Kerogen and uranium resources in the Cambrian alum shales of the Billingen—Falbygden and Närke areas, Sweden

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Abstract
The Cambrian alum shales contain Sweden's major reserve of fossil energy and Europe's largest low-grade source of uranium. The most uraniferous shales occur in the Billingen-Falbygden area of Västergötland. The most kerogen and oil-rich shales occur in Närke. Elsewhere the resources are vast but the concentrations of these components are somewhat lower. In the Billingen-Falbygden area the most uraniferous shales (contained in the uranium-rich unit of the upper member of the formation) occur within an area of ca. 490 km2. They vary in thickness from 2.0–4.5 m, and contain 240–365 ppm U; they average ca. 290 ppm U, ca. 15.5 % Corg and ca. 18% kerogen. In-ground resources of uranium in this unit alone are estimated to ca. 1 million tonnes. In the Närke area, the shales arc composed of two members. The Upper Member is divisible into an Oil shale unit and an overlying Uraniferous Shale. The Upper Member contains an average of 175 ppm U, with the Oil Shale averaging 135 ppm U and the Uraniferous Shale 210 ppm U. The most uranium-rich part of the latter is ca. 4.5 m thick and averages ca. 245 ppm U. The Upper Member composes the fossil energy reserve. The Oil Shale and Uraniferous Shale units together are up to ca. 18 m thick and contain 18–22 % kerogen; they occur in an area of ca. 80 km2 and contain 350 million tonnes of kerogen.