Multiple carbon and nitrogen sources associated with the parental mantle fluids of fibrous diamonds from Diavik, Canada, revealed by SIMS microanalysis

Petts, Duane C.; Stachel, Thomas; Stern, Richard A.; Hunt, Lucy; Fomradas, G.

doi:10.1007/s00410-016-1231-2

Cited by 11 publications

(2 citation statements)

References 54 publications

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“…in previous studies as evidence for a new growth event from a different fluid (e.g. Boyd et al, 1992;de Vries et al, 2013;Petts et al, 2016;Smart et al, 2011). The N contents and δ 13 C compositions of the monocrystalline outer zones of diamonds 20, 27, and 29 are different to those of their fibrous growth zones.…”

Section: Changes In Hdf and Diamond Carbon Isotope Compositionmentioning

confidence: 81%

N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh fractionation and multiple fluids

et al. 2018

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Six diamonds with a fibrous core, intermediate zone and monocrystalline outer zone ('cloudy diamonds') from the Koffiefontein mine, South Africa, were investigated for N concentrations, carbon isotope compositions and micro-inclusion compositions along core to rim traverses. This study evaluates the nature of the change from fibrous to gem diamond growth and the relation between major element composition of high density fluid inclusions and N−δ 13 C in fibrous growth zones. Three diamonds contain saline to carbonatitic fluid micro-inclusions with constant or increasing carbon isotope values which are inferred to have formed by varying amounts of Rayleigh fractionation in a closed system of a carbonate-bearing fluid. Continuous N−δ 13 C fractionation trends from the fibrous to gem growth zone in two of the diamonds and equally low nitrogen aggregation states indicate formation of diamond shortly before kimberlite eruption from a single fluid without a time gap between fibrous and gem diamond growth. High major element/CO3 2ratios in the growth media resulted in a constant major element composition of the fluid inclusions found in the studied fibrous diamonds. The transition from fibrous to gem diamond growth is likely caused by the precipitation of diamond reducing the degree of oversaturation of carbon in the fluid and hence decreasing the rate of diamond growth. Two other diamonds have inclusions that change from silicate minerals in the inner fibrous growth zones towards pure saline fluid compositions in the outer fibrous growth zones. This decrease in Si, Mg and Ca and increase in K and Cl in the inclusions is accompanied by a decrease in δ 13 C values and N contents. These trends are suggested to be the result from gradually mixing in more saline fluids with lower δ 13 C values. One diamond with silicic inclusions has significant N aggregation into Bcentres, suggesting this fluid is different and that diamond formation occurred significantly (e.g. 1250°C gives ≥10 Ma) before the kimberlite eruption.

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Section: Changes In Hdf and Diamond Carbon Isotope Compositionmentioning

confidence: 81%

N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh fractionation and multiple fluids

et al. 2018

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“…Coated diamonds are principally found in the production from the DRC (Kamiya and Lang 1965;Boyd et al 1987;Akagi and Masuda 1988;Navon et al 1988), although noticeable amounts are recovered from Sierra Leone and Canada (Grantham and Allen 1960;Yelisseyev et al 2004;Petts et al 2016).…”

Section: Coated Stonesmentioning

confidence: 99%

Morphology of Monocrystalline Diamond and its Inclusions

Harris

Smit

Fedortchouk

et al. 2022

Reviews in Mineralogy and Geochemistry

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Formation of unusual yellow Orapa diamonds

et al. 2018

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Twenty eclogitic diamonds from Orapa Mine (Botswana) with an unusual yellow colour are characterised for their growth structure, N systematics, and C isotope composition, and the major element composition of their silicate inclusions. The diamonds show complex luminescence with green, blue and non-luminescent zones and occasional sector zonation. All parts of the diamonds have low total N concentrations (<50 at.ppm, with one exception of <125 at.ppm) and a limited range in C isotope composition (−5.7 to −10.6‰). Fourier Transform Infrared spectra show bands at 1334, 1332, 1282, and 1240 cm −1 typical for Ib-IaA diamonds. Relict unaggregated N defects (N s o and N s +) are present and the preservation is likely caused by the low N concentrations and possible low mantle residence temperatures rather than young diamond formation (inclusion ages of 140, 1096, 1699 Ma; Timmerman et al. Earth Planet Sc Lett 463:178-188, 2017). Garnet and clinopyroxene inclusions extracted from 14 diamonds have an eclogitic composition with relatively low Ca contents and based on all characteristics, these diamonds form a distinct population from Orapa.

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Multiple carbon and nitrogen sources associated with the parental mantle fluids of fibrous diamonds from Diavik, Canada, revealed by SIMS microanalysis

Cited by 11 publications

References 54 publications

N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh fractionation and multiple fluids

N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh fractionation and multiple fluids

Morphology of Monocrystalline Diamond and its Inclusions

Formation of unusual yellow Orapa diamonds

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