The mineralogy and mineral associations of platinum-group elements and precious metals in the Aurora Cu-Ni-Au-PGE deposit, Northern Limb, Bushveld Complex

McFall, Katie; McDonald, Iain; Tanner, Dominique; Harmer, R. E.

doi:10.1016/j.oregeorev.2019.02.008

Cited by 16 publications

(6 citation statements)

References 68 publications

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“…In contrast, pentlandite PGE concentrations from Turfspruit are commonly below the detection limit, except for Pd, which often has concentrations of~10 ppm [22]. The pentlandite PGE concentrations from Aurora display values below tens of ppm for Pt, Rh, Ru, Os and Ir, and 30 ppm for Pd [29], whereas Pd concentrations in pentlandite for the Flatreef can range up to 500 ppm [19]. The pentlandite Pd concentrations display a broad range concerning the location (i.e., Overysel, Sandsloot and Aurora) and the host rock type (cf.…”

Section: Pge In Bmsmentioning

confidence: 96%

“…LA-ICP-MS results reveal pentlandite as the major carrier of Pd (Table 5; Figure 9), whereas chalcopyrite and pyrrhotite host almost no PGE [8,11,12,16,21,29,85]. High Pt and IPGE contents were interpreted to be due to discrete micro-inclusions in pentlandite, or due to the substitution of PGM for Ni and/or Fe in BMS (cf.…”

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

“…Recent investigations on the Aurora limb show a wide range of BMS-S/Se ratios between 774 and 23384 (cf. [29]). However, the here-investigated bulk-samples show S/Se between 454 and 2500, i.e., lower than typical values of mantle and crustal rocks ( Figures 12A and 13).…”

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

“…However, the BMS reaction-textures, and their frequent association with hydrothermal alteration products in the studied clinopyroxenite, suggest that the low S/Se results from secondary S-loss (cf. [29,88,89]). This is supported by a S/Se and S isotope study of primary and secondary sulphides from the Grasvally Norite-Pyroxenite-Anorthosite (GNPA) member of the northern Bushveld limb [72,76].…”

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

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Magmatic PGE Sulphide Mineralization in Clinopyroxenite from the Platreef, Bushveld Complex, South Africa

et al. 2020

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The Platreef, at the base of the northern limb of the Bushveld Complex in South Africa, hosts platinum-group element (PGE) mineralization in association with base-metal sulphides (BMS) and platinum-group minerals (PGM). However, whilst a magmatic origin of the stratiform mineralization of the upper Platreef has been widely confirmed, the processes responsible for the PGE and BMS mineralization and metasomatism of the host rocks in the Platreef are still under discussion. In order to contribute to the present discussion, we present an integrated petrographical, mineral-chemical, whole-rock trace- and major-element, sulphur- and neodymium-isotope, study of Platreef footwall clinopyroxenite drill core samples from Overysel, which is located in the northern sector of the northern Bushveld limb. A metasomatic transformation of magmatic pyroxenite units to non-magmatic clinopyroxenite is in accordance with the petrography and whole-rock chemical analysis. The whole-rock data display lower SiO2, FeO, Na2O and Cr (<1700 ppm), and higher CaO, concentrations in the here-studied footwall Platreef clinopyroxenite samples than primary magmatic Platreef pyroxenite and norite. The presence of capped globular sulphides in some samples, which display differentiation into pyrrhotite and pentlandite in the lower, and chalcopyrite in the upper part, is attributed to the fractional crystallization of a sulphide liquid, and a downward transport of the blebs. In situ sulphur (V-CDT) isotope BMS data show isotopic signatures (δ34S = 0.9 to 3.1 ‰; Δ33S = 0.09 to 0.32‰) close to or within the pristine magmatic range. Elevated (non-zero) Δ33S values are common for Bushveld magmas, indicating contamination by older, presumably crustal sulphur in an early stage chamber, whereas magmatic δ34S values suggest the absence of local crustal contamination during emplacement. This is in accordance with the εNd (2.06 Ga) (chondritic uniform reservoir (CHUR)) values, of −6.16 to −6.94, which are similar to those of the magmatic pyroxenite and norite of the Main Zone and the Platreef in the northern sector of the northern Bushveld limb. Base-metal sulphide textures and S–Se-ratios give evidence for a secondary S-loss during late- to post-magmatic hydrothermal alteration. The textural evidence, as well as the bulk S/Se ratios and sulphide S isotopes studies, suggest that the mineralization in both the less and the pervasively hydrothermally altered clinopyroxenite samples of Overysel are of magmatic origin. This is further supported by the PPGE (Rh, Pt, Pd) concentrations in the BMS and mass-balance calculations, in both of which large proportions of the whole-rock Pd and Rh are hosted by pentlandite, whereas Pt and the IPGE (Os, Ir, Ru) were interpreted to mainly occur in discrete PGM. However, the presence of pentlandite with variable PGE concentrations on the thin section scale may be related to variations in the S content, already at S-saturation during magmatic formation, and/or post-solidification mobilization and redistribution.

