Earth's Mantle Melting in the Presence of C–O–H–Bearing Fluid

Litasov, Konstantin D.; Shatskiy, Anton; Ohtani, Eiji

doi:10.1002/9781118529492.ch2

Cited by 21 publications

(24 citation statements)

References 148 publications

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“…The porous fl ow is controlled by infi ltration of nonporous silicate mantle. The estimated CO 2 outfl ux from slab to overlying mantle in the transition zone does not exceed 2 × 10 11 g/yr (calculated using data in Hammouda and Laporte, 2000; see also Litasov et al, 2013). The difference between the estimated fl uxes in and out is three orders of magnitude; thus, carbonatite melt formed during melting of subducted carbonate will accumulate at the slabmantle interface rather than percolate upward by porous fl ow.…”

Section: Discussionmentioning

confidence: 95%

“…Which scenario actually occurs depends on the fl ux of incoming carbonates subducted to the transition zone and the redox buffering capacity of interacting reservoirs. A reasonable estimation of CO 2 subduction infl ux is 1-5 × 10 14 g/yr if 2-3 wt% CO 2 is concentrated in the uppermost 500 m of the slab and the average subduction rate is 6 cm/yr (Litasov et al, 2013). The porous fl ow is controlled by infi ltration of nonporous silicate mantle.…”

Section: Discussionmentioning

confidence: 99%

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Solidus of alkaline carbonatite in the deep mantle

Litasov

Shatskiy

Ohtani

et al. 2013

Geology

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146

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Solidus of alkaline carbonatite in the deep mantle

Litasov

Shatskiy

Ohtani

et al. 2013

Geology

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146

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“…These data are based on a study of both pyrolitic and chondritic solidi as 'dry' systems composed of only major elements (Si, Al, Fe, Ca and Mg), while the presence of alkalis and particularly C, O, H and other volatiles depress the solidus position drastically. The experimental data performed at 10-15 GPa pressure conditions demonstrated that the presence of C-O-H fluid and/or even the minor admixture of alkalis in peridotite produce carbonatitic melt at temperatures lower than adiabatic ones by as much as 400-500 °C (Litasov et al 2013a(Litasov et al , 2013b. It was demonstrated, in experiments at up to 80 GPa, that the melting behavior of simple carbonate systems is a suitable proxy for many carbonate-bearing lithologies (Thomson et al 2014).…”

Section: Formation Of Carbonatitic Partial Melts In the Lowermost Mantlementioning

confidence: 89%

A primary natrocarbonatitic association in the Deep Earth

2015

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In addition to ultramafic and mafic associations, a primary natrocarbonatitic association occurs in the lower mantle. To date, it was identified as inclusions in diamonds from the Juina area, Mato Grosso State, Brazil. It comprises almost 50 mineral species: carbonates, halides, fluorides, phosphates, sulfates, oxides, silicates, sulfides and native elements. In addition, volatiles are present in this association. Among oxides, coexisting periclase and wüstite were identified, pointing to the formation of the natrocarbonatitic association at a depth greater than 2,000 km. Some ironrich (Mg,Fe)O inclusions in diamond are attributed to the lowermost mantle. The initial lower-mantle carbonatitic melt formed as a result of low-fraction partial melting of carbon-containing lower-mantle material, rich in P, F, Cl and other volatile elements, at the core-mantle boundary. During ascent to the surface, the initial carbonatitic melt dissociated into two immiscible parts, a carbonate-silicate and a chloride-carbonate melt. The latter melt is parental to the natrocarbonatitic lower-mantle association. Diamonds with carbonatitic inclusions were formed in carbonatitic melts or high-density fluids.

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“…Preliminary calculations of carbonatite melt mobility in the reduced mantle domains of the transition zone and lowermost upper mantle indicate that 0.5-1 km carbonatite diapir can move through overlying mantle domain (e.g., from depth of 550 to 200 km). First diapir will oxidize the overlying mantle section and only 30% of modal carbonate in the melt will be reduced (Litasov et al, 2013a(Litasov et al, , 2013b). …”

Section: Discussionmentioning

confidence: 99%

The reactions between iron and magnesite at 6 GPa and 1273–1873 K: Implication to reduction of subducted carbonate in the deep mantle

Martirosyan

Litasov

Shatskiy

et al. 2015

Journal of Mineralogical and Petrological Sciences

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The interaction between Fe-metal and magnesite was studied in multianvil experiments at 6 GPa and 1273-1873 K using different capsule materials: Fe, BN, and MgO. It was observed that at subsolidus conditions reaction proceeds with the formation of Fe 3 C and magnesiowüstite in the stoichiometric proportions according to relation: MgCO 3 + 5Fe = 3(Fe 0.66 Mg 0.33 )O + Fe 3 C. At melting conditions (1673-1873 K) magnesite and iron react in nearly equivalent molar proportions with formation of Mg-Fe-carbonatite melt, Fe-C alloy, magnesiowüstite and graphite. The reactions clearly show that free carbon and metallic iron phases cannot coexist in the upper mantle and presumably in transition zone and will always form Fe-carbide. The carbon content in Fe-C alloy and its coexistence with diamond will be strongly dependent on the oxygen fugacity. The studied reactions can be considered as intermediate processes in the reduced mantle domains at the contact with submerging subduction slabs and have further implication to the processes at the core-mantle boundary.

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Earth's Mantle Melting in the Presence of C–O–H–Bearing Fluid

Cited by 21 publications

References 148 publications

Solidus of alkaline carbonatite in the deep mantle

Solidus of alkaline carbonatite in the deep mantle

A primary natrocarbonatitic association in the Deep Earth

The reactions between iron and magnesite at 6 GPa and 1273–1873 K: Implication to reduction of subducted carbonate in the deep mantle

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