Laserfiche WebLink
Underlying the Entrada/Carmel Formation is the Navajo Sandstone, another eolian fine <br />grain clean quartz sandstone that overlies the siliceous cemented Kayenta Formation, a <br />resistant bench - forming unit, consisting of sandstones, mudstones and conglomerates that <br />overlie the massive Wingate Sandstone. The cliff forming Wingate consists of fine grain, <br />well -sorted sand and is commonly an important source of low to moderate quantities of <br />groundwater in the Colorado Plateau region. Red shales and mudstones of the Chinle <br />Formation complete the geologic section in the immediate area of the mine. For a <br />detailed description and map of the area geology refer to Figure Ul. <br />8.2 Mineralization <br />The name "Uravan Mineral Belt" is applied to a narrow, elongate area in southwestern <br />Colorado in which carnotite deposits in the Morrison formation have a closer spacing, <br />larger size, and higher grade than those in adjoining areas. The belt extends from <br />Gateway through Uravan to Slick Rock. The deposits within the belt tend to be clustered <br />in patches (Fischer and Hilpert, 1952). <br />Cater et al. (1955) state that the most common ore minerals found in the region are <br />carnotite and the micaceous vanadium minerals. The ore consists mostly of sandstone <br />selectively impregnated and in part replaced by uranium and vanadium minerals and are <br />also associated with thin mudstone partings, beds of mudstone pebbles, and carbonized <br />fossil plant material. In general, the ore minerals were deposited in irregular layers that <br />roughly follow the sandstone beds. In most deposits, the highest grade concentrations of <br />ore minerals occur in sharply bounded structures called "rolls." Precipitation likely <br />resulted from slight changes in the chemical composition of the solutions, perhaps in the <br />environment of decaying organic material (Fischer and Hilpert, 1952). <br />Factors of geology, geochemistry and arid climatic conditions have combined to form the <br />Uravan Mineral Belt — dominantly sandstone deposits of uranium, vanadium and <br />associated metals. These same conditions restrict the movement of these minerals into <br />the environment. The only viable transport mechanism for the migration of these <br />minerals from ore deposits located deep in geologic formations to possible exposure in <br />the environment is via a groundwater pathway. <br />8.3 Regional Groundwater <br />To understand possible exposure routes resulting from mining, the geology that forms the <br />framework for the movement of groundwater needs to be understood. <br />8.3.1 Area Aquifers <br />A review of well records from the Colorado State Engineers office indicates that there are <br />no water supply wells located within two miles of the JD -9 mine site. Considering the <br />remote location of the mine, this is not unexpected. There are three monitoring wells <br />located to the north that were installed for another uranium property owned by <br />NUVEMCO. Records submitted to the state indicate that minor amounts of water were <br />encountered in the Entrada Formation. <br />O'Connor Design Group Inc. U - 12 <br />