fluids and metasomatism

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Chapter 30: Metamorphic Fluidsand Metasomatism

“Wet -chems”: gravimetric/volumetricModern Spectroscopic Techniques

much fastercapable of analyzing to very low concentrationsstill requires standards

Still express as weight % oxides holdover to wet chemsOK for most rocks (O the common anion) but I’dreally prefer mole % oxides



Chapter 30: Metamorphic Fluidsand Metasomatism

Figure 30-1 . Fluid speciation in the C-O-H-S system at 1100 oC and 0.5 GPa projected from S to the C-O-H triangle (mole proportions).

f S2 is determined by pyrrhotite with the composition Fe 0.905 S. After Holloway (1981) Compositions and volumes of supercritical fluids inthe Earth's crust. In L. S. Hollister and M. L. Crawford (1981). Short Cour se in F lu id I nclusions: Appli cations to Petrology . Mineral.Assoc. Canada. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.



Chapter 30:Metamorphic

Fluids andMetasomatism

Figure 30-1 . Speciation in C-O-H-S fluidscoexisting with graphite at 0.2 GPa with f O2 buffered by quartz-fayalite-magnetite andf S2 controlled as in Figure 30-1. is the molefraction of each species in the fluid. FromHolloway (1981) Compositions and volumes

of supercritical fluids in the Earth's crust. InL. S. Hollister and M. L. Crawford (1981).Short Course in F lu id I nclusions:Appl icati ons to Petrology . Mineral. Assoc.Canada. Winter (2001) An Introduction toIgneous and Metamorphic Petrology.Prentice Hall.



Chapter 30: Metamorphic Fluids & Metasomatism

Figure 30-3 . Variation in the dissociation constant of NaCl in aqueous solutions with temperature and pressure. Shaded arrows

indicate regional and contact metamorphic P-T paths. After Sverjensky (1987) In I. S. E. Carmichael and H. P. Eugster (eds.),Thermodynamic M odeli ng of Geological M ateri als: Mineral s, Fluids, Melts . Rev. in M ineralogy , 17, Mineral. Soc. Amer, pp. 177-209.Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-4 . Speciation in aqueous-chloride fluids calculated for an ultramafic bulk composition assuming a geothermal gradient of0.1 oC/bar. m i is the molality of species i in the fluid. After Eugster and Baumgartner (1987) Mineral solubilities and speciation in

supercritical metamorphic fluids. In I. S. E. Carmichael and H. P. Eugster (eds.), Thermodynamic modeli ng of geological materi als:M ineral s, flu ids, melts . Rev. in M in eralogy , 17, Mineral. Soc. Amer, pp. 367-403. Winter (2001) An Introduction to Igneous andMetamorphic Petrology. Prentice Hall.




Figure 30-5 . Three-dimensional distribution of fluid about a single grain at < 60 o (left) and > 60 o (right). In the center is a cross sectionthrough a fluid tube at the intersection of three mineral grains for which = 60 o. After Brenan (1991) Development and maintenance of

metamorphic permeability: Implications for fluid transport. In D. M. Kerrick (ed.), Contact M etamorphism. Rev. i n M ineralogy , 26,Mineral. Soc. Amer, pp. 291-320.




Figure 30-6 . A hypothetical column of rock proposed by J. B. Thompson (1959) Local equilibrium in metasomatic processes. In P. H.Abelson (ed.), Researches in Geochemistry . v. 2. John Wiley. 427-457. pp. 427-457. The left end is pure periclase and the right end pure

quartz. Between these ends the bulk composition varies continuously so that the wt. % SiO 2 increases linearly from left to right(dashed line). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-7 . A hypothetical column of rock proposed by J. B. Thompson (1959) Local equilibrium in metasomatic processes. In P. H.Abelson (ed.), Researches in Geochemistry . v. 2. John Wiley. 427-457. pp. 427-457. The left end is pure periclase and the right end pure

quartz. Between these ends the bulk composition varies continuously so that the wt. % SiO 2 increases linearly from left to right(dashed line). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-8 . Schematic G-X SiO2 diagram for the SiO 2-MgO system at fixed temperature and pressure. Winter (2001) An Introductionto Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-9 . Expanded view of the monomineralic enstatite zone in Figure 30-7, showing the profiles of X SiO2 and SiO2 . Winter (2001)An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-7 . The hypothetical column of rock of J. B. Thompson (1959) with the sequences of mineral assemblages expected to form ifdiffusion is effective and the amounts of periclase and quartz prove inexhaustible. The dashed line shows the variation in wt.% SiO 2 across the column and the lighter dot-dashed lines show the variation in SiO2 and MgO . After J. B. Thompson (1959) Localequilibrium in metasomatic processes. In P. H. Abelson (ed.), Researches in Geochemistry . v. 2. John Wiley. 427-457. pp. 427-457.

Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-11 . a

SiO2 – a

H2O diagram for fluids in the MgO-SiO 2-H 2O system at 600o

C and 0.2 GPa calculated using the TQW program(Berman, 1988, 1990, 1991). Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-12 . SiO 2-MgO chemographic diagram assuming only Qtz, Fo, En, and Per are stable. Winter (2001) An Introduction toIgneous and Metamorphic Petrology. Prentice Hall.




Figure 30-13 . “Gresens -type” variation diagram showing the gains or losses (in grams per 100 grams of original rock A) as a functionof the volume factor, f v, in eq. (30-13). Rock A is a garnet phyllite from Stavanger, Norway, and rock B is a metasomatized albite schist,

supposedly derived from (A) After Gresens (1967)Chem. Geol.

, 2, 47-65. Winter (2001) An Introduction to Igneous and MetamorphicPetrology. Prentice Hall.




Figure 30-14 . Isocon diagram of Grant (1986) for the data from Table 30-1. Some oxides have been scaled to provide a better

distribution of data points. Econ. Geol. , 81, 1976-1982. Winter (2001) An Introduction to Igneous and Metamorphic Petrology.Prentice Hall.




Figure 30-15 . “Ideal” mineral zonation due to metasomatism in < 3 -m long ultramafic pods in low-grade regionally metamorphosedpelites at Unst, Shetland Islands. After Read (1934) M ineral. M ag. , 23, 519-540. Winter (2001) An Introduction to Igneous andMetamorphic Petrology. Prentice Hall.




Figure 30-16 . Variation in mineral proportions across the zones between the ultramafic and quartzo-feldspathic gneiss contact atGrafton, Vermont, after Sanford (1982). Zone letters at the top correspond to the zones listed in the text. Zone letters at the top are: A= Tlc + Ath, B = Tlc, C = Act + Chl, D = transitional, E = quartzo-feldspathic country rock. The vertical dashed line represents theestimated initial contact. After Sanford (1982) Amer. J. Sci. , 282, 543-616. Winter (2001) An Introduction to Igneous and MetamorphicPetrology. Prentice Hall.




Figure 30-17 . AMS diagram (A = Al 2O 3, M = MgO + FeO, and S = SiO 2), projected from K 2O, for ideal lower-temperaturemetasomatic zones around ultramafic bodies. After Brady (1977) Geochim. Cosmochi m. Acta , 41, 113-125. Winter (2001) AnIntroduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-18 . Hypothetical M - SiO2 diagram for fluids in the AMS system (Figure 30-16). Paths (1), (2), and (P&H) refer to thetheoretical paths in Figure 30-16, and the observed sequence of Phillips and Hess (1936). After Brady (1977) Geochim. Cosmochim.Acta , 41, 113-125. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-19 . The same portion of the AMS diagram as in Figure 30-16, projected from K 2O and CaO, with the locations of analyzedrocks from the metasomatized zones of Read (1934, see Figure 30-14), reported by Curtis and Brown (1969). The dashed curverepresents a path through the zonal sequence. After Brady (1977) Geochim. Cosmochim. Acta , 41, 113-125. Winter (2001) AnIntroduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-20 . Schematic representation of major silicate mineral reactions and component fluxes associated with metasomatism of theultramafic body at Grafton, Vt. Elemental fluxes across various zones are indicated by the arrows at the top. Arrows between mineralboxes (somewhat distorted from the true modes in Figure 30-15) indicate reactions. When horizontal, these arrows involvemetasomatic reactions; when vertical they are approximately isochemical. The zones listed at the bottom correspond to those in Figure30-15, and the heavy dashed line is the estimated original contact. After Sanford (1982) Amer. J. Sci. , 282, 543-616. Winter (2001) AnIntroduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-21 . Variation in chemical potentials of major components across the metasomatic zones at Grafton, Vt. Estimatedtemperature = 530 oC. Typical data points and error bars are illustrated for the MgO profile. Lettered zones at the top correspond tothose in Figure 30-15. The dashed vertical line is the estimated original contact. After Sanford (1982). Amer. J. Sci. , 282, 543-616.Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-22 . The three principal types of skarns. From Kerrick (1977) J. Petrol . , 18, 144-181. Winter (2001) An Introduction toIgneous and Metamorphic Petrology. Prentice Hall.




