Gold enrichment in active geothermal systems by accumulating colloidal suspensions

Hannington, Mark D., Haroardottir, Vigdis, Garbe-Schönberg, Dieter and Brown, Kevin L. (2016) Gold enrichment in active geothermal systems by accumulating colloidal suspensions Nature Geoscience, 9 (4). pp. 299-302. DOI 10.1038/ngeo2661.

[img] Text
ngeo2661.pdf - Published Version
Restricted to Registered users only

Download (512Kb) | Contact
[img] Text (Supplementary information)
ngeo2661-s1.pdf - Supplemental Material
Restricted to Registered users only

Download (551Kb) | Contact

Supplementary data:

Abstract

The origins of high-grade hydrothermal ore deposits are debated, but active geothermal systems provide important clues to their formation. The highest concentrations of gold are found in geothermal systems with direct links to island arc magmatism. Yet, similar concentrations have also been found in the absence of any input from arc magmas, for example, in the Reykjanes geothermal field, Iceland. Here we analyse brine samples taken from deep wells at Reykjanes and find that gold concentrations in the reservoir zone have increased over the past seven years from an average of 3 ppb to 14 ppb. The metal concentrations greatly exceed the maximum solubility of gold in the reservoir under saturated conditions and are now nearly two orders of magnitude higher than in mid-ocean ridge black smoker fluids—the direct analogues of Reykjanes deep liquids. We suggest that ongoing extraction of brine, the resulting pressure drop, and increased boiling have caused gold to drop out of solution and become trapped in the reservoir as a colloidal suspension. This process may explain how the stock of metal in the reservoirs of fossil geothermal systems could have increased over time and thus become available for the formation of gold-rich ore deposits.

Document Type: Article
Additional Information: WOS:000373374100015
Keywords: economic geology, geochemistry, hydrogeology, gold-rich ore deposits, Reykjanes geothermal field, Iceland
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems > Marine Mineralische Rohstoffe
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Kiel University
Refereed: Yes
DOI etc.: 10.1038/ngeo2661
ISSN: 1752-0894
Projects: Future Ocean
Date Deposited: 04 Apr 2016 13:40
Last Modified: 19 Dec 2017 12:48
URI: http://eprints.uni-kiel.de/id/eprint/31955

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...