Local structure of Zn in Cretaceous-Tertiary boundary clay from Stevns Klint

Research at Stevns Klint, Denmark, reveals the unique local structure of zinc (Zn) atoms in Cretaceous-Tertiary boundary clay. Using Zn K-edge XAFS spectroscopy at KEK's Photon Factory, scientists found that Zn in this clay resembles the tetrahedral ZnO4 site of willemite, a zinc silicate, with first shell Zn-O and second shell Zn-cation distances of 1.953(3) Å and 3.51(2) Å, respectively. This structure differs from typical clay minerals and aligns with crystalline phases where Zn predominantly occupies tetrahedral sites. The study's findings, published in the Journal of Mineralogical and Petrological Sciences, provide insights into the atomic-scale behavior of Zn at a critical geological boundary.

OKUBE, M., SASAKI, S., YOSHIASA, A., WANG, L., NAKATANI, T., HONGU, H., MURAI, K.-i., NAKATSUKA, A., & MIYAWAKI, R. (2012). Local structure of Zn in Cretaceous-Tertiary boundary clay from Stevns Klint. Journal of Mineralogical and Petrological Sciences, 107(5), 192–196. https://doi.org/10.2465/jmps.110606b