Collaborative Research: Deconvolving the southern South American Pleistocene-Holocene dust production pathways

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Dust blown from the South American continent into the oceans has been an important source of nutrients for marine organisms and is part of a complex natural system that influences atmospheric CO2 levels over geologic time. Our current understanding of how this system has operated in the past is limited, largely because we have little information on when, where or how dust has been generated on the continent. This project will trace individual grains of wind-blown dust archived in the geologic record of southern South America in order to determine where dust has been produced in the recent past, how it was transported across the continent and then blown into the atmosphere, and how these processes have changed through time and under different climates. The information will help link terrestrial, atmospheric and ocean sciences, refine future climate models, and foster collaborations between U.S. and South American scientists. This project will determine sediment sources and transport pathways of central and southern South American loess deposits using single-grain detrital mineral geochronology on silt- to sand-sized sediment. Large observation (i.e., Large-n) U-Pb detrital zircon geochronology will be applied to trace sediments through their production pathways in order to determine the location and relative contribution of dust sources over time. Samples will be collected from the Andes mountains, modern and recent river deposits, and from loess and loessoid units in the foreland basin. These data will help resolve conflicting models of South American dust production derived from previous geochemical and geological approaches, and be used to reconstruct spatio-temporal variations in dust production across the region. Results from this investigation will shed light on hypothesized dust-climate feedback systems operating in this sector of the southern Hemisphere.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.