Multiple growth events during diamond genesis: an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stones

Boyd, Stuart R.; Mattey, D. P.; Pillinger, C. T.; Milledge, H. J.; Mendelssohn, M.J.; Seal, M.

doi:10.1016/0012-821x(87)90231-7

Cited by 191 publications

(62 citation statements)

References 15 publications

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“…Nitrogen in fluid inclusions of Mid-Ocean Ridge Basalts (MORB) sampling the underlying mantle and of fibrous diamonds derived from the subcontinental mantle is depleted in 15 N by a few parts per mil relative to the atmosphere (δ 15 N ATM = -3 to -7 ‰: Javoy et al, 1984: Boyd et al, 1987: Javoy and Pineau, 1991: Marty and Humbert, 1997: Nishio et al, 1999: Marty and Zimmermann, 1999. Javoy et al (1984) proposed that the light N component in the mantle is a remnant of a N isotopic composition found in enstatite chondrites (δ 15 N = -30 to -40 ‰).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Yokochi

Marty

Chazot

et al. 2009

Geochimica et Cosmochimica Acta

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International audienceIn order to document the origin and speciation of nitrogen in mantle-derived rocks and minerals, the N and Ar contents and isotopic compositions were investigated for hydrous and anhydrous peridotite xenoliths from Ataq, Yemen, from Eifel, Germany, and from Massif Central, France. Nitrogen and Ar were extracted by stepwise combustion with a fine temperature resolution, followed by fusion in a platinum crucible. A large isotopic disequilibrium of up to 25.4‰ is observed within single peridotite xenoliths, with δ15N values as low as −17.3‰ in phlogopite whereas clinopyroxene and olivine show positive δ15N values. Identical Sr isotopic ratios of phlogopite, clinopyroxene and whole rock in this wehrlite sample are consistent with crystallization from a common reservoir, suggesting that the light N signature of phlogopite might be the result of isotopic fractionation during N uptake from the host magma. The nitrogen concentration is systematically high in phlogopite, (7.6–25.7 ppm), whereas that of bulk peridotite xenoliths is between 0.1 and 0.8 ppm. The high N content of phlogopite is at least partly due to host magma–mineral interaction, and may also suggest the occurrence of N as View the MathML source that substituted for K+ during mineral growth in mafic magmas. Such speciation is consistent with the fact that N and Rb contents correlate well for a set of samples from mantle regions that were affected by subduction-related metasomatism and magmatism. The N/Rb ratios of these samples are comparable with values estimated for subduction zone magmas, but are one order of magnitude lower than the N/Rb ratios characterizing subducting slabs. This difference suggests preferential release of N relative to alkalis in the forearc region. N/40Ar* ratios of minerals from analyzed mantle xenoliths are much higher than those of vesicles in MORBs and OIBs, requiring either the occurrence of nitrogen speciation in the mantle more compatible than Ar, significant loss of fluid phase during entrainment, or long residence time of volatile elements in the mantle source(s) of fluids to increase drastically the 40Ar* budget of the latter

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Section: Introductionmentioning

confidence: 99%

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Yokochi

Marty

Chazot

et al. 2009

Geochimica et Cosmochimica Acta

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“…An IR study disclosed that the inclusions still re tain pressure corresponding to that of the upper mantle (Navon, 1991). The diamonds are valuable sources of information about the composition of fluids in the upper mantle (Akagi and Masuda, 1988;Navon et al, 1988;Boyd et al, 1987;Ozima et al, 1989;Schrauder and Navon, 1994;Schrauder et al, 1996). Schrauder and Navon (1994) reported that the composition of the fluids varies between carbonatitic and hydrous end members.…”

Section: Introductionmentioning

confidence: 99%

Relationship of strontium isotope ratio and chemical composition of micro inclusions in fibrous diamonds: Implication for isotopically different components of the upper mantle.

Akagi

1999

Geochem. J.

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Strontium isotope ratios in whole fibrous diamonds from Zaire do not correlate with Rb/Sr ratios , but with La/Ba and La/Nd ratios. Diamonds with lower La/Ba and higher La/Nd gave higher 87Sr/86Sr . Leaching experiments on crushed diamonds gave lower La/Ba and higher La/Nd for water leachate and higher La/Ba and lower La/Nd for acid leachate , and more importantly, the former has higher 87Sr/86Sr ratios than the latter, which is in accord with the experiments of whole diamonds . The two leachates are considered to be from water-rich fluid and carbonates, respectively . It is likely that the diamonds have formed in the environment where water-rich fluid and carbonate-rich fluid or melt were mixing and that the mixing may have triggered kimberlitic magmatism.

