Variability of magmatic sulphide compositions at the Kabanga nickel prospect, Tanzania

Evans, David M.; Byemelwa, L.; Gilligan, Jon

doi:10.1016/s0899-5362(99)00101-3

Cited by 23 publications

(19 citation statements)

References 14 publications

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“…This evolution is parallel to the mg# variation of both pyroxenes. These characteristics strongly suggest that fractional crystallization was the major differentiation mechanism operating in the various magma chambers, as also noted by Evans et al (1999) for the Kabanga intrusion.…”

Section: The Mukanda-buhoro and Musongati Intrusionssupporting

confidence: 70%

“…anorthosites, are not different from the least evolved gabbronorite and pyroxenite. These characteristics suggest (1) that the high Sr initial ratios (second group) probably result from strong local contamination with country rocks, as also observed by Evans et al (1999) in the Kabanga intrusion, and (2) that continuous assimilation during fractional crystallization (AFC process) was not significant. Variations within bodies are not related to structural height in the intrusion and distinct influxes of magma with different isotopic signature cannot be identified.…”

Section: Strontium Initial Ratio In Cumulate Rocksmentioning

confidence: 69%

“…1: ''Boundary Zone'') between the WID and EED domains, together with some A-type granitoids (Tack et al, 1994). These intrusions form the Kabanga-Musongati (KM) alignment, named after the Kabanga intrusion in Tanzania, explored for Ni-sulphides (Evans et al, 1999(Evans et al, , 2000, and the Musongati ultramafic intrusion in Burundi, a potential Ni lateritic deposit (Deblond and Tack, 1999 and references therein; Fig. 1).…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…Such segregation would have depleted the coexisting silicate melt in chalcophile elements and PGE, and olivine would have been strongly depleted in Ni (Thompson and Naldrett, 1984;Naldrett, 1989). Therefore, unlike the occurrence of the Kabanga Ni-sulphide deposits in Tanzania (Evans et al, 1999(Evans et al, , 2000, large bodies of massive Ni-Cu-Co sulphide 3 3 3 3 3 3 3 6 29 3 3.4 9 10 Sr 3 3 3 21 12 47 49 113 162 160 148 179 267 Ba 15 15 41 41 15 15 43 15 174 34 56 47 81 Ni 4048 2983 3377 1591 132 52 12 12 12 12 61 12 12 V 28 12 82 94 414 225 455 208 373 406 337 156 77 Cr 1704 2790 2746 3604 5027 3576 1710 1176 77 104 152 199 12 Zn 53 44 62 70 74 86 78 36 76 68 66 35 27 Co 155 164 150 143 100 92 40 12 37 65 43 12 are not to be expected in the Musongati and Waga bodies in Burundi. On the other hand, S-saturation started du...…”

Section: Cumulate Chemistry the Chromitite Issue And Sulphide Segrementioning

confidence: 99%

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Petrogenesis of the Kabanga–Musongati layered mafic–ultramafic intrusions in Burundi (Kibaran Belt): geochemical, Sr–Nd isotopic constraints and Cr–Ni behaviour

Duchesne

Liégeois

Deblond

et al. 2004

Journal of African Earth Sciences

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A succession of mafic-ultramafic layered intrusions forms an alignment in the boundary zone between the Kibaran belt and the Tanzania craton. The intrusions represent a continuous series of cumulate rocks. For instance, in the Mukanda-Buhoro and Musongati (MBM) contiguous bodies, the series starts with dunite and passes to lherzolite, pyroxenite, norite, gabbronorite and anorthosite on top. Cumulate textures are conspicuous in all rock types and cryptic layering characterises cumulus mineral compositions, thus evidencing fractional crystallization as a major differentiation mechanism. The increase of Cr in the ultramafic members of the series indicates that chromite was not a liquidus mineral in dunite and lherzolite rocks, thus unable to form chromitite layers. The high Ni-content of dunite seems to preclude the existence of conjugate Ni-rich sulphide deposits. The 87 Sr/ 86 Sr initial ratio is relatively constant and averages 0.7087, with some values up to 0.712 due to local assimilation. Fine-grained rocks from the MBM area are isotopically (Nd and Sr) similar to the MBM cumulates. Modelling their crystallization produces cumulus mineral compositions similar to those in the Musongati ultramafic rocks, which suggests a broadly picritic parental magma. On the other hand, finegrained rocks from the Nyabikere area are not related to the Nyabikere cumulates. Nd and Sr isotope ratios show that the MBM magmatism is related to an enriched source, possibly an old subcontinental lithospheric mantle. The Nyabikere dykes, as well as the Waga dykes, come from a depleted mantle source, as do the A-type granitoids occurring in the same boundary zone. Several lines of evidence point to two types of parental magmas, a picritic magma, and a more evolved magma, broadly similar to the Bushveld Main Zone magma.

