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Phase Relations, Redox and Melting Reactions in Carbonate-bearing Systems in...
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Phase Relations, Redox and Melting Reactions in Carbonate-bearing Systems in the Earth's Mantle

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Geochemistry and Geochronology".

Deadline for manuscript submissions: closed (1 August 2020) | Viewed by 11455

Special Issue Editors

Prof. Anton Shatskiy

E-Mail Website
Guest Editor
Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Interests: experimental mineralogy and petrology; high-pressure experiment; phase relations; single crystal growth; diffusion; chemical kinetics; in situ X-ray diffraction; Raman spectroscopy; multianvil technique
Prof. Konstantin D. Litasov

E-Mail Website
Guest Editor
Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Interests: experimental mineralogy and petrology; high-pressure experiment; phase relations; single crystal growth; diffusion; chemical kinetics; in situ X-ray diffraction; Raman spectroscopy; multianvil technique

Special Issue Information

Dear Colleagues,

The study of carbonates under various P-T-X-fO2 conditions provides insights into both the deep carbon cycle and the transport of atmospheric CO2 to the Earth’s mantle. Carbonates are one of the important classes of minerals lowering the solidus temperatures of mantle rocks, which, in turn, influences the generation of deeply seated magmas. Carbonates may have a substantial role in mantle processes relevant to partial melting, metasomatism, and diamond formation. Recent findings of alkali and alkaline earth carbonates in mantle minerals and xenoliths including superdeep diamonds call for further study of the carbonate-bearing systems in a wider range of compositions, pressures and redox conditions. Accordingly, we invite researchers to contribute to this Special Issue on "Phase Relations, Redox and Melting Reactions in Carbonated Systems in the Earth's Mantle".

The potential topics include, but are not limited to:

  • Subsolidus and melting phase relations in carbonate and carbonate-bearing systems under high pressures
  • Crystal chemistry and thermodynamics of simple and double carbonates versus pressure and temperature
  • Redox reactions involving reduction of carbonates under mantle P-T conditions
  • Compositions, structure and physical properties of carbonate-bearing melts in the Earth’s mantle
  • Mantle-derived carbonate-bearing inclusions in minerals from kimberlites and UHPM rocks
  • Origin of deep-seated carbonate magmas and possible mechanisms of their transport in the Earth's mantle

Prof. Anton Shatskiy
Prof. Konstantin D. Litasov
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • carbonates
  • carbonate melts
  • high-pressure experiment
  • phase relations
  • melting reactions
  • redox reactions
  • reaction kinetics
  • Raman spectroscopy
  • X-ray diffraction
  • Earth’s mantle

Published Papers (3 papers)

