Phase relationships in the system K2CO3-CaCO3 at 6 GPa and 900–1450 °C

Anton Shatskiy; Yuri M. Borzdov; Konstantin D. Litasov; Igor S. Sharygin; Yuri N. Palyanov; Eiji Ohtani

doi:10.2138/am-2015-5001

Article navigation

Research Article| January 01, 2015

Phase relationships in the system K₂CO₃-CaCO₃ at 6 GPa and 900–1450 °C

Anton Shatskiy;

Anton Shatskiy *

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

*

E-mail: [email protected]

Search for other works by this author on:

GSW

Google Scholar

Yuri M. Borzdov;

Yuri M. Borzdov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

Search for other works by this author on:

GSW

Google Scholar

Konstantin D. Litasov;

Konstantin D. Litasov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Search for other works by this author on:

GSW

Google Scholar

Igor S. Sharygin;

Igor S. Sharygin

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Search for other works by this author on:

GSW

Google Scholar

Yuri N. Palyanov;

Yuri N. Palyanov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Search for other works by this author on:

GSW

Google Scholar

Eiji Ohtani

3

Department of Earth and Planetary Material Science, Tohoku University, Sendai 980-8578, Japan

Search for other works by this author on:

GSW

Google Scholar

Author and Article Information

Anton Shatskiy *

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Yuri M. Borzdov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

Konstantin D. Litasov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Igor S. Sharygin

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Yuri N. Palyanov

1

V.S. Sobolev Institute of Geology and Mineralogy, Russian Academy of Science, Siberian Branch, Koptyuga pr. 3, Novosibirsk 630090, Russia

2

Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia

Eiji Ohtani

3

Department of Earth and Planetary Material Science, Tohoku University, Sendai 980-8578, Japan

*

E-mail: [email protected]

Publisher: Mineralogical Society of America

Received: 08 Apr 2014

Accepted: 06 Aug 2014

First Online: 03 Mar 2017

Online ISSN: 1945-3027

Print ISSN: 0003-004X

American Mineralogist (2015) 100 (1): 223–232.

https://doi.org/10.2138/am-2015-5001

Abstract

Phase relations in the system K₂CO₃-CaCO₃ have been studied in the compositional range, X(K₂CO₃), from 100 to 10 mol%, at 6.0 GPa and 900–1450 °C. At 900–950 °C, the system has three intermediate compounds: K₆Ca₂(CO₃)₅, K₂Ca(CO₃)₂, and K₂Ca₃(CO₃)₄. The K₂Ca(CO₃)₂ compound decomposes to the K₆Ca₂(CO₃)₅ + K₂Ca₃(CO₃)₄ assembly above 950 °C. The K₆Ca₂(CO₃)₅ and K₂Ca₃(CO₃)₄ compounds melt congruently slightly above 1200 and 1300 °C, respectively. The eutectics were established at 64 and 44 mol% near 1200 °C and at 23 mol% near 1300 °C. K₂CO₃ remains as a liquidus phase at 1300 °C and 75 mol% and melts at 1425 ± 20 °C. Aragonite remains as a liquidus phase at 1300 °C and 20 mol% and at 1400 °C and 10 mol%. CaCO₃ solubility in K₂CO₃ and K₂CO₃ solubility in aragonite are below the detection limit (<0.5 mol%).

Infiltration of subduction-derived K-rich Ca-Mg-Fe-carbonatite into the Fe⁰-saturated mantle causes the extraction of (Mg,Fe)CO₃ components from the melt, which shifts its composition toward K-Ca-carbonatite. According to our data this melt can be stable at the P-T conditions of subcratonic lithosphere with geothermal gradient of 40 mW/m² corresponding to temperature of 1200 °C at 6 GPa.