Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet

Details Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet

Oct 1983

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1983gecoa..47.1661k&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 47, Issue 10, pp.1661-1679

Physics

17

Scientific paper

Experiments were made on the orthopyroxene-garnet relationships in the system FeSiO 3 -MgSiO 3 -Al 2 O 3 at 50 kbar and 1100-1500°C. Combining new and previously published data, thermodynamic analysis was carried out on the following equilibria: 1. (1) Mg 2 Si 2 O 6 + MgAl 2 SiO 6 = Mg 3 Al 2 Si 3 O 12 opx solid solution garnet 2. (2) Fe 2 Si 2 O 6 + FeAl 2 SiO 6 = Fe 3 Al 2 Si 3 O 12 opx solid solution garnet 3. (3) 1/2Fe 2 Si 2 O 6 + 1/3Mg 3 Al 2 Si 3 O 12 = 1/2Mg 2 Si 2 O 6 + 1/3Fe 3 Al 2 Si 3 O 12 opx garnet opx garnet 4. (4) 1/2Fe 2 SiO 4 + 1/3Mg 3 Al 2 Si 3 O 12 = 1/2Mg 2 SiO 4 + 1/3Fe 3 Al 2 Si 3 O 12 . olivine garnet olivine garnet The free energy changes of reactions (1), (2), (3) and (4) were obtained as a function of temperature (kcal/mol) for 50 kbar: G 0 1 = (-16.54 ± 0.72) - (-2.02 ± 0.25) × 10 -3 T ( K ) G 0 2 = (-27.52 ± 2.10) - (-7.17 ± 1.31) × 10 -3 T ( K ) G 0 3 = (-4.74 ± 0.24) - (-2.16 ± 1.53) × 10 -3 T ( K ) G 0 4 = (-1.96 ± 0.15) - (-0.82 ± 0.10) × 10 -3 T ( K ). The intracrystalline exchange of Fe 2+ and Mg 2+ between M1 and M2 sites of the Al 2 O 3 -free orthopyroxene is given by RT In . A multisite regular solution for orthopyroxene and regular solutions for both olivine and garnet are sufficient to describe equilibria between these phases. The microscopic model shows that the ferrosilite-enstatite solid solution system is macroscopically an asymmetric mixture with an excess free energy that is practically temperature-independent above 1100°C.

Affiliated with

Also associated with

No associations

Rating

Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermodynamic analyses of equilibria involving olivine, orthopyroxene and garnet will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1193117