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

哥伦比亚高原的成对风成体系由广泛的厚度不等的帕卢塞黄土和逆风沙丘区组成，这些沙丘区来自于威斯康星州多期大洪水从冰川湖米苏拉爆发的富含砂和粉砂的静水沉积物的改造。很少有模型能够解释黄土堆积层厚度和分布的变化。我们将研究三种模型来描述迁移的沙与黄土的相互作用，以及地形、生物气候和源沉积物特征对黄土厚度和分布的影响。实地测绘将包括在区域范围内收集样本，以确定跃移与悬浮为主的风成岩单位的时空分布。稳定性（以古土壤为代表）和风成活动（以风成沙和黄土为代表）的时间将通过测定沉积物最后暴露在阳光下的时间的发光测年来确定。我们将确定1）何时何地黄土沉积开始后，最新的威斯康星州突发洪水，2）如果风成跃在迎风沙丘是活跃的同时，悬浮沉降顺风，3）如果saltator释放的时间推断，从黄土中的富砂间隔与干旱加剧的时期，和4）黄土的质量积累率。今天，哥伦比亚高原上旱地耕作产生的灰尘排放是危险的，因为空气中存在小于10微米的颗粒物，能见度降低。这项区域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，从而预测未来的粉尘排放。虽然成对的风成系统确实存在于世界其他地方（中国，欧洲，阿拉斯加，北美大平原），哥伦比亚高原提供了一个可行的地理尺度上研究黄土生成的多种模式的机会，以增加成对的风成系统的动力学知识，并提高晚更新世到全新世气候变化的记录哥伦比亚高原。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的研究生涯。

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.