DIAGENETIC HISTORY OF SEDIMENTARY CARBONATES - CONSTRAINTS FROM COMBINED CATHODOLUMINESCENCE AND TRACE-ELEMENT ANALYSES BY MICRO-PIXE

Trace element data for a succession of cements can contribute to the reconstruction of the diagenetic history of sediments. In the case of carbonate cements, cathodoluminescence (CL) microscopy has been successfully utilized for qualitative description of different cementation environments. In order to interpret correctly CL colour, trace element data other than Mn and Fe are often required. Due to frequent microscale zonation of trace elements in natural calcites and due to their low threshold concentration for CL activation, microsampling techniques with high spatial resolution and low detection limits are required. In this case study, trace element concentrations have been correlated with the CL behaviour of carbonate cements using the Bochum proton microprobe (PIXE) and a hot cathode luminescence device. The CL patterns, including the fine zonation, correlate well with the trace element distribution.