Mn-equilibria
Mn-bearing phases were introduced into the data set of HP90, but were limited to few usable end-members through lack of suitable experiments linking garnet to other common phases. The recent experimental study of Wood et al. (1994) on exchange equilibria between olivine and oxides, fo + 2mang = teph + 2per, and between olivine and garnets, 2spss + 3fo = 2py + 3teph, has allowed the incorporation of a much more reliable set of data for Mn phases. The enthalpy for spessartine was retrieved from the experiments of Wood et al. (1994), using their derived mixing properties for both olivine and garnet. Their study of the exchange of Mg and Mn between olivine and oxides provides a powerful check on the quality of mutual agreement between calorimetric and phase equilibrium data. With the enthalpy of spessartine known, the enthalpies of several other Mn-bearing end-members were extracted from measured partitioning in natural assemblages. The results of Mahar et al. (1997) were incorporated into this data set, using the methods outlined in that paper. The data for Mn-biotite, Mn-chlorite, Mn-staurolite, Mn-cordierite, Mn-chloritoid are to be taken as those of fictive end-members which mix ideally with the real Fe and Mg end-members in the dilute composition ranges found in typical metamorphosed metapelitic rocks. The data for the other Mn end-members, however, refer to the accessible real phases (e.g. manganosite, spessartine, pyrophanite, rhodonite, pyroxmangite, rhodochrosite and tephroite).
295) pxmn = rhod (Maresch & Mottana, 1976)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 - 3.0 425 450 0.77 0.80 438 20 1 (0.77 <-> 0.80)
0 - 6.0 475 525 0.76 0.82 493 20 cH = 0.79 (sd 0.01)
0 - 20.0 900 0.96 753 20 within bracket
0 - 25.0 800 900 0.73 0.85 847 20 uH = 0.01, d/s = 2.4, h = 1.00
0 - 30.0 900 1000 0.74 0.86 940 20
296) rhc + q = pxmn + CO2 (Peters, 1971)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 0.90 2.0 503 509 84.72 85.31 6 515 14 2 (84.83 <-> 86.06)
0 0.60 2.0 490 503 85.58 86.90 493 14 cH = 85.93 (sd 0.73) 2
within bracket
uH = 0.52, d/s = -0.3, h = 0.58
297) rhc = mang + CO2 (Huebner, 1969)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 1 1.0 699 713 111.37 112.85 709 8 3 (111.75 <-> 113.19)
0 1 1.5 739 757 111.72 113.54 746 8 cH = 112.39 (sd 0.43)
0 1 2.0 770 785 111.84 113.31 776 8 within bracket
uH = 0.55, d/s = 0.9, h = 0.76
298) pxmn + rhc = teph + CO2 (Huebner & Eugster, 1968)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 1 2.0 555 570 87.32 88.74 561 14 1 (87.34 <-> 88.71)
cH = 87.90 (sd 0.71)
within bracket
uH = 0.51, d/s = 1.4, h = 0.83
299) fo + 2mang = teph + 2per (Wood et al., 1994)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-1.25 - 0.0 1300 5.08 8.19 -1.26 0.15 1 (5.32 <-> 7.96)
cH = 6.72 (sd 0.98)
within bracket
uH = 0.83, d/s = 1.9, h = 0.43
300) 2spss + 3fo = 2py + 3teph (Wood et al., 1994)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-5.97 - 27.0 1300 37.97 43.94 -6.15 0.78 1 (38.52 <-> 43.38)
cH = 43.24 (sd 5.07) 2
within bracket
uH = 1.38, d/s = 2.2, h = 0.84
301) spss + 3ilm = alm + 3pnt (Pownceby et al., 1987)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-5.55 - 5.0 600 3.29 11.56 -0.60 -4.39 1.75 3 (-0.98 <-> 0.45)
-4.68 - 5.0 700 -3.17 7.15 -4.31 1.57 cH = -1.03 (sd 6.34) 2
-3.93 - 5.0 800 -8.97 1.88 -4.22 1.42 too low but OK
-3.34 - 5.0 900 -14.43 -2.93 -0.19 -4.12 1.30 uH = 0.51, d/s = -6.1, h = 0.80
302) phl + 3mnctd = mnbi + 3mctd (Mahar et al., 1997)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-8.95 - 4.5 550 68.82 71.49 -8.95 0.70 1 (69.11 <-> 71.20)
cH = 70.15 (sd 2.38) 2
within bracket
uH = 0.47, d/s = 2.9, h = 1.00
303) 4phl + 3mnst = 4mnbi + 3mst (Mahar et al., 1997)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-37.63 - 4.5 550 327.72 337.25 -37.63 2.54 1 (328.67 <-> 336.30)
cH = 332.48 (sd 8.70) 2
within bracket
uH = 2.04, d/s = 2.3, h = 1.00
304) 2phl + 3mncrd = 2mnbi + 3crd (Mahar et al., 1997)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-7.77 - 4.5 550 63.22 68.95 -7.77 1.78 1 (63.41 <-> 68.76)
cH = 66.08 (sd 6.09) 2
within bracket
uH = 0.47, d/s = 6.1, h = 1.00
305) 5phl + 3mnchl = 5mnbi + 3clin (Mahar et al., 1997)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-0.65 - 4.5 550 25.82 37.34 -0.65 5.22 1 (23.74 <-> 39.42)
cH = 31.58 (sd 17.87) 2
within bracket
uH = 0.51, d/s = 11.2, h = 1.00
306) phl + spss = mnbi + py (Mahar et al., 1997)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-16.63 - 4.5 550 116.91 119.10 -16.63 0.68 1 (116.99 <-> 119.03)
cH = 118.01 (sd 2.32) 2
within bracket
uH = 0.73, d/s = 1.5, h = 1.00
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