The Spatial Distribution of Aeolian Dust and Terrigenous Fluxes in the Tropical Atlantic Ocean Since the Last Glacial Maximum

The flux of terrestrial material from the continents to the oceans links the lithosphere, hydrosphere, and biosphere through physical and biogeochemical processes, with important implications for Earth's climate. Quantitative estimates of terrigenous fluxes from sources such as rivers, aeolian dust, and resuspended shelf sediments are required to understand how the processes delivering terrigenous material respond to and are influenced by climate. We compile thorium‐230 normalized 232Th flux records in the tropical Atlantic to provide an improved understanding of aeolian fluxes since the Last Glacial Maximum (LGM). By identifying and isolating sites dominated by aeolian terrigenous inputs, we show that there was a persistent meridional gradient in dust fluxes in the eastern equatorial Atlantic at the LGM, arguing against a large southward shift of the intertropical convergence zone during LGM boreal winter. The ratio of LGM to late‐Holocene 232Th fluxes highlights a meridional difference in the magnitude of variations in dust deposition, with sites 700 km away, characterized by 232Th fluxes approximately twice as large as aeolian‐dominated sites in the east. Plain Language Summary The movement of dust and sediment (“detritus”) by winds, rain, and rivers, from land to the oceans is affected by Earth's climate. Measurements of past amounts of detritus can help us understand how the processes that move detritus have changed. We collected published measurements of two types of the element thorium from sediments in the tropical Atlantic Ocean dating back to the last ice age (20,000 years ago). The two types of thorium have different sources—seawater and detritus—and allow us to calculate the accumulation of detritus through time. We show that the pattern of desert dust near the equator did not change much between recent times and the peak of the last ice age, suggesting that the monsoon rains—which wash a lot of dust from the atmosphere—were also in the same p