Fine-grained clastic sediments make up the gross lithology in interior basins of ancient epicontinental seas, such as the Cretaceous Western Interior Seaway. This study provides a high-resolution thin-bedded facies analysis and regional correlations to determine how the heterolithic units of the Juana Lopez Member of the Mancos Shale were transported and deposited in the San Juan Basin. Data for this study was obtained from outcrop observations in eleven measured sections, spanning a distance of 115 kilometers. Eleven facies are observed, four sequences and eleven parasequence sets are identified. A depositional model is determined through the high-resolution facies analysis, which suggests deposition on a proximal to distal mudbelt through multiple processes, including turbidity currents, hypopycnal plumes, wave enhanced sediment gravity flows (WESGFs), storm surges, tides and oceanic currents. Overall, the Juana Lopez is dominated by upward-shoaling parasequence sets, with an increasing number and thickness of sandstone dominated bedsets, suggesting regressive sedimentation with distal expressions of transgression found in two parasequence sets. The source of sediment is determined through 520 paleocurrent measurements and plaeogeographic data, and is determined to be transported by along-shelf currents, dominantly from proximal NE clastic wedges. / Thesis / Master of Science (MSc)

Thesis (M.S.)--University of Massachusetts Amherst, 2008. / Includes bibliographical references (p. 81-97).

Coal reservoir quality in the Ferron Sandstone Member of the Mancos Shale, and in the Fruitland Formation is dependent on coal cleat characteristics. Coal reservoir permeability increases as a result of high cleat density. From careful outcrop examination, we were able to identify several factors that increase cleat density. Vitrain coal typically has the highest fracture density as a result of having well-developed face cleats and conchoidal fractures. Clarain coal contains face and butt cleats. Cleat density in clarain is also controlled by mechanical layer thickness. As mechanical layer thickness decreases, cleat density increases. Durain and fusain coals typically contain no welldeveloped cleat system, although their presence can affect mechanical layer thickness in adjacent coals, as they may form bounding units. Cleat density increases in the damage zone of faults and in the hinge-line of folds. Cleat-controlled reservoir permeability has beneficially affected methane production in one portion of the Drunkards Wash Gas Field, Utah, and appears to have negatively influenced methane production in the coalbed methane field.

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