Geochemical assemblages in orogenic gold deposits of the Abitibi greenstone belt, Canada: constraints from PCA analysis

Major and trace element composition of ore-bearing rocks from ten orogenic gold deposits in Canada was systematically analyzed. These data were used to unravel the relationship among elements, as well as the host rock, alteration and mineralization by principal component analysis (PCA). Results show that Re is coupled with Au but decoupled from Mo, indicating that Re is associated with Au-bearing phases rather than molybdenite. This demonstrates that Re-Os age of pyrite in gold deposits can represent the timing of Au mineralization. The lithophile elements and alteration minerals can be discriminated from each other by the defined principle components with characteristic element assemblages. The visible close association of PGE, Hg, and W implies that they were formed by the hydrothermal process. PGE were mobilized at around 300 degrees C. Importantly, the size-fraction analyses provide detailed information on the nature and extent of the alteration associated with orogenic gold deposits.