Geologic Report on East Chaco Canyon Drilling Project, McKinley and San Juan Counties, New Mexico

摘要

The East Chaco Canyon drilling project of northwestern New Mexico was comprised of 15 holes drilled to an average depth of 4695 feet (1431 m). These holes were drilled to obtain data on extensions of the uranium producing strata of the Grants mineral belt into a deeper unexplored portion of the San Juan Basin. The goal of the project was to obtain subsurface data that would reduce the uncertainty of resource estimates of the Morrison Formation within the project area and other deeper portions of the basin. Preliminary geologic and land status studies were initiated in June 1977. Drilling began in July 1978 and was completed during November 1978. A total of 70,421 feet (21,464.3 m) was drilled of which 4938 feet (1505 m) was cored. The cored intervals included virtually all the Westwater Canyon Member and portions of the Brushy Basin and Recapture Members of the Morrison Formation. A suite of lithologic and geophysical logs was obtained from each drill hole. A comprehensive study of the Westwater Canyon Member core from each drill hole is being made by the Department of Geology of the University of New Mexico. Zones of minor uranium mineralization were encountered in both the Westwater Canyon and Brushy Basin Members of the Morrison Formation. The zones commonly occurred at the contacts between beds of altered, originally arkosic, coarse-grained, poorly sorted sandstones and finer grained sedimentary units. The best developed zone of mineralization (8 feet (2.4 m) of 0.125% eU sub 3 O sub 8 ) occurred within a sandstone of this type that was separated from the underlying Westwater Canyon Member sandstones by about 27 feet (8.2 m) of typical Brushy Basin Member claystone. (ERA citation 05:026931)