Microanalytical investigations of gold-bearing rocks from the An Najadi region in Saudi Arabia

Abstract

The Proton Induced X-ray Emission technique with a scanning microbeam (micro-PIXE) and Scanning Electron Microscopy (SEM) were employed to study gold-bearing rocks from the An Najadi and adjacent regions situated within the exposed northeastern part of the Arabian Shield. These microanalytical investigations, together with routine petrological and ore microscopic studies, demonstrated the presence of important partitioning of major minerals and trace elements in several samples. These measurements also revealed microstructural features including brecciation within quartz grains and metal concentrations within these fracture-controlled micro-conduits. Results showed promise in terms of using distinctive geochemical signatures for ore body recognition. Of particular interest to this study is the presence of an identifiable geochemical trend pertaining to As, Ti, Zn, Cu, Fe and Au. Overall geochemical and petrological data indicate an epithermal mineralization phenomenon for the metal deposits in the An Najadi regions. Mineralization not only postdated brecciation but also followed the regional structural grain of this area.