Experimental investigation of the composition of incipient melts in upper mantle peridotites in the presence of CO2 and H2O

Pintér, Zsanett; Foley, Stephen F.; Yaxley, Gregory M.; Rosenthal, Anja; Rapp, Robert P.; Lanati, Anthony; Rushmer, Tracy

doi:10.1016/j.lithos.2021.106224

Cited by 39 publications

(51 citation statements)

References 69 publications

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“…If one assumes water content is a proxy for metasomatism and/or enriched mantle, a reasonable interpretation of the MT analysis is that kimberlites are preferentially emplaced through mantle that has been previously metasomatized or never depleted (e.g., Foley et al., 2019; Giuliani et al., 2014). In this scenario, primary carbonatitic magma can easily penetrate metasomatized regions of the mantle regions during ascent by assimilating H 2 O‐ and CO 2 ‐rich wall rocks, thus lowering the CO 2 + H 2 O depressed solidus (Pintér et al., 2021). In contrast, in depleted regions of the mantle: (a) Any carbonatitic magma will have less available CO 2 until it reaches the 3.5 GPa orthopyroxene assimilation zone, thus CO 2 + H 2 O oxidized solidus temperatures will be higher to maintain the propagation; (b) there is likely to be less orthopyroxene available <3.5 GPa to accommodate crack‐tip propagation.…”

Section: Metasomatism Of the Mantle And Kimberlite Genesismentioning

confidence: 99%

The Relationship Between Kimberlitic Magmatism and Electrical Conductivity Anomalies in the Mantle

Özaydın

Selway

2022

Geophysical Research Letters

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Kimberlites are igneous rocks whose formation remains enigmatic due to their severely altered nature, highly variable compositions and rapid ascent through the lithosphere. The spatiotemporal distribution of kimberlites suggests that mantle metasomatism may play an essential role in their emplacement. Since the magnetotelluric (MT) method is sensitive to metasomatic mantle modification in the forms of interconnected minerals and water, we compiled MT models from Australia, Brazil, Botswana, Canada, Namibia, South Africa and the USA, calculated water content variations and compared them to the distribution of kimberlites. Results indicate that kimberlites mostly ascend through hydrated/metasomatized lithosphere and avoid both dry and heavily metasomatized lithosphere. Diamondiferous kimberlites preferentially occur on moderately metasomatized lithosphere, with the diamondiferous rate increasing with the degree of metasomatism in Archean terranes and decreasing in Proterozoic terranes. These results link geophysical observations of mantle metasomatism to kimberlite magmatism and will improve mineral systems models for diamond exploration.

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Section: Metasomatism Of the Mantle And Kimberlite Genesismentioning

confidence: 99%

The Relationship Between Kimberlitic Magmatism and Electrical Conductivity Anomalies in the Mantle

Özaydın

Selway

2022

Geophysical Research Letters

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“…Current summaries of metasomatic types in peridotites of the Kaapvaal Craton in South Africa recognize principally two types of phlogopite-bearing assemblages, known as MARID (mica-amphibole-rutile-ilmenite-diopside) and PIC (phlogopite-ilmeniteclinoproxene) [9,53], although other minor types (e.g., IRPS; [51]) may have been neglected. Candidates for melt types for cratonic processes include kimberlite, orangeite (formerly Group II kimberlite), lamproite, as well as carbonate-rich melts such as carbonatites and carbonated silicate melts with <30 wt% SiO 2 that are recognized as potential metasomatic agents from high-pressure experiments more than from natural rocks [56,57].…”

Section: Reactivity Of Different Alkaline Melts With Peridotitementioning

confidence: 99%

Dynamic Metasomatism Experiments Investigating the Interaction between Migrating Potassic Melt and Garnet Peridotite

