The effect of fractures, faults, and sheared shale zones on the hydrology of Bear Creek Burial Grounds A-South, Oak Ridge, Tennessee
Date
1997
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Texas A&M University
Abstract
Previous hydrologic models of flow in Bear Creek Valley have presented lateral flow as occurring through the Nolichucky Shale in parallel to strike fractures within thin carbonate beds; the effects of faults were not considered. This study presents a ground water flow model that incorporates lateral flow through parallel-to-strike fractures and thrust faults, and perpendicular-to-strike cross valley strike-slip faults. These latter cross-valley structures cause flow to be diverted to other strikeparallel zones of enhanced permeability towards the south side of the valley. Using core, geophysical and hydrologic data from five boreholes in the Bear Creek Burial Grounds three types of potential fluid-flow conduits were identified: fractures, faults, and shale shear zones. Open fractures decrease in abundance with depth and tend to occur most frequently in oolitic limestone beds relative to other carbonate lithologies. Fractures below 1 00 ft BGS in the Nolichucky Shale and below 250 ft in the Maynardville Limestone do not appear to be caused by dissolution; instead, they appear to be the result of a change in the local stress field due to erosion effects. Faults, both cross-valley and thrust faults, and sheared shale zones are interpreted to disrupt the lateral continuity of the bedding and increase the rock-mass permeability of the Nolichucky Shale, permitting ground water to flow these structural zones. This study provided opportunity to interpret DNAPL migration patterns from Burial Ground A-South. DNAPL migration parallel to the valley's axis is affected by parallel-to-strike fractures and thrust faults, and its lateral migration perpendicular to strike is influenced by cross valley strike-slip faults and decreasing collect at depth because of decreasing fracture occurrence and reduced permeability and then migrate laterally along the cross valley strike-slip faults until it encounters and enters a zone of higher permeability parallel to strike.
Description
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Includes bibliographical references: p. 151-156.
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references: p. 151-156.
Issued also on microfiche from Lange Micrographics.
Keywords
geology., Major geology.