Role of CO2 in the formation of gold deposits
MetadataShow full item record
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.
Showing items related by title, author, creator and subject.
Raman characterization of carbonaceous material in the Macraes orogenic gold deposit and metasedimentary host rocks, New ZealandHu, Siyu; Evans, Katy; Craw, D.; Rempel, Kirsten; Bourdet, J.; Dick, Jeffrey; Grice, Kliti (2015)Raman spectroscopic and petrographic analyses were performed on samples collected from zones distal and proximal to the Macraes gold deposit in the Otago Schist of New Zealand to characterize the features and possible ...
Wu, Yafei (2019)Yafei Wu’s PhD project has explored different ore-forming aspects of a world-class Chinese orogenic gold deposit. The results show that orogenic gold could be sourced from either metamorphism or magmatism. Silica has an ...
Crede, L.; Rempel, Kirsten; Hu, S.; Evans, Katy (2018)Organic matter can be found in many different types of ore deposits, but its role in ore-forming processes is not yet fully understood. Here, we present an experimental method that can be used to determine the partition ...