The Current Status of Thermobarometry in Metamorphic Rocks E. J. Essene

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The current status of thermobarometry in metamorphic rocks

E. J. Essene

S U MMA RY: Information on pressure (P) and temperature (T) is a fundamental aspect of research on metamorphic terrains. Unfortunately, many workers employ thermobarometers that are not experimentally calibrated, are insensitive or too sensitive to P- T changes, depend on a priori assumptions of water pressure (such as most petrogenetic grids), or are rapidly reset on cooling. Many systems are based on inaccurate thermodynamic data, involve solids with inadequately characterized structural states, neglect effects of thermal expansion and compressibility, or require long extrapolations in P-T-X space. For instance, application of the widely used garnet-clinopyroxene KD thermometer may require extrapolation to temperatures where current thermodynamic models of pyroxenes and garnets remain uncertain. Current versions of the Mg/Fc exchange thermometer for biotite-garnet involve substantial compositional extrapolations for many applications and the biotite is easily reset while cooling from higher T. The most widely employed barometer is based on dilution of the reaction grossular + kyanite + quartz = anorthite, but failure to correct molar volumes for P- T-X may yield systematic errors of 1-2 kbar for barometry of crustal metamorphites. Application of this barometer to rocks equilibrated at T < 600-650°C is presently unwarranted in view of unknown a-X relations of garnets and plagioclases at these T. However, by careful selections, thermobarometry may be accurate to +50°C and + 1 kbar in many metamorphic terrains if a variety of different equilibria can be applied. Well-calibrated barometers that are useful for T > 600-650°C rely on continuous reactions based on equilibria such as almandine + rutile = ilmenite + sillimanite + quartz, garnet + quartz = ferrosilite + plagioclase, garnet + futile = ilmenite + anorthite + quartz, and almandine + sillimanite = hercynite + quartz. An extensive survcy of the recent literature on thermobarometry of individual metamorphic facies reveals the range of P-T encountered in each facies. Temperature estimates are in good agreement with the inferences of Turner (1968). Barometry reveals that the blueschist, amphibolite and granulite facies give way to the eclogite facies over the pressure range of 12-16 kbar.

This paper provides an update of a review of Thermodynamic data base thermobarometry (Essene 1982). There will be minimal overlap of discussion although thematic When unravelling the effects of P- T-X on the duplication cannot be eliminated entirely. I shall thermodynamics of minerals, it is imperative emphasize the most recent literature and at- that an accurate thermodynamic data base be tempt to provide a critique of present-day petro- available for the minerals that occur in meta- logical practices in acquiring thermobarometric morphic equilibria. While a comprehensive dis- data on rocks of specific metamorphic facies. cussion of this topic is beyond the scope of this Variations in pressure (P) and temperature (T) paper, it must be addressed in order to correct with time (t) will be considered elsewhere adequately for the effects of solid solution in in this volume, although these variations are natural and synthetic systems. For compilation usually deduced by the application of thermo- of thermodynamic properties of solids and barometry to zoned minerals. In the discussion fluids, the reader is referred to Clark (1966), that follows, 60 equilibria that may be useful for Robie et al. (1966, 1978), Burnham et al. (1969), thermobarometry are listed with reactants as Hultgren et al. (1973), Mills (1974), Helgeson the high pressure (and/or low temperature) et al. (1978), Barton & Skinner (1979), Jacobs side, followed by recent experimental refer- & Kerrick (1981), Kerrick & Jacobs (1981), ences on them. At the beginning of each section, Pankratz (1982), G. R. Robinson et al. (1982), a representative set of references is provided Chase et al. (1985), Berman et al. (1986), and for recent (1980-1988) applications of thermo- Berman (1988). There is no doubt that these barometry in a particular facies. Many values are becoming more accurate with time, additional references to the literature of meta- but data from different sources cannot be morphic petrology before 1980 are given combined with impunity because they may be by Mueller & Saxena (1977), Essene (1982), based on different sets of data for entropy, P. Robinson et al. (1982) and Hyndman (1985). enthalpy or volume. It is important to use

From DALY, J. S., CLIFF, R. A. & YARDI.~V, B. W. D. (eds) 1989, Evolution of Metamorphic Belts, Geological Society Special Publication No. 43, pp. 1-44. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

