Sulfide mineralogy and chalcophile and siderophile element abundances in the Ivrea-Verbano mantle peridotites (Western Italian Alps)

Garuti, Giorgio; Gorgoni, C.; Sighinolfi, G. P.

doi:10.1016/0012-821x(84)90210-3

Cited by 97 publications

(29 citation statements)

References 24 publications

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“…The mantle sulfide assemblage, as observed sub-solidus in peridotite xenoliths and massifs, is typically a combination of pyrrhotite (Fe 1-X S), pentlandite ((Fe,Ni) 9 S 8 ) and chalcopyrite (CuFeS 2 ) (Garuti et al 1984;Szabo and Bodnar 1995). Near the sulfide solidus, there is extensive solid solution between ternary (Fe, Ni, Cu) S mono-sulfide compositions, and for expected Fe-Ni-Cu compositions only a single Mss phase is likely.…”

Section: Iiia Mantle Sulfide Abundances and Petrologymentioning

confidence: 99%

Mantle Pb paradoxes: the sulfide solution

Hart

Gaetani

2006

Contrib Mineral Petrol

113

108

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There is growing evidence that the budget of Pb in mantle peridotites is largely contained in sulfide, and that Pb partitions strongly into sulfide relative to silicate melt. In addition, there is evidence to suggest that diffusion rates of Pb in sulfide (solid or melt) are very fast. Given the possibility that sulfide melt 'wets' sub-solidus mantle silicates, and has very low viscosity, the implications for Pb behavior during mantle melting are profound. There is only sparse experimental data relating to Pb partitioning between sulfide and silicate, and no data on Pb diffusion rates in sulfides. A full understanding of Pb behavior in sulfide may hold the key to several long-standing and important Pb paradoxes and enigmas. The classical Pb isotope paradox arises from the fact that all known mantle reservoirs lie to the right of the Geochron, with no consensus as to the identity of the "balancing" reservoir. We propose that long-term segregation of sulfide (containing Pb) to the core may resolve this paradox.Another Pb paradox arises from the fact that the Ce/Pb ratio of both OIB and MORB is greater than bulk earth, and constant at a value of 25. The constancy of this "canonical ratio" implies similar partition coefficients for Ce and Pb during magmatic processes (Hofmann et al. 1986), whereas most experimental studies show that Pb is more incompatible in silicates than Ce. Retention of Pb in residual mantle sulfide during melting has the potential to bring the bulk partitioning of Ce into equality with Pb if the sulfide melt/silicate melt partition coefficient for Pb has a value of ~ 14. Modeling shows that the Ce/Pb (or Nd/Pb) of such melts will still accurately reflect that of the source, thus enforcing the paradox that OIB and MORB mantles have markedly higher Ce/Pb (and Nd/Pb) than the bulk silicate earth. This implies large deficiencies of Pb in the mantle sources for these basalts. Sulfide may play other important roles during magmagenesis: 1). advective/diffusive sulfide networks may form potent metasomatic agents (in both introducing and obliterating Pb isotopic heterogeneities in the mantle); 2). silicate melt networks may easily exchange Pb with ambient mantle sulfides (by diffusion or assimilation), thus 'sampling' Pb in isotopically heterogeneous mantle domains differently from the silicate-controlled isotope tracer systems (Sr, Nd, Hf), with an apparent 'de-coupling' of these systems.

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Section: Iiia Mantle Sulfide Abundances and Petrologymentioning

confidence: 99%

Mantle Pb paradoxes: the sulfide solution

Hart

Gaetani

2006

Contrib Mineral Petrol

113

108

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“…The sulfides which are enclosed in silicates are believed to represent trapped immiscible melts, enclosed by secondary grain growth of silicates in the upper mantle (Lorand 1987) after the melting event On the other hand, the sulfides which occur as interstitial phases with curvilinear margins molded around silicates represent the solidification of immiscible sulfide liquids that are in equilibrium with the silicate phases (Garuti et al 1984;Lorand 1987). The latter are much more likely to be affected by later metamorphic events.…”

Section: Sulfidesmentioning

confidence: 99%

“…8.2 A Note Regarding the Effect of Serpentinization on Sulfides Garuti et al (1984) reported that pentlandite can be altered to heazlewoodite and magnetite during low-temperature serpentinization. Pyrite can be altered to secondary pyrrhotite, accompanied by the reaction of mack:inawite after pentlandite when the serpentinization is complete (Lorand, 1989a).…”

Section: Mineralogy and Occurrencementioning

confidence: 99%

Petrological and geochemical studies of an abyssal periodotite from the Atlantis II fracture zone

Lee¹

1997

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“…Because of their unique geochemical characteristics, the PGEs can be used to identify the magma sources and unravel the complex petrogenetic processes, such as partial melting, melt percolation, and metasomatism in the mantle [1]. Mafic-ultramafic rocks have lower REE contents but higher PGE contents than other rocks, so the PGEs have advantages in studying their petrogenetic processes [1,[3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Different Origins of the Fractionation of Platinum-Group Elements in Raobazhai and Bixiling Mafic-Ultramafic Rocks from the Dabie Orogen, Central China

Liu

Hou

Xie

et al. 2012

Journal of Geological Research

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Concentrations of the platinum group elements (PGEs), including Ir, Ru, Rh, Pt, and Pd, have been determined for both Raobazhai and Bixiling mafic-ultramafic rocks from the Dabie Orogen by fire assay method. Geochemical compositions suggest that the Raobazhai mafic-ultramafic rocks represent mantle residues after variable degrees of partial melting. They show consistent PGE patterns, in which the IPGEs (i.e., Ir and Ru) are strongly enriched over the PPGEs (i.e., Pt and Pd). Both REE and PGE data of the Raobazhai mafic-ultramafic rocks suggest that they have interacted with slab-derived melts during subduction and/or exhumation. The Bixiling ultramafic rocks were produced through fractional crystallization and cumulation from magmas, which led to the fractionated PGE patterns. During fractional crystallization, Pd is in nonsulfide phases, whereas both Ir and Ru must be compatible in some mantle phases. We suggest that the PGE budgets of the ultramafic rocks could be fractionated by interaction with slab-derived melts and fractional crystallization processes.

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Sulfide mineralogy and chalcophile and siderophile element abundances in the Ivrea-Verbano mantle peridotites (Western Italian Alps)

Cited by 97 publications

References 24 publications

Mantle Pb paradoxes: the sulfide solution

Mantle Pb paradoxes: the sulfide solution

Petrological and geochemical studies of an abyssal periodotite from the Atlantis II fracture zone

Different Origins of the Fractionation of Platinum-Group Elements in Raobazhai and Bixiling Mafic-Ultramafic Rocks from the Dabie Orogen, Central China

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