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

• Published in: Journal of Mineralogical and Petrological Sciences Vol. 107; no. 5; pp. 192 - 196
• Main Authors: OKUBE, Maki, SASAKI, Satoshi, YOSHIASA, Akira, WANG, Ling, NAKATANI, Tomotaka, HONGU, Hidetomo, MURAI, Kei-ichiro, NAKATSUKA, Akihiko, MIYAWAKI, Ritsuro
• Format: Journal Article
• Language: English
• Published: Japan Association of Mineralogical Sciences 2012
• Subjects: EXAFS; K-T boundary clay; Local structure of Zn; XAFS; XANES
• ISSN: 1345-6296; 1349-3825
• DOI: 10.2465/jmps.110606b

The local structure around zinc atoms in Cretaceous-Tertiary (K-T) boundary clay from Stevns Klint, Denmark, was studied by Zn K-edge XAFS spectroscopy. XAFS measurements were performed at the BL-12C and BL-9C beamlines at the Photon Factory in the High Energy Accelerator Research Organization (KEK), Japan. The local structure around Zn in the K-T clay resembles the framework structure of the tetrahedral ZnO4 site in the zinc silicate willemite, judging from first shell Zn-O and second shell Zn-cation distances [1.953(3) and 3.51(2) Å, respectively], X-ray absorption near edge structure (XANES) spectra, and radial structure function. The Debye-Waller factor σ2 of the K-T clay sample is similar to those for the tetrahedral sites in crystalline phases, where Zn occupies mainly tetrahedral sites. The local structure of Zn in the K-T clay is peculiar and differs from that found in many clay minerals.