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Research

15 pages, 1199 KiB  
Article
High-Pressure Phase Diagrams of Na2CO3 and K2CO3
by Pavel N. Gavryushkin, Altyna Bekhtenova, Sergey S. Lobanov, Anton Shatskiy, Anna Yu. Likhacheva, Dinara Sagatova, Nursultan Sagatov, Sergey V. Rashchenko, Konstantin D. Litasov, Igor S. Sharygin, Alexander F. Goncharov, Vitali B. Prakapenka and Yuji Higo
Minerals 2019, 9(10), 599; https://doi.org/10.3390/min9100599 - 30 Sep 2019
Cited by 11 | Viewed by 3472
Abstract
The phase diagrams of Na 2 CO 3 and K 2 CO 3 have been determined with multianvil (MA) and diamond anvil cell (DAC) techniques. In MA experiments with heating, γ -Na 2 CO 3 is stable up to 12 GPa and above [...] Read more.
The phase diagrams of Na 2 CO 3 and K 2 CO 3 have been determined with multianvil (MA) and diamond anvil cell (DAC) techniques. In MA experiments with heating, γ -Na 2 CO 3 is stable up to 12 GPa and above this pressure transforms to P 6 3 /mcm-phase. At 26 GPa, Na 2 CO 3 - P 6 3 /mcm transforms to the new phase with a diffraction pattern similar to that of the theoretically predicted Na 2 CO 3 - P 2 1 /m. On cold compression in DAC experiments, γ -Na 2 CO 3 is stable up to the maximum pressure reached of 25 GPa. K 2 CO 3 shows a more complex sequence of phase transitions. Unlike γ -Na 2 CO 3 , γ -K 2 CO 3 has a narrow stability field. At 3 GPa, K 2 CO 3 presents in the form of the new phase, called K 2 CO 3 -III, which transforms into another new phase, K 2 CO 3 -IV, above 9 GPa. In the pressure range of 9–15 GPa, another new phase or the mixture of phases III and IV is observed. The diffraction pattern of K 2 CO 3 -IV has similarities with that of the theoretically predicted K 2 CO 3 - P 2 1 /m and most of the diffraction peaks can be indexed with this structure. Water has a dramatic effect on the phase transitions of K 2 CO 3 . Reconstruction of the diffraction pattern of γ -K 2 CO 3 is observed at pressures of 0.5–3.1 GPa if the DAC is loaded on the air. Full article
(This article belongs to the Special Issue Phase Relations, Redox and Melting Reactions in Carbonate-bearing Systems in the Earth's Mantle)
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20 pages, 5777 KiB  
Article
The K2CO3–CaCO3–MgCO3 System at 6 GPa: Implications for Diamond Forming Carbonatitic Melts
by Anton V. Arefiev, Anton Shatskiy, Ivan V. Podborodnikov and Konstantin D. Litasov
Minerals 2019, 9(9), 558; https://doi.org/10.3390/min9090558 - 16 Sep 2019
Cited by 16 | Viewed by 3935
Abstract
Carbonate micro inclusions with abnormally high K2O appear in diamonds worldwide. However, the precise determination of their chemical and phase compositions is complicated due to their sub-micron size. The K2CO3–CaCO3–MgCO3 is the simplest system [...] Read more.
Carbonate micro inclusions with abnormally high K2O appear in diamonds worldwide. However, the precise determination of their chemical and phase compositions is complicated due to their sub-micron size. The K2CO3–CaCO3–MgCO3 is the simplest system that can be used as a basis for the reconstruction of the phase composition and P–T conditions of the origin of the K-rich carbonatitic inclusions in diamonds. In this regard, this paper is concerned with the subsolidus and melting phase relations in the K2CO3–CaCO3–MgCO3 system established in Kawai-type multianvil experiments at 6 GPa and 900–1300 °C. At 900 °C, the system has three intermediate compounds K2Ca3(CO3)4 (Ca# ≥ 97), K2Ca(CO3)2 (Ca# ≥ 58), and K2Mg(CO3)2 (Ca# ≤ 10), where Ca# = 100Ca/(Ca + Mg). Miscibility gap between K2Ca(CO3)2 and K2Mg(CO3)2 suggest that their crystal structures differ at 6 GPa. Mg-bearing K2Ca(CO3)2 (Ca# ≤ 28) disappear above 1000 °C to produce K2Ca3(CO3)4 + K8Ca3(CO3)7 + K2Mg(CO3)2. The system has two eutectics between 1000 and 1100 °C controlled by the following melting reactions: K2Ca3(CO3)4 + K8Ca3(CO3)7 + K2Mg(CO3)2 → [40K2CO3∙60(Ca0.70Mg0.30)CO3] (1st eutectic melt) and K8Ca3(CO3)7 + K2CO3 + K2Mg(CO3)2 → [62K2CO3∙38(Ca0.73Mg0.27)CO3] (2nd eutectic melt). The projection of the K2CO3–CaCO3–MgCO3 liquidus surface is divided into the eight primary crystallization fields for magnesite, aragonite, dolomite, Ca-dolomite, K2Ca3(CO3)4, K8Ca3(CO3)7, K2Mg(CO3)2, and K2CO3. The