Chronologies and mechanisms of last glacial loess deposition in the Central Lowlands of North America

该项目将促进对末次冰期北美中西部地区风沙（黄土）沉积的了解。黄土沉积物是该地区丰富的农业土壤的重要组成部分，其中嵌有螺化石和古土壤，是重要的古气候档案。然而，中西部黄土的年代仍然很差，与其他气候和冰川记录脱节，限制了我们对黄土沉积时间和驱动因素的理解。新的放射性碳年代学将把沉积速率的变化与2.5万至1.8万年前大湖地区沉积物来源、气候和冰瓣波动的过去变化联系起来。这一研究将提高对末次冰期区域古气候记录和大气沙尘收支的认识。一个关于伊利诺伊州更新世景观的互动模块，用于课后丰富计划，STEAM（科学，技术，工程，艺术和数学），将向当地学生介绍这些重要的沉积物。新的、高分辨率的黄土放射性碳年代学，结合U-Pb锆石定年以及黄土和冰川的微量元素分析，将提供详细的沉积物来源历史。蜗牛壳的稳定氧和碳同位素分析，以及物种组合和稳定氧同位素正演模拟，将有助于确定黄土沉积速率变化的气候背景。将这些沉积速率与区域冰瓣波动的时间进行比较，将有助于更好地理解冰川运动、气候、冰川沉积物供应和下风黄土沉积之间的关系。

This project will advance understanding of windblown silt (loess) deposition during the last glaciation across Midwestern North American landscapes. Loess deposits are a vital ingredient to the region's rich agricultural soil and, with embedded fossil snails and ancient soils, are important paleoclimate archives. However, Midwestern loess remains poorly dated and disconnected from other climate and glacial records, limiting our understanding of the timing and drivers of loess deposition. New radiocarbon chronologies will relate deposition rate variations to past changes in sediment sources, climate, and ice lobe fluctuations in the Great Lakes region from ~ 25,000 to 18,000 years ago. This research will improve understanding of regional paleoclimate records and atmospheric dust budgets during this last glacial period. An interactive module on the Pleistocene Illinois landscape for an after-school enrichment program, STEAM (Science, Technology, Engineering, Arts, and Math), will introduce these important deposits to local students. New, high resolution radiocarbon chronologies of loess, coupled with U-Pb zircon dating and trace elemental analyses of loess and glacial tills will provide detailed sediment sourcing history. Stable oxygen and carbon isotope analyses of snail shells, along with species assemblages and stable oxygen isotope forward modeling, will aid determinations of the climatic context of changing loess deposition rates. Comparing these deposition rates with the timing of regional ice lobe fluctuations will permit better understanding of the relationships among glacier movement, climate, glacial sediment supply, and downwind loess deposition.