Report for the Joint Use/Research of the Institute for Planetary Materials,
Okayama University
2019 fiscal year / period of stay 14/11/2019-24/12/2019
22/01/2020
Category:International Joint Research

Name of the research project: Experimental study of the systems Na2CO3-CaCO3,
Na2CO3-MgCO3, and CaCO3-MgCO3 at 11 GPa.
Principal applicant: Ivan V. PODBORODNIKOV
Position: PhD student (second year)*(Supervisor): Anton SHATSKIY

Affiliated institution and department: Sobolev Institute of Geology and Mineralogy Siberian
Branch of Russian Academy of Science (IGM SB RAS)Name of the faculty member of IPM : Takashi YOSHINO
Must apply after consulting with a faculty member of IPM（□ Already consulted）

List of collaborators (A faculty member of IPM must be included as a collaborator for joint
research and workshop)
Name
1

Podborodnikov I.V.

Affiliatedinstitute
IGM SB RAS

Position or school year

E-mailPhD

podborodnikov@igm.nsc.ru

2

Yoshino T.

IMPProf.

tyoshino@misasa.okayama-u.ac.jp

3

Arefiev A.V.

IGM SB RAS

PhD

arefievanton@igm.nsc.ru

4

Litasov K.D.

IGM SB RAS

Prof.

klitasov@igm.nsc.ru

5Shatskiy A.F.

IGM SB RAS

Prof.

shatskiy@igm.nsc.ru

Research report:
Background (motivation):
High-pressure phase relations in carbonate systems attract a lot of attention because
carbonates participate in various mantle processes connected with deep carbon circle, generation of
deep-seated magmas such as kimberlites and magnesiocarbonatites, mantle metasomatism, anddiamond formation. Carbonate minerals may enter subduction zones incorporated in hydrothermallyaltered basaltic crust, overlying marine sediments and underlying mantle lithosphere. Experimental
constraints and thermal modeling of subducting slabs indicate that a significant amount of carbonate
could survive hydrous melting under forearcs and sink to the deeper mantle as a part of relatively
dry eclogites.
Thomson et al. (2016) have shown that decreasing compatibility of Na2O results in dramatic
drop in the solidus temperature of carbonated oceanic crust subducted down to the mantle transitionzone. They found that decreasing fraction of clinopyroxene owing its dissolution in garnet structure

yields Na2O redistribution from silicate to carbonate portion of the system and stabilizes a fusibleNa2(Ca,Mg)4(CO3)5 compound, which control the solidus temperature and yields formation of
Na-rich carbonatite melt. Similar melts were recently found as inclusions in asthenosphericdiamonds from the Juina, Mato Grosso State, Brazil (Kaminsky et al., 2009, 2013, 2016).
It is, therefore, essential to know the phase relations in the Na 2CO3−CaCO3−MgCO3 andclinopyroxene-carbonate systems under pressure and temperature conditions of the mantle
asthenosphere.
Research purpose
The study of subsolidus and melting phase relations in the following binary systems
Na2CO3−CaCO3, Na2CO3−MgCO3, CaCO3−MgCO3 at 14 GPa in order to constrain corresponding
T-X phase diagrams. This study is a contribution to the Na 2CO3−CaCO3−MgCO3 ternary and morecomplex systems modelling subducting carbonated mid-ocean-ridge basalt.
Actually conducted research and research outcomes
During the last stay on 14/11/2019-24/12/2019, the following experiments were carried out at14 GPa. Each experiment contained 16 samples of different composition.
Run number, temperature, duration, systems (remarks on troubles if any):1) 5k3454, 1100 °C, 72 h., Na2CO3−CaCO3, Na2CO3−MgCO3;2) 1k3165, 1200 °C, 48 h., Na2CO3−CaCO3, Na2CO3−MgCO3;3) 1k3166, 1300 °C, 20 h., Na2CO3−CaCO3, Na2CO3−MgCO3;4) 5k3457, 1400 °C, 5 h., Na2CO3−CaCO3, Na2CO3−MgCO3 (unstable heating);
5) 5k3458, 1500 °C, 2.5 h., Na2CO3−CaCO3, Na2CO3−MgCO3, CaCO3−MgCO3 (unstable heating);
6) 5k3455, 1600 °C, 2.5 h., Na2CO3−CaCO3, Na2CO3−MgCO3, CaCO3−MgCO3;7) 1k3175, 1700 °C, 1 h., Na2CO3−CaCO3, Na2CO3−MgCO3, CaCO3−MgCO3;8) 1k3169, 1800 °C, Na2CO3−CaCO3, Na2CO3−MgCO3, CaCO3−MgCO3 (blowout during compression,before heating).

‘1k…..’ – USSA 1000-ton press, ‘5k….’ – USSA 5000-ton press.
Pressure calibration experiment. Run number, temperature, duration:9) 5k3450, 1300 °C, 4 h.

Additional experiments in the system CaCO3−CaSiO3−MgSiO3−MgCO3 at 6 GPa using
USSA 5000-ton. Each experiment contained 16 samples of different composition:
Run number, temperature, duration:10) 5k3447, 1350 °C, 24 h.;11) 5k3443, 1450 °C, 15 h.;12) 5k3445, 1600 °C, 2 h.;13) 5k3444, 1700 °C, 1 h.

A total of 13 experiments were conducted. In total, about 190 samples were obtained.
Currently we study these samples using a SEM with EDS.