Gold–palladium mineralization at Bleïda Far West, Bou Azzer–El Graara Inlier, Anti-Atlas, Morocco

Ghorfi, Mustapha El; Oberthür, Thomas; Melcher, Frank; Lüders, Volker; Boukhari, Abdelmajid El; Maacha, Lhou; Ziadi, Rachid; Baoutoul, Hssain

doi:10.1007/s00126-006-0077-3

Cited by 33 publications

(12 citation statements)

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“…Occurrences and ores of hydrothermal PGE-Au dominated mineralization (typically Au>Pd>Pt) are known from the Serra Pelada in Brazil (Meireles et al ., 1982; Moroni et al ., 2001; Şener et al ., 2002; Cabral et al ., 2002 a , b ; Cabral, 2006), from the New Rambler Mine, Wyoming, USA (McCallum et al ., 1976), from the unconformity-related uranium deposits in the Northern Territory of Australia (Jabiluka, Coronation Hill, Gold Ridge; Wilde et al ., 1989; Carville et al ., 1990; Şener et al ., 2002; Wilde, 2005), the Bleïda Far West deposit in Morocco (Barakat et al , 2002; El Ghorfi et al ., 2006), and from unconformity-related, Triassic to early Jurassic mineralization in South Devon, UK (Clark and Criddle, 1982; Gunn and Styles, 2002; Shepherd et al ., 2005).…”

Section: Discussionmentioning

confidence: 99%

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part 1: Geochemistry and ore mineralogy

et al. 2018

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The Waterberg platinum deposit is an extraordinary example of a vein-type hydrothermal quartz-hematite-PGE (platinum-group element) mineralization. This study concentrates on the geochemical character of the ores and the platinum-group mineral (PGM) assemblage by application of reflected-light and scanning electron microscopy followed by electron probe microanalysis.The PGM-bearing quartz veins show multiple banding indicating numerous pulses of fluid infiltration. Mineralization was introduced contemporaneously with the earliest generation of vein quartz and hematite. High oxygen and low sulfur fugacities of the mineralizing fluids are indicated by hematite as the predominant opaque mineral and the lack of sulfides.The ‘Waterberg type’ mineralization is characterized by unique metal proportions, namely Pt>Pd>Au, interpreted as a fingerprint to the cradle of the metals, namely rocks and ores of the Bushveld Complex, or reflecting metal fractionation during ascent of an oxidized, evolving fluid. The PGM assemblage signifies three main depositional and alteration events. (1) Deposition of native Pt and Pt–Pd alloys (>90% of the PGM assemblage) and Pd–Sb–As compounds (Pt-rich isomertieite and mertieite II) from hydrothermal fluids. (2) Hydrothermal alteration of Pt by Cu-rich fluids and formation of Pt–Cu alloys and hongshiite [PtCu]. (3) Weathering/oxidation of the ores producing Pd/Pt-oxides/hydroxides.Platinum-group element transport was probably by chloride complexes in moderately acidic and strongly oxidizing fluids of relatively low salinity, and depositional temperatures were in the range 400–200°C. Alternatively, quartz and ore textures may hint to noble metal transport in a colloidal form and deposition as gels.The source of the PGE is probably in platiniferous rocks or ores of the Bushveld Complex which were leached by hydrothermal solutions. If so, further Waterberg-type deposits may be present, and a prime target area would be along the corridor of the Thabazimbi-Murchison-Lineament where geothermal springs are presently still active.

