Greg F. Paju HBSc thesis abstract

Thesis Title: 
Nature of alteration associated with Co mineralization in the Bol©o Cu-Co-Zn-Mn deposit
Greg F.

Bol©o is a low-grade, sediment-hosted stratiform Cu-Co-Zn-Mn deposit located midway along the eastern side of the Baja Peninsula. The deposit consists of multiple conformable, laterally extensive horizons of disseminated sulphide and oxide mineralization, which extends over 90 square kilometres.

All four mantos studied display similar mineralogy, but manto 3 contains a greater proportion of both Mn- and Fe-oxides.  Both the breccia and parallel laminated claystone lithofacies have nearly identical mineralogy, but are texturally different, while the massive claystone lithofacies is dominantly composed of chrysocolla and Mn-oxide altered smectite-group clays. The gangue mineralogy of the three alteration facies, sulphide, oxide and mixed sulphide/oxide, are largely similar, except that the oxide facies contains higher, albeit variable, abundances of Mn-and Fe-oxides.

There is no direct correlation between Co concentrations of the lithofacies and mantos, all of which display localized high and low cobalt concentrations. Based on the concentration of Co within the various alteration facies, the higher Co concentrations are associated the sulphide facies, which implies that Co is occurring as a sulphide. Locally, high cobalt grades appear to be associated with high copper grades. As no discernable Co-bearing minerals were identified by optical microscopy and XRD analysis, additional study using SEM-EDS and/or EMP analysis is required to determine the host mineral(s) for Co within the mantos.