The nickel sulfide deposits of Western Australia in global perspective

Ross, J. R.; Travis, G. A.

doi:10.2113/gsecongeo.76.6.1291

Cited by 23 publications

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“…Suggested classification schemes for these deposits are given by Naldrett and Cabri (1976), Naldrett (1979), and Ross and Travis (1981). Most workers consider these ores to have formed by the separation of an immiscible sulphide liquid from a parent marie or ultramafic silicate magma with subsequent crystallization of sulphides from the melt.…”

Section: Copyright the Mineralogical Societymentioning

confidence: 99%

Pyrrhotine-pentlandite ore textures: a mechanistic approach

Kelly

Vaughan

1983

Mineral. mag.

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ABSTRACT. The kinetics and mechanisms of pentlandite [(Fe,Ni)9Ss] exsolution from the monosulphide solid solution [or MSS (Fe,Ni)l_xS ] have been studied by synthesis and annealing experiments in part of the Fe-Ni-S system particularly relevant to sulphide nickel orebodies. This experimental work has been combined with the examination of the compositions and textures of pyrrhotine-pentlandite intergrowths from a variety of ore deposits. Isothermal annealing of MSS compositions with varying M:S and Fe:Ni ratios at 400 ~ shows the formation of a sequence of textures which depend for their full development chiefly on initial M:S ratio and annealing time. The full sequence of textures starts with heterogeneous nucleation of pentlandite at MSS grain boundaries, the growth of these blebs to form 'rims', nucleation of finer bladed particles arranged 'en 6chelon' along fractures, and, finally, homogeneous nucleation of fine orientated pentlandite lameUae. Using the information from the annealing experiments, the intergrowths produced by cooling in the natural ores are interpreted using a simplified Time-TemperatureTransformation Model.

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Section: Copyright the Mineralogical Societymentioning

confidence: 99%

Pyrrhotine-pentlandite ore textures: a mechanistic approach

Kelly

Vaughan

1983

Mineral. mag.

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“…Nickel-copper sulfide deposits associated with komatiitic rocks in Archean greenstone belts currently account for over 25070 of the world's identified resources of sulfide Ni with greater than 0.8% Ni (Ross and Travis 1981). Field relationships and geochemical data suggest that the sulfides in these deposits are magmatic in origin (Groves et al 1979, Naldrett 1979.…”

Section: Introductionmentioning

confidence: 99%

Controls on the Formation of Komatiite-Associated Nickel-Copper Sulfide Deposits

Lesher

Groves

1986

Special Publication No. 4 of the Society for Geology Applied to Mineral Deposits

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Nickel-copper sulfide deposits associated with rocks of komatiitic affinity may be divided into two associations on the basis of host rock composition and ore distribution: (1) stratiform, massive-matrix-disseminated sulfides hosted by cumulate komatiite lava flows (lava conduits), or strata-bound, coarse disseminated sulfides hosted by cumulate komatiite bodies near volcanic vents, and (2) strata-bound, finely disseminated sulfides and more restricted massive sulfides hosted by subvolcanic komatiitic dunites (high-level magma chambers). These deposits represent a continuum in environments of emplacement from distal volcanic through proximal and central volcanic to subvolcanic.Field relationships and geochemical data suggest that the sulfides in these deposits are magmatic in origin. Previous models for their formation involve derivation of sulfides directly from the mantle or from low-level magma chambers, but there are several field, physical, and thermodynamic constraints which suggest that this may not be feasible: (1) the spatial concentration of mineralization within certain parts of otherwise virtually barren host units suggests that the latter were not uniformly saturated in sulfide at the time of emplacement; (2) there are physical problems in transporting dense sulfides in low viscosity komatiite magmas, although dispersed sulfide droplets may be supported during rapid ascent; and (3) high temperature komatiitic melts generated by high-degree partial melting, or sequential melting, of mantle source rocks are unlikely to be sulfide-saturated in the source region or to remain sulfide-saturated during adiabatic ascent. These deposits are, however, commonly associated with specific country rocks, particularly sulfidic sediments, and the distribution of the ores appears to be related to the distribution of these rocks. It is most likely that the sulfide ores exsolved from the komatiitic magmas in situ, in response to assimilation of the country rocks during emplacement. The distribution and texture of the mineralization was probably influenced by (1) the mode of emplacement (volcanic vs subvolcanic) and amount of assimilation; (2) the relative volume of magma (lava conduit vs magma chamber) and its capacity to dissolve sulfur; and (3) the timing of sulfide separation and opportunity for segregation. A fundamental aspect of this model is the coincidence of cumulate komatiitic host units (representing dynamic lava conduits and magma chambers) and siliceous, sulfidic, or ferric iron oxide-rich sediments, the former representing a source of heat for assimilation and of ore metals, and the latter a source of sulfur or of components to induce sulfide separation. Mineralized greenstones appear to have formed in deeper water under conditions of greater extension than unmineralized greenstones; rifting environments represent the most favorable tectonic environment for voluminous komatiite eruption/irruption and for accumulation of sulfidic sediments. Variations in the degree of extension along or within the r...

