Formation and Deformation of Pyrite and Implications for Gold Mineralization in the El Callao District, Venezuela

Velásquez, Germán; Béziat, Didier; Salvi, Stefano; Siebenaller, Luc; Borisova, Anastassia Y.; Pokrovski, Gleb S.; Parseval, Philippe de

doi:10.2113/econgeo.109.2.457

Cited by 121 publications

(59 citation statements)

References 54 publications

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“…The small gold inclusions in the pyrite probably represent co-precipitation of gold with this sulfide (e.g., Simon et al, 1999;Reich et al, 2005). The fact that free gold is commonly associated with silver and other metals such as Te, Bi, Pb -i.e., the same elements that were found in the pyrite structure -and that these metals correlate well with silver, suggests that some remobilisation may have taken place, i.e., that some leaching of pyrite could have produced secondary concentrations of gold in association with these metals (cf., Velásquez et al, 2014). This was probably a localized phenomenon, that reflects a continuum of precipitation/dissolution, as fluid saturation with respect to gold changed in the mineralizing system, as suggested by the variable amount of invisible gold found in pyrites.…”

Section: Discussionmentioning

confidence: 95%

Geology and geochemistry of the shear-hosted Julie gold deposit, NW Ghana

Amponsah

Salvi

Béziat

et al. 2015

Journal of African Earth Sciences

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Section: Discussionmentioning

confidence: 95%

Geology and geochemistry of the shear-hosted Julie gold deposit, NW Ghana

Amponsah

Salvi

Béziat

et al. 2015

Journal of African Earth Sciences

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“…6a). In orogenic deposits, the analysed pyrite is related to a large variety of protholith including: black shales, intermediate volcanic rocks, granitic rocks and felsic porphyries, banded iron formations; and host-rocks include: dolerite, basalts, metabasalts, syenite, and ryodacite (Ho et al, 1995;Large et al, 2007;Wood and Large 2007;Morey et al, 2008;Cook et al, 2009;Sung et al, 2009;Thomas et al, 2011;Valásquez et al, 2014). Most pyrite analyses in these systems cluster within the same area in Au-As plots.…”

Section: Orogenic Au Depositsmentioning

confidence: 99%

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

Deditius¹,

Reich²,

Kesler³

et al. 2014

Geochimica et Cosmochimica Acta

440

205

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The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au,

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“…Extreme growth rates (and largest degrees of oversaturation) yield submicronsized raspberry-textured ("framboid") pyrite. Such textures have not been observed in NWA 7533, nor is there evidence of multistage growths marked by framboidal cores and euhedral rims (e.g., McClay and Ellis 1983;Velasquez et al 2014). Cubes have the lowest Gibbs free energy of formation and their {100} faces the lowest atom density and the highest growth rate, which makes cubic crystals and cubo-octahedra form spontaneously from H 2 S fluids, without requiring a high degree of supersaturation (Wang et al 2010;Barnard and Russo 2007).…”

Section: Pyrite Growth Processes In Regolith Brecciasmentioning

confidence: 99%

Nickeliferous pyrite tracks pervasive hydrothermal alteration in Martian regolith breccia: A study in NWA 7533

Lorand

Hewins

Rémusat

et al. 2015

Meteorit & Planetary Scien

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Martian regolith breccia NWA 7533 (and the seven paired samples) is unique among Martian meteorites in showing accessory pyrite (up to 1% by weight). Pyrite is a late mineral, crystallized after the final assembly of the breccia. It is present in all of the lithologies, i.e., the fine‐grained matrix (ICM), clast‐laden impact melt rocks (CLIMR), melt spherules, microbasalts, lithic clasts, and mineral clasts, all lacking magmatic sulfides due to degassing. Pyrite crystals show combinations of cubes, truncated cubes, and octahedra. Polycrystalline clusters can reach 200 μm in maximum dimensions. Regardless of their shape, pyrite crystals display evidence of very weak shock metamorphism such as planar features, fracture networks, and disruption into subgrains. The late fracture systems acted as preferential pathways for partial replacement of pyrite by iron oxyhydroxides interpreted as resulting from hot desert terrestrial alteration. The distribution and shape of pyrite crystals argue for growth at moderate to low growth rate from just‐saturated near neutral (6 < pH<10), H2S‐HS‐rich fluids at minimum log fO2 of >FMQ + 2 log units. It is inferred from the maximum Ni contents (4.5 wt%) that pyrite started crystallizing at 400–500 °C, during or shortly after a short‐duration, relatively low temperature, thermal event that lithified and sintered the regolith breccias, 1.4 Ga ago as deduced from disturbance in several isotope systematics.

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Formation and Deformation of Pyrite and Implications for Gold Mineralization in the El Callao District, Venezuela

Cited by 121 publications

References 54 publications

Geology and geochemistry of the shear-hosted Julie gold deposit, NW Ghana

Geology and geochemistry of the shear-hosted Julie gold deposit, NW Ghana

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

Nickeliferous pyrite tracks pervasive hydrothermal alteration in Martian regolith breccia: A study in NWA 7533

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