Muddy-Shelf Dispersal Systems in the Cretaceous Western Interior Seaway

本文是对北美白垩纪西部内海细粒沉积物扩散途径和过程的研究。这项研究将专注于暴露在犹他州中部和南部的Mancos页岩中的Tununk成员。这项研究的具体目标是：1)记录屯敦海沿岸河口的位置，以及相关的细粒泥沙扩散系统的方位和面积范围；2)重建古陆架上的泥沙运移过程。实地观察和实验室研究将包括分析在与古代海岸线垂直和平行的不同位置暴露的Tununk成员的时间等效地平线。古代分散系统的重建将采用现代泥质陆架研究中的概念和技术，并将包括记录粒度、沉积宏观和微观组构以及有机碳同位素比率的横向趋势。对古陆架上的过程的解释将依赖于详细的实地观察，以及使用定量的沉积物迁移模型。这项研究的总体目标是为准确的白垩纪海道的古地理、古构造和古海洋重建做出贡献，并为重建其他细粒沉积物沉积的古代环境提供技术支持。这项工作将有助于开发用于能源资源勘探的模型。

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.