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The Spatial Distribution of Aeolian Dust and Terrigenous Fluxes in the Tropical Atlantic Ocean Since the Last Glacial Maximum
Author(s) -
Rowland George H.,
Robinson Laura F.,
Hendry Katharine R.,
Ng Hong Chin,
McGee David,
McManus Jerry F.
Publication year - 2021
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2020pa004148
Subject(s) - terrigenous sediment , last glacial maximum , geology , oceanography , aeolian processes , intertropical convergence zone , climatology , deglaciation , holocene , environmental science , sediment , geomorphology , geography , precipitation , meteorology
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 232 Th 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 232 Th fluxes highlights a meridional difference in the magnitude of variations in dust deposition, with sites <10°N showing larger changes over time. This supports an interpretation of increased trade wind strength at the LGM, potentially combined with differential changes in soil moisture and reductions in higher altitude summer winds. Our results also highlight the persistent importance of continental margins as sources of high terrigenous flux to the open ocean. This is especially evident in the western tropical Atlantic, where study locations reveal the primary influence of the South American continent up to >700 km away, characterized by 232 Th fluxes approximately twice as large as aeolian‐dominated sites in the east.