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

从南美大陆吹入海洋的尘埃一直是海洋生物营养物质的重要来源，是一个复杂的自然系统的一部分，该系统在地质时期影响大气中的二氧化碳水平。我们目前对这一系统过去如何运行的了解有限，主要是因为我们对非洲大陆何时、何地或如何产生沙尘的信息很少。该项目将追踪南美洲南部地质记录中记录的单个风尘颗粒，以确定最近在哪里产生尘埃，它是如何穿越大陆然后被吹入大气的，以及这些过程如何随着时间和不同气候的变化而变化。这些信息将有助于将陆地、大气和海洋科学联系起来，完善未来的气候模型，并促进美国和南美科学家之间的合作。该项目将利用粉砂大小的沉积物上的单颗粒碎屑矿物年代学来确定南美洲中部和南部黄土沉积物的沉积物来源和运移路径。将采用大观测(即大N)碎屑锆石年代学来追踪沉积物的产生途径，以确定尘源的位置和随时间的相对贡献。样本将从安第斯山脉、现代和现代河流沉积以及前陆盆地的黄土和黄土单元中收集。这些数据将有助于解决从以前的地球化学和地质学方法得出的南美洲尘埃产生的相互矛盾的模型，并将用于重建整个区域尘埃产生的时空变化。这项调查的结果将揭示在南半球这一区域运行的假想的沙尘气候反馈系统。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.