Gold, arsenic, and copper zoning in pyrite: A record of fluid chemistry and growth kinetics
MetadataShow full item record
Chemical zoning in minerals records fluid-rock interaction and crystal growth kinetics via texturally complex features, the genesis of which remains a subject of debate. Here, we combined nanoscale secondary ion mass spectrometry (NanoSIMS) and atom probe tomography to better characterize trace-element zoning in a gold (Au)-rich pyrite crystal from the Daqiao epizonal orogenic Au deposit, China. Observations on the micron to atomic scale were used to recognize the multiple processes and mechanisms that created the zoning. Chemically distinct, micron-scale concentric zones of pyrite formed in response to changing fluid composition in a dynamic hydraulic fracturing environment. At a smaller scale, within an Au-rich zone, sector zones of Au, As, and Cu at the micron to sub-micron scale were controlled by the structure of the crystal surface. Micron-scale patchy distribution of Au, As, and Cu and atomic-scale transitions from homogeneous to heterogeneous "island" arsenian pyrite formed as a consequence of heteroepitaxial Stranski-Krastanov growth. Nanoscale Au oscillatory zoning is interpreted as a consequence of diffusion-limited self-organization processes at the crystal-fluid interface. The multiple scales of observation enabled us to see how kinetically driven intrinsic processes interacted with extrinsic factors (e.g., pressure decreases) to produce the complexity in mineral zoning. Nanoscale heterogeneities in Au, As, and Cu present as solid solution in pyrite suggest that interpretation of spikes on microbeam-derived depth-concentration profiles as metallic particles should be treated with caution.
Showing items related by title, author, creator and subject.
Metal remobilization and ore-fluid perturbation during episodic replacement of auriferous pyrite from an epizonal orogenic gold depositWu, Y.; Evans, Katy; Li, J.; Fougerouse, Denis; Large, R.; Guagliardo, P. (2019)Mineral-scale episodic replacement of auriferous pyrite by texturally-complex pyrite, marcasite and minor arsenopyrite occurred in breccia ores from the Daqiao epizonal orogenic gold deposit, West Qinling Orogen, China. ...
Wu, Y.; Evans, Katy ; Hu, S.; Fougerouse, Denis ; Zhou, M.; Fisher, L.A.; Guagliardo, P.; Li, J. (2021)Gold (Au) is largely hosted by pyrite in a variety of hydrothermal systems, but the incorporation of Au into pyrite under disequilibrium conditions remains poorly understood. We integrate synchrotron X-ray fluorescence ...
Trace element zoning of sulfides and quartz at sheba and fairview gold mines: Clues to mesoarchean mineralisation in the barberton greenstone belt, south africaAgangi, Andrea; Hofmann, A.; Przybylowicz, W. (2014)The Fairview and Sheba mines are two of the major gold mines in the Paleoarchean Barberton Greenstone Belt of Southern Africa. At these mines, gold is associated with quartz-carbonate. ±. rutile veins and occurs both as ...