Platinum-group minerals in chromite seams of the Stillwater Complex, Montana

Talkington, Raymond W.; Lipin, Bruce R.

doi:10.2113/gsecongeo.81.5.1179

Cited by 96 publications

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“…Osmium and Re concentrations of chromite vary from 5.8 to 15 ppb, and 0.37 to 0.72 ppb, respectively (Table 4). Osmium concentrations of chromite separates are significantly higher than the associated whole rock powders, and are consistent with earlier findings that ophiolite chromites tend to concentrate Os due to the preferential association of Os with alloys or sulfide-bearing minerals which may be included in the chromites (Talkington and Lipin, 1984;Walker et al, 1996;Tsuru et al, 2000;Walker et al, 2002b). The initial 187 Os/ 188 Os ratios of the chromites range from 0.1186 to 0.1273.…”

Section: Re-os Isotopic and Concentration Systematicssupporting

confidence: 90%

Chemical and chronologic complexity in the convecting upper mantle: Evidence from the Taitao ophiolite, southern Chile

Schulte

Schilling

Anma

et al. 2009

Geochimica et Cosmochimica Acta

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Section: Re-os Isotopic and Concentration Systematicssupporting

confidence: 90%

Chemical and chronologic complexity in the convecting upper mantle: Evidence from the Taitao ophiolite, southern Chile

Schulte

Schilling

Anma

et al. 2009

Geochimica et Cosmochimica Acta

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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: 77%

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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“…10). On the other hand, the laurite composition of the Oman ophiolite is quite different from those in some ophiolites and layered intrusions, i.e., New Caledonia (Augé & Maurizot 1995) and Vourinos (Augé 1988) ophiolites, Stillwater Complex, Montana (Talkington & Lipin 1986), and the Bird River Sill complex, Manitoba (Ohnenstetter et al 1986). The laurite in these complexes is usually Ru-rich and Osand Ir-poor relative to those of the first group (Fig.…”

Section: The Oman Ophiolite Among Others: a Comparisonmentioning

confidence: 89%

“…3. Layered intrusions: Stillwater complex, Montana (Talkington & Lipin 1986), and Bird River Sill complex, Manitoba, Canada (Ohnenstetter et al 1986). Garuti et al 1999a, Brenan & Andrews 2001.…”

Section: Origin Of Primary Pgm Assemblagesmentioning

confidence: 99%

Platinum-Group Minerals in Podiform Chromitites of the Oman Ophiolite

Ahmed¹,

Arai²

2003

The Canadian Mineralogist

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Chromitite lenses rich in the platinum-group elements (PGE) have recently been discovered in the deeper part of the mantle section of the northern part of the Oman ophiolite. In terms of stratigraphic level, there are two types of chromitite: Moho transition zone (MTZ) and mantle types. The mantle type can be further classified into two subtypes: PGE-poor and PGE-rich. Platinum-group minerals (PGM) have been mainly observed in the PGE-rich mantle chromitite and, to a lesser extent, in the PGEpoor mantle chromitite, although a few PGM grains have been detected from the MTZ chromitites. The PGM comprise four main categories in the following order of abundance: (1) sulfides [Os-rich laurite, erlichmanite and unnamed (Ir,Rh)(Ni,Cu,Fe) 2 S 3 ], (2) sulfarsenide and arsenide (irarsite-hollingworthite series, palladoarsenide), (3) alloys and native metals [Os-Ir alloy, (Cu-Pt-FeIr-Rh) alloy, Pt-Fe alloy, (Ni-Ru-Os-Ir) alloy, Ir-Pt alloy, Ir-Rh alloy and native Pd metal], and (4) PGE oxide (Ru-Os-Ir oxide). Base-metal sulfides (BMS) and base-metal alloys (BMA) also are found, as inclusions in chromian spinel and interstitial matrix, mainly in the MTZ and PGE-poor mantle chromitites. The common abundance of PGE sulfides, i.e., Os-rich laurite, in the Oman chromitites is ascribed to the sulfide-undersaturated nature of the magma involved in chromitite formation. However, the sulfur fugacity was sufficiently high to produce the Os-rich laurite and, to a lesser extent, erlichmanite and Ru-poor Os-Ir alloy. The sulfur fugacity was higher in the formation of the PGE-poor mantle chromitite relative to the PGE-rich chromitite, as indicated by the presence of the unnamed Ir-rich sulfides and, to a lesser extent, BMS. The presence of PGE oxide commonly associated with fractured chromian spinel indicates that the PGE distribution in rocks can easily be modified at an early stage of serpentinization.Keywords: laurite, chromitite, ophiolite, platinum-group elements, platinum-group minerals, sulfur fugacity, northern Oman. SOMMAIRENous avons récemment découvert des lentilles de chromitite enrichies en éléments du groupe du platine (EGP) dans la partie la plus profonde de la séquence mantellique de la partie nord de l'ophiolite d'Oman. Du point de vue niveau stratigraphique, nous distinguons deux sortes de chromitites, celles qui sont associées à la zone de transition du Moho (MTZ), et celles provenant du manteau sousjacent. Ces dernières comprennent à leur tour deux types, l'un pauvre en EGP et l'autre enrichi en EGP. Les minéraux du groupe du platine se trouvent surtout dans les chromitites mantelliques enrichies en EGP, quoique qu'on en trouve aussi, mais à un degré moindre, dans les chromitites mantelliques à faible teneur en EGP et dans les chromitites de type MTZ. Nous documentons quatre groupes de ces minéraux, présentés ici dans un ordre selon leur abondance: (1) (4) oxyde des EGP (oxyde Ru-Os-Ir). Nous avons aussi trouvé des sulfures et des alliages de métaux de base, en inclusion dans le spinelle chromifère et dans l...

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Platinum-group minerals in chromite seams of the Stillwater Complex, Montana

Cited by 96 publications

References 0 publications

Chemical and chronologic complexity in the convecting upper mantle: Evidence from the Taitao ophiolite, southern Chile

Chemical and chronologic complexity in the convecting upper mantle: Evidence from the Taitao ophiolite, southern Chile

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

Platinum-Group Minerals in Podiform Chromitites of the Oman Ophiolite

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