High-Fe (Mg, Fe)O inclusion in diamond apparently from the lowermost mantle

Wirth, Richard; Dobrzhinetskaya, L.; Harte, B.; Schreiber, Anja; Green, H.W.

doi:10.1016/j.epsl.2014.08.010

Cited by 55 publications

(42 citation statements)

References 51 publications

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“…Close comparison of inclusion and experimental ferropericlase compositions in specific cases have led to the interpretation that diamonds have been exhumed from depths spanning the entire lower mantle, including the D'' layer above the core-mantle-boundary (e.g. Hayman et al, 2005;Wirth et al, 2014). However, both natural samples (Kopylova et al, 1997;Stachel et al, 2000b) and experiments (Brey et al, 2004;Thomson et al, 2016) demonstrate the stability of ferropericlase with a range of compositions in equilibrium with diamond throughout the upper mantle in regions of low silica activity.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Thomson

Kohn

Bulanova

et al. 2016

Lithos

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Trace element composition of silicate inclusions in sublithospheric diamonds from the juina-5 kimberlite: Evidence for diamond growth from slab melts, LITHOS (2016), doi: 10.1016/j.lithos.2016.08.035 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E DM A N U S C R I P T ACCEPTED MANUSCRIPT ABSTRACTThe trace element compositions of inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite, Brazil, are presented. Literature data for mineral/melt partition coefficients were collated, refitted and employed to interpret inclusion compositions. As part of this process an updated empirical model for predicting the partitioning behaviour of trivalent cations for garnet-melt equilibrium calibrated using data from 73 garnet-melt pairs is presented. High levels of trace element enrichment in inclusions interpreted as former calcium silicate perovskite and majoritic garnet preclude their origin as fragments of an ambient deep mantle assemblage. Inclusions believed to represent former bridgmanite minerals also display a modest degree of enrichment relative to mantle phases. The trace element composition of 'NAL' and 'CF phase' minerals are also reported. Negative Eu, Ce, and Y/Ho anomalies alongside depletions of Sr, Hf and Zr in many inclusions are suggestive of formation from a low-degree carbonatitic melt of subducted oceanic crust. Observed enrichments in garnet and 'calcium perovskite' inclusions limit depths of melting to less than ~ 600 km, prior to calcium perovskite saturation in subducting assemblages. Less enriched inclusions in sub-lithospheric diamonds from other global localities may represent deeper diamond formation. Modelled source rock compositions that are capable of producing melts in equilibrium with Juina-5 'calcium perovskite' and majorite inclusions are consistent with subducted MORB. Global majorite inclusion compositions suggest a common process is responsible for the formation of many superdeep diamonds, irrespective of geographic locality. Global transition zone inclusion compositions are reproduced by fractional crystallisation from a single parent melt, suggesting that they record the crystallisation sequence and melt evolution during this interaction of slab melts with ambient mantle. All observations are consistent with the previous hypothesis that many superdeep diamonds are created as slab-derived carbonatites interact with peridotitic mantle in the transition zone.

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Thomson

Kohn

Bulanova

et al. 2016

Lithos

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“…Fe-bearing phases with M 4 O 5 stoichiometry are relevant phases of the Earth's upper mantle and transition zone due to formation of solid solutions with Mg and Cr substituting for Fe 2+ and Fe 3+ , respectively (Woodland et al 2013;Ishii et al 2014Ishii et al , 2015 a Fe 2+ -rich magnesioferrite (Mg 0.42 Fe 0.58 )Fe 2 O 4 coexisting with ferropericlase (Mg,Fe)O and blebs of Fe-Ni alloy in a diamond host possibly from the lower mantle. The magnesioferrite was suggested to be exsolved from the original pure (Mg,Fe)O inclusion during upwelling in a plume (Wirth et al 2014). At pressures and temperatures of the transition zone, this Fe 2+ -rich magnesioferrite most likely was stable as Mg 2 Fe 2 O 5 +Fe 2 O 3 , making the Mg-end-member Mg 2 Fe 2 O 5 a relevant phase of the transition zone and the lower upper mantle.…”

