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.
