Uranium in black shale deposits, northern Rocky Mountains and Great Plains

Abstract

Reconnaissance examinations for uranium in 22 formations containing black shale were made in parts of Montana, North Dakota, Utah, Idaho, and Oregon in 1953. About 150 samples from 80 outcrop localities and 5 oil and gas wells were submitted for uranium determinations. Most of the black shale deposits examined contain less than 0.003 percent of uranium; however, thin beds of black shale at the base of the Mississippian system contain 0.005 percent of uranium at 2 outcrop localities in southwestern Montana and as much as 0.007 percent of uranium in a well in northeastern Montana. An 8-foot bed of phosphatic black shale at the base of the Brazer limestone of middle and late Mississippian age in Rich County, Utah, contains as much as 0.009 percent of uranium. Commercial gamma-ray logs of oil and gas wells drilled in Montana and adjacent parts of the Dakotas indicate that locally the Heath shale of late Mississippian age contains as much as 0.01 percent of equivalent uranium, and black shales of Late Cretaceous age contain as much as 0.008 percent of equivalent uranium. INTRODUCTION PURPOSE AND LOCATION A reconnaissance search for uranium in black shale in the northern Rocky Mountains and Great Plains regions was carried out during the summer of 1953 by the U. S. Geological Survey on behalf of the Division of Raw Materials, U. S. Atomic Energy Commission. The work is part of a continuing program to investigate the uranium possibility of untested or incompletely tested black shale deposits* in the Western States. Most of the localities visited are in southwestern and central Montana, central and southeastern Idaho, and northwestern Utah. About 150 gamma-ray logs from wells drilled for oil and gas in Montana and adjacent parts of North and South 211 212 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM 53 <a S ' nd so Mont