Chronology of the Late Pleistocene Yellowstone Ice Cap

摘要：了解北美西部和北大西洋地区之间的气候联系，对于确定末次冰期（过去约21000年）北半球气候突变的原因至关重要。高山冰川的进退是反映冰期气候变化的敏感指标。前黄石冰帽是美国西部最大的高山冰川系统，它留下的沉积物保存了北美西部过去气候的宝贵记录。在之前的研究中，我们成功地建立了一个高分辨率的黄石北部出口冰川波动年表。然而，在黄石的初步调查仅限于单一的排水，因此并没有解决黄石冰川历史复杂的许多方面。在此，我们建议进一步研究这一重要的气候信号及其来源。我们将把同位素测年技术应用于黄石地区其他流域的冰川沉积物。新的结果将大大提高目前对黄石冰川历史的认识，并将提供美国西部空前分辨率的高山冰川年代学。黄石冰川年代学的改进将使与美国西部其他地方的高山冰川记录进行令人信服的详细比较，并与北大西洋地区突发气候事件的时间进行比较。因此，改进的年代学将加强和完善基于冰川记录的气候解释，并将为进一步评估北半球千年尺度气候变率的起源提供重要的证据基础。

ABSTRACTChronology of the Late Pleistocene Yellowstone Ice CapbyJoseph M. Licciardi and Mark D. Kurz An understanding of climatic linkages between western North America and the North Atlantic region is essential for identifying causes of abrupt climate variability in the Northern Hemisphere during the last glacial period (over the past ~21,000 years). Advances and retreats of alpine glaciers are sensitive indicators of changes in Ice Age climate. The former Yellowstone Ice Cap was the largest alpine glacier system in the western U.S., and the deposits it left behind preserve a valuable record of past climates in western North America. In prior research, we successfully established a high-resolution chronology of fluctuations of the northern Yellowstone outlet glacier. The initial investigation at Yellowstone, however, was restricted to a single drainage, and therefore did not resolve many aspects of the complex Yellowstone glacial history. Here we propose a further investigation of this important climate signal and its origin. We will apply isotopic dating techniques to glacial deposits in additional drainages within the Yellowstone region. The new results will greatly enhance current knowledge of the Yellowstone glacial history, and will provide an alpine glacial chronology of unprecedented resolution in the western U.S. An improved chronology of Yellowstone glaciation will enable a compelling and detailed comparison with alpine glacier records elsewhere in the western U.S., and with the timing of abrupt climate events in the North Atlantic region. Consequently, the improved chronology will strengthen and refine climatic interpretations derived from the glacial record, and will provide an important base of evidence for further evaluating the origin of millennial-scale climate variability in the Northern Hemisphere.