变质温度压力计

1、Figure 5-1. Stability states. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. zzGGVdPSdTT PT PTTPP21112122-=-DG for any reaction = 0 at equilibriumMineralS(J)G (J)V (cm3/mol) Low Albite207.25-3,710,085100.07 Jadeite133.53-2,844,15760.04 Quartz41.36-856,64822.688Fro

2、m Helgeson et al. (1978).Table 27-1. Thermodynamic Data at 298K and0.1 MPa from the SUPCRT DatabaseFigure 27-1. Temperature-pressure phase diagram for the reaction: Albite = Jadeite + Quartz calculated using the program TWQ of Berman (1988, 1990, 1991). Winter (2001) An Introduction to Igneous and M

3、etamorphic Petrology. Prentice Hall. ThusdPdTSV=DDFigure 27-1. Temperature-pressure phase diagram for the reaction: Albite = Jadeite + Quartz calculated using the program TWQ of Berman (1988, 1990, 1991). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. GGVdPPPPP211

4、2-=z 变质作用中，许多进变质作用中的反应都是脱水或脱碳酸反应。与固-固反应不同，脱挥发分反应在温压图上表现为曲线。 A B + H2O. 对于这个反应，可以写出： S = SB + SH2O - SA = S固体 + SH2O V = VB + VH2O - VA = V固体 + VH2O 温度升高时，一般 S 为正。尤其在这种有气体或液体相产生的反应中，因为气体的熵要高于固体。在低压的情况下， V固体 通常为负。但在低压情况下 VH2O 却会很大，因为气体或水会膨胀，填充可能的空间。这样 dP/dT 为正。当压力升高时，气体和液体比固体容易压缩，所以总的 V 将逐渐变小，dP/dT 会升

5、高。最终由于气体和液体的可压缩性V固体与 VH2O 相等，反应的V 变为0，使得dP/dT为无穷。压力高于这一点，水的体积会越来越小，使得反应中的 V 变为负增长，因此 dP/dT 也为负增长。P x V is a constant at constant TFigure 5-5. Piston-and-cylinder apparatus to compress a gas. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. GGVdPPPPP2112-=zGGRTPdPPPP

6、P2112-=zzGGRTPdPPPPP2112-=11xdxx=zlnoodPdTSV=DDFigure 27-2. Pressure-temperature phase diagram for the reaction muscovite + quartz = Al2SiO5 + K-feldspar + H2O, calculated using SUPCRT (Helgeson et al., 1978). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. nnFigur

7、e 27-3. Activity-composition relationships for the enstatite-ferrosilite mixture in orthopyroxene at 600oC and 800oC. Circles are data from Saxena and Ghose (1971); curves are model for sites as simple mixtures (from Saxena, 1973) Thermodynamics of Rock-Forming Crystalline Solutions. Winter (2001) A

8、n Introduction to Igneous and Metamorphic Petrology. Prentice Hall. All coefficients = 1numbers are values for KFigure 27-4. P-T phase diagram for the reaction Jadeite + Quartz = Albite for various values of K. The equilibrium curve for K = 1.0 is the reaction for pure end-member minerals (Figure 27

9、-1). Data from SUPCRT (Helgeson et al., 1978). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. T oCInitial X(Fe-Bt)Final X(Fe-Bt)Final X(Fe-Grt)Final (Mg/Fe)GrtFinal (Mg/Fe)BtKT Kelvins1/T KelvinslnK7991.000.7500.9050.1050.3330.31510720.00093-1.1557990.500.7100.896

10、0.1160.4080.28410720.00093-1.2587490.500.6950.8960.1160.4390.26410220.00098-1.3307381.000.7300.9060.1040.3700.28110110.00099-1.2716980.750.7040.9010.1100.4200.2619710.00103-1.3426980.500.6900.8960.1160.4490.2589710.00103-1.3536510.750.6790.9010.1100.4730.2329240.00108-1.4596510.500.6610.8970.1150.51

11、30.2249240.00108-1.4975990.750.6450.9020.1090.5500.1978720.00115-1.6235990.500.6100.8980.1140.6390.1788720.00115-1.7285500.750.6200.9030.1070.6130.1758230.00122-1.7415500.500.5900.8980.1140.6950.1638230.00122-1.8116010.500.5000.8000.2501.0000.2508740.00114-1.3866010.250.3920.7970.2551.5510.1648740.0

12、0114-1.8076970.750.5740.8040.2440.7420.3299700.00103-1.1116970.250.4680.7960.2571.1370.2269700.00103-1.487Table 27-2. Experimental results of Ferry and Spear (1978) on a Garnet-Biotite GeothermometerFigure 27-5. Graph of l lnK vs. 1/T (in Kelvins) for the Ferry and Spear (1978) garnet-biotite exchan

