Response of Eolian and Associated Depositional Systems to Climate and Dynamic External Factors-Toward an Eolian Sequence Stratigraphic Model

对Eath环境对全球变暖等不断变化的条件的反应进行建模的不确定性，源于对这些环境的动态缺乏了解。在过去的20,000年里，撒哈拉经历了戏剧性的转变，从比今天更广阔的沙海发展到长满了常见的湖泊和河流。虽然这些波动与米兰科维奇周期相对应，但我们在过程反应模型中理解这些周期的基础直到最近才开始出现。撒哈拉地区从阿特拉斯山脉延伸到突尼斯的撒哈拉平台，提供了一个多样化环境的缩影，那里的矿藏存放在一个下沉的谷底。遥感首先被用来绘制现在的环境图，识别残留的特征，并为详细的野外工作定位特定的沉积中心。野外工作包括通过实地绘制土壤-地貌和地层关系图、相分析和地球物理方法，为该地区的风成、河流和湖泊沉积建立一个不整合界限的地层格架。随后的实验室分析包括对序列进行年代测定，以便将它们与气候事件相关联。由于风成及相关沉积体系对气候和其他因素的响应是层序地层学的基础，因此这些结果有望帮助形成一个通用的过程-响应风成层序模型，该模型将具有预测外部控制变化的能力。

Uncertainty in modeling the response of Eath environments to changing conditions such as global warming arises from a poor understanding of the dynamics of these environments. It is established that over the past 20,000 years the Sahara has undergone dramatic swings from more extensive and sand-sea devlopment than today to being vegetated with common lakes and rivers. While these swings correspond to Milankovitch cycles, our basis for understanding these in a process-reponse model has only recently begun to emerge. The area of the Sahara extending from the Atlas Mountains onto the Sahara Platform in Tunisia offers a microcosm of diverse environments, where deposits are housed in a subsiding trough. Remote sensing is first used to map present environments, recognize relict features, and locate specific depocenters for detailed field work. Field work involves the establishment of an unconformity-bounded stratigraphic framework for eolian, fluvial and lacustrine deposits in the area through field mapping of soil-geomorphic and stratigraphic relationships, facies analysis, and geophysical methods. Subsequent lab analysis involves the dating of the sequences so they can be correlated with climatic events. Because the response of eolian and associated depositional systems to climatic and other factors is the basis for sequence stratigraphy, the results are expected to help formulate a general process-response eolian sequence model that will have predictive capabilities with respect to changing external controls.