Weathering and precipitation after meteorite impact of Ni, Cr, Fe, Ca and Mn in K T boundary clays from Stevns Klint
Ni, Cr, Fe, Ca and Mn K edge XANES and EXAFS spectra were measured on K T boundary clays from Stevns Klint in Denmark. According to XANES spectra and EXAFS analyses, the local structures of Ni, Cr and Fe in K T boundary clays is similar to Ni(OH)2, Cr2O3 and FeOOH, respectively. It is assumed that the Ni, Cr and Fe elements in impact related glasses is changing into stable hydrate and oxide by the weathering and diagenesis at the surface of the Earth. Ca in K T boundary clays maintains the diopside like structure. Local structure of Ca in K T clays seems to keep information on the condition at meteorite impact. Mn has a local structure like MnCO3 with divalent state. It is assumed that the origin on low abundant of Mn in the Fe group element in K T clays was the consumption by life activity and the diffusion to other parts.