Molybdenum-uranium-vanadium geochemistry in the lower Paleozoic Alum Shale of Scandinavia: Implications for vanadium exploration

This paper investigates the hyper-enrichments of molybdenum (Mo), uranium (U), and vanadium (V) in the lower Paleozoic, Alum Shale of Denmark, Sweden, Norway, and Estonia. Molybdenum and U are mainly associated with organic matter and the highest contents are found in the Furongian part of the Alum Shale. This Furongian hyper-enrichment of Mo and U commenced with the Steptoean Positive Carbon Isotope Excursion (SPICE) event. The temporal distribution of V content increases moderately from the Miaolingian to the Furongian, followed by a significant increase in the Early Ordovician. In addition, the vanadium content generally increases towards the offshore, distal part of the Alum Shale basin. The geochemical affinity of V seems to change from organic matter in the Cambrian to minerals in the Early Ordovician. The hyper-enrichment of V in the Lower Ordovician succession appears to result from upwelling of deep oceanic water. The spatial distribution of V in the Alum Shale indicates that the highest concentrations are located in Scania, southernmost Sweden.