Deposits in the porphyry copper family include porphyry copper ones proper (Au to 0.3-0.4 ppm, Cu/100Au usually 500-2000) and porphyry ones (Au 0.5-3 ppm, Cu/100Au 11-150), which are distinguished by the markedly different gold contents in the sulfides (respectively 0.01-0.8 and 1-11 ppm). The apical levels in deposits of the porphyry copper type proper often have zones where there are high-gold pyrites, which shows that gold can accumulate selectively in the upper parts of porphyry copper columns with the formation of porphyry copper-gold deposits and also the Au-Ag polymetallic type. The latter usually are characterized by subvolcanic emplacement conditions.
|Состояние||Опубликовано - сен 1996|
ASJC Scopus subject areas
- Geochemistry and Petrology