Decoupling of Au and As during rapid pyrite crystallization
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 microscopy, electron backscatter diffraction, nanoscale secondary ion mass spectr...
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| Format: | Journal Article |
| Language: | English |
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GEOLOGICAL SOC AMER, INC
2021
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| Online Access: | http://purl.org/au-research/grants/arc/DE190101307 http://hdl.handle.net/20.500.11937/91629 |
| _version_ | 1848765563224981504 |
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| author | Wu, Y. Evans, Katy Hu, S. Fougerouse, Denis Zhou, M. Fisher, L.A. Guagliardo, P. Li, J. |
| author_facet | Wu, Y. Evans, Katy Hu, S. Fougerouse, Denis Zhou, M. Fisher, L.A. Guagliardo, P. Li, J. |
| author_sort | Wu, Y. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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 microscopy, electron backscatter diffraction, nanoscale secondary ion mass spectrometry, and laser ablation–multicollector–inductively coupled plasma–mass spectrometry to constrain the processes that sequester Au into zoned pyrite in the hydrothermal cement of breccia ores from the world-class Daqiao orogenic Au deposit, central China. Euhedral pyrite cores with oscillatory and sector zoning, variable δ34S values, and lower Au-As contents than the mantles are attributed to crystallization during oxidation of metal-depleted ore fluids with local variation in fluid conditions. The isotopically uniform colloform mantles are formed by pyrite crystallites separated by low-angle boundaries and are characterized by unusual decoupling of Au and As. Mantle formation is attributed to rapid disequilibrium precipitation from a metal-rich FeS2-supersaturated fluid. Incorporation of Au into the pyrite mantles was facilitated by abundant lattice defects produced by rapid nucleation. Gold-As–poor pyrite rims were deposited from an evolved ore fluid or other metal-depleted fluids. These results show that chemical variations recorded by fine layering within minerals can provide valuable insights into disequilibrium mass transfer and ore formation. The decoupling between Au and As in pyrite mantles indicates that As is not always a reliable proxy for Au enrichment in rapidly crystallized porous pyrite. |
| first_indexed | 2025-11-14T11:37:14Z |
| format | Journal Article |
| id | curtin-20.500.11937-91629 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:37:14Z |
| publishDate | 2021 |
| publisher | GEOLOGICAL SOC AMER, INC |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-916292023-05-17T07:48:01Z Decoupling of Au and As during rapid pyrite crystallization Wu, Y. Evans, Katy Hu, S. Fougerouse, Denis Zhou, M. Fisher, L.A. Guagliardo, P. Li, J. Science & Technology Physical Sciences Geology GOLD DEPOSIT SULFUR DISEQUILIBRIUM PRECIPITATION FRACTIONATION ISOTOPES TEXTURES SULFIDE 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 microscopy, electron backscatter diffraction, nanoscale secondary ion mass spectrometry, and laser ablation–multicollector–inductively coupled plasma–mass spectrometry to constrain the processes that sequester Au into zoned pyrite in the hydrothermal cement of breccia ores from the world-class Daqiao orogenic Au deposit, central China. Euhedral pyrite cores with oscillatory and sector zoning, variable δ34S values, and lower Au-As contents than the mantles are attributed to crystallization during oxidation of metal-depleted ore fluids with local variation in fluid conditions. The isotopically uniform colloform mantles are formed by pyrite crystallites separated by low-angle boundaries and are characterized by unusual decoupling of Au and As. Mantle formation is attributed to rapid disequilibrium precipitation from a metal-rich FeS2-supersaturated fluid. Incorporation of Au into the pyrite mantles was facilitated by abundant lattice defects produced by rapid nucleation. Gold-As–poor pyrite rims were deposited from an evolved ore fluid or other metal-depleted fluids. These results show that chemical variations recorded by fine layering within minerals can provide valuable insights into disequilibrium mass transfer and ore formation. The decoupling between Au and As in pyrite mantles indicates that As is not always a reliable proxy for Au enrichment in rapidly crystallized porous pyrite. 2021 Journal Article http://hdl.handle.net/20.500.11937/91629 10.1130/G48443.1 English http://purl.org/au-research/grants/arc/DE190101307 GEOLOGICAL SOC AMER, INC restricted |
| spellingShingle | Science & Technology Physical Sciences Geology GOLD DEPOSIT SULFUR DISEQUILIBRIUM PRECIPITATION FRACTIONATION ISOTOPES TEXTURES SULFIDE Wu, Y. Evans, Katy Hu, S. Fougerouse, Denis Zhou, M. Fisher, L.A. Guagliardo, P. Li, J. Decoupling of Au and As during rapid pyrite crystallization |
| title | Decoupling of Au and As during rapid pyrite crystallization |
| title_full | Decoupling of Au and As during rapid pyrite crystallization |
| title_fullStr | Decoupling of Au and As during rapid pyrite crystallization |
| title_full_unstemmed | Decoupling of Au and As during rapid pyrite crystallization |
| title_short | Decoupling of Au and As during rapid pyrite crystallization |
| title_sort | decoupling of au and as during rapid pyrite crystallization |
| topic | Science & Technology Physical Sciences Geology GOLD DEPOSIT SULFUR DISEQUILIBRIUM PRECIPITATION FRACTIONATION ISOTOPES TEXTURES SULFIDE |
| url | http://purl.org/au-research/grants/arc/DE190101307 http://hdl.handle.net/20.500.11937/91629 |