Geochemistry of platinum-group elements of the zoned ultramafic Alto Condoto Complex, Northwest Colombia

Tistl, Michael

doi:10.2113/gsecongeo.89.1.158

Cited by 37 publications

(22 citation statements)

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“…Literature data show that the Pt anomaly is also present in hornblendite and hornblendeplagioclase pegmatite from a number of Uralian-Alaskan-type complexes (St. Louis et al 1986;Tistl 1994;Garuti et al 1997a), thus indicating that the chromititedunite event could not consume the Pt content of the magma completely. Unfortunately, we do not have knowledge of the initial concentration of Pt and Ir in the parent melt of the Uktus complex.…”

Section: Origin Of the Pt And Ir Anomalies In Uralian-alaskan-type Mamentioning

confidence: 99%

“…Such a mineralogical specialization is remarkably consistent with geochemical data showing positive anomalies of Pt or Pt plus Ir as distinctive features of the chondritic PGE distribution patterns of Uralian-Alaskan-type dunites and chromitites from all over the world (Fominykh and Kvostova 1970;St. Louis et al 1986;Malitch 1990;Nixon et al 1990;Lazarenkov and Malitch 1991;Tistl 1994;Garuti et al 1997b). These observations reflect an anomalous behavior of Pt which still remains poorly understood.…”

Section: Introductionmentioning

confidence: 97%

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Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia)

et al. 2003

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Chromitite segregations in dunites of the Uktus Uralian-Alaskan-type complex (Central Urals, Russia) display large variation of the chromite composition: Cr/ (Cr+Al)=0.46-0.77, Fe 2+ /(Fe 2+ +Mg)=0.28-0.66, and Fe 3+ /(Fe 3+ +Fe 2+ )=0.23-0.59. Three types of PGM assemblages have been recognized, varying in accordance with chromite composition: type I, dominated by Ru-Os-Ir (sulfides), is associated with magnesiochromite having Fe 3+ /(Fe 3+ +Fe 2+ )<0.30, in the southern dunite body. Type II, containing abundant PtIr (alloys, minor sulfides), is found in magnesiochromite with Fe 3+ /(Fe 3+ +Fe 2+ )=0.40-0.44; type III, consisting of Ir-Rh-Pt-Pd (alloys, sulfarsenides, antimonides) in Fe-rich chromite having Fe 2+ /(Fe 2+ +Mg)=0.66 and Fe 3+ /(Fe 3+ +Fe 2+ )=0.59. Positive anomalies of Ir and Pt, and a negative peak of Ru characterize the PGE patterns of chromitites with type II and III PGM assemblages, whereas a positive Pt anomaly is observed in their dunite host. Intensive fractionation of Pt-Fe alloys in the Uktus chromitites reflects the anomalous behavior of Pt which is decoupled from Rh and Pd. Among other factors, the high iron activity and oxygen fugacity in the parent melt appear to exert a major control on precipitation of Pt-Fe alloys, below sulfur saturation. The strong Pt anomaly in chromitites from Uktus may indicate that Uralian-Alaskan-type magmas were derived from a Pt-rich mantle source.

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Section: Origin Of the Pt And Ir Anomalies In Uralian-alaskan-type Mamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia)

et al. 2003

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“…Over a period of about 180 years, mining operations yielded about 330 tonnes of platinum (Barannikov & Volchenko 1997). These deposits, once the largest PGE deposits in the world, are closely linked to mafic-ultramafic massifs that are located in elongate tectonic belts, developed at convergent plate margins, and termed zoned-type or Alaskan-type massifs (Taylor & Noble 1960, Naldrett & Cabri 1976, Nixon et al 1990, Johan et al 1991, Hattori & Hart 1991, Tistl 1994, Cabri et al 1996 or Uralian-Alaskan-type massifs (Foley et al 1997, Garuti et al 1997 in the western literature. In Russia, however, massifs located within similar tectonic settings are known as of Uralian-type (e.g., Nizhny Tagil, Kytlym, Gal'moenan, etc.…”

