COLLABORATIVE RESEARCH: Global Change: The Geologic and Pedologic Record of Climate and Vegetation in Pleistocene Palouse Loess, Pacific Northwestern U.S.

哥伦比亚高原帕劳斯黄土中的五个地点，每个地点都跨越了过去75000年(当前间冰期的最后一个冰川周期)，将被绘制成暴露图，进行描述和采样。该序列将形成降水量约200 mm至700 mm、温度暖和至凉爽、灌丛草原至森林的生物气候样带。年代学、土壤地层学和热释光测年将提供地点间的年代学控制和对比。蛋白石植硅体的稳定同位素地球化学和丰度以及土壤形成的碳酸钙的稳定同位素地球化学将提供有关植物盖度、植物群落类型和温度随时间的波动的信息。场地地层学和古土壤的微观形态(土壤显微镜)、物理和化学性质将对黄土沉积和侵蚀循环、土壤发育以及植被和气候变化与土壤形成过程和景观演变的关系做出解释。古土壤和黄土的磁化率测量将是对中国黄土气候代理模型的关键检验。上面的子项目将被综合成一个量化的描述性模型，描述过去75,000年中5,000至10,000年的变化。随后将对两个可追溯到175,000年前的较长地层剖面进行采样和分析，以重建倒数第二个冰川-间冰期旋回的记录。项目的目标是提供有关气候和植被变化的直接信息，量化整个区域土壤学、沉积学和山坡地貌系统对这些变化的响应，进一步记录科迪勒冰盖活动的无损替代记录，并测试几个气候替代记录。

Five sites in the Palouse Loess of the Columbia Plateau, that each span the last 75,000 yr (the last glacial cycle through the current interglacial), will be mapped in exposures, described, and sampled. The sequence of sites will form a bioclimatic transect from about 200 mm to 700 mm precipitation, warm to cool temperature, and shrub-steppe to forest. Tephrochronology, soil stratigraphy, and thermoluminescence dating will provide chronological control and correlation among sites. The stable isotope geochemistry and abundances of opal phytoliths and the stable isotope geochemistry of soil-formed calcium carbonates will yield information about fluctuations in plant cover, plant community type, and temperature through time. Site stratigraphy and the micromorphology (soil microscopy), physical, and chemical properties of paleosols will yield interpretations of loess aggradation and erosion cycles, of soil development, and of relationships of changing vegetation and climate to soil-forming processes and landscape evolution. Measurement of magnetic susceptibility of paleosols and loess will serve as a critical test of the climate proxy model developed from Chinese loess. The sub projects above will be synthesized into a quantitative descriptive model of change in 5,000 to 10,000 year time slices through the last 75,000 yr. Two longer stratigraphic sections that date back to 175,000 yr B.P. then will be sampled and analyzed using the same techniques to reconstruct the record of the penultimate glacial-interglacial cycle Project goals are to provide direct information on changes in climate and vegetation, to quantify region-wide responses of the pedologic, sedimentologic, and hillslope-geomorphic systems to those changes, to further document a losess-based proxy record of activity of the Cordilleran Ice Sheet, and to test several climate proxy records.