Ni-Ti-Zr-bearing equilibria
New phases in this subsystem are nickel, nickel oxide (bunsenite), zircon, baddeleyite, geikielite and pyrophanite. For both nickel and nickel oxide, a Landau excess heat capacity was used to model their lambda anomalies. The experimental data of O'Neill (1987) was used to derive the enthalpy of formation of nickel oxide. Data for zircon were added using the reaction zrc = bdy + q from Robie et al. (1978). The geikielite enthalpy was derived from the experiments of Haselton et al. (1978) on the reaction mag + ru = geik + CO2. Pyrophanite data were retrieved from the experimental exchange data of Pownceby et al. (1987) on the equilibrium spss + 3ilm = alm + 3pnt.
Ilmenite and ulvospinel data have been further refined through inclusion of the experiments of O'Neill et al. (1988) for the reactions 2ilm = 2iron + 2ru + O2 and 2usp = 2ilm + 2iron + O2 in the fitting process. The entropy of ulvospinel was changed to 175 J/K on the basis of arguments in O'Neill et al. (1988). The data for sphene was also fitted to the experiments of Manning & Bohlen (1991) for the reaction sph + ky = an + ru.
261) mag + ru = geik + CO2 (Haselton et al., 1978)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 1 13.7 12.7 950 92.52 94.31 -0.29 12.41 0.60 3 (94.05 <-> 95.66)
0 1 19.5 18.5 1100 94.12 95.64 19.02 0.73 cH = 94.85 (sd 0.55)
0 1 26.4 25.4 1250 94.71 96.03 26.29 0.85 within bracket
uH = 0.68, d/s = -0.3, h = 1.00
262) sph + ky = an + ru (Manning & Bohlen, 1991)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 - 15.9 15.5 900 11.23 11.98 0.12 16.02 0.38 3 (10.21 <-> 11.84)
0 - 18.0 17.6 1000 10.79 11.54 17.88 0.39 cH = 11.00 (sd 0.36)
0 - 19.1 18.7 1050 10.50 11.24 18.83 0.39 within bracket
0 - 20.3 19.9 1100 10.03 10.77 -0.12 19.78 0.39 uH = 0.69, d/s = -0.3, h = 0.79
* ru + cc + q = sph + CO2 (Hunt & Kerrick, 1977; Jacobs & Kerrick, 1981)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 0.50 2.0 490 510 76.04 77.78 -29 461 10 ** NOT USED **
0 0.50 3.5 525 545 74.71 76.34 -14 511 10 cH = 73.55 (sd 0.43)
0 0.78 2.0 510 530 75.63 77.27 -25 485 10
0 0.50 5.0 580 75.56 554 12
0 0.97 5.0 635 75.71 604 12
263) ru + cc + q = sph + CO2 (Jacobs & Kerrick, 1981)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 0.25 6.0 540 560 73.01 74.70 546 10 3 (73.15 <-> 74.14)
0 0.48 6.0 570 580 73.09 73.85 576 12 cH = 73.55 (sd 0.43) 2
0 0.65 6.0 590 610 73.20 74.65 595 12 within bracket
0 0.82 6.0 610 630 73.25 74.65 614 12 uH = 0.42, d/s = 0.7, h = 0.40
264) 2ilm = 2iron + 2ru + O2 (O'Neill et al., 1988)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-48.06 - 0.0 800 573.91 575.64 -47.98 0.16 3 (570.57 <-> 576.45)
-42.52 - 0.0 900 573.40 574.63 -42.53 0.15 cH = 574.11 (sd 0.73)
-40.10 - 0.0 950 573.12 574.34 -40.14 0.14 within bracket
uH = 2.50, d/s = 0.1, h = 0.23
265) 2ilm = 2iron + 2ru + O2 (Anovitz et al., 1985)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-37.88 - 0.0 1000 569.78 577.10 -37.94 0.14 3 (569.86 <-> 575.80)
-36.72 - 0.0 1025 568.41 575.90 -36.91 0.14 cH = 574.11 (sd 0.73) 2
-35.81 - 0.0 1050 569.15 576.78 -35.91 0.13 within bracket
-34.88 - 0.0 1075 569.47 577.20 -34.95 0.13 uH = 2.13, d/s = 1.4, h = 0.06
-33.96 - 0.0 1100 569.42 577.28 -34.03 0.13
-32.93 - 0.0 1125 567.61 575.64 -33.14 0.13
266) 2usp = 2ilm + 2iron + O2 (O'Neill et al., 1988)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-42.29 - 0.0 850 531.46 532.72 -42.32 0.28 3 (529.94 <-> 535.24)
-37.72 - 0.0 950 531.85 533.12 -37.71 0.26 cH = 532.38 (sd 1.30)
-33.85 - 0.0 1050 531.56 533.50 -33.84 0.24 within bracket
uH = 2.25, d/s = 0.2, h = 0.91
267) 2usp = 2ilm + 2iron + O2 (Anovitz et al., 1985)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-32.01 - 0.0 1100 527.03 534.93 -32.13 0.23 1 (527.62 <-> 532.92)
-30.28 - 0.0 1150 525.11 533.29 -30.55 0.22 cH = 532.38 (sd 1.30) 2
-29.01 - 0.0 1200 527.25 535.70 -29.09 0.21 within bracket
uH = 1.75, d/s = 1.7, h = 0.09
268) alm + 3ru = 3ilm + sill + 2q (Bohlen et al., 1983)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 - 11.9 11.4 750 -5.67 -4.71 11.64 0.29 3 (-5.84 <-> -4.54)
0 - 12.4 11.9 800 -5.54 -4.58 12.21 0.29 cH = -5.17 (sd 0.25)
0 - 12.7 12.3 850 -5.00 -4.22 0.09 12.79 0.29 within bracket
0 - 13.4 13.0 900 -5.18 -4.40 13.40 0.29 uH = 0.55, d/s = 0.2, h = 0.99
0 - 14.8 14.4 1000 -5.47 -4.69 14.65 0.29
0 - 15.5 15.1 1050 -5.60 -4.83 15.28 0.29
0 - 16.1 15.7 1100 -5.53 -4.76 15.92 0.30
* 2alm + gr + 6ru = 6ilm + 3an + 3q (Bohlen & Liotta, 1986)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
5.32 - 10.9 10.5 800 12.30 15.94 10.50 0.18 ** NOT USED **
5.32 - 12.3 11.9 900 11.22 14.87 -0.12 11.78 0.18 cH = 15.92 (sd 0.80)
5.32 - 13.5 13.1 1000 12.12 15.75 -0.02 13.08 0.18
5.32 - 14.5 14.1 1100 14.95 18.56 14.39 0.18
269) zrc = bdy + q (Robie et al., 1979)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
0 - 0.0 1665 1685 19.55 19.78 1675 18 1 (19.57 <-> 19.76)
cH = 19.67 (sd 0.11)
within bracket
uH = 0.06, d/s = 2.0, h = 1.00
270) 2NiO = 2Ni + O2 (O'Neill, 1987)
ln_K x(CO2) P(kbar) T(C) H(low) H(high) miss calc 2sd summary
-44.18 - 0.0 600 477.90 481.24 -44.09 0.21 3 (476.43 <-> 482.80)
-32.08 - 0.0 800 477.54 481.63 -32.00 0.17 cH = 478.89 (sd 0.76)
-27.59 - 0.0 900 477.35 481.85 -27.52 0.16 within bracket
-20.59 - 0.0 1100 476.95 482.24 -20.53 0.13 uH = 2.70, d/s = 0.6, h = 0.27
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