Element partitioning during carbonated pelite melting at 8, 13 and 22GPa and the sediment signature in the EM mantle components

Grassi, Daniele; Schmidt, Max W.; Günther, Detlef

doi:10.1016/j.epsl.2012.01.023

Cited by 54 publications

(35 citation statements)

References 76 publications

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“…The diamond-graphite line is a kinetic boundary showing the conditions of spontaneous diamond nucleation in experiments longer than 24 h; the line of graphite-diamond equilibrium lies beyond the diagram, and all the experiments were conducted in the diamond stability field D REE Cpx/L values are low to very low, especially for the middle and heavy REE. This is in line with the results of Grassi et al (2012), who attributed these differences to the jadeiterich composition of their clinopyroxenes. A positive correlation exists in our experiments between D REE Cpx/L and pressure (correspondingly, with jadeite content in clinopyroxene).…”

Section: Clinopyroxenesupporting

confidence: 92%

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Reduced sediment melting at 7.5–12 GPa: phase relations, geochemical signals and diamond nucleation

Brey

Гирнис

Bulatov

et al. 2015

Contrib Mineral Petrol

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garnet. Clinopyroxene stability depends strongly on the Na content in the starting mixture; it remains in the Na-gloss composition up to 1600 °C at 12 GPa, but was not observed in K-gloss experiments above 1200 °C. The composition of melt or fluid changes gradually with increasing temperature from hydrous carbonate-rich (<10 wt% SiO 2 ) at 800-1000 °C to volatile-rich silicate liquids (up to 40 wt% SiO 2 ) at high temperatures. Trace elements were analyzed in melts and crystalline phases by LA ICP MS. The garnetmelt and clinopyroxene-melt partition coefficients are in general consistent with results from the literature for volatile-free systems and silicocarbonate melts derived by melting carbonated peridotites. Most trace elements are strongly incompatible in kyanite and silica polymorphs (D < 0.01), except for V, Cr and Ni, which are slightly compatible in kyanite (D > 1). Aragonite and Fe-Mg carbonate have very different REE partition coefficients (D Mst-Sd/L ~ 0.01 and D Arg/L ~ 1). Nb, Ta, Zr and Hf are strongly incompatible in both carbonates. The bearthite/melt partition coefficients are very high for LREE (>10) and decrease to ~1 for HREE. All HFSE are strongly incompatible in bearthite. In contrast, Ta, Nb, Zr and Hf are moderately to strongly compatible in ZrSiO 4 and TiO 2 phases. Based on the obtained partition coefficients, the composition of a mobile phase derived by sediment melting in deep subduction zones was calculated. This phase is strongly enriched in incompatible elements and displays a pronounced negative Ta-Nb anomaly but no Zr-Hf anomaly. Although all experiments were conducted in the diamond stability field, only graphite was observed in low-temperature experiments. Spontaneous diamond nucleation and the complete transformation of graphite to diamond were observed at temperatures above 1200-1300 °C. We speculate that the observed character of graphite-diamond transformation is controlled by relationships between the kinetics of metastable graphite Abstract Melting of carbonated sediment in the presence of graphite or diamond was experimentally investigated at 7.5-12 GPa and 800-1600 °C in a multianvil apparatus. Two starting materials similar to GLOSS of Plank and Langmuir (Chem Geol 145:325-394, 1998) were prepared from oxides, carbonates, hydroxides and graphite. One mixture (Na-gloss) was identical in major element composition to GLOSS, and the other was poorer in Na and richer in K (K-gloss). Both starting mixtures contained ~6 wt% CO 2 and 7 wt% H 2 O and were doped at a ~100 ppm level with a number of trace elements, including REE, LILE and HFSE. The near-solidus mineral assemblage contained a silica polymorph (coesite or stishovite), garnet, kyanite, clinopyroxene, carbonates (aragonite and magnesite-siderite solid solution), zircon, rutile, bearthite and hydrous phases (phengite and lawsonite at <9 GPa and the hydrous aluminosilicates topaz-OH and phase egg at >10 GPa). Hydrous phases disappear at ~900 °C, and carbonates persist up to 1000-1100 °C. At temperatures >1200 °C, the ...