13、ge equilibrium at 0.2 GPa from Table 27-2. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. lnKD = -2108 T(K) + 0.781DGP,T = 0 = DH 0.1, 298 - TDS0.1, 298 + PDV + 3 RTlnKDDH P V1SK3RT3Rln-D - DD=oD52 0902 494P MPaTC27319 506 12 943K,.ln=-Figure 27-6. AFM projections

14、 showing the relative distribution of Fe and Mg in garnet vs. biotite at approximately 500oC (a) and 800oC (b). From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths. Mineral. Soc. Amer. Monograph 1. Figure 27-7. Pressure-temperature diagram similar to Figure 27-4 showin

15、g lines of constant KD plotted using equation (27-35) for the garnet-biotite exchange reaction. The Al2SiO5 phase diagram is added. From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths. Mineral. Soc. Amer. Monograph 1. Figure 27-8. P-T phase diagram showing the experime

16、ntal results of Koziol and Newton (1988), and the equilibrium curve for reaction (27-37). Open triangles indicate runs in which An grew, closed triangles indicate runs in which Grs + Ky + Qtz grew, and half-filled triangles indicate no significant reaction. The univariant equilibrium curve is a best

17、-fit regression of the data brackets. The line at 650oC is Koziol and Newtons estimate of the reaction location based on reactions involving zoisite. The shaded area is the uncertainty envelope. After Koziol and Newton (1988) Amer. Mineral., 73, 216-233 Figure 27-8. P-T diagram contoured for equilib

18、rium curves of various values of K for the GASP geobarometer reaction: 3 An = Grs + 2 Ky + Qtz. From Spear (1993) Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths. Mineral. Soc. Amer. Monograph 1.Wt. % OxidesGarnetBiotiteMuscovite Plagioclase SiO237.2634.2244.5064.93 Al2O321.0318.973

19、4.5022.59 TiO21.230.40 FeO32.4517.500.70 MgO2.469.980.46 MnO6.080.120.02 CaO1.030.010.032.90 Na2O0.271.649.36 K2O7.798.050.45 Total100.3190.0990.30100.23 Si3.005.436.172.84 AlIV2.002.571.831.17 AlVI0.983.81 Ti0.150.04 Fe2.192.320.08 Mg0.302.360.10 Mn0.420.020.00 Ca0.090.000.14 Na0.080.440.83 K1.581.

20、420.03 Fe/(Fe+Mg)0.880.500.46Prp 10An 14Alm 73Ab 83Sps 14Or 3Grs 3 From Hodges and Spear (1982) and Spear (1993).Table 27-3. Mineral Compositions, Formulas, and End-Members for Sample 90A from Mt. Moosilauke, New HampshireCationsFigure 27-10. P-T diagram showing the results of garnet-biotite geother

21、mometry (steep lines) and GASP barometry (shallow lines) for sample 90A of Mt. Moosilauke (Table 27-4). Each curve represents a different calibration, calculated using the program THERMOBAROMETRY, by Spear and Kohn (1999). The shaded area represents the bracketed estimate of the P-T conditions for t

22、he sample. The Al2SiO5 invariant point also lies within the shaded area. Figure 27-11. P-T phase diagram calculated by TQW 2.02 (Berman, 1988, 1990, 1991) showing the internally consistent reactions between garnet, muscovite, biotite, Al2SiO5 and plagioclase, when applied to the mineral compositions

23、 for sample 90A, Mt. Moosilauke, NH. The garnet-biotite curve of Hodges and Spear (1982) Amer. Mineral., 67, 1118-1134 has been added. Figure 27-12. Chemically zoned plagioclase and poikiloblastic garnet from meta-pelitic sample 3, Wopmay Orogen, Canada. a. Chemical profiles across a garnet (rim rim

24、). b. An-content of plagioclase inclusions in garnet and corresponding zonation in neighboring plagioclase. After St-Onge (1987) J. Petrol. 28, 1-22 .P-T-t PathsFigure 27-13. The results of applying the garnet-biotite geothermometer of Hodges and Spear (1982) and the GASP geobarometer of Koziol (198

25、8, in Spear 1993) to the core, interior, and rim composition data of St-Onge (1987). The three intersection points yield P-T estimates which define a P-T-t path for the growing minerals showing near-isothermal decompression. After Spear (1993). P-T-t PathsFigure 27-14. An illustration of precision v

26、s. accuracy. a. The shots are precise because successive shots hit near the same place (reproducibility). Yet they are not accurate, because they do not hit the bulls-eye. b. The shots are not precise, because of the large scatter, but they are accurate, because the average of the shots is near the bulls-eye. c. The shots are both precise and accurate. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prenti