Section: Structural Behavior Of Mg 2 Fe 2 O 5 With Pressurementioning

confidence: 95%

Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅

Siersch

Ballaran

Uenver‐Thiele

et al. 2017

American Mineralogist

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The compressibility and structural behavior of the novel Mg 2 Fe 2 O 5 oxide has been investigated by in situ single-crystal X-ray diffraction in a diamond-anvil cell up to a pressure of 17 GPa. The bulk compressibility of Mg 2 Fe 2 O 5 can be described using a second-order Birch-Murnaghan equation of state (BM2 EoS) with V 0 = 352.4(2) Å 3 and K 0 = 171(4) GPa. Three linear BM2 EoS were used to describe the axial compressibility of Mg 2 Fe 2 O 5 , which was found to be highly anisotropic. The a and b lattice parameters have very similar compressibilies, with a 0 = 2.8917(11) Å and linear modulus M a = 572(16) GPa and b 0 = 9.736(3) Å and linear modulus M b = 583(15) GPa, respectively. The c-axis is the most compressible direction as indicated by the smaller linear modulus [c 0 = 12.520(15) Å and M c = 404(28) GPa]. The Mg 2 Fe 2 O 5 structure consists of edge-sharing octahedra alternating with layers of trigonal prisms. The compression behavior of the M-O bonds of the M1 and M2 octahedra and of the M3 prisms depend on their location in either an edge-sharing environment, which makes them stiffer, or a corner-sharing environment where they have more freedom to distort and compress. The main compression mechanism consists of a polyhedral tilting around the M2-O1-M2 angle, which decreases with increasing pressure. Mg 2 Fe 2 O 5 has recently been added to the list of stable end-members of phases with M 4 O 5 stoichiometry, making it a potentially relevant phase in the Earth's upper mantle and transition zone. To develop thermodynamic activity-composition models for high-pressure phases, it is crucial to know the accurate elastic parameters of each individual end-member. Currently these have only been measured for Mg 2 Fe 2 O 5 (this study) and Fe 4 O 5 .

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“…Both Harte et al (1999) and Wirth et al (2014) report features that exceed 100 nm in size and reach up to 3 µm long, while Kaminsky et al (2015) report much smaller Fe 3+ -rich regions that are less than 20 nm in size and as small as 1-2 nm. Results from the present study show a magnetic phase that is significantly larger than those observed by Kaminsky et al (2015) in diamonds from kimberlite pipes in the same area (Juina, Brazil).…”

Section: Accepted Manuscriptmentioning

confidence: 95%

Synchrotron Mössbauer Source technique for in situ measurement of iron-bearing inclusions in natural diamonds

Nestola

Cerantola

Milani

et al. 2016

Lithos

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We describe a new methodology to collect energy domain Mössbauer spectra of inclusions in natural diamonds using a Synchrotron Mössbauer Source (SMS). Measurements were carried out at the Nuclear Resonance beamline ID18 at the European Synchrotron Radiation Facility (Grenoble, France). We applied this non-destructive approach to collect SMS spectra of a ferropericlase inclusion still contained within its diamond host from Juina (Brazil). The high spatial resolution of the measurement (~ 15 µm) enabled multiple regions of the 190 × 105 µm 2 inclusion to be sampled and showed that while Fe 3+ /Fe tot values in ferropericlase were below the detection limit (0.02) overall, there was a magnetic component whose abundance varied systematically across the inclusion. Hyperfine parameters of the magnetic component are consistent with magnesioferrite, and the absence of superparamagnetism allows the minimum particle size to be estimated as ~ 30 nm. Bulk Fe 3+ /Fe tot values are similar to those reported for other ferropericlase inclusions from Juina, and their variation across the inclusion can provide constraints on its history.

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High-Fe (Mg, Fe)O inclusion in diamond apparently from the lowermost mantle

Cited by 55 publications

References 51 publications

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅

Synchrotron Mössbauer Source technique for in situ measurement of iron-bearing inclusions in natural diamonds

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High-Fe (Mg, Fe)O inclusion in diamond apparently from the lowermost mantle

Cited by 55 publications

References 51 publications

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

Compressibility and high-pressure structural behavior of Mg2Fe2O5

Synchrotron Mössbauer Source technique for in situ measurement of iron-bearing inclusions in natural diamonds

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Compressibility and high-pressure structural behavior of Mg₂Fe₂O₅