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“…1) of the Yilgarn Block (Gee et al 1980) with almost 90% of the pre-mining reserve occurring between Kalgoorlie and Norseman . VPA deposits of Western Australia represent a much more significant component of Australia's ~0.8% nickel resource and production than similar deposits do in southern Africa and Canada (Ross and Travis 1981). The Western Australian volcanic peridotite-associated deposits constitute close to 50% of the identified nickel metal in ores ~0.8% nickel in Australia and to date account for more than 90% of the nickel metal produced by Australia.…”

Section: Introductionmentioning

confidence: 95%

“…These deposits are usually small (several thousand to 5 million tonnes) and high grade (1-50/0 Ni) and are known to occur in the Archaean mafic and ultramafic sequences (Greenstone belts) of Canada (Green and Naldrett 1981), Zimbabwe (Williams 1979) and Western Australia . However from the identified metal resource (Ross and Travis 1981) 52% of the nickel metal occurring in this class of deposit occurs in the Australian deposits with 28% and 20% being contained in the Canadian and southern African deposits respectively.…”

Section: Introductionmentioning

confidence: 99%

Depositional Environments of Volcanic Peridotite-Associated Nickel Sulphide Deposits with Special Reference to the Kambalda Dome

Gresham

1986

Special Publication No. 4 of the Society for Geology Applied to Mineral Deposits

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Volcanic peridotite-associated Fe -Ni sulphide deposits in the Archaean Yilgarn Block of Western Australia display a strong volcanological control on the distribution of individual ore shoots. Although considerably modified by tectonism and amphibolite facies metamorphism, there are distinctive stratigraphic relationships within the host ultramafic komatiite sequence that distinguish ore environments from adjacent areas barren of Fe -Ni sulphides.At the well documented Kambalda Dome deposits, contact ores which occur at the base of the lowermost flow of the ultramafic sequence are commonly confined within narrow (100 -300 m), elongate embayments or troughs in the underlying tholeiitic footwall metabasalt. Hangingwall ores occur at the base of immediately overlying flows and generally directly overlie the troughs and contact ores.Compared to adjacent barren areas, ore environments are characterized by thicker more-magnesian basal ultramafic flows, fewer interflow metasediments and better textural development and compositional differentiation in overlying thin flow units. The ultramafic sequence overlying ore environments is generally less ordered than that in adjacent non-ore environments where there is a more consistent trend of diminishing magnesium content upward through the ultramafic sequence.The major ore-confining troughs are interpreted as original elongate linear depressions within the footwall metabasalt, and some of the local ore-confining structures probably represent original topographic or volcanological features. Ore deposition in an active rift environment may account for the close spatial relationship of contact and hangingwall ores, and the development of the distinctive stratigraphic features of the ore environment. Analogies are drawn with oceanic rift systems and recent submarine volcanism.

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The nickel sulfide deposits of Western Australia in global perspective

Cited by 23 publications

References 0 publications

Pyrrhotine-pentlandite ore textures: a mechanistic approach

Pyrrhotine-pentlandite ore textures: a mechanistic approach

Controls on the Formation of Komatiite-Associated Nickel-Copper Sulfide Deposits

Depositional Environments of Volcanic Peridotite-Associated Nickel Sulphide Deposits with Special Reference to the Kambalda Dome

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