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Section: The Mukanda-buhoro and Musongati Intrusionssupporting

confidence: 70%

Section: Strontium Initial Ratio In Cumulate Rocksmentioning

confidence: 69%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Cumulate Chemistry the Chromitite Issue And Sulphide Segrementioning

confidence: 99%

See 2 more Smart Citations

Petrogenesis of the Kabanga–Musongati layered mafic–ultramafic intrusions in Burundi (Kibaran Belt): geochemical, Sr–Nd isotopic constraints and Cr–Ni behaviour

Duchesne

Liégeois

Deblond

et al. 2004

Journal of African Earth Sciences

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“…As a consequence, in these deposits, IPGE were previously concentrated into the crystallizing MSS and the residual Asrich sulfide melt became enriched in the most incompatible noble metals, namely Pd, Pt, and Au. Once arsenide melts form, because arsenide melts are significantly denser than sulfide melts, they tend to concentrate by gravitational accumulation in basal regions of magmatic deposits (e.g., Beni Bousera, Gervilla et al, 1996; Kabanga intrusion, Tanzania, Evans et al, 1999). The wetting behavior of arsenide melt against previously solidified sulfide minerals will play an important role in effectively concentrating the arsenide melt.…”

Section: Geologic Implicationsmentioning

confidence: 99%

Partition Coefficients of Platinum Group and Chalcophile Elements Between Arsenide and Sulfide Phases as Determined in the Beni Bousera Cr-Ni Mineralization (North Morocco)

et al. 2013

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The partition coefficients of platinum group elements (PGE) and chalcophile elements Au, Re, Ag, Se, Bi, Te, and Sb, between arsenide and sulfide phases (DAs/sulf) have been estimated by measuring in situ concentrations of these elements using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in coexisting arsenide and sulfide minerals from the Beni Bousera Cr-Ni mineralization (North Morocco). Previous experimental studies and observations on the distribution of PGE in a number of As-rich, Ni-Cu-PGE ore deposits have shown that arsenide minerals may play an important role controlling the distribution of these metals in magmatic sulfide systems. However to date, there is no comprehensive study quantifying the partitioning behavior of these elements when arsenide minerals crystallize either directly from a sulfide melt or from an arsenide melt previously segregated by immiscibility from a sulfide melt. The Beni Bousera mineralization represents an excellent natural laboratory to evaluate these partition coefficients because maucherite (Ni11As8) coexists in equilibrium with pyrrhotite, pentlandite, and chalcopyrite in form of globules mostly associated with pyrrhotite, and arsenide and sulfide minerals account for the bulk of the PGE (with the exception of Pt) and chalcophile elements in the samples. The laser ablation analyses reveal that maucherite is strongly enriched in all chalcophile elements, except Se, relative to sulfide minerals. The calculated DPGEAs/sulf are the following: DIrAs/sulf = 920 DRhAs/sulf = 620, DPtAs/sulf = 330, DPdAs/sulf = 250, DOsAs/sulf = 140, and DRuAs/sulf = 50. For the rest of elements, the obtained values are the following: DSbAs/sulf = 890, DTeAs/sulf = 190, DBiAs/sulf = 50, DReAs/sulf = 6, DAuAs/sulf = 310, DAgAs/sulf = 4, and DSeAs/sulf = 0.6. These results clearly highlight the strong affinity of PGE for arsenide phases and the importance of these phases as potential carriers of PGE in Ni-Cu-PGE ore deposits.

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The Kabanga Ni sulfide deposit, Tanzania: I. Geology, petrography, silicate rock geochemistry, and sulfur and oxygen isotopes

et al. 2010

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Variability of magmatic sulphide compositions at the Kabanga nickel prospect, Tanzania

Cited by 23 publications

References 14 publications

Petrogenesis of the Kabanga–Musongati layered mafic–ultramafic intrusions in Burundi (Kibaran Belt): geochemical, Sr–Nd isotopic constraints and Cr–Ni behaviour

Petrogenesis of the Kabanga–Musongati layered mafic–ultramafic intrusions in Burundi (Kibaran Belt): geochemical, Sr–Nd isotopic constraints and Cr–Ni behaviour

Partition Coefficients of Platinum Group and Chalcophile Elements Between Arsenide and Sulfide Phases as Determined in the Beni Bousera Cr-Ni Mineralization (North Morocco)

The Kabanga Ni sulfide deposit, Tanzania: I. Geology, petrography, silicate rock geochemistry, and sulfur and oxygen isotopes

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