2 E.J. Essene self-consistent data sets to avoid introducing Ca3AI2Si3012 + SiO2 = CaAI2Si2Os systematic errors. However, serious errors may + 2CaSiO3 persist even in self-consistent thermodynamic (WAGS, Newton 1966, Gasparik 1984, data sets because of reliance on a single erroneous Chatterjee et al. 1984) data set. Thermodynamic parameters should quartz = coesite (3) always be tested against carefully reversed experiments to evaluate their ability to reproduce SiO 2 = SiO 2 (Mirwald & Massonne 1980, Bohlen & the reaction of interest, and thermodynamically Boettcher 1982) calibrated thermobarometers must be regarded with scepticism until evaluated against ex- jadeite + quartz = albite (4) perimentally based equilibria. NaAISi206 + SiO2 = NaAISi3Os (Johannes et al. 1971, Holland 1980) Volume changes of solids almandine + rutile = ilmenite + kyanite or (5) sillimanite + quartz Calculations of solid-solid equilibria must Fe3A12Si3012 + 3TIO2 = 3FeTiO3 + AI2SiO5 include corrections of the volumes for changes + 2SIO2 in pressure (or compressibility: Birch 1966, (GRAIL, Bohlen et al. 1983a; Fig. 3) Vaidya et al. 1974, Hazen & Finger 1982) and temperature (or thermal expansion: Skinner The assumption of constant AVs may be inad- 1966, Hazen & Finger 1982), even if these data equate for calculation of equilibria, e.g. it causes need be approximated (Helgeson et al. 1978, errors of as much as 1-2 kbar in the location of Powell & Holland 1985). Systematic errors may some reactions. Disparate thermodynamic data be generated in calculations assuming that AV~ will thus be generated from experimentally de- is constant at all P- T. The use of equilibria that rived equilibria depending upon the assump- have been derived with a constant AVP = AV~298 tions used to determine the volumes of solids, (e.g. Chatterjee et al. 1984, Berman et al. 1986) and use of these same equilibria for barometry must be regarded as suspect, especially for may yield significantly different results de- thermobarometry employing solid-solid reac- pending on the details of the calculation of AVs. tions with small changes in entropy and/or volume. Even when volume has been corrected for Thermodynamic properties of solid solutions the effects of pressure and temperature, small errors may still persist, because compressibility Thermodynamic models of activity-com- is usually measured at room temperature and position relations are requisite for application thermal expansion at room pressure, and the of barometers involving solid solutions and for volume calculated at P-T will depend on the correction of petrogenetic grids for components path chosen for the calculation. For consistency, encountered in natural systems. Unfortunately, it is recommended that volume be calculated at there is still no consensus concerning the a-X 1 bar and T followed by volume at P and T relations of even the common anhydrous using the compressibility data measured at 25°C. mineral groups such as spinel, ilmenite, plagio- Even though this is an arbitrary procedure, it is clase, alkali feldspar, garnet, orthopyroxene, convenient for calculations of different press- clinopyroxene, olivine and carbonate. Ganguly ures at constant temperature and is congruent & Saxena (1987) reviewed mixing models and with a 1 bar, T standard state for fluids. Any thermodynamic properties of selected mineral errors produced are unlikely to be significant at solutions. Spencer & Lindsley (1981), Sack P < 20 kbar for most reconstructive trans- (1982), Engi (1983), Lehman & Roux (1984), formations. Examples of the result of different Oka et al. (1984), O'Neill & Navrotsky (1984), assumptions for AVs upon the placement of Mattioli et al. (1987) and Shulters & Bohlen calculated equilibria are illustrated in Fig. 1 for (1987) presented mixing models for spinel solid the following equilibria: solutions. Spencer & Lindsley (1981) and Pownceby et al. (1987) evaluated the mixing grossular + kyanite + quartz = anorthite (1) properties of ilmenite solid solutions based Ca3A12Si3012 + 2A12SIO5 + SiO2 = on experimental data. Orville (1972), Kerrick 3CaAl2Si208 & Darken (1975), Newton et al. (1980), (GASP, Goldsmith 1980, Gasparik 1984, Kotel'nikov et al. (1981), Newton & Haselton Chatterjee et al. 1984, Koziol & Newton 1988a; (1981) and Blencoe et al. (1982) assessed plagio- Fig. 2) clases, although Carpenter & Ferry (1984) grossular + quartz = anorthite (2) questioned the standard state of CaAI2Si208 + wollastonite appropriate for intermediate plagioclases. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 3

