Geology and Development of Marquez, New Mexico, Uranium Deposit: ABSTRACT

Abstract

Uranium deposition in the Marquez, New Mexico, area occurs almost exclusively in the lower Westwater Canyon Member of the Morrison Formation of Jurassic age. The average aggregate thickness of the Westwater is 90 m but ranges from a minimum of 73 m to a maximum of 100 m. A K shale separates the upper and lower Westwater sandstone boundaries. The lower Westwater sandstone development is more pronounced in an east-southeast direction parallel with strike of the orebody(ies). Three distinct ore zones were deposited in peneconcordant elongate patterns. The upper zone occupies a stratigraphic interval just below the K shale and two lower zones lie above and below the K1 shale. Coffinite and uraninite predominate as the stable uranium species; other extrinsic e ements were added during the mineralization process. Humates undoubtedly exerted major control on formation of the uranium. Ferrous iron pervades both within and outside the deposit whereas ferric iron, though limited in quantity, is confined principally to the orebody(ies). The lower K1 shale, parameters of permeability, and recurrence of meanders along the paleochannels also seem to influence enrichment. Surface drilling is continuing, a vertical mine shaft to approximately 2,100 ft (630 m) is nearing completion, and a mill is being constructed on the property. End_of_Article - Last_Page 691------------