Local structure and concentration factor of Sb in K-T boundary clays

Abstract

The Cretaceous-Tertiary (K-T) boundary clay is also enriched in Cu, Zn, As and Sb.
We have already clarified about the local structure around antimony atoms in
K-T boundary clay by XAFS spectroscopy. In this study, additionally, the Sb
K-edge XANES spectrum of K-T boundary clays is compared with those of various
kinds of reference Sb minerals. There is almost no shift in the threshold
energies between K-T boundary clays and other Sb⁵⁺ oxides. The
oxidation state of Sb is estimated Sb⁵⁺ and Sb seems to form the
Sb-O bond. Sb co-precipitated with As and Fe ions, and then may co-exist in ferric
hydroxides throughout precipitation and diagenesis.