Geology of Superior Ridge uranium deposits, Ventura County, California

Epigenetic uranium deposits with potential commercial value have been found in the lower part of the upper Eocene to lower Miocene Sespe Formation near Ojai, in Ventura County, California. This report describes the geological and geochemical setting of these deposits and postulates a model for their origin. Several uranium deposits are located on Superior Ridge, a topographic high about 3 miles long located just south of White Ledge Peak and 6 to 9 miles west of Ojai (Photo 1). A single uranium deposit on Laguna Ridge is located about 3 miles south of Superior Ridge, and was included with the Superior Ridge deposits in the White Ledge Peak district. A few small deposits are known to exist in other parts of Ventura County. A preliminary model for uranium mineralization in the Sespe Formation postulated that the organic material necessary for concentrating the uranium by chemical reduction or precipitation originated as terrestrial humic acid or humate