Many authors, including Haselton et al. (1983), models of silicate solid solutions should not be addressed the thermodynamics of alkali feld- applied for precise thermobarometry on rocks spar solid solutions. Ghiorso (1984), Green & metamorphosed below the mid- to upper- Usdansky (1986b) and Fuhrman & Lindsley amphibolite facies. Thermodynamic models of (1988) developed thermodynamic models for solids need to be developed and tested against ternary feldspars. Ganguly & Saxena (1984) equilibrium experiments on well-characterized presented a comprehensive mixing model for solids at temperatures of 300-600°C if we are garnet solid solutions that is used widely, al- to make further progress in the thermo- though revisions have been proposed (Anovitz barometry of lower grade metamorphic rocks. & Essene 1987b, Geiger et al. 1987, Koziol & Thermodynamic mixing models for hydrous Newton 1988b). Several authors, including Bird silicates (e.g. amphiboles, micas, epidotes, & Helgeson (1980), concluded that grossular- chlorites) are based largely on unreversed ex- andradite is well represented as an ideal ionic perimental data or on simple ionic mixing solution, although Cosea et al. (1986) and Engi models generally unsupported by reversed ex- & Wersin (1987) calculated non-ideal a-X periments. One should correct equilibria for relations based on the experimental data of complex solid solutions of hydrous silicates with Huekenholz et al. (1981). Many workers, in- great caution. Unfortunately, many workers eluding Sack (1980) and Kawasaki & Matsui continue to use ideal ionic solution multi-site (1984), evaluated the mixing properties of Mg- models for hydrous solids without justification. Fe olivines and orthopyroxenes. Davidson & As a first approximation, correction for the Lindsley (1985) combined available exper- effects of solid solution should employ charge- imental and cation distribution data on clino- balanced ionic models: pyroxenes and orthopyroxenes to generate 2 2 muscovite: aKAI2Si3AIOII,(OH)2 ~--- XK.X~I.X6H a thermodynamic model for quadrilateral pyr- 3 2 oxenes. The bulk of the reversed experimental biotite: aKFe3Si~AIO,,,(OH)2 = XK.X~e.X~DH data on pyroxenes were obtained at T > 850°C, aKMg~Si3AIO,0(OH)2 = XK.X3g.X2 H and the validity of their model at metamorphic hornblende: au]ca2MgsSisO~2(OH)2 = T (< 800°C) remains speculative. Their model Xul.g2a.g5g.X2 H is not explicitly formulated to yield a-X re- 2 lations for pyroxenes, which makes its appli- epidote: aCa2A1AI2Si30,z(OH) = X~a.XAI.XoH cability to thermobarometry problematical. This approach is equivalent to that of Holdaway However, Davidson (pers. comm. 1987) devel- (1980) and Hodges & Spear (1982), except that oped an activity program based on their model dilutions on the OH sites are also considered. for quadrilateral pyroxenes that can be used There is no need to correct for dilutions on the explicitly for pyroxene barometry once the ef- tetrahedral sites because they are already fects of additional dilutions are considered accounted for by charge-balanced substitutions (Moecher et al. 1988). Bertrand et al. (1987) on other sites. Though better than the multi-site evaluated the mixing properties of ortho- ionic models, they are still only approximations pyroxenes in the system MgO-Al203-Si02, to be used if no measured a-X data are avail- and Aranovieh & Kosyakova (1987) modelled able. Kurepin (1987) confirmed this model for the mixing properties of orthopyroxenes in the biotite solid solutions based on evaluation of system MgO-FeO-Al203-Si02. Gasparik available experiments on biotite equilibria. (1985,1986) calculated the mixing properties of Nevertheless, without direct analyses of H2, F2, clinopyroxenes in the systems CaMgSi206- CI 2 and Fe3+/Fe 2+ for hydrous minerals, one NaAISizO6-Ca0.sAISi206 and CaMgSi206- cannot reliably compute the activity of a given CaA12SiO6-Ca0.sA1Si206 based on exper- component because of unmeasured dilutions by iments at high pressures and temperatures. O, CI, or F on the OH site. These can often Davidson & Mukhopadhyay (1984) modelled approach 50% at high metamorphic grades Ca-Mg-Fe olivines, but their model should be (Bohlen et al. 1980, Valley et al. 1982, Edwards reprocessed to include the reversed experiments & Essene 1988, Peacor & Dunn 1988). Even of Adams & Bishop (1985) on the monticellite- with these charge-balanced models, some forsterite solvus. None of the data on these substitutions may be counted twice, e.g. solid solutions should be extrapolated below (Mg,Fe2+)O = (AI,Fe 3+ )(OH), which may be about 600-700°C because the calculated co- a significant exchange in hydrous silicates. efficients of the thermodynamic mixing models Cation ordering on the different octahedral sites of most solids have not been shown to realisti- in amphiboles (Hawthorne 1982) will further cally represent the behaviour of minerals at low reduce the activity of any end-member com- temperatures. This means that thermodynamic ponent in hornblende. Crystal-structure and Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

