MICROANALYTICAL INVESTIGATIONS OF GOLD-BEARING ROCKS FROM THE AN NAJADI REGION IN SAUDI-ARABIA

The Proton Induced X-ray Emission technique with a scanning microbeam (micro-PIXE) and Scanning Electron Microscopy (SEM) were employed to s tudy gold-bearing rocks from the An Najadi and adjacent regions situat ed within the exposed northeastern part of the Arabian Shield. These m icroanalytical investigations, together with routine petrological and ore microscopic studies, demonstrated the presence of important partit ioning of major minerals and trace elements in several samples. These measurements also revealed microstructural features including brecciat ion within quartz grains and metal concentrations within these fractur e-controlled micro-conduits. Results showed promise in terms of using distinctive geochemical signatures for ore body recognition. Of partic ular interest to this study is the presence of an identifiable geochem ical trend pertaining to As, Ti, Zn, Cu, Fe and Au. Overall geochemica l and petrological data indicate an epithermal mineralization phenomen on for the metal deposits in the An Najadi regions. Mineralization not only postdated brecciation but also followed the regional structural grain of this area. (C) 1997 Elsevier Science B.V.