2020-03-30_HYDROLOGY - M1981021 - Laserfiche WebLink

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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT mining at the SMC was somewhat steady from the mid-1960s until 1984, when the Uravan mill, owned by Union Carbide, closed. Since that time, brief periods of mining occurred mostly associated with spikes in uranium or vanadium prices in the late 1980s by Union Carbide Corporation, mid-1990s with International Uranium Corporation, and from 2006 to 2009 by Denison (Adkins, 2015). Adkins (2015) estimates that at least 1,419 exploration drill holes were drilled on the SMC property for an estimated total drilled distance of 850,100 ft. Some underground long holes were drilled. A conservative estimate of total linear underground workings is 50,000 ft with many stopes (Adkins, 2015). An underground workings and drill hole map is shown in Figure 3-1.For information on estimated ore reserves and minable reserves, see Adkins (2015). 4.0 GEOLOGY Local and regional geologic conditions described in this section were obtained from professional literature, Denison reports, and field data collected at the project site. Cater (1955)was the major literature source for regional and local geologic information. All following geologic information is from Cater (1955) unless otherwise cited. 4.1 Regional Geology As mentioned, the SMC lies within the Canyon Lands sub province of the Colorado Plateau physiographic province (see Figure 4-1). The Colorado Plateau is characterized by nearly flat- lying sedimentary rock of Paleozoic and Mesozoic age, deposited between 525 to 381 million years ago on top of a nearly smooth basement of Precambrian age crystalline rock (Gavan and Wegner, 2020). During the Laramide Orogeny, 70 to 40 million years ago, the Colorado Plateau province remained relatively tectonically stable while uplift and deformation formed the Rocky Mountains to the north and east. Several additional periods of mountain building occurred during this period ago forming isolated mountain ranges cored with igneous rock. Younger mountain ranges formed by the intrusion of igneous rock occurred during a period from about 20 to 31 million years ago (Sullivan, 1997). Tensional forces formed the Basin and Range province to the south and the Great Basin to the west and the Rio Grande Rift to the southeast. Uplift of the Colorado Plateau continued during this time and is still occurring today (Flowers, 2010), although the exact cause is under debate. The regional geologic structure consists of geologic structural basins separated by uplifted or gently folded terrain. The basin is defined by the maximum extent of salt-bearing formations of Western Water& Land, Inc. 5