4 E.J. Essene

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Thermobarometry in metamorphic rocks 5

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6 E.J. Essene other crystal-chemical studies should be used to mineral assemblages. The most widely used sys- document the degree of octahedral site ordering tems involve exchange of Mg and Fe 2+ or 160 in amphiboles at high temperatures. and 180 between two solid phases. References Unfortunately, ideal solution models are to specific exchange thermometers are given in sometimes demonstrably in error at large di- Essene (1982) and in Ganguly & Saxena (1987). lutions. For instance, pargasite frequently co- While the potential for geothermometric appli- exists with clinopyroxene, orthopyroxene and cation of such thermometers is excellent, a quartz in high-grade rocks, and this assemblage number of obstacles may be encountered when is buffered by the equilibrium tremolite = applying these systems to metamorphites. The enstatite + diopside + quartz + water vapour. drawbacks may have an effect on all equilibria, The A site may be fully occupied with Na and K but they have the greatest impact on exchange in pargasite (Leake 1968), yet the activity of reactions with their small AS and very small tremolite cannot approach zero, as this would AV. These difficulties are detailed in the fol- require infinite temperatures or zero H20 fuga- lowing subsections. city at finite activities of SiO2, CaMgSi206 in clinopyroxene and MgSiO3 in orthopyroxene. Imprecise calibration of exchange reactions The use of any thermodynamic model at large dilutions that is unsupported by experimental Proper calibration involves compositional re- data at similar temperatures may be a chimera versals for the structure states stable at the tem- leading to absurd petrological conclusions. perature of interest, and the lack of reversals Careful experimental and thermodynamic may explain differences in various versions of studies with complete chemical and structural the same thermometer. Discrepancies may also characterizations are needed at metamorphic be caused by long P- T-X extrapolations from temperatures before one may rely on any quan- the conditions of the experiment to those ap- titative thermobarometry using hydrous phases propriate for application in rocks. Exchange with significant solid solutions. equilibria derived solely from thermodynamic calculations may have substantial imprecisions due to residual errors in the location of the Exchange thermometry reaction.

Many equilibrated mineral pairs partition iso- Inaccurate models for the thermodynamics of valent elements with a measurable temperature solids dependence. For one mole of exchanging isovalent cations, the exchange may be represented This poses severe constraints on applications of as: KD thermometry to complex solid solutions (e.g. hornblende, biotite) or in extrapolation to A(i) + B(j) = A(j) + B(i) temperatures below those of the calibration. where i, j are the exchanging cations and A, B Extrapolation of any KD thermometer to are the two phases in equilibrium. This may be temperatures lower than the measured a-X written as an equilibrium constant relation: data may yield serious errors for thermobarometry. Because experiments that constrain exp (-AG°T/RT) K A B A B = = a i a i/a i a~ a-X relations on silicate solid solutions are and because a = yX, largely restricted to >700°C, extrapolations to K AB AB A B :4 B below 600°C, i.e. at or below the mid-amphibolite = [Yi Y,/'7, Yj ][X~ X~/X; X~ ] = Kv.K D and hornblende-hornfels facies, are questionable. The first product term is K¥ and the second is Only if reversed experiments are available on KD the distribution coefficient, which may be mineral chemistries and structures closely determined from chemical analyses. If the ac- matching that of the actual minerals at the P- T tivity coefficient ratio, Yi/Yi is known for each of equilibration, may