Micro-PIXE elemental imaging of pyrites from the Bulawayan-Bubi Greenstone Belt, Zimbabwe

Micro-PIXE at the NAC nuclear microprobe was used for studies of a sequence of unusual pyrite-bearing carbonate sediments from the east of Turk Mine, Bubi Greenstone Belt, Zimbabwe. This pyrite mineralization shows a variety of textures, and its petrographic interpretation needed more solid geochemical evidence. Elemental maps were obtained using Dynamic Analysis (DA) (a rapid matrix transform method) which forms part of the GeoPIXE software package, and were complemented by point analyses in selected areas. The implemented on-demand beam deflection system allowed for count rates of the order of 3000 counts/s with negligible dead time. The distribution of As and other elements confirmed the petrographic interpretation of three different pyrite generations. In addition, point analyses showed that Sb and Pb were significantly elevated in the zones of As enrichment