Foley

Pertermann

2021

Geosciences

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Dynamic metasomatism experiments were performed by reacting a lamproite melt with garnet peridotite by drawing melt through the peridotite into a vitreous carbon melt trap, ensuring the flow of melt through the peridotite and facilitating analysis of the melt. Pressure (2–3 GPa) and temperature (1050–1125 °C) conditions were chosen where the lamproite was molten but the peridotite was not. Phlogopite was formed and garnet and orthopyroxene reacted out, resulting in phlogopite wehrlite (2 GPa) and phlogopite harzburgite (3 GPa). Phlogopites in the peridotite have higher Mg/(Mg + Fe) and Cr2O3 and lower TiO2 than in the lamproite due to buffering by peridotite minerals, with Cr2O3 from the elimination of garnet. Compositional trends in phlogopites in the peridotite are similar to those in natural garnet peridotite xenoliths in kimberlites. Changes in melt composition resulting from the reaction show decreased TiO2 and increased Cr2O3 and Mg/(Mg + Fe). The loss of phlogopite components during migration through the peridotite results in low K2O/Na2O and K/Al in melts, indicating that chemical characteristics of lamproites are lost through reaction with peridotite so that emerging melts would be less extreme in composition. This indicates that lamproites are unlikely to be derived from a source rich in peridotite, and more likely originate in a source dominated by phlogopite-rich hydrous pyroxenites. Phlogopites from an experiment in which lamproite and peridotite were intimately mixed before the experiment did not produce the same phlogopite compositions, showing that care must be taken in the design of reaction experiments.

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“…The resulting homogenised large area measurements are in good agreement with chemical compositions determined from RQPC experiments and can therefore be routinely used when determining glass compositions from quench-modified glasses. Despite these improvements in quenching rates, further challenges lie ahead, most notably for carbonate-rich melts, which usually produce complex intergrowths of quench crystals with little or no glass preserved (Weidendorfer et al, 2020;Pintér et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

“…Several intricate, time-consuming and expensive methods have been introduced in an attempt to better characterise the compositions of high-pressure melts. These include: [1] a series of "sandwich" experiments in which the analysed melt composition is run in additional experiments together with its source rock (Wallace and Green, 1988;Davis et al, 2011);[2] Melt traps consisting of vitreous carbon or diamond that separate the melt from the rock during the experiment and before the quenching procedure (Hirose and Kushiro, 1993);and [3] volume integration of microprobe analyses achieved by repolishing and analysing several levels through quenched melt pockets (Pintér et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Rapid quench piston cylinder apparatus: an improved design for the recovery of volatile-rich geological glasses from experiments at 0.5 - 2.5 GPa

Ezad¹,

Shcheka²,

Buhre³

et al. 2022

Preprint

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The accurate and precise determination of the compositions of silicate glasses formed from melts containing the volatile components H2O and CO2 recovered from high-pressure, high-temperature experiments is essential to our understanding of geodynamic processes taking place within the planet. Silicate melts are often difficult to analyse chemically because the formation of quench crystals and overgrowths on silicate phases is rapid and widespread upon quenching of experiments, preventing the formation of glasses in low-SiO2 and volatile-rich compositions. Here, we present experiments conducted in a novel rapid quench piston cylinder apparatus on a series of partially molten low-silica alkaline rock compositions (lamproite, basanite, calk-alkaline basalt) with a range of water contents. Quench modification of the volatile-bearing silicate glasses is significantly reduced compared to those produced in older piston-cylinder apparatuses. The recovered glasses are almost completely free of quench modification and facilitate the determination of precise chemical compositions. We illustrate the significantly improved quench textures and provide an analytical protocol that recovers accurate chemical compositions from both poorly and well-quenched silicate glasses.

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Experimental investigation of the composition of incipient melts in upper mantle peridotites in the presence of CO2 and H2O

Cited by 39 publications

References 69 publications

The Relationship Between Kimberlitic Magmatism and Electrical Conductivity Anomalies in the Mantle

The Relationship Between Kimberlitic Magmatism and Electrical Conductivity Anomalies in the Mantle

Dynamic Metasomatism Experiments Investigating the Interaction between Migrating Potassic Melt and Garnet Peridotite

Rapid quench piston cylinder apparatus: an improved design for the recovery of volatile-rich geological glasses from experiments at 0.5 - 2.5 GPa

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