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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> the Middle Pennsylvanian Paradox Formation. The basin formed by an accumulation of thick <br /> deposits of halite, carbonate, and clastic sediments as a result of downwarping and uplift to the <br /> northeast. The area of study falls near the east-central portion of the Paradox Basin. The <br /> Paradox Basin is a geologic structural basin that extends up to 190 miles from southeast to <br /> northwest and 95 miles southwest to northeast (Nuccio and Condon, 1996). This includes the <br /> area from just northwest of Green River, Utah, to the very northern part of New Mexico near the <br /> state line with Colorado, and just east of Naturita, Colorado to east of Hanksville, Utah. The <br /> basin makes up a large portion of the Colorado Plateau province. <br /> In general, the basin is bound to the northeast by the Uncompahgre Plateau (a broad anticline), <br /> the San Juan uplift or dome to the southeast, the Four Corners Platform to the south, the <br /> Monument Uplift (Comb Ridge area) to the southwest and the San Rafael Swell to the <br /> northwest. The northern portion of the basin is characterized by northwest-trending faults, <br /> synclines and anticlines, some of which have been intruded by salt from the Paradox Formation <br /> (Nuccio and Condon, 1996). Dissolution of salt in the anticlines has resulted in downfaulting and <br /> collapse of some of these structures. These structural relationships are present in the area of <br /> the SMC in Big Gypsum Valley. Figure 4-2 illustrates the key structural features in the region. <br /> The regional geologic setting for the SMC and vicinity is characterized by generally flat lying <br /> sedimentary formations interrupted in areas by faulting and northwest trending folds. Regional <br /> stratigraphy is shown in Figure 4-3 and a regional geologic map is presented in Figure 4-4.To <br /> the northeast, Precambrian crystalline rock is exposed at the base of the Uncompahgre Plateau. <br /> Sinbad Valley, Paradox Valley, and Gypsum Valley are underlain by well-developed anticlines <br /> comprised of an intrusive salt core of the Paradox member of the Hermosa Formation. A local <br /> geologic map is shown in Figure 4-5, and a related geologic cross-section is shown in Figure 4- <br /> 6; both of these figures are sourced from Cater (1955). <br /> Basement rocks in the region consist of Early Proterozoic metamorphic gneiss and schist, <br /> locally intruded by granite. Early and Middle Proterozoic sediments and metasediments are <br /> present in the southern, southwestern and southeastern part of Paradox Basin (Nuccio and <br /> Condon, 1996). These rocks are exposed in the Grand Canyon to the south and on the <br /> Uncompahgre Plateau to the northeast. <br /> Older sedimentary rocks overlie the Precambrian rocks, and include such stratum as the Bright <br /> Angle Shale (Cambrian), the Elbert Formation and Ouray Formation (Devonian), and the <br /> Leadville Limestone (Mississippian). These strata are not exposed locally and are best <br /> Western Water& Land, Inc. 6 <br />