Section: Introductionmentioning

confidence: 99%

Pt Fe NUGGETS DERIVED FROM CLINOPYROXENITE DUNITE MASSIFS, RUSSIA: A STRUCTURAL, COMPOSITIONAL AND OSMIUM-ISOTOPE STUDY

Malitch¹,

Thalhammer²

2002

The Canadian Mineralogist

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Combined structural, compositional and osmium-isotope data on selected Pt-Fe nuggets from economically important placer deposits closely linked to clinopyroxenite-dunite massifs of the Siberian Platform (Kondyor, Inagli, Guli) and the Middle Urals (Nizhny Tagil), Russia, are presented for the first time. Pt-Fe alloys investigated are ferroan platinum (space group Fm3m) with a composition close to Pt 3 Fe. This emphasizes the necessity of an X-ray study in identifying the particular Pt-Fe alloy species. Less common are compositions such as Pt 2 Fe and an intimate intergrowth of Pt 3 Fe 2 and PtFe. Other platinum-group minerals (PGM) observed in ferroan platinum include a diversity of Os-Ir-Ru alloys, PGE sulfides [laurite, malanite, cuproiridsite, cooperite, and an unnamed base metal -(Ir,Pt) monosulfide], PGE sulfarsenides (hollingworthite, irarsite), Pt-Pd tellurides (moncheite, telluropalladinite) and stibiopalladinite. This suite of PGM is consistent with those from other zoned or UralianAlaskan-type massifs. However, unusually Ru-rich alloys included in ferroan platinum of Guli are characteristic of PGM derived from an ophiolite source and underline the transitional signature of the Guli massif between zoned-and ophiolite-type complexes. Pd-rich ferroan platinum nuggets indicate a derivation from clinopyroxenite source-rock, whereas Ir-rich Pt-Fe alloys suggest a chromitite source. The presence of numerous Os-Ir-Ru exsolution lamellae in ferroan platinum are indicative of a hightemperature origin of the PGM. The first Os-isotope data from Os-rich minerals from chromitites and placers closely associated to the Kondyor and Inagli massifs reveal low 187 Os/ 188Os values with a very narrow range, indicative of a common mantle source of the PGE, implying that the PGM are of primary origin. Disintegration of parent ultramafic source-rocks and short-range mechanical transport of liberated PGM formed the placers. Os-isotope model ages in the range of 340 to 355 Ma constrain the formation age of the Kondyor and Inagli massifs of the Aldan Province at the southeastern part of the Siberian Craton, and closely match those from the Guli massif (370 Ma) of the Maimecha-Kotui Province at the northern part of the Siberian Craton.

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“…Accessory PGM are found dispersed in dunites (Alto Condoto, Colombia; Kondyor and Galmoenan, Russia), or other mafic lithologies, including pyroxenites and gabbros (Galmoenan, Russia), and magnetite-rich clinopyroxenites (Kachkanar, Russia; Fifield, Australia). The PGM identified by Tistl (1994) in the dunites of the zoned complex of Alto Condoto are mainly Pt-Fe alloys (possibly isoferroplatinum) containing lamellae of native Os (Supplementary Table 3). Tistl (1994) reported a second type of primary PGM mineralization (Viravira-type) within fragments of largely serpentinized, orthopyroxenebearing peridotites (dunite, harzburgite, lherzolite) hosted in high-Mg basalts.…”

Section: Pgm In Dunite Pyroxenite and Gabbromentioning

confidence: 99%

“…The PGM identified by Tistl (1994) in the dunites of the zoned complex of Alto Condoto are mainly Pt-Fe alloys (possibly isoferroplatinum) containing lamellae of native Os (Supplementary Table 3). Tistl (1994) reported a second type of primary PGM mineralization (Viravira-type) within fragments of largely serpentinized, orthopyroxenebearing peridotites (dunite, harzburgite, lherzolite) hosted in high-Mg basalts. The PGM associated with dunite in the Kondyor massif are Pt-Fe alloys located in the interstices of chromite, olivine, and pyroxene aggregates (Rudashevsky et al 1982;Ukhanov et al 1997;Cabri et al 1998).…”

Section: Pgm In Dunite Pyroxenite and Gabbromentioning

confidence: 99%

Petrogenesis of the Platinum-Group Minerals

O’Driscoll¹,

Gonzáléz-Jiménez²

2015

Reviews in Mineralogy and Geochemistry

148

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Geochemistry of platinum-group elements of the zoned ultramafic Alto Condoto Complex, Northwest Colombia

Cited by 37 publications

References 0 publications

Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia)

Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia)

Pt Fe NUGGETS DERIVED FROM CLINOPYROXENITE DUNITE MASSIFS, RUSSIA: A STRUCTURAL, COMPOSITIONAL AND OSMIUM-ISOTOPE STUDY

Petrogenesis of the Platinum-Group Minerals

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