Chemical weathering of lower paleozoic black shales of south Sweden
- 1 — post-graduate student Saint-Petersburg State University
- 2 — Ph.D., Dr.Sci. professor Saint-Petersburg State University
Abstract
Lower Paleozoic black shales are widespread in Sweden and form part of the Baltic paleobasin, which deposits are also known in Estonia and the Leningrad Oblast of Russia. These rocks are enriched in a carbon substance and characterized by the significant content of uranium, vanadium, molybdenum, copper, nickel, cobalt, zinc, and lead. Black shales contain high levels of Sr – 968; Ba – 337; U – 229; V – 509; Mo – 165; Zn – 411; Ni – 214; Cu – 112 (ppm) in secondary minerals composition formed on their surface. Retrograde diagenetic conditions facilitate the black shales chemical weathering. Elements of the first (U), second (Mo, Sr, Zn), and third (V) hazard classes are washed out of black shales and secondary minerals and can further enter biological cycles.
The authors thank Bert Allard for his participation in fieldwork. Analytical work was carried out in the following resource centres of SPBU: «Geomodel», «Centre for Microscopy and Microanalysis», «Centre for X-ray Diffraction Studies», «Chemical Analysis and Materials Research Centre»