Scandium geochemistry of phosphorites, Guizhou, Southwest China

Geochemical characteristics of scandium are described with respect to its source, evolution and correlation with REE as observed in Late Sinian and Early Cambrian phosphorites and tuffs in Guizhou. Comparison of chondrite-normalized REE patterns and some other parameters between the phosphorite and tuff shows that scandium and REE are most likely to have been derived from earlier or contemporaneous marine volcanics or tuffs, with no indication of genetic link to the purple shales, siltstones and dolomites in the area. The conditions under which the Sc-bearing phosphorites were formed are discussed in the light of sulfur isotopes and Eh-Ph constrains.