Platinum-group-mineral inclusions in chromite from the bird river sill, Manitoba

Talkington, W.; Watkinson, David H.; Whittaker, P J; Jones, Peter Tom

doi:10.1007/bf00206212

Cited by 28 publications

(6 citation statements)

References 17 publications

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“…The observed IPGE-bearing PGM inclusion suite in these chromites is very similar or identical to chromite PGM inclusion suites observed in other layered intrusions, such as the Campo Formoso layered intrusion, Brazil (Garuti et al, 2007); the Bird River Sill, Manitoba, Canada (Talkington et al, 1983); and the Stillwater intrusion, Montana, USA (Talkington and Lipin, 1986). The observed IPGE-bearing PGM inclusion suite in these chromites is very similar or identical to chromite PGM inclusion suites observed in other layered intrusions, such as the Campo Formoso layered intrusion, Brazil (Garuti et al, 2007); the Bird River Sill, Manitoba, Canada (Talkington et al, 1983); and the Stillwater intrusion, Montana, USA (Talkington and Lipin, 1986).…”

Section: Origin Of Pge-host Phasessupporting

confidence: 78%

Understanding Re–Os systematics and model ages in metamorphosed Archean ultramafic rocks: A single mineral to whole-rock investigation

Coggon

Luguet

Fonseca

et al. 2015

Geochimica et Cosmochimica Acta

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Section: Origin Of Pge-host Phasessupporting

confidence: 78%

Understanding Re–Os systematics and model ages in metamorphosed Archean ultramafic rocks: A single mineral to whole-rock investigation

Coggon

Luguet

Fonseca

et al. 2015

Geochimica et Cosmochimica Acta

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“…Keays (1982) argued that because Ir, Os, and Ru alloys represent residual mantle phases during mantle melting (Mitchell and Keays, 1981), partial melts should be saturated with Ir and would therefore precipitate an Ir-Os-Ru alloy early during magma evolution. If alloys do commonly form, their small size (e.g., in Bushveld rocks) requires that other minerals (e.g., chromite or olivine) remove them since they will not settle on their own (Hiemstra, 1979;Keays and Campbell, 1981;Talkington et al, 1983). Removal of alloys early in the process of magma evolution might explain the very high Pd/Ir of Leg 115 basalts.…”

Section: Behavior Of Noble Metals During Magma Evolutionmentioning

confidence: 99%

Distribution of Gold, Palladium, Platinum, Rhodium, Ruthenium, and Iridium in Leg 115 Hotspot Basalts: Implications for Magmatic Processes

Greenough¹,

Fryer²

1990

Proceedings of the Ocean Drilling Program

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A comparison of 50 basalts recovered at Sites 706, 707, 713, and 715 along the Reunion hotspot trace during Ocean Drilling Program Leg 115 in the Indian Ocean shows that seafloor alteration had little effect on noble metal concentrations (Au, Pd, Pt, Rh, Ru, and Ir), determined by inductively coupled plasma-mass spectrometry (ICP-MS), which generally tend to decrease with magma evolution. Their compatible-element behavior may be related to the precipitation of Ir-Os-based alloys, chromite, sulfides, and/or olivine and clinopyroxene in some combination. The simplest explanation indicates silicate control of concentrations during differentiation.Basalts from the different sites show varying degrees of alkalinity. Noble metal abundances tend to increase with decreasing basalt alkalinity (i.e., with increasing percentages of mantle melting), indicating that the metals behave as compatible elements during mantle melting. The retention of low-melting-point Au, Pd, and Rh in mantle sulfides, which mostly dissolve before significant proportions of Ir-Os-based alloys melt, explains increasing Pd/Ir ratios with decreasing alkalinity (increasing melting percentages) in oceanic basalts. High noble metal concentrations in Indian Ocean basalts (weighted averages of Au, Pd, Rh, Pt, Ru, and Ir in Leg 115 basalts are 3.2, 8.1, 0.31, 7.3, 0.22, and 0.11 ppb, respectively), compared with basalts from some other ocean basins, may reflect fundamental primary variations in upper-mantle noble metal abundances.

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“…First, an immiscible sulphide PGE/ silicate liquid trapped during chromite precipitation crystallizing at lower temperatures to form PGM sulphide and silicate inclusions. Second, an immiscible PGE alloy liquid is trapped during chromite precipitation and converted to a PGM sulphide by sulphurization [22]. In other possibilities the chromite precipitation may also produce a local increase of sulphur due to Fe 2+ extraction from the magma [23,24].…”

Section: Discussionmentioning

confidence: 99%

“…In other possibilities the chromite precipitation may also produce a local increase of sulphur due to Fe 2+ extraction from the magma [23,24]. The increase of sulphur due to chromite precipitation may be sufficient to convert PGE alloys to sulphides [22], and can be compared with occurrence of PGM in KLC. The KLC magma rich in MgO, SiO 2 and Cr -which is basically shows boninitic or high-Mg andesite in composition [25,26] Ni 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 an island arc basalt affinity and clearly fits in the field of supra subduction zone residual peridotites [27][28][29], which shows the stratiform layered type petrogenetic setting for the KLC chromitites ( Figure 5).…”

Section: Discussionmentioning

confidence: 99%

PGE distribution in the Chromite bearing mafic-ultramafic Kondapalli Layered Complex, Krishna district, Andhra Pradesh, India

Meshram

Nannaware

et al. 2015

Open Geosciences

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Abstract:The Kondapalli Layered Complex (KLC) is a dismembered mafic-ultramafic layered intrusion, mainly composed of gabbroic and anorthositic rocks with subordinate ultramafics and chromitite. Chromitite occurs as lenses, pods, bands and disseminations. Platinum group of minerals (PGMs) occur as inclusions within chromite and silicates. The study indicates an inhomogeneous distribution of PGMs and distinct dominance of IPGEs over the PPGEs. The average ΣPGE content of chromite of KLC varies from 64 ppb to 576 ppb with Pt ranging from 5 to 495 ppb, Pd 5 to 191 ppb, Ir 3 to 106 ppb, Ru 3 to 376 ppb and Rh 3 to 135 ppb. The PGMs identified in the KLC indicate primary deposition of the IPGE, preceding chromite, indicating its orthomagmatic nature. Most of the PGM grains are usually below 10 µm. The identified PGMs are Laurite (RuS 2 ), irarsite (Ir, As, S), iridosmine (Os,Ir), undetermined Os-Ir sulphide and Ru-Os-Ir-Zn alloys. Chromite also contains inclusions of pentlandite, millerite, chalcopyrite and pyrite. Study indicating that the KLC have orthomagmatic origin for PGE which are dominated by IPGE group and formed under surpa-subduction zone peridotite setting.

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Platinum-group-mineral inclusions in chromite from the bird river sill, Manitoba

Cited by 28 publications

References 17 publications

Understanding Re–Os systematics and model ages in metamorphosed Archean ultramafic rocks: A single mineral to whole-rock investigation

Understanding Re–Os systematics and model ages in metamorphosed Archean ultramafic rocks: A single mineral to whole-rock investigation

Distribution of Gold, Palladium, Platinum, Rhodium, Ruthenium, and Iridium in Leg 115 Hotspot Basalts: Implications for Magmatic Processes

PGE distribution in the Chromite bearing mafic-ultramafic Kondapalli Layered Complex, Krishna district, Andhra Pradesh, India

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