High-resolution Stratigraphy: Application to Hydrologic- Climatic Reconstruction in Southwestern United States

这是一项研究的更新，目的是建立一个气候参照区，以考察在最后一次冰川最大时期(~35Ka至12.5ka)之前、期间和之后发生的气候异常大而迅速的变化的同步性。位于新墨西哥州中部的水文封闭的埃斯坦西亚盆地特别适合作为参考剖面，因为它以前位于极锋急流之下，因为它有不间断的高分辨率地层和古生物学记录，而且它记录了对气候强迫的强烈、清晰和可测量的响应。丰富的介形虫和花粉可用于AMS测年。采样间隔具有较高的累积速率和较弱的生物扰动，对于不到十年的气候变化具有实际的分辨率。对沉积物成分、氧18和碳13以及水化学(介形虫物种丰度)的近距离(约50年)分析，以及质量平衡计算和水文模型，将用于在数百年至数千年的时间尺度上量化P-E。与以更紧密间隔分析的成分和其他变化相联系的灰度级图像将表征年际到百年尺度的气候变异性。有记录的气候变化模式包括约2000年的高水位和低水位，非常强的约200至250年的周期，蒙德尺度的振荡和~20年的周期。更准确的年龄模型和基于大量介形虫AMS测年的年代地层学将确定Estancia地点在冰川盛期和同位素阶段3后期记录到的异常大而快速的气候波动的时间。Estancia参考剖面将是这一重要时间段内第一个完整的陆基高分辨率气候变化年代学。它将作为关联和解释区域气候变化以及半球和全球气候事件的基础。

This is a renewal of research to establish a climatic reference section for examining the synchroneity of the exceptionally large and rapid changes in climate that occurred before, during, and after the last glacial maximum (~35Ka to 12.5ka). The hydrologically closed Estancia basin in central New Mexico is especially well suited as a reference section because of its previous location under the Polar Front Jet Stream, because of its uninterrupted high-resolution stratigraphic and paleontologic record, and because it recorded a strong, clear, and measurable response to climate forcing. Abundant ostracodes and pollen are available for AMS dating. The sampling interval, owing to a high accumulation rate and weak bioturbation, has a practical resolution for changes in climate of less than a decade. Closely spaced (~50- yr) analyses of sediment composition, oxygen 18 and carbon 13, and hydrochemistry (ostracode species abundance), along with mass- balance calculations and a hydrologic model will be used to quantify P-E on the time scale of centuries to millennia. Gray- scale images linked to compositional and other changes analyzed at more closely spaced intervals will characterize interannual to century-scale climatic variability. Patterns of recorded climatic variability include ~2000-yr highstand and lowstands, very strong ~200-to 250-yr, Maunder-scale oscillations, and ~20-years cycles. A more accurate age model and chronostratigraphy based on AMS dating of abundant ostracodes will determine the timing of the unusually large and rapid climatic fluctuations recorded at the Estancia site during the glacial maximum and during the later part of isotope stage 3. The Estancia reference section will be the first complete, land-based high-resolution chronology for changes in climate during this important time interval. It will serve as the basis for correlating and interpreting regional shifts in climate as well as hemispheric and global climatic events.