View article

In order to evaluate whether clay minerals or accessory phases control the REE pattern of the <2-μm fraction of pelitic sediments, a set of samples from a borehole in the southern Apennines, Italy, was analysed for mineralogy and chemical composition (major elements, Rb, Sr, Y, Zr, Nb and REE). SEM analyses showed the presence of accessory phases such as Ti-oxides, apatite, zircon and pyrite. XRD procedures revealed that the <2-μm fraction essentially consists of illite, smectite, dickite, kaolinite and chlorite. Illite and smectite probably derived by leaching from a micaceous “biotite-like” mineral while dickite took origin from post-depositional, interstitial fluids.

Only illite is correlated with REE, while a smectite-rich sample is characterized by the lowest content in REE. Strong correlations exist between REE and TiO₂, Nb, Zr and a less significant one with Sr; no correlations exist between these elements and Y.

R …