Platinum-group mineralization in the Tertiary Igneous 
Province: new data from Mull and Skye, Scottish Inner Hebrides, UK

Pirrie, Duncan; Power, Matthew; Butcher, Alan R.

doi:10.1017/s0016756800004520

Cited by 9 publications

(14 citation statements)

References 20 publications

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“…Type-2 BMS and PGM crystallized from this fluid phase and are thus locally intimately associated with ferrian chromite. A very similar process was proposed by Coghill & Wilson (1993) for the Great Dyke (but they invoked "microscale" remobilization of PGM, not observed in the Baula Complex), and by Pirrie et al (2000), where a combined orthomagmatic-hydromagmatic origin is proposed for the Mull Complex in Scotland.…”

Section: Synthesissupporting

confidence: 56%

Magmatic and Hydrothermal Platinum-Group Minerals and Base-Metal Sulfides in the Baula Complex, India

Augé

Salpeteur

Bailly

et al. 2002

The Canadian Mineralogist

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The 3 ϫ 0.5 km gabbro-hosted Precambrian Baula Complex, in Orissa, India, comprises a steeply dipping pyroxenite unit in tectonic contact to the east with a peridotite unit that contains three chromitite layers and that becomes pyroxene-rich eastward toward the top. The ultramafic formations are intruded by the Bangur Gabbro, the top of which entered a shear zone, forming a breccia zone. The breccia, 1 to 40 m thick and almost continuous along strike for 2000 m, shows extensive vertical and lateral variations. It is made up of ultramafic blocks of various sizes derived from the Baula Complex within a matrix of hydrothermally altered Bangur Gabbro. The brecciation process has affected one of the chromitite layers. Two categories of platinum-groupelement (PGE) mineralization have been observed in the Baula Complex, both associated with the Bangur Gabbro. The first (type 1) occurs within a sulfide-free magmatic environment within the Bangur Gabbro near its contact with the peridotite, and is clearly formed within a magmatic environment. The PGE-bearing rock contains relics of dunite and chromitite extracted mechanically from the ultramafic formations by the intrusive gabbro. This mineralization is dominated by Pt (Pt/Pd in the range 8-9), is anomalous in Rh, and the platinum-group-mineral (PGM) assemblage is dominated by isoferroplatinum, braggite and malanite, with sperrylite and laurite, included in pyroxene and plagioclase. The second category (types 2A and 2B) is restricted to the hydrothermally altered matrix of the breccia zone. Type 2A has PGE associated with base-metal mineralization; the PGE assemblages are characterized by Pd (Pt/Pd 0.5), and the PGM are mainly sudburyite, minerals of the system Pd-Bi-Te-Sb, and sperrylite. Type 2B is not associated with base metals, the PGE are characterized by Pt (Pt/Pd in the range 2-3), and PGM phases of the Pt-Sb-As system (geversite, sperrylite) coexist with Pd antimony (mertieite-II). The PGE minerals form discrete grains, a) in the hydrous silicate matrix (commonly as clusters) without base-metal sulfides (BMS) or in the silicate matrix accompanying BMS trails, where they are in some cases adjacent to disseminated BMS, b) within ferrian chromite, c) within BMS in silicates, and d) within or adjacent to BMS in ferrian chromite. We present the results of electron-microprobe analyses of the PGM and BMS phases, and propose a model in which type-1 mineralization results from an orthomagmatic episode, whereas the type-2 mineralization is a result of hydromagmatic processes affecting the gabbroic matrix of the complex breccia zone.

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Section: Synthesissupporting

confidence: 56%

Magmatic and Hydrothermal Platinum-Group Minerals and Base-Metal Sulfides in the Baula Complex, India

Augé

Salpeteur

Bailly

et al. 2002

The Canadian Mineralogist

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“…However, it is worth noting that Day et al (2008) reported Os concentrations of > 200 ppb in unit 22 chromitite (an order of magnitude greater than that reported by Barnes and Francis, 1995), suggesting that there may be a degree of intra-reef variability too. Other detailed PGM studies, such as those carried out by Pirrie et al (2000) on chromitites in the ∼ 60 Ma Mull and Skye layered intrusions (British Paleogene Igneous Province) support the general point however, that LMIhosted (stratiform) chromitite seams tend to be enriched in PGM. Furthermore, Halkoaho et al (1990) describe the Sompujärvi PGE Reef at the boundary between the third and fourth megacyclic unit in the Penikat layered intrusion (Finland), noting that where associated with disseminated chromite, the PGE grade is distinctly higher.…”