temperature increase is accompanied by the sequential disappearance of crystalline phases in the following sequence: K8Ca3(CO3)7 (1220 °C) → K2Mg(CO3)2 (1250 °C) → K2Ca3(CO3)4 (1350 °C) → K2CO3 (1425 °C) → dolomite (1450 °C) → CaCO3 (1660 °C) → magnesite (1780 °C). The high Ca# of about 40 of the K2(Mg, Ca)(CO3)2 compound found as inclusions in diamond suggest (1) its formation and entrapment by diamond under the P–T conditions of 6 GPa and 1100 °C; (2) its remelting during transport by hot kimberlite magma, and (3) repeated crystallization in inclusion that retained mantle pressure during kimberlite magma emplacement. The obtained results indicate that the K–Ca–Mg carbonate melts containing 20–40 mol% K2CO3 is stable under P–T conditions of 6 GPa and 1100–1200 °C corresponding to the base of the continental lithospheric mantle. It must be emphasized that the high alkali content in the carbonate melt is a necessary condition for its existence under geothermal conditions of the continental lithosphere, otherwise, it will simply freeze. Full article
(This article belongs to the Special Issue Phase Relations, Redox and Melting Reactions in Carbonate-bearing Systems in the Earth's Mantle)
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20 pages, 6149 KiB  
Article
The System K2CO3–CaCO3–MgCO3 at 3 GPa: Implications for Carbonatite Melt Compositions in the Shallow Continental Lithosphere
by Anton V. Arefiev, Anton Shatskiy, Ivan V. Podborodnikov, Altyna Bekhtenova and Konstantin D. Litasov
Minerals 2019, 9(5), 296; https://doi.org/10.3390/min9050296 - 15 May 2019
Cited by 21 | Viewed by 3701
Abstract
Potassic dolomitic melts are believed to be responsible for the metasomatic alteration of the shallow continental lithosphere. However, the temperature stability and range of compositions of these melts are poorly understood. In this regard, we performed experiments on phase relationships in the system [...] Read more.
Potassic dolomitic melts are believed to be responsible for the metasomatic alteration of the shallow continental lithosphere. However, the temperature stability and range of compositions of these melts are poorly understood. In this regard, we performed experiments on phase relationships in the system K2CO3–CaCO3–MgCO3 at 3 GPa and at 750–1100 °C. At 750 and 800 °C, the system has five intermediate compounds: Dolomite, Ca0.8Mg0.2CO3 Ca-dolomite, K2(Ca≥0.84Mg≤0.16)2(CO3)3, K2(Ca≥0.70Mg≤0.30)(CO3)2 bütschliite, and K2(Mg≥0.78Ca≤0.22)(CO3)2. At 850 °C, an additional intermediate compound, K2(Ca≥0.96Mg≤0.04)3CO3)4, appears. The K2Mg(CO3)2 compound disappears near 900 °C via incongruent melting, to produce magnesite and a liquid. K2Ca(CO3)2 bütschliite melts incongruently at 1000 °C to produce K2Ca2(CO3)3 and a liquid. K2Ca2(CO3)3 and K2Ca3(CO3)4 remain stable in the whole studied temperature range. The liquidus projection of the studied ternary system is divided into nine regions representing equilibrium between the liquid and one of the primary solid phases, including magnesite, dolomite, Ca-dolomite, calcite-dolomite solid solutions, K2Ca3(CO3)4, K2Ca2(CO3)3, K2Ca(CO3)2 bütschliite, K2Mg(CO3)2, and K2CO3 solid solutions containing up to 24 mol % CaCO3 and less than 2 mol % MgCO3. The system has six ternary peritectic reaction points and one minimum on the liquidus at 825 ± 25 °C and 53K2CO3∙47Ca0.4Mg0.6CO3. The minimum point resembles a eutectic controlled by a four-phase reaction, by which, on cooling, the liquid transforms into three solid phases: K2(Mg0.78Ca0.22)(CO3)2, K2(Ca0.70Mg0.30)(CO3)2 bütschliite, and a K1.70Ca0.23Mg0.07CO3 solid solution. Since, at 3 GPa, the system has a single eutectic, there is no thermal barrier for liquid fractionation from alkali-poor toward K-rich dolomitic compositions, more alkaline than bütschliite. Based on the present results we suggest that the K–Ca–Mg carbonate melt containing ~45 mol % K2CO3 with a ratio Ca/(Ca + Mg) = 0.3–0.4 is thermodynamically stable at thermal conditions of the continental lithosphere (~850 °C), and at a depth of 100 km. Full article
(This article belongs to the Special Issue Phase Relations, Redox and Melting Reactions in Carbonate-bearing Systems in the Earth's Mantle)
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