructing long, continuous, and well-dated records of continental climate