Insight on the possible use of black shales for geological storage of radioactive wastes

A. Ayach1, S. Fakhi, O. Ait Malek, Z. Faiz, S. El Aouidi, A. Bouih, M. Benmansour, M. Aadjour, Y. El Batal, I. Vioque and G. Manjon

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This study was undertaken to investigate the natural materials before and after appropriate physicochemical treatments. The samples were collected at different depths from the outcrop Lamsied located in the Tarfaya-Boujdour basin. This work concerns a mineralogical and geochemical characterization of local black shale. For instance, mineralogical and granulometric analysis showed that the local black shale is composed essentially of calcite, and the texture does not depend neither on the depth nor on the lithology. The distribution of stable elements such as rare earth elements (RRE) and other trace and major elements was determined. Different techniques of analysis were used for the characterization of the samples. Enrichment or depletion of major elements was observed. NASC-normalized REE patterns revealed a heavy REE (HREE) enrichment, a light REE (LREE) depletion, a positive Eu anomaly and a negative Ce anomaly. The result indicates reduction conditions. Results of correlation analysis suggest the association of La, Ce, Dy, Ho, Er, Yb and Lu with terrigenous minerals and of Eu, Sm and Tm with carbonates and TOC (total organic carbon).