Olivine compositional changes in primitive magmatic skarn environments: A reassessment of divalent cation partitioning models to quantify the effect of carbonate assimilation

Stefano, Flavio Di; Mollo, Silvio; Scarlato, Piergiorgio; Nazzari, Manuela; Caruso, Marco

doi:10.1016/j.lithos.2018.07.008

Cited by 18 publications

(11 citation statements)

References 138 publications

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“…Comparison of c REE melt and D REE fo/melt of the high-Al composition of this study with experiment MMC-2 of DiStefano et al (2018). The concentrations of the REE vary by over four orders of magnitude between the two experiments but this variation results in negligible deviation from a 1:1 correlation (dashed line), attesting to the validity of Henry's Law.…”

supporting

confidence: 51%

Mineral–melt partition coefficients and the problem of multiple substitution mechanisms: insights from the rare earths in forsterite and protoenstatite

Burnham

O’Neill

2019

Contrib Mineral Petrol

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A trace element may substitute into a mineral by more than one substitution mechanism, complicating the thermodynamic description of its partition coefficients. In order to understand this phenomenon better, the mineral/melt partition coefficients for all 14 rare earth elements (REE) plus Y and Sc were measured experimentally for coexisting forsterite and protoenstatite in the system CaO-MgO-SiO 2 ±Al 2 O 3 ±TiO 2 at 1406 °C and atmospheric pressure. For both phases, the results show these large trivalent cations (REE 3+) replace Mg 2+ on octahedral sites, but with charge-balanced achieved by two different mechanisms: 1) cation vacancies (2 REE 3+ + vacancy = 3 Mg 2+); and 2) substitution of Al for Here we report an experimental study of this problem, in which we investigate how the partitioning of REE between olivine and melt changes as a function of Al 2 O 3 in the melt, while holding temperature, pressure and a SiO 2 melt constant. The buffering of a SiO melt was achieved with coexisting protoenstatite, Mg 2 Si 2 O 6 ; serendipitously, this mineral shows the same two substitution mechanisms for REE as forsterite (i.e., the components REE 4/3 □ 2/3 Si 2 O 6 and REEMgSiAlO 6), allowing the same phenomenon to be compared side-by-side in different minerals. The partition coefficients of all 14 REEs plus Y and Sc were determined, to see whether the two mechanisms affect the REE differently, with implications for the use of lattice strain theory in modelling trace element partitioning. We also included a melt composition rich in TiO 2 in order to change melt composition independently of olivine composition and alumina activity. Our aim is to obtain quantitative information on an example of the phenomenon of multiple substitution mechanisms in trace-element partitioning, which will be of heuristic value in refining the way mineral/melt trace-element partition coefficients in general are parameterized. The

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supporting

confidence: 51%

Mineral–melt partition coefficients and the problem of multiple substitution mechanisms: insights from the rare earths in forsterite and protoenstatite

Burnham

O’Neill

2019

Contrib Mineral Petrol

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“…Although one can expect an elevated content of Ca in olivine from magmatic carbonatites (e.g. Di Stefano et al, 2018), there are reports of both relatively high (Guzmics et al, 2011) and very low Ca contents (Xie et al, 2019 1 and on Figure 1. The error bars correspond to two standard deviations.…”

Section: Discussionmentioning

confidence: 99%

Major and trace element composition of olivine from magnesian skarns and silicate marbles

