| dc.description.abstract | The focus of this thesis is creating a geologic map of the Woodford Shale in McAlister Cemetery Quarry, and providing data indicating how the bitumen in fractures came to be in this location. Prior studies have focused on defining the stratigraphy of the Woodford within the quarry, agreeing on at least three distinct segments: the Upper, Middle, and Lower Woodford.
Key results of this thesis include a map of the quarry created using newly acquired GPS points noting the locations of significant structures, landmarks, and contacts as well as an analysis of thin sections taken from samples within the quarry. Contacts between beds were mapped using a combination of data from Andrea Serna’s thesis and new GPS data. Initially this meant that the Upper, Middle, and Lower Woodford were 95, 133, and 144 feet thick, however part way through mapping, the definition of the boundary between the Middle and Upper Woodford was changed based on the first appearance of phosphate nodules. With this change, the Middle Woodford thickened to approximately 185 feet thick, and the Upper Woodford thinned to approximately 92 feet thick.
While gathering data for the geologic map, measurements of the mounds in the center of the quarry were taken to ascertain whether or not the mounds were in situ or were piles of debris from quarrying activities. Most of the mounds were in situ, with the only exception being the circular portion of the southernmost tip of the mounds, which can be seen on the map near the intersection of the gravel roads.
Faulting and folding within the quarry was investigated and what structures are currently visible in the quarry were documented. This included a NW trending fault which can be seen on the North Wall of the quarry, and a series of folds visible on the Eastern Wall, including a syncline, an anticline, and an overturned syncline.
Thin sections were taken from samples from the Middle Woodford and analyzed for a mineralogical evaluation and to confirm the hypothesis that the mounds are in situ. Thin sections displayed fractures occasionally infilled with bitumen and calcite. In at least one instance, the bitumen infill was observed cutting through a calcite filled fracture while taking advantage of a previous plane of weakness, indicating that the event which created the bitumen-filled fractures happened after the event which created the calcite-filled fractures. In addition, all five samples displayed graded bedding, indicating sediment gravity flow and not suspension settling. | en_US |
