Publication
- Names
-
- Ivan V. Podborodnikov
- Anton Shatskiy
- Anton V. Arefiev
- Artem D. Chanyshev
- Konstantin D. Litasov
- Title
- The system Na2CO3-MgCO3 at 3 GPa
- Abstract
- It was suggested that Na-Mg carbonates might play a substantial role in mantle metasomatic processes through lowering melting temperatures of mantle peridotites. Taking into account that natrite, Na$_2$CO$_3$, eitelite, Na$_2$Mg(CO$_3$)$_2$, and magnesite, MgCO$_3$, have been recently reported from xenoliths of shallow mantle (110-115 km) origin, we performed experiments on phase relations in the system Na$_2$CO$_3$-MgCO$_3$ at 3 GPa and 800-1250°C. We found that the subsolidus assemblages comprise the stability fields of Na-carbonate + eitelite and eitelite + magnesite with the transition boundary at 50 mol% Na$_2$CO$_3$. The Na-carbonate- eitelite eutectic was established at 900°C and 69 mol% Na$_2$CO$_3$. Eitelite melts incongruently to magnesite and a liquid containing about 55 mol% Na$_2$CO$_3$ at 925 $\pm$ 25°C. At 1050°C, the liquid, coexisting with Na-carbonate, contains 86-88 mol% Na$_2$CO$_3$. Melting point of Na$_2$CO$_3$ was established at 1175 $\pm$ 25°C. The Na$_2$CO$_3$ content in the liquid coexisting with magnesite decreases to 31 mol% as temperature increases to 1250°C. According to our data, the Na- and Mg-rich carbonate melt, which is more alkaline than eitelite, can be stable at the P-T conditions of the shallow lithospheric mantle with thermal gradient of 45 mW/m$^2$ corresponding to temperature of 900 °C at 3 GPa.
- Keywords
- Raman spectra, mid-IR, far-IR, band position, high pressure, high temperature, phase change, phase diagram, mineral, carbonate, eitelite, Na2CO3, MgCO3, Earth mantle, carbonatite
- Content
- spectral data, band list data, experimental physics
- Year
- 2018
- Journal
- High Pressure Research
- Volume
- 38
- Number
- 3
- Pages
- 281 - 292
- Document type
- article
- Publication state
- published
- Doi
- 10.1080/08957959.2018.1488972
- Identifiers
-
- bibcode: 2018HPR....38..281P