Doctoral Dissertation Research: Paleoclimatology and Geochronology of a Late Quaternary Eolian System, Columbia Plateau, U.S.A.

博士论文研究：美国哥伦比亚高原晚第四纪风成系统的古气候学和地质年代学

• 批准号: 0202096
• 负责人: Alan Busacca
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0202096&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Paleoclimatology; Geochronology

The paired eolian system of the Columbia Plateau is composed of the extensive Palouse loess of variable thickness and upwind dune fields that are derived from reworking of sand- and silt-rich slackwater deposits from multiple episodes of Wisconsin giant outburst flooding from Glacial Lake Missoula. Few models exist that explain changes in the thickness and distribution of loess accumulations. We will investigate three models that describe the interaction of migrating sands with loess and influences of topography, bioclimate, and source sediment character that control the thickness and distribution of loess. Field mapping will include sample collection on a regional scale to determine the temporal and spatial distribution of saltation- versus suspension-dominated eolian units. Timing of stability (represented by paleosols) and eolian activity (represented by eolian sand an loess units) will be determined by luminescence dating that measures the last time sediments were exposed to sunlight. We will determine 1) when and where loess deposition began following latest-Wisconsin outburst floods, 2) if eolian saltation in upwind dunes was active concurrently with suspension fallout downwind, 3) if periods of saltator release inferred from sand-rich intervals in the loess were associated with periods of heightened aridity, and 4) the mass accumulation rates of loess. Dust emissions on the Columbia Plateau today resulting from dryland farming are hazardous through the presence of particulate matter less than 10 microns in size in the air and reduced visibility. This regional study will show how the Columbia Plateau system has responded to climate change through time, allowing future dust emissions to be predicted. While paired eolian systems do exist elsewhere in the world (China, Europe, Alaska, North American Great Plains), the Columbia Plateau offers the opportunity to study multiple models of loess generation on a workable geographic scale, to add to the knowledge of the dynamics of paired eolian systems, and to enhance the record of late-Pleistocene to Holocene climate change for the Columbia Plateau. As a Doctoral Dissertation Research Improvement award, this award will also provide support to enable a promising student to establish a strong independent research career.

哥伦比亚高原的成对风沙系统由广袤的可变厚度的帕劳斯黄土和迎风沙丘田组成，这些沙丘田是由威斯康星州从冰川湖米苏拉湖爆发的多期洪水中富含沙子和粉砂的死水沉积重新加工而成的。很少有模型能解释黄土堆积厚度和分布的变化。我们将研究三种描述流沙与黄土相互作用的模型，以及控制黄土厚度和分布的地形、生物气候和源岩性质的影响。实地测绘将包括在区域范围内收集样本，以确定以跃变为主与以悬浮为主的风成单位的时间和空间分布。稳定性(由古土壤表示)和风化活动(由风沙和黄土单位表示)的时间将通过发光测年来确定，发光测年测量沉积物最后一次暴露在阳光下的时间。我们将确定1)威斯康星州最近一次暴发洪水后黄土沉积开始的时间和地点，2)上风沙丘上的风沙跃迁是否与顺风向悬浮物同时活跃，3)黄土富沙段的跳跃释放时期是否与高度干旱时期有关，以及4)黄土的质量积累速率。今天，哥伦比亚高原旱地农业产生的粉尘排放是危险的，因为空气中存在小于10微米的颗粒物，能见度降低。这项地区性研究将展示哥伦比亚高原系统如何随着时间的推移对气候变化做出反应，从而能够预测未来的尘埃排放。虽然世界其他地方(中国、欧洲、阿拉斯加、北美大平原)确实存在成对风沙系统，但哥伦比亚高原提供了在可行的地理尺度上研究多种黄土生成模式的机会，增加了对成对风沙系统动力学的了解，并加强了哥伦比亚高原晚更新世至全新世气候变化的记录。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。