Partition Coefficients for Ni, Cu, Pd, Pt, Rh and Ir Between Monosulphide Solid Solution and Sulphide Liquid and the Implications for the Formation of Compositionally Zoned Ni-Cu Sulphide Bodies by Fractional Crystallization of Sulphide Liquid

1994 ◽  
Vol 58A (1) ◽  
pp. 51-52 ◽  
Author(s):  
S.-J. Barnes
Keyword(s):  
Solid Solution ◽  
Fractional Crystallization ◽  
Partition Coefficients ◽  
Sulphide Liquid

Partition coefficients for Ni, Cu, Pd, Pt, Rh, and Ir between monosulfide solid solution and sulfide liquid and the formation of compositionally zoned Ni – Cu sulfide bodies by fractional crystallization of sulfide liquid

1997 ◽  
Vol 34 (4) ◽  
pp. 366-374 ◽  
Author(s):  
Sarah-Jane Barnes ◽  
E. Makovicky ◽  
M. Makovicky ◽  
J. Rose-Hansen ◽  
S. Karup-Moller
Keyword(s):  
Solid Solution ◽  
Sulfur Content ◽  
Fractional Crystallization ◽  
Copper Sulfide ◽  
Partition Coefficients ◽  
Crystal Fractionation ◽  
Sulfide Liquid ◽  
Monosulfide Solid Solution ◽  
Experimental Systems ◽  
Nickel Copper

Many nickel–copper sulfide orebodies contain Cu- and Fe-rich portions. The Fe-rich ore is generally richer in Os, Ir, Ru, and Rh and poorer in Pt, Pd, and Au than the Cu-rich ore. In komatiite-hosted ores Ni tends to be concentrated in the Cu-rich ore, whereas in tholeiitic ores it tends to be concentrated in the Fe-rich ore. The origin of this zonation could be due to crystal fractionation of Fe-rich monosulfide solid solution from a sulfide liquid. The crystal fractionation would produce an Fe-rich cumulate enriched in Os, Ir, Ru, and Rh and a fractionated liquid enriched in Cu, Pt, Pd, and Au. This model can be tested for zoned orebodies by applying experimentally determined partition coefficients for the metals into monosulfide solid solution. We have compared our experimental results with those of other workers to show that the partition coefficients are strongly influenced by the sulfur content of the system. There is a positive correlation between the partition coefficients and sulfur content of the monosulfide solid solution and between the partition coefficients and the sulfur content of the liquid. In sulfur-saturated and sulfur-over-saturated experimental systems, the metals behave in a manner consistent with the model, that is, Os, Ir, Ru, and Rh are compatible with monosulfide solid solution, Cu, Pd, and Pt are incompatible, and Ni has a partition coefficient close to 1. The use of the experimental partition coefficients is demonstrated in the numerical modelling of a zoned komatiite-related ore (Alexo, Abitibi Greenstone Belt) and a zoned tholeiite-related ore (Oktyabr'sky, Noril'sk region, Siberia). In both cases, the experimental partition coefficients numerically model the composition zones of the actual ores. This supports the model of fractional crystallization of a monosulfide solid solution from a sulfide liquid to form zoned orebodies. Furthermore, it indicates that the experimentally determined partition coefficients are geologically reasonable.

Platinum-group element mineralization in an As-rich magmatic sulphide system, Talnotry, southwest Scotland

2004 ◽  
Vol 68 (2) ◽  
pp. 395-411 ◽  
Author(s):  
M. R. Power ◽  
D. Pirrie ◽  
J. Jedwab ◽  
C. J. Stanley
Keyword(s):  
Solid Solution ◽  
Mineral Assemblage ◽  
Platinum Group Element ◽  
Group Element ◽  
Sulphide Mineralization ◽  
Group Mineral ◽  
Intermediate Solid Solution ◽  
Sulphide Liquid ◽  
Mineral Assemblages ◽  
Platinum Group

