Applied Mineral Exploration
Discussion and research relevant to mineral exploration.

Home

Rapid fluid inclusion data for exploration (decrepitation)

Topics

Discussion points

Bicycles

Much of global gold production has come from deposits with uneconomic concentrations of base metals, such as copper, lead and zinc. These gold-only deposits are thought to have formed from hot, aqueous fluids rich in carbon dioxide, but only minor significance has been attached to the role of the CO₂ in the process of gold transport. This is because chemical bonding between gold ions and CO₂ species is not strong, and so it is unlikely that CO₂ has a direct role in gold transport. An alternative indirect role for CO₂ as a weak acid that buffers pH has also appeared unlikely, because previously inferred pH values for such gold-bearing fluids are variable. Here we show that such calculated pH values are unlikely to record conditions of gold transport, and propose that CO₂ may play a critical role during gold transport by buffering the fluid in a pH range where elevated gold concentration can be maintained by complexation with reduced sulphur. Our conclusions, which are supported by geochemical modelling, may provide a platform for new gold exploration methods.

Back to main contents