Microstructural evolution and trace element mobility in Witwatersrand pyrite

Reddy, Steven M.; Hough, R. M.

doi:10.1007/s00410-013-0925-y

Cited by 40 publications

(19 citation statements)

References 69 publications

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“…The EBSD data show a relative change in crystallographic orientation for each grain (Figs and ). Consistent with other studies investigating sulphides' crystal plasticity (Reddy and Hough, ), we define high‐angle grain boundaries to have misorientations ≥10°. All boundaries <10° are low‐angle grain boundaries, representing subgrains.…”

Section: Resultsmentioning

confidence: 64%

“… Arsenopyrite is robust, maintaining its trace element content through conditions of high wall‐rock strain and metamorphism. This behaviour stands in contrast to other sulphides such as pyrite, which are characterised by multiple slip systems that can be activated at temperatures as low as 260 °C (Barrie et al ., ; Reddy and Hough, ). Such robust properties for arsenopyrite contribute to our understanding of its common association with world‐class gold deposits. The ability of arsenopyrite to absorb gold into the crystal lattice and as nanoparticles (Cabri et al ., ) establishes a clear link with mineralisation.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast to arsenopyrite, the crystal plasticities of other sulphide phases such as pyrite, pyrrhotite, sphalerite, chalcopyrite, galena, stibnite and pentlandite have been investigated in detail (Kelly and Clark, ; Cox, ; Boyle et al ., ; Barrie et al ., ; Vukmanovic et al ., ). These studies conclude that crystal plasticity of phases such as pyrite occurs relatively easily at temperatures as low as 260 °C and strain rates of approximately 10 −12 –10 −16 s −1 (Barrie et al ., ) and can have a significant impact on trace element mobility (Reddy and Hough, ).…”

Section: Introductionmentioning

confidence: 99%

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The golden ark: arsenopyrite crystal plasticity and the retention of gold through high strain and metamorphism

et al. 2016

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Quantitative electron backscatter diffraction analysis and ion microprobe imaging of gold-rich arsenopyrites provide the first insights into the crystal plasticity and element mobility behaviour of arsenopyrites through metamorphism (340°-460°and 2 kbar). Remarkably, the gold-rich arsenopyrites remained structurally and chemically robust during high strain deformation. It was only during a superimposed lower strain deformation event, at a high angle to the preferred orientation of the arsenopyrites, that small amounts of crystal plasticity affected the arsenopyrites. During the low strain event, a dissolution-reprecipitation reaction resulted in loss of gold from the crystal lattice, facilitated by localised domains of recrystallisation, most likely due to fluid percolation along sub-and new grain boundaries. We suggest that the abundance and rheologically robust nature of gold-rich arsenopyrite in giant gold deposits, affected by greenschistamphibolite metamorphism, is actually critical in the preservation of those deposits.

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Section: Resultsmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The golden ark: arsenopyrite crystal plasticity and the retention of gold through high strain and metamorphism

et al. 2016

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“…Other studies [61][62][63] used EBSD to address the growth of colloform and framboidal pyrite. Reddy and Hough (2013) [64] investigated Witwatersrand pyrite, linking trace element distribution patterns to sulphide deformation, and showed that some of the genetic controversies on the Witwatersrand gold ores can be explained with a model of gold mobilization before and after the re-deposition of pyrite. Iron-(Ti)-oxides are also refractory minerals in which genetic and deformational history can be preserved.…”

Section: Electron Back-scatter Diffraction (Ebsd)mentioning

confidence: 99%

Advances and Opportunities in Ore Mineralogy

et al. 2017

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Abstract:The study of ore minerals is rapidly transforming due to an explosion of new microand nano-analytical technologies. These advanced microbeam techniques can expose the physical and chemical character of ore minerals at ever-better spatial resolution and analytical precision. The insights that can be obtained from ten of today's most important, or emerging, techniques and methodologies are reviewed: laser-ablation inductively-coupled plasma mass spectrometry; focussed ion beam-scanning electron microscopy; high-angle annular dark field scanning transmission electron microscopy; electron back-scatter diffraction; synchrotron X-ray fluorescence mapping; automated mineral analysis (Quantitative Evaluation of Mineralogy via Scanning Electron Microscopy and Mineral Liberation Analysis); nanoscale secondary ion mass spectrometry; atom probe tomography; radioisotope geochronology using ore minerals; and, non-traditional stable isotopes. Many of these technical advances cut across conceptual boundaries between mineralogy and geochemistry and require an in-depth knowledge of the material that is being analysed. These technological advances are accompanied by changing approaches to ore mineralogy: the increased focus on trace element distributions; the challenges offered by nanoscale characterisation; and the recognition of the critical petrogenetic information in gangue minerals, and, thus the need to for a holistic approach to the characterization of mineral assemblages. Using original examples, with an emphasis on iron oxide-copper-gold deposits, we show how increased analytical capabilities, particularly imaging and chemical mapping at the nanoscale, offer the potential to resolve outstanding questions in ore mineralogy. Broad regional or deposit-scale genetic models can be validated or refuted by careful analysis at the smallest scales of observation. As the volume of information at different scales of observation expands, the level of complexity that is revealed will increase, in turn generating additional research questions. Topics that are likely to be a focus of breakthrough research over the coming decades include, understanding atomic-scale distributions of metals and the role of nanoparticles, as well how minerals adapt, at the lattice-scale, to changing physicochemical conditions. Most importantly, the complementary use of advanced microbeam techniques allows for information of different types and levels of quantification on the same materials to be correlated.

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“…Carbon coats should be given to samples to reduce charging effects. Since pyrite is a hard mineral and tends to occur as larger grains, it can provide high quality electron backscatter diffraction patterns, and thus an ideal mineral for EBSD experiment (Barrie et al, 2008(Barrie et al, , 2011Reddy et al, 2013).…”

Section: Ebsd Methodologymentioning

confidence: 99%

Revealing the Evolution History of Orogenic Deposits: Evidence from Pyrite Using the EBSD Technique

Zhang

2014

Acta Geologica Sinica (Eng)

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Microstructural evolution and trace element mobility in Witwatersrand pyrite

Cited by 40 publications

References 69 publications

The golden ark: arsenopyrite crystal plasticity and the retention of gold through high strain and metamorphism

The golden ark: arsenopyrite crystal plasticity and the retention of gold through high strain and metamorphism

Advances and Opportunities in Ore Mineralogy

Revealing the Evolution History of Orogenic Deposits: Evidence from Pyrite Using the EBSD Technique

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