Section: Petrogenesis Of the Merensky Reef And The Ug2 Chromitite: 'Umentioning

confidence: 86%

Petrogenesis of the Platinum-Group Minerals

O’Driscoll¹,

Gonzáléz-Jiménez²

2015

Reviews in Mineralogy and Geochemistry

147

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“…On Skye, the Cu and Ni Laurite, irarsite, braggite, kotulskite, 1999;Power et al 2000a) s u l phides michenerite, moncheite, electrum, hongshiite, etc. Ben Buie, Mull (Pirrie et al 2000) Chromitite (sulphide-poor) Laurite, irarsite, sperrylite, Pd-Bi-Sb, Pd-Bi-Te, etc. Peridotite Series, Skye (Pirrie et al 2000) Chromitite (largely sulphide-poor) Laurite, sperrylite, ruarsite, Pd-Bi-Te, etc.…”

Section: Geological Settingmentioning

confidence: 99%

“…Ben Buie, Mull (Pirrie et al 2000) Chromitite (sulphide-poor) Laurite, irarsite, sperrylite, Pd-Bi-Sb, Pd-Bi-Te, etc. Peridotite Series, Skye (Pirrie et al 2000) Chromitite (largely sulphide-poor) Laurite, sperrylite, ruarsite, Pd-Bi-Te, etc. Greenland Skaergaard (Bird et al 1991; First appearance of disseminated Cu (Cu,Fe)(Pd,Au,Pt) alloys, electrum, atokite, et al 1998) sulphides zvyagintsevite, hongshiite, kotulskite, etc.…”

Section: Geological Settingmentioning

confidence: 99%

“…1995). In contrast, in the southern North Atlantic Igneous Province, PGE mineralization has only previously been identified in association with ultramafic-hosted chromitites in the central intrusive complexes of Rum (Butcher et al 1999;Power et al 2000a) and Mull and Skye (Pirrie et al 2000) (Table 1). However, on Rum, disseminated sulphides occur around the margin of the West Sgaorishal plug external to the main Rum intrusive centre (Wadsworth, 1994), together with previously undocumented crosscutting sulphide-rich dykes.…”

Section: Introductionmentioning

confidence: 99%

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Diversity of platinum-group element mineralization styles in the North Atlantic Igneous Province: new evidence from Rum, UK

Power

Pirrie

2003

Geol. Mag.

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Two generations of sulphide-hosted platinum-group element mineralization occur in the West Sgaorishal ultramafic plug, Rum. Disseminated Cu and Ni sulphides around the margin of the plug host a restricted platinum-group mineral assemblage that is dominated by Pd bismutho-tellurides and sperrylite (PtAs2) with subordinate electrum (AuAg), froodite (PdBi2) and unidentified Pt–Bi–Te phases. Later sulphide-rich dykes cross-cut the plug and host an assemblage dominated by Pd bismutho-tellurides, sperrylite and locally very abundant paolovite (Pd2Sn). Whole rock combined platinum-group element+Au concentrations are proportional to the sulphide abundance with slightly elevated values in disseminated sulphide lithologies (>400 ppb) and very high values (>2000 ppb) in the sulphide-rich dykes. Both generations have relatively flat chondrite-normalized plots indicating a primitive magmatic source. Negative δ34S values (−9.2 to −18.3 ‰) indicate that the disseminated mineralization is due to contamination probably derived from Jurassic sedimentary rocks leading to sulphur saturation and collection of platinum-group elements. The sulphide-rich dykes must have entrained a platinum-group element-rich sulphide liquid collected from a much larger volume of magma. The presence of platinum-group elements and sulphide-rich dykes with δ34S values between −10.8 and −15.0 ‰ indicates that parts of the Rum Layered Suite became sulphur saturated through magmatic contamination. It appears likely that platinum-group element mineralization styles within the southern North Atlantic Igneous Province are diverse and may be present in a wider variety of mineralogical associations than previously recognized.

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Platinum-group mineralization in the Tertiary Igneous Province: new data from Mull and Skye, Scottish Inner Hebrides, UK

Cited by 9 publications

References 20 publications

Magmatic and Hydrothermal Platinum-Group Minerals and Base-Metal Sulfides in the Baula Complex, India

Magmatic and Hydrothermal Platinum-Group Minerals and Base-Metal Sulfides in the Baula Complex, India

Petrogenesis of the Platinum-Group Minerals

Diversity of platinum-group element mineralization styles in the North Atlantic Igneous Province: new evidence from Rum, UK

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