PGE and PGM in the Luanga mafic-ultramafic intrusion in Serra dos Carajás (Pará State, Brazil)

The Serra Pelada garimpo (1980)(1981)(1982)(1983)(1984) was the site of the most spectacular gold rush in recent history, but the mineralogy of the bonanza-style mineralization has not so far been documented in detail. Rediscovery of an early drill-core, recovered in 1982 from the near-surface lateritic portion of the garimpo area, has provided coarse-grained gold aggregates for this study. The centimeter-long aggregates of gold occur in powdery, earthy material. They exhibit a delicate arborescent fabric and are coated by goethite. Four compositional types of gold are recognized: palladian gold with an atomic ratio Au:Pd of 7:1 ("Au 7 Pd"), Hgbearing palladian gold (Au-Pd-Hg), Pd-bearing gold with up to 3 wt.% Pd (Pd-poor gold) and pure gold. A number of platinumgroup minerals (PGM) are included in, or attached to the surface of, palladian gold: "guanglinite", Sb-bearing "guanglinite", atheneite and isomertieite, including the noteworthy presence of Se-bearing PGM (Pd-Pt-Se, Pd-Se, Pd-Hg-Se and Pd-Bi-Se phases, and sudovikovite and palladseite). They define an As-Sb-Hg-Se mineral assemblage typical of hydrothermal vein-type deposits formed at relatively low temperatures. Native palladium, characteristically situated in the goethite coating, is intimately associated with a Pd-O phase. The remarkable occurrence of native platinum associated with Pd-bearing gold, PGM (compositionally close to mertieite-II and isomertieite) and berzelianite from a nearby prospect (Elefante prospect) is also recorded.

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“…1988, Diella et al 1995), a few kilometers east-southeast of Serra Pelada. All these rocks were affected by the reactivation (ca.…”

Section: (Traduit Par La Rédaction)mentioning

confidence: 99%

PALLADIUM AND PLATINUM MINERALS FROM THE SERRA PELADA Au-Pd-Pt DEPOSIT, CARAJAS MINERAL PROVINCE, NORTHERN BRAZIL

Cabral

Lehmann

Kwitko-Ribeiro

et al. 2002

The Canadian Mineralogist

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“…However, the present data compilation indicates that high-grade reefs may also occur in smaller intrusions as exemplified by the Luanga intrusion of Brazil (Diella et al, 1995), the Panton sill of Australia Hoatson and Blake, 2000), and the Penikat and Portimo intrusions of northern Finland (Alapieti and Lahtinen, 2002;Iljina and Hanski, 2002). This suggests that the correlation between high-grade reefs and the size of the intrusions is less well founded than commonly believed.…”

Section: Size and Shape Of The Intrusions Geotectonic Settingmentioning

confidence: 89%

Platinum-group element (PGE) deposits and occurrences: Mineralization styles, genetic concepts, and exploration criteria

Maier

2005

Journal of African Earth Sciences

158

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“…Luanga chromitites are characterized by their high Pd/Ir ratios and PGE contents. They have elevated Pt concentrations (up to 8,900 ppb; Diella et al 1995); which are comparable to those of layered mineralized complexes, such as Stillwater Complex, Montana, and UG2, Bushveld Complex (Diella et al 1995;Girardi et al 2006).…”

Section: Introductionmentioning

confidence: 85%

“…Ore minerals are pentlandite, pyrrhotite, millerite, chalcopyrite, mackinawite, Fe-Ni alloy, braggite, sperrylite, and PGE-bearing sulfo-arsenides (Suita 1988;Diella et al 1995). The PGE are hosted in three rock types: (i) meta-pyroxenite cumulate layer with intercumulus pyrrhotite and pentlandite; (ii) folded layers of disseminated to massive chromite (1 mthick and extending for about 1 km), near the contact between mafic and ultramafic units (peridotite/serpentinite); and (iii) chlorite-amphibole-(tremolite-actinolite)-talc mylonite, originated from shearing of the meta-ultramafic rocks (Nunes 2002).…”

Section: Luanga Chrome-pge Depositmentioning

confidence: 99%

Spatial Analysis of Airborne Geophysical Data Applied to Geological Mapping and Mineral Prospecting in the Serra Leste Region, Carajás Mineral Province, Brazil

et al. 2007

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The Serra Leste region, located in the northeast portion of Carajás Mineral Province (PA), hosts important chrome-PGE, Au-Pd-Pt, Cu-Mo-Au, iron, and manganese deposits and occurrences related to different geological settings. We present a regional prospective model with focus on PGE mineralizations based on airborne geophysics (magnetometry, gamma-ray spectrometry and time domain electromagnetometry) and geological data. Geological and geophysics data analysis indicate a plausible correspondence between areas with meta-mafic-ultramafic rocks and low values in gamma spectrometry, mainly for the thorium channel. The meta-ultramafic units of the complexes, the main host rock of the PGE mineralization, are well defined by analytic signal from the anomalous magnetic field and by the apparent conductance anomalies derived from the GEOTEM system. The combination of the derivative products with updated geological data of the Serra Leste region and PGE-Luanga deposit enable to establish a regional prospective model for PGE and the identification of new targets within the studied area.

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PGE and PGM in the Luanga mafic-ultramafic intrusion in Serra dos Carajás (Pará State, Brazil)

Cited by 20 publications

References 5 publications

PALLADIUM AND PLATINUM MINERALS FROM THE SERRA PELADA Au-Pd-Pt DEPOSIT, CARAJAS MINERAL PROVINCE, NORTHERN BRAZIL

PALLADIUM AND PLATINUM MINERALS FROM THE SERRA PELADA Au-Pd-Pt DEPOSIT, CARAJAS MINERAL PROVINCE, NORTHERN BRAZIL

Platinum-group element (PGE) deposits and occurrences: Mineralization styles, genetic concepts, and exploration criteria

Spatial Analysis of Airborne Geophysical Data Applied to Geological Mapping and Mineral Prospecting in the Serra Leste Region, Carajás Mineral Province, Brazil

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