Figure 30-23 . Chert nodule in carbonate with layer sequence: calcite | tilleyite | wollastonite | quartz. Christmas Mts., Texas. From

Joesten and Fisher (1988) Geol. Soc. Amer. Bul l. , 100, 714-732.




Figure 30-24 . Schematic isothermal isobaricCO2

- H2O

diagram for fluids in the CaO-SiO2-H

2O system at high temperatures. After

Joesten (1974) Amer. J. Sci. , 274, 876-901. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-26 . Schematic CaO-MgO-SiO 2-CO 2-H 2O diagram showing the composition of the fluid solution in equilibrium with thephases shown at approximately 600 oC and 0.2 GPa (projected from H 2O and CO 2 at a constant 1:1 ratio). After Frantz and Mao(1976) Amer. J. Sci. , 276, 817-840. Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.




Figure 30-27 . a. Metasomatic zones separating quartz diorite (bottom) from marble (top). Zonation corresponds to third row frombottom in Table 30-1. b. Symmetric metasomatic vein in dolomite. Zonation corresponds to last row in Table 30-1. Adamello Alps.After Frisch and Helgeson (1984) Amer. J. Sci. , 284, 121-185. Photos courtesy of Hal Helgeson. Winter (2001) An Introduction toIgneous and Metamorphic Petrology. Prentice Hall.

b

a

1 cm

1 cm




Figure 30-28 . Mineral zones and modes developed at the contact between quartz diorite and dolomitic marble in Figure 30-26a. Initialcontact may be at either side of the contact zone. Index numbers at the top indicate the locations of bulk chemical analyses. AfterFrisch and Helgeson (1984) Amer. J. Sci. , 284, 121-185. Winter (2001) An Introduction to Igneous and Metamorphic Petrology.Prentice Hall.

h h l d




Figure 30-29 . a. log a CaO - log a SiO2 diagram in the system CaO-MgO-SiO 2-H 2O-CO 2 at 425 oC, 0.05 GPa, and X CO2 = 0.007. Numberedpoints correspond to the index numbers in Figure 30-27. After Frisch and Helgeson (1984) Amer. J. Sci. , 284, 121-185. Winter (2001)An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.

Ch 30 hi l id & i




Figure 30-29 . b. log a CaO - log a MgO diagram in the system CaO-MgO-SiO 2-H 2O-CO 2 at 425 oC, 0.05 GPa, and X CO2 = 0.007. Numberedpoints correspond to the index numbers in Figure 30-27. After Frisch and Helgeson (1984) Amer. J. Sci. , 284, 121-185. Winter (2001)An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.

Ch 30 M hi Fl id & M i




Figure 30-29 c. log a CaO - log a SiO2 diagram for the system CaO-MgO-SiO 2 -Al 2O 3 -H 2O-CO 2 at 425 oC, 0.05 GPa, and X CO2 = 0.007.Numbered points correspond to the index numbers in Figure 30-27. After Frisch and Helgeson (1984) Amer. J. Sci. , 284, 121-185.Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.

Ch 30 M hi Fl id & M i




Figure 30-30 . Zonation in an experimental skarn formed at the contact between granodiorite and limestone at 600 oC, P fluid = 0.1 GPa(X CO2 = 0.07). After Zharikov, V.A. and G.P. Zaraisky (1991) Experimental modeling of wall-rock metasomatism. In L. L Perchuck(ed.), Progress in M etamorphic and M agmatic Petrology. A Memori al Volume in H onor of D. S. Korzhinskii . Cambridge University

Press Cambridge pp 197-245 Photo courtesy G Zaraisky Winter (2001) An Introduction to Igneous and Metamorphic Petrology

fluids and metasomatism

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