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“…There are two types of variations in carbon isotope ratios from core to rim: gradually decreasing and then increasing   13 C for H1 and QH2, and gradually increasing and then decreasing   13 C for QH1. In contrast to Liaoning and Shandong diamonds, two Hunan diamonds show an overall trend of first decreasing and then increasing   13 C, remaining high in 13 C during the final growth stage.…”

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confidence: 75%

“…Specifically, carbon isotope ratios of diamonds in the Yangtze Craton were dominated by isotopically light carbon, with an average  13 C of 7.4‰ for two Hunan samples, while diamonds from the North China Craton were dominantly heavy in their carbon isotope compositions, with an average   13 C of 3.0‰ for both three Liaoning and three Shandong diamonds. This suggests that during initial diamond growth, the carbon available in the mantle beneath the North China Craton was 13 C enriched (relative to the average  13 C of 5.5‰ for global mantle) and depleted in 13 C beneath the Yangtze Craton.…”

Section: Primitive Cores Of Diamonds and Their Carbon Isotope Ratios mentioning

confidence: 99%

“…Since the 1950s, extensive investigations on carbon isotopes of diamond have been performed [1][2][3][4][5][6][7][8][9][10][11][12][13]. It was recognized that peridotitic diamonds and eclogitic diamonds have rather distinct ranges of carbon isotopes: while the carbon isotopic compositions of peridotitic diamonds or graphite are, by comparison, 13 C-enriched and record narrow ranges, eclogitic diamonds may be strongly depleted in 13 C, and its range in carbon isotopic composition is broader [2,[7][8][9][10][11][12][13]. The carbon isotopic distribution of diamond is not only affected by mantle carbon isotopic fractionation, but is also related to its carbon reservoir and source.…”

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confidence: 99%

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Variations in carbon isotopic composition in the subcontinental lithospheric mantle beneath the Yangtze and North China Cratons: Evidence from in-situ analysis of diamonds using SIMS

Chen¹,

Zhili

Lu³

et al. 2012

Chin. Sci. Bull.

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The components and evolution of subcontinental lithospheric mantle beneath the North China Craton and the Yangtze Craton is a current topic in the geological study of China and the carbon isotopic composition of diamond is one of the most direct probes into cratonic lithospheric mantle processes. In this paper, in-situ SIMS (Secondary Ion Mass Spectrometry) techniques were used to analyze the carbon isotope compositions at different internal growth zones of diamonds from Shandong and Liaoning in the North China Craton and Hunan in the Yangtze Craton. It was found that the carbon isotopic range of diamonds from the North China Craton are rather distinct from those of the Yangtze Craton; the former has a range of 6.0‰ to 2.0‰ (relative to VPDB) with an average value of 3.0‰ in their core areas, which is consistent with global peridotitic diamonds; the diamonds from the Yangtze Craton, however, have a carbon isotopic range from 8.6‰ to 3.0‰ with an average value of 7.4‰ in their core areas, being more consistent with global eclogitic diamonds. The variations of carbon isotope ratios between different internal growth zones in individual diamonds were different in the three diamond localities studied. There was a clear correlation between changes in carbon isotopic composition and phases of diamond dissolution and new growth, while no correlation was observed between   13 C and internal inclusions. The variations suggest that the carbon isotopic compositions of mantle fluids were changing during the process of diamond crystallization, and that the heterogeneity of the carbon isotopic composition in mantle carbon reservoirs was a more important factor than carbon isotope fractionation in controlling the carbon isotopic compositions and their variation in diamonds. In addition, the preliminary results of in-situ nitrogen analyses demonstrated that the variation of carbon isotopic compositions between the core and outer growth zones does not correlate with nitrogen abundances, implying either that diamonds crystallized in an open environment or that the carbon isotopic composition and nitrogen contents in mantle fluids were controlled by other, not yet understood factors. The experimental results provide hints that the isotopic composition of carbon and its original sources were different in metasomatic fluids controlling diamond formation in the mantle beneath the North China Craton and the Yangtze Craton.

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Multiple growth events during diamond genesis: an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stones

Cited by 191 publications

References 15 publications

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Nitrogen in peridotite xenoliths: Lithophile behavior and magmatic isotope fractionation

Relationship of strontium isotope ratio and chemical composition of micro inclusions in fibrous diamonds: Implication for isotopically different components of the upper mantle.

Variations in carbon isotopic composition in the subcontinental lithospheric mantle beneath the Yangtze and North China Cratons: Evidence from in-situ analysis of diamonds using SIMS

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