Abstract

In rapidly developing areas throughout the Rocky Mountain region, the availability and quality of ground water has become a major concern. Fractured bedrock aquifers provide much of the ground water supplies for this region. Structural analysis may be a useful and inexpensive technique applied toward the evaluation of complexly deformed sedimentary bedrock aquifers. We integrate detailed structural analysis with hydrogeology in a subdivision that directly overlies its ground water resources near Park City, Utah. We characterize the structures and stratigraphy that may influence ground water flow with geologic mapping at a scale of 1:4500. In detail, the dominant structures influencing the hydrogeology of the study area are (names follow Ashland et al, 1996): 1) the Twomile Canyon anticline: a non-cylindrical, generally north-east plunging, partially conical and box-like anticline; 2) the Toll Canyon fault: a moderate- to high-angle reverse fault; 3) two macroscopic faults related to folding, the Twomile Canyon fault and unnamed fault. Pervasive fracturing in this area may either provide conduits or barriers to fluid flow depending on their structural and stratigraphic positions. At this scale, this analysis may improve local ground water management strategies by establishing the geometry of the structures and the flow properties of folded and faulted rocks.