Metasomatic origin of diamonds in the world's largest diamondiferous eclogite

Liu, Yang; Taylor, L. A.; Sarbadhikari, A. Basu; Valley, John W.; Ushikubo, T.; Spicuzza, Michael J.; Kita, N. T.; Ketcham, Richard A.; Carlson, William D.; Shatsky, V. S.; Sobolev, N. V.

doi:10.1016/j.lithos.2009.06.036

Cited by 53 publications

(18 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The carbon isotopes of the studied diamonds from three localities in China are thus interpreted to reflect the isotopic signature of their mantle source. Between core areas and outer growth zones within individual diamond or among separate diamonds, there are no correlations between the intensity of cathode luminescence and carbon isotope ratios, in accordance with the results of previous studies [19,38,39].…”

Section: Growth Zones Of Diamonds and Their Relationship To Carbon Issupporting

confidence: 90%

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.

View full text Add to dashboard Cite

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.

show abstract

Section: Growth Zones Of Diamonds and Their Relationship To Carbon Issupporting

confidence: 90%

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.

View full text Add to dashboard Cite

show abstract

“…While a number of studies have proposed an origin for cratonic eclogites as vestiges of subducted altered oceanic crust (Jacob 2004;Taylor and Anand 2004;Snyder et al 1995;Lowry et al 1999), it has also been proposed that at least some eclogites may have formed as cumulates within the mantle (Taylor and Neal 1989). Strong metasomatism of eclogitic rocks further complicates their interpretation in terms of their original protolith (Liu et al 2009;Smart et al 2012;Gréau et al 2011;Huang et al 2012).…”

Section: Introductionmentioning

confidence: 99%

The oxygen fugacity at which graphite or diamond forms from carbonate-bearing melts in eclogitic rocks

Stagno

Frost

McCammon

et al. 2015

Contrib Mineral Petrol

107

View full text Add to dashboard Cite

eclogites. The raised prevalence of diamonds in eclogites compared to peridotites may, therefore, reflect more effective scavenging of carbon by melts in these rocks. The ferric iron contents of monomineralic layers of clinopyroxene and garnet contained in the same experiments were also measured using Mössbauer spectroscopy. A preliminary model was derived for determining the fO 2 of eclogitic rocks from the compositions of garnet and clinopyroxene, including the Fe 3+ /ΣFe ratio of garnet, using the equilibrium,The model, which reproduces the independently determined fO 2 of the experimental data to within 0.5 log units, can be used to estimate the fO 2 of ultrahigh-pressure metamorphic eclogites and cratonic eclogitic xenoliths. Although there are very few analyses of garnet Fe 3+ /ΣFe ratios from eclogite samples, the range in fO 2 recorded by available eclogitic xenoliths is similar to that reported for peridotitic xenoliths and generally within the graphite/diamond stability field. Estimates for the average bulk Fe 3+ / ΣFe ratio of modern basaltic oceanic crust, however, are higher than the values for most of these xenoliths, and upon subduction, crustal carbon is likely to remain in the carbonate stability field to depths of at least 250 km. If eclogite xenoliths originated from subducted oceanic crust, then their generally lower fO 2 most likely reflects either lower initial basaltic Fe 3+ /ΣFe ratios, loss of Fe 2 O 3 through partial melting or the initial presence of organic carbon. AbstractThe oxygen fugacity (fO 2 ) at which carbonatebearing melts are reduced to either graphite or diamond in synthetic eclogite compositions has been measured in multi-anvil experiments performed at pressures between 3 and 7 GPa and temperatures between 800 and 1,300 °C using iron-iridium and iron-platinum alloys as sliding redox sensors. The determined oxygen fugacities buffered by the coexistence of elemental carbon and carbonatebearing melt are approximately 1 log unit below thermodynamic calculations for a similar redox buffering equilibrium involving only solid phases. The measured oxygen fugacities normalized to the fayalite-magnetite-quartz oxygen buffer decrease with temperature from ~−0.8 to ~−1.7 log units at 3 GPa, most likely as a result of increasing dilution of the carbonate liquid with silicate. The normalized fO 2 values also decrease with pressure and show a similar decrease with temperature at 6 GPa from ~−1.5 log units at 1,100 °C to ~−2.4 log units at 1,300 °C. In contrast to previous arguments, the stability field of the carbonatebearing melt extends to lower oxygen fugacity in eclogite rocks than in peridotite rocks, which implies a wider range of conditions over which carbon remains mobile in natural Communicated by Chris Ballhaus. Electronic supplementary materialThe online version of this article (

show abstract

“…In order to compare the equilibration conditions of eclogites worldwide, it is important to be able to employ a geobarometer that is based only on garnet and clinopyroxene (cpx) that are present in all eclogites. This has proved difficult, however, (Koons 1984;Mukhopadhyay 1991;Newton 1986), and has been proposed to be also complicated by metasomatic overprinting (Liu et al 2009;Smart et al 2009;Tappe et al 2011). Only a few such studies exist, and these are either limited in their application by the chemical system (e.g., CMAS and Cr content), the narrow compositional range of the calibration, or by the reliance on data from non-eclogitic assemblages (Brey et al 1986;Mukhopadhyay 1991;Nimis and Taylor 2000;Simakov and Taylor 2000;Simakov 2008).…”

Section: Introductionmentioning

confidence: 99%

Experimental calibration of a garnet–clinopyroxene geobarometer for mantle eclogites

Beyer

Frost

Miyajima

2015

Contrib Mineral Petrol

View full text Add to dashboard Cite

Metasomatic origin of diamonds in the world's largest diamondiferous eclogite

Cited by 53 publications

References 60 publications

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

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

The oxygen fugacity at which graphite or diamond forms from carbonate-bearing melts in eclogitic rocks

Experimental calibration of a garnet–clinopyroxene geobarometer for mantle eclogites

Contact Info

Product

Resources

About