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Section: Discussionmentioning

confidence: 99%

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part 1: Geochemistry and ore mineralogy

et al. 2018

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“…Details of the geochemistry of the PGE in low-to high temperature hydrothermal and magmatic fluids are presented in Hanley (2005) and a recent review by Barnes and Liu (2012). Evidence of PGE transport and reprecipitation has been observed at various scales and in different geological settings (Augé et al 2005;Bursztyn and Olivo 2010;Cabral et al 2002;El-Ghorfi et al 2006;Molnar et al 2001;Moroni et al 2001;Olivo et al 2001). …”

Section: Role Of Fluids On Pge Distribution and Redistributionmentioning

confidence: 95%

Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Godel

2015

Springer Geology

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“…These deposits display remarkably similar features to Bohaun, typically including abundant hematite, sulphide-poor ore mineral assemblages, an association with brittle structures, open-space textures, variable to typically strongly saline fluids, at temperatures of <300°C. Chloritic alteration is also described from Bleida Far West (Ghorfi et al, 2006) and Coronation Hill (Mernagh et al, 1994). In common with Coronation Hill and South Devon, the Bohaun mineralization is located proximal to major unconformity.…”

Section: Late Stage Brinesmentioning

confidence: 96%

“…Evidence for transport of gold by comparable fluids is seen in red-bed Au-Pd mineralization e.g. Coronation Hill, Australia (Mernagh et al, 1994); South Devon, UK (Shepherd et al, 2005); and Bleida Far West, Morocco (Ghorfi et al, 2006). These deposits display remarkably similar features to Bohaun, typically including abundant hematite, sulphide-poor ore mineral assemblages, an association with brittle structures, open-space textures, variable to typically strongly saline fluids, at temperatures of <300°C.…”

Section: Late Stage Brinesmentioning

confidence: 96%

Atypical Gold Mineralization in an Orogenic Setting--The Bohaun Deposit, Western Irish Caledonides

et al. 2011

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The Bohaun gold deposit in County Galway, western Ireland is located in the Caledonian orogenic belt, proximal to a major accretionary boundary. The mineralization is hosted in a normal extensional fault, representing a zone of repeated extension and vein infilling of open cavities, within clastic sedimentary rocks, which have only reached the late diagenetic zone of low-grade metamorphism.The mineralization consists of undeformed veins, stockworks and breccias. Quartz dominates all the veins and commonly displays multiple growth stages and a variety of classic epithermal textures, including comb, plumose and banded, indicative of low confining pressures. The veins have a simple mineralogy comprising quartz-sericite-chlorite with minor sulfides, hematite, rare visible gold, with a high silver content (up to 41 wt %), and late barite and dolomite.Vein quartz is associated with two fluids compositions: Type I with moderate to high salinity (8.0-23.6 wt % NaCl equiv) and Type II with low to moderate salinity (0.0-7.8 wt % NaCl equiv). CO 2 contents in both fluid types are <3.5 wt percent. The majority of fluid inclusion homogenization temperatures range from 126 to 257 o C and geologically constrained depth estimates (≤5 km) indicate maximum fluid inclusion trapping temperatures between 175 and 245°C.The geodynamic setting of Bohaun, which comprises a deformed continental margin of an allochthonous terrane, is typical of orogenic gold deposits. However, an orogenic association for the Bohaun mineralization is discounted on the basis of fluid inclusion evidence, atypical vein textures, gold grain composition and undeformed veins. While vein textures locally resemble those found in epithermal quartz-adularia mineralization, there is no obvious magmatic association and alteration is restricted to the veins and immediate host rocks. The origin of the gold at Bohaun remains enigmatic. However, we favor an association with widespread Carboniferous or later mineralizing fluids and a model which involves transport and deposition of gold from a basinal brine type fluid, in a similar fashion to red-bed Au-Pd mineralization. Bohaun provides further evidence that low temperature brines may be capable of generating economic grade gold mineralization, independent of other fluids.3

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Gold–palladium mineralization at Bleïda Far West, Bou Azzer–El Graara Inlier, Anti-Atlas, Morocco

Cited by 33 publications

References 36 publications

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part 1: Geochemistry and ore mineralogy

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part 1: Geochemistry and ore mineralogy

Platinum-Group Element Deposits in Layered Intrusions: Recent Advances in the Understanding of the Ore Forming Processes

Atypical Gold Mineralization in an Orogenic Setting--The Bohaun Deposit, Western Irish Caledonides

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