AbstractArsenic-rich magmatic sulphide mineralization is hosted by a diorite intrusion at Talnotry, southwest Scotland. A relatively abundant and diverse platinum-group mineral assemblage is present and is dominated by sperrylite, irarsite and electrum with subordinate merenskyite, michenerite and froodite. Early euhedral gersdorffite is enriched with respect to Rh, Ir and Pt and in some cases contains exsolved blebs of irarsite or euhedral grains of sperrylite. Sperrylite is also enclosed within silicates and sulphides indicating that it crystallized directly from an As-rich sulphide liquid. Pyrrhotite-chalcopyrite mineral assemblages are consistent with the fractional crystallization of monosulphide solid solution and are overlain by PGE-, Ni- and As-rich mineral assemblages indicative of crystallization from a NiAs liquid. Late-stage, cross-cutting, electrum-bearing chalcopyrite veins are consistent with the crystallization of Cu- and Au-rich intermediate solid solution. The chemistry, mineralogy and lithological relationships of the diorite suggest that it may be an appinite and as such is potentially analogous to the Au-rich lamprophyre dykes present within southwest Scotland.

The metal-rich portions of the phase system Cu-Fe-Pd-S at 1000°C, 900°C and 725°C: implications for mineralization in the Skaergaard intrusion

2008 ◽  
Vol 72 (4) ◽  
pp. 941-951 ◽  
Author(s):  
S. Karup-Møller ◽  
E. Makovicky ◽  
S.-J. Barnes
Keyword(s):  
Solid Solution ◽  
Electron Microprobe ◽  
Partition Coefficients ◽  
Compositional Data ◽  
Phase System ◽  
Reaction Products ◽  
Skaergaard Intrusion ◽  
Intermediate Solid Solution ◽  
Pd Alloy ◽  
Glass Tubes

AbstractThe sulphur-poor portions of the dry condensed Cu-Fe-Pd-S system were studied at 1000°C, 900°C and 725°C by synthesis in evacuated silicate glass tubes, along with textural observations and electron microprobe analyses of equilibrated reaction products. Sulphide melt coexists with Cu-Fe-Pd alloys, bornite, Fe1-xS and iss (intermediate solid solution, Cabri, 1973) and Pd4S. Compositional data were obtained for the associations bornite-alloy-melt, pyrrhotite-alloy-melt and for immiscible Cu-rich sulphide melts. Partition coefficients for all three metals were derived for the association alloy-melt. Formation of the two new Cu-Pd alloy minerals, skaergaardite and nielsenite, is discussed in terms of the present findings.

scholarly journals REE zoning in allanite related to changing partition coefficients during crystallization: implications for REE behaviour in an epidote-bearing tonalite

2006 ◽  
Vol 70 (4) ◽  
pp. 419-435 ◽  
Author(s):  
J. S. Beard ◽  
S. S. Sorensen ◽  
B. Gieré
Keyword(s):  
Cell Volume ◽  
Fractional Crystallization ◽  
Electron Microprobe ◽  
Partition Coefficients ◽  
Unit Cell Volume ◽  
Sampling Error ◽  
Detection Limits ◽  
Unit Cell ◽  
Statistical Sampling

AbstractAllanite is present in most samples of the tonalitic Bell Island Pluton, with an average mode near 0.05 wt.%. Allanite occurs as cores in igneous epidote-clinozoisite and exhibits characteristic and consistent zoning patterns. REE-rich cores (All40-70) grade out towards epidote-clinozoisite with REE below electron microprobe detection limits. La, Ce and Pr contents are highest in the REE-rich cores of zoned crystals. Nd and Sm contents both initially increase as total REE decreases and are highest in intermediate zones. Y contents are generally low throughout, but tend to be highest in analyses with A115-20. The zoning behaviour exhibited by the allanite, specifically the rimward increases in Nd, Sm, and Y, cannot be accounted for by simple fractionation and are best explained by increases in allanite/ melt partition coefficients (Kd values) for these elements during crystallization. We propose that the variation in Kd values reflects modification of the allanite structure with changing REE content. These modifications are manifested by changes in colour, extinction, and pleochroism within the zoned crystals and include changes in unit-cell volume and dimensions. The changes in Kd values are large enough to result in crossing REE patterns within single allanite crystals. Fractional crystallization of zoned allanite can have noticeable effects on LREE contents and La/Sm (and almost certainly La/Lu) in magmas. In the Bell Island pluton, 80% of La, but <3% of Y is contained in allanite. Although some of the variation in the LREE chemistry of the pluton is attributable to statistical sampling error, much of it appears to reflect petrogenetic processes that controlled LREE abundance and, ultimately, allanite mode. One sample of Bell Island tonalite is depleted in LREE and has low La/Lu and La/Sm. These chemical features can be modelled by fractionation of zoned allanite.

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