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| Titel |
Melting Relations of Multicomponent Carbonate System MgCO3 - FeCO3- CaCO3- Na2CO3 at 12-23 GPa |
| VerfasserIn |
Anna Spivak, Natalia Solopova, Yuriy Litvin, Leonid Dubrovinsky, Egor Zakharchenko |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094528
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| Publikation (Nr.) |
 EGU/EGU2014-9941.pdf |
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| Zusammenfassung |
| Considerable attention is focused on high-pressure high-temperature experimental study
of
melting phase relations of carbonates which were involved into a ‘super-deep’ diamond
genesis.
High-pressure stability of carbonate melts and their role in ‘ultra-deep’ diamonds genesis
are
most essential.
Experimental study of melting relations of multicomponent carbonate system was carried
out using multi-anvil press at the pressures 12 - 23 GPa and temperatures 800 to 1650 oC.
Chemical compositions of starting carbonate system used for melting experiment were
prepared by mixing: FeCO3 – 26,00; MgCO3– 26,00; CaCO3 – 25,00; Na2CO3 – 23,00 wt
%.
A region of partial melting for the system is experimentally determined. The partial
melting field is arranged between low-temperature boundary of eutectics melting (solidus
line) of the multicomponent carbonate and the boundary of complete melting (liquidus line)
at higher temperature. From experimental observations, a Mg-Fe carbonate solid
solution is the liquidus phase. At temperature lowering, the assemblage (Mg,Fe)CO3 +
(Ca,Na2,Fe)CO3 + L (liquid) is formed. Then, the invariant eutectic assemblage (Mg,Fe)CO3
+ (Ca,Na2,Fe)CO3 + Na2(Ca,Fe)(CO3)2+ L (liquid) which is determining for subsolidus
assemblage (Mg,Fe)CO3 + (Ca,Na2,Fe)CO3 + Na2(Ca,Fe)(CO3)2 is formed. Next to liquidus
line is one-phase field of completely miscible multicomponent carbonate melt. On the whole,
the results demonstrate phase relations of solid carbonates and multicomponent carbonate
liquid in the immediate vicinity to the low-temperature melting boundary. The early
melting of the multicomponent carbonate system is compatible with the lower mantle
geothermal conditions because the primary melting temperatures are noticeably
below than the geothermal values. It is significant that multicomponent carbonate
melts are stable and completely miscible under conditions as partial so complete
melting. Thus, high-pressure high-temperature experimental data demonstrate that
multicomponent carbonate melts are stable under the transition zone and lower mantle
conditions.
Support: grant of the President of RF #MK-1386.2013.5, grants of RFBR 12-05-33044,
13-05-00835, 14-05-00537. |
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