Bacterially-mediated supergene alteration and redistribution of copper in mineralised rocks at the Salobo IOCG deposit, Brazil

Henne, Anicia; Craw, Dave; Gagen, Emma J.; Southam, Gordon

doi:10.1016/j.oregeorev.2019.103210

Cited by 5 publications

(11 citation statements)

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“…More detailed textural and geochemical observations were made using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) on polished thin sections and freshlybroken surfaces. Details regarding SEM instrument parameters and settings are given in Kerr et al, (2018) and Henne et al, (2019aHenne et al, ( , 2020. Synchrotron X-ray fluorescence microscopy was used on selected samples to obtain relative element-distribution maps of transition metals, with detection limits of ∼100 ppm.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…In laboratory-scale weathering experiments of fresh rocks from the Salobo iron-oxide copper-gold (IOCG) deposit in Brazil, finely laminated metalliferous precipitates were produced within ∼400 days in a biogeochemical system dominated by Acidithiobacillus ferrooxidans, an acidophilic, iron-oxidising bacterium (Henne et al, 2018(Henne et al, , 2019a(Henne et al, , 2020. These experiments were conducted in small-scale (10 cm 3 ) polypropylene columns, partially filled with crushed, weakly mineralised rock.…”

Section: Laminated Precipitates In Laboratory Weathering Experimentsmentioning

confidence: 99%

“…The rocks were dominated by iron-bearing silicates with minor disseminated chalcopyrite and bornite. A strain of A. ferrooxidans was cultured from the Salobo mine site and used for the experiments, as described by Henne et al (2018, 2019a,b, 2020). Samples of the column solutions (2 mL) were obtained every two days and replaced with fresh growth medium to sustain active metabolic activity of bacteria.…”

Section: Descriptions Of Laminated Metalliferous Deposits In Differenmentioning

confidence: 99%

“…Long-term (geological time scales) biologically mediated metal mobility is also of interest for geochemical exploration of mineral deposits (Reith et al, 2012a(Reith et al, , 2015Wakelin et al, 2012b). In addition, the precipitates from long-term biologically mediated metal mobility can be significant for mineral processing and resource economics, especially in settings such as supergene alteration (Nordstrom and Southam, 1997;Enders et al, 2006;Reith et al, 2007Reith et al, , 2013Henne et al, 2019a).…”

Section: Introductionmentioning

confidence: 99%

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Biogeochemical formation of metalliferous laminations in surficial environments

Henne

Craw

Hamilton

et al. 2021

MinMag

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Finely laminated (cm–μm scale) metalliferous precipitates are widespread in the surficial environment, especially around mineral deposits and reflect biogeochemical processes that can pervade near-surface environments on a larger scale. Examples in this paper involve precipitates of the transition metals Fe, Cu and Mn with minor Co, Ni, V and Zn; the metalloids As and Sb; and authigenic Au. Mobility and re-precipitation are driven primarily by geochemical disequilibrium, especially with respect to pH and redox states, that arises from complex interactions between biological processes, geological processes, and variations in the surrounding environment. Different degrees of chemical disequilibrium arise on small spatial scales on time scales of days to millennia. Interactions between biota, waters and rocks in these small near-surface settings affect the biogeochemical environments. Sulfur- and iron-oxidising bacteria are common biogeochemical agents associated with sulfide-bearing lithologies, but localised reductive environments can also develop, leading to gradients in pH and redox state and differential metal mobility. In general, there is commonly a spatial separation of Fe-rich precipitates from those with Cu and Mn, and other transition metals also follow Cu and Mn rather than Fe. Metalloids As and Sb have a strong affinity for Fe under oxidising conditions, but not under more reducing conditions. However, complex biogeochemical parageneses of laminated metalliferous deposits preclude prediction of finer formation details. The textures, mineral species, and metal associations within these deposits are likely to be encountered in all facets of mineral deposit development: initial exploration activity of near-surface locations, mining of shallow portions of orebodies, especially supergene zones, and downstream environmental management with respect to discharging metalliferous waters.

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Section: Methodsmentioning

confidence: 99%