Nekrylov¹,

Plechov²,

Gritsenko

et al. 2021

American Mineralogist

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Olivine is a major rock-forming mineral in various magmatic and metamorphic rocks and the upper mantle. In this paper, we present the first high-precision analyses of olivine from 15 samples of magnesian skarns and silicate marbles (MSSM) from the collection of the Fersman Mineralogical Museum (Moscow, Russia). Mg# [Mg/(Mg+Fe2+)·100, mol%] of olivine from the samples studied varies from 86 to nearly 100. The main distinctive features of the olivine are anomalously low contents of Co (<51 mg/g), Cr (<5 mg/g), and Ni (<44 mg/g) and high content of B (23–856 mg/g), which correlate with host-rock compositions. Phosphorus (5–377 mg/g) incorporation in olivine is charge balanced by the incorporation of Li (0.15–61 mg/g) and Na (<14.3 mg/g). Y and REE contents exhibit positive correlations with Na, which suggests that REE incorporation into MSSM olivine could occur via charge-balanced coupled substitution with Na at low temperature and low aSiO2 conditions during MSSM formation. The documented compositional features of olivine from magnesian skarns and silicate marbles can help reconstruct the genesis of the host-rocks and identify xenocrysts of MSSM olivine in magmatic rocks.

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“…Natural Alban Hills clinopyroxenes show good correlation between δ 18 O and IV Al with increasing CaO content 51 . Experimental modelling of AFC process adding carbonate component to a silicatic magma shows the same compositional evolution of clinopyroxenes, with the highest kushiroitic component recorded in the experimental runs with higher amounts of added carbonates (e.g., refs 78,81 ). If these stable isotope data cannot be used to definitively assume a sedimentary origin for the carbonate fraction of Polino rocks, they are at least compatible with such an origin.…”

Section: Carbonatite Melt-silicate Solid Vs Silicate Melt-carbonatitmentioning

confidence: 69%

“…Other reactions include the increase of larnite component in olivine, but not the formation of pure monticellite 81 :…”

Section: Carbonate-silicate Magma Interaction Stylesmentioning

confidence: 99%

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Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

Lustrino

Luciani

Stagno

2019

Sci Rep

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The small upper Pleistocene diatreme of Polino (central Italy) is known in literature as one of the few monticellite alvikites (volcanic Ca-carbonatite) worldwide. This outcrop belongs to the Umbria-Latium Ultra-alkaline District (ULUD), an area characterized by scattered and small-volume strongly SiO 2 -undersaturated ultrabasic igneous rocks located in the axial sector of the Apennine Mts. in central Italy. Petrographic and mineralogical evidences indicate that Polino olivine and phlogopite are liquidus phases rather than mantle xenocrysts as instead reported in literature. The presence of monticellite as rim of olivine phenocrysts and as groundmass phase indicates its late appearance in magma chambers at shallow depths, as demonstrated by experimental studies too. The absence of plagioclase and clinopyroxene along with the extremely MgO-rich composition of olivine (Fo 92–94 ) and phlogopite (average Mg# ~93) suggest for Polino magmas an origin from a carbonated H 2 O-bearing mantle source at depths at least of 90–100 km, in the magnesite stability field. In contrast with what reported in literature, the ultimate strongly ultrabasic Ca-rich whole-rock composition (~15–25 wt% SiO 2 , ~31–40 wt% CaO) and the abundant modal groundmass calcite are not pristine features of Polino magma. We propose that the observed mineral assemblage and whole-rock compositions result mostly from the assimilation of limestones by an ultrabasic melt at a depth of ~5 km. A reaction involving liquidus olivine + limestone producing monticellite + CO 2 vapour + calcite is at the base of the origin of the Polino pseudocarbonatitic igneous rocks.

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Olivine compositional changes in primitive magmatic skarn environments: A reassessment of divalent cation partitioning models to quantify the effect of carbonate assimilation

Cited by 18 publications

References 138 publications

Mineral–melt partition coefficients and the problem of multiple substitution mechanisms: insights from the rare earths in forsterite and protoenstatite

Mineral–melt partition coefficients and the problem of multiple substitution mechanisms: insights from the rare earths in forsterite and protoenstatite

Major and trace element composition of olivine from magnesian skarns and silicate marbles

Fuzzy petrology in the origin of carbonatitic/pseudocarbonatitic Ca-rich ultrabasic magma at Polino (central Italy)

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