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Section: Clinopyroxenesupporting

confidence: 92%

“…There is no apparent dependency of D Grt/L on pressure or on garnet composition for most trace elements. The compatibility of Zr, Hf and Ti appears to increase with increasing pressure in agreement with the results of Grassi et al (2012) and Dasgupta et al (2009).…”

Section: Garnetsupporting

confidence: 86%

Reduced sediment melting at 7.5–12 GPa: phase relations, geochemical signals and diamond nucleation

Brey

Гирнис

Bulatov

et al. 2015

Contrib Mineral Petrol

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“…In contrast, variable LILE/HFSE ratios such as La/Nb and Th/Ta, which reach values not observed in any common rocks, require that some phases containing Ta-Nb were left in the residue at some stage of magma formation and/or contamination of mantle sources by sedimentary materials (e.g. Grassi et al 2012).…”

Section: The Roman Provincementioning

confidence: 99%

“…Marly sediments provide both H 2 O and CO 2 to the mantle wedge. Moreover, melts at 8 GPa from marls have incompatible element patterns similar to Roman rocks (Grassi et al 2012) and could be suitable contaminants for the mantle wedge in this region. Introduction of H 2 O + CO 2 lowers the solidus of peridotite more than is done by H 2 O or CO 2 alone (Foley et al 2009), thus promoting extensive melting and favouring large-scale explosive volcanism.…”

Section: The Roman Provincementioning

confidence: 99%

Magmatism, mantle evolution and geodynamics at the converging plate margins of Italy

Peccerillo

Frezzotti

2015

JGS

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Abstract:The Plio-Quaternary magmatism in the Tyrrhenian Sea area exhibits wide compositional variations, which cover almost entirely those observed for volcanic rocks worldwide. Some volcanoes (Etna, Iblei, Sardinia, etc.) range from tholeiitic to Na-alkaline, and display elemental and isotope signatures typical of FOZO and EM-1 ocean-island basalts (OIB). Other volcanoes (Aeolian Arc, Italian peninsula) range from calc-alkaline-shoshonitic to K-alkaline, exhibit typical 'subduction-related' trace element signatures (low Ta-Nb, high Rb-Cs-LREE), and show a large range of radiogenic isotope ratios, from mantle-like in the Aeolian Arc to crustal-like in central Italy. Geochemical data suggest that OIB-type magmatism originated in lithosphere-asthenosphere sources that were unaffected by recent subduction. In contrast, subduction-related magmas come from mantle sources that underwent Eocene to present mixing with various amounts and types of subducted crustal components. Fluxing of the mantle wedge by water-rich fluids from a mid-ocean ridge basalt-type slab occurred in the southern Tyrrhenian Sea, whereas interaction between peridotite and various types of sediments occurred in central Italy. These contrasting styles of mantle contaminations relate to the nature (oceanic or continental) of the foreland, slab geometry and pre-metasomatic mantle compositions, which vary greatly along the Apennine arc and are the reason for the formation of the wide variety of orogenic magmas in Italy.

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“…Data from 73 garnet-containing experiments were collated (Bennett et al, 2004;Bobrov et al, 2014;Corgne et al, 2012;Dalou et al, 2009;Dasgupta et al, 2009;Draper et al, 2006;Dwarzski et al, 2006;Grassi et al, 2012;Hauri et al, 1994;Klemme et al, 2002;Pertermann et al, 2004;Salters et al, 2002;Suzuki et al, 2012;Tuff and Gibson, 2007;van Westrenen et al, 1999;2000;Walter et al, 2004) and fitted the data for trivalent cations from each dataset using lattice strain models (experimental literature data available as a supplementary file).…”

Section: Mineral/melt Partition Coefficientsmentioning

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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Element partitioning during carbonated pelite melting at 8, 13 and 22GPa and the sediment signature in the EM mantle components

Cited by 54 publications

References 76 publications

Reduced sediment melting at 7.5–12 GPa: phase relations, geochemical signals and diamond nucleation

Reduced sediment melting at 7.5–12 GPa: phase relations, geochemical signals and diamond nucleation

Magmatism, mantle evolution and geodynamics at the converging plate margins of Italy

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

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