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Section: Pge In Bmsmentioning

confidence: 96%

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

Section: Sulphide Mineralization and Distribution Of Pgesmentioning

confidence: 99%

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Magmatic PGE Sulphide Mineralization in Clinopyroxenite from the Platreef, Bushveld Complex, South Africa

et al. 2020

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“…Third, montmorillonite attracts more Cr(III) ions than kaolin 25 . Finally, a significant role in the absorption by bentonite is played by cation exchange reactions 26 and sponge structure of this material 27 . The temperature has an influence on the adsorption by bentonite, namely the adsorption capacity decreases with the increase of temperature due to the spontaneous and exothermic nature of adsorption process 28 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of the remediation of chromium ion contamination with bentonite by terahertz time-domain spectroscopy

Cheng

Huang

Yang

et al. 2022

Sci Rep

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Heavy metal pollution of agricultural and urban soils limits economic progress in the rapidly developing society. Terahertz technology is applied to detect heavy metal pollutants under existence of multiple pathways of their dissemination. In this study, terahertz time-domain spectroscopy (THz-TDS) is employed as an advanced probing technique in combination with traditional detecting methods to measure the adsorption ability of trivalent chromium ions on bentonite. The concentration of chromium ions and the weight of bentonite are known to influence on the adsorption capacity of the latter. It is tested here by both qualitative and quantitative measurements of two mentioned parameters. The adsorption process of chromium ions by bentonite is monitored using THz-TDS. The adsorptions signal from samples at 0.5 THz gradually increases with the increase of bentonite weight or chromium ion concentration. It would appear to indicate that terahertz could be used for quantitative detection of metal ions. Secondly, the ratios of results obtained by inductively coupled plasma mass spectrometry (ICP-MS) and the THz-TDS ones are stabilized at 0.105 ± 0.014 as the bentonite weight or chromium ion concentration increase. Such finding confirms that terahertz technology can be used for the quantitative detection of metal ions. Using the relationship between the ICP-MS test results and the THz-TDS ones, the amplitude value of bentonite is obtained to be 13.925 at the concentration of chromium ions of 0.05 mol/L, the mass of bentonite sample involved in adsorption of 1.5 g, and the detection frequency in THz-TDS measurements of 0.5 THz. The adsorption coefficient of bentonite is calculated to be 1.44%. Increase of the chromium ion concentration to 0.2 mol/L, and the mass of bentonite involved in adsorption to 3 g leads to the increase of the amplitude corresponding to adsorbed chromium ions to about 19.463, and the adsorption coefficient to about 2.1%. Obtained results demonstrate that terahertz technology is promising to meet the ever-increasing requirements in mineral analyses for rapid detection of chemical contaminants and measurement of the adsorption efficiencies of materials.

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Introduction to the special issue on the Flatreef PGE-Ni-Cu deposit, northern limb of the Bushveld Igneous Complex

2020

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More than 30 years ago, Cox and Singer (1986) suggested that magmatic platinum-group element (PGE)-Ni-Cu deposits are amongst the best understood of ore deposits, yet the origin of PGE mineralization in the Bushveld Igneous Complex (BIC) remains controversial after a century of study. In the northern limb of the BIC, the unravelling of ore formation proved particularly difficult due to relatively poor outcrop, which is typically affected by contamination of the intruding magmas with the host rocks and expressed in the form of abundant xenoliths, footwall rafts and disturbance of magmatic stratigraphy. In this thematic issue, we present contributions on the Flatreef, a recently discovered world-class PGE-Ni-Cu deposit constituting a downdip extension of the mineralized unit of the Platreef of the northern limb. Two deep shafts are currently being sunk, making the Flatreef one of the most significant new mine development on the Bushveld in several decades.

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The mineralogy and mineral associations of platinum-group elements and precious metals in the Aurora Cu-Ni-Au-PGE deposit, Northern Limb, Bushveld Complex

Abstract: 2019. The mineralogy and mineral associations of platinum-group elements and precious metals in the Aurora Cu-Ni-Au-PGE deposit, Northern Limb, Bushveld Complex. Ore Geology Reviews 106 , pp. 403-422.

Cited by 16 publications

References 68 publications

Magmatic PGE Sulphide Mineralization in Clinopyroxenite from the Platreef, Bushveld Complex, South Africa

Magmatic PGE Sulphide Mineralization in Clinopyroxenite from the Platreef, Bushveld Complex, South Africa

Characterization of the remediation of chromium ion contamination with bentonite by terahertz time-domain spectroscopy

Introduction to the special issue on the Flatreef PGE-Ni-Cu deposit, northern limb of the Bushveld Igneous Complex

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