Composition and phase chemistry of sulfide globules in basalt from the Mid-Atlantic Ridge rift valley near 37°N lat

Czamanske, Gerald K.; Moore, James G.

doi:10.1130/0016-7606(1977)88<587:capcos>2.0.co;2

Cited by 203 publications

(117 citation statements)

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“…Westerveldite likely formed from minor amounts of Fe present in the Ni-As melt. The globular texture of maucherite, analogous to sulfide globules found in basalts (e.g., Czamanske and Moore, 1977), as well as the presence of nickeline nuclei in some maucherite globules (Fig. 2H) support this interpretation.…”

Section: Geologic Implicationssupporting

confidence: 60%

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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Section: Geologic Implicationssupporting

confidence: 60%

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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“…Czamanske & Moore (1977) speculated that droplets displaying fine-grained textures may have undergone more rapid cooling than coarsegrained droplets. They did not speculate on cause of the textural variability, but did note that it is not linked to the distance of the droplet from the lava surface, i.e., not linked to cooling rate.…”

mentioning

confidence: 99%

“…The textures vary from fine-grained intergrowth of Monosulfide Solid Solution (Mss) and Intermediate Solid Solution (Iss), to coarser-grained intergrowth of Mss and Iss with pentlandite and oxide (Mathez 1976, Czamanske & Moore 1977. and Czamanske & Moore (1977) suggested that such samples quenched from ~1200 °C to 700-600 °C in tens of seconds. With such rapid cooling one might expect the texture of droplets to be similar.…”

mentioning

confidence: 99%

Textural Variations in Morb Sulfide Droplets Due to Differences in Crystallization History

Patten¹,

Barnes²,

Mathez³

2012

The Canadian Mineralogist

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Sulfide droplets from fresh Mid-Ocean-Ridge Basalt (MORB) glasses show different textures. Some are fine-grained droplets consist of Monosulfide Solid Solution (Mss) and Intermediate Solid Solution (Iss) micrometric intergrowths with pentlandite at the Mss-Iss interface and disseminated Fe-oxide grains; other droplets display a characteristic "zoned" texture consisting of segregated massive grains of Mss and Iss, with euhedral Fe-oxides and pentlandite occuring as equant grains and as flame-shaped domains in the Mss formed by exsolutions. The difference in the textures implies a difference in the crystallization history of the sulfide droplets. These different textures are observed in droplets that are only millimeters apart in the same sample, and thus had an identical cooling history. Therefore, some other factors controlled the textural development. There is relationship between the size and the texture of the droplets. The larger sulfide droplets tend to have zoned textures and the smaller ones fine-grained textures. We propose that the latter have experienced greater undercooling before crystallization. The reason for the delay in crystallization could be that, in the small sulfide droplets, large stable grains with low surface to volume ratio cannot form, which results in higher effective solubility of the Mss. Due to the high degree of undercooling in the small droplets, there were numerous nucleation sites and the diffusion rates of the crystal components in the liquid were lower, leading to fine-grained Mss-Iss intergrowths. In contrast, larger droplets with lower effective solubility of Mss began to crystallize at higher temperature, and thus had fewer nucleation sites, higher diffusion rates, and more time for sulfide differentiation.

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“…Studies of sulfide globules occurring in submarine basalts from the MidAtlantic Ridge (37°N, Czamanske and Moore, 1977) show that the globules contain only about 1.5 wt% of the sulfur content in the rock; most of what remains is dissolved in the glass. Other investigations of submarine basalts (Kanehira et al, 1973;Mathez, 1976) and Hawaiian lavas (Desborough et al, 1968) have given similar results.…”

Section: Discussionmentioning

confidence: 99%

Sulfur Isotope Ratios of Leg 126 Igneous Rocks

Torsser¹

1992

Proceedings of the Ocean Drilling Program

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Sulfur isotope ratios have been determined in 19 selected igneous rocks from Leg 126. The δ 34 S of the analyzed rocks ranges from -0.1 o/ 00 to +19.60 o/oo. The overall variation in sulfur isotope composition of the rocks is caused by varying degrees of seawater alteration. Most of the samples are altered by seawater and only five of them are considered to have maintained their magmatic sulfur isotope composition. These samples are all from the backarc sites and have δ 34 S values varying from +0.2 o/oo to +1.6 o/oo , of which the high δ 34 S values suggest that the earliest magmas in the rift are more arc-like in their sulfur isotope composition than the later magmas. The δ 34 S values from the forearc sites are similar to or heavier than the sulfur isotope composition of the present arc.

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Composition and phase chemistry of sulfide globules in basalt from the Mid-Atlantic Ridge rift valley near 37°N lat

Cited by 203 publications

References 0 publications

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

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

Textural Variations in Morb Sulfide Droplets Due to Differences in Crystallization History

Sulfur Isotope Ratios of Leg 126 Igneous Rocks

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