Muddy-Shelf Dispersal Systems in the Cretaceous Western Interior Seaway

本文研究了北美洲白垩纪西部内陆海道细粒沉积物扩散的途径和过程。这项研究将集中在Mancos页岩的Tununk成员，暴露在犹他州中部和南部。本研究的具体目标是1)记录Tununk海沿岸河口的位置，以及相关的细粒沉积物扩散系统的方向和面积范围；2)重建古陆架上的沉积物运输过程。实地观察和实验室研究将包括分析Tununk成员的时间等效层，这些层暴露在垂直和平行于古海岸线的不同位置。古代扩散系统的重建将采用源自现代泥质陆架研究的概念和技术，并将包括对粒度、沉积宏观和微观结构以及有机碳同位素比率的横向趋势的记录。对古陆架过程的解释将依赖于详细的实地观测，以及使用定量的沉积物运输模型。本研究的总体目标是为白垩纪海道古地理、古构造和古海洋学的精确重建做出贡献，并为其他古细粒沉积环境的重建技术的发展做出贡献。这项工作将有助于开发用于能源勘探的模式。

This is an investigation of pathways and processes of fine- grained sediment dispersal in the Cretaceous Western Interior Seaway of North America. The study will focus on the Tununk Member of the Mancos Shale, exposed in central and southern Utah. The specific objectives of this study are 1) to document the location of river mouths along the coastline of the Tununk Sea, and the orientation and areal extent of associated fine-grained- sediment dispersal systems, and 2) to reconstruct processes of sediment transport on the ancient shelf. Field observations and laboratory studies will involve analyses of time-equivalent horizons in the Tununk Member, exposed at localities situated at various positions perpendicular and parallel to the ancient shoreline. Reconstructions of the ancient dispersal systems will employ concepts and techniques derived from study of modern, muddy shelves, and will include documentation of lateral trends in grain size, sedimentary macro- and microfabric, and organic carbon isotopic ratios. Interpretations of processes on the ancient shelf will rely on detailed field observations, as well as the use of quantitative, sediment-transport models. The overall goals of this study are to contribute to accurate paleogeographic, paleotectonic, and paleoceanographic reconstruction of the Cretaceous Seaway, and to the development of techniques for the reconstruction of other ancient environments of fine-grained sediment deposition. Work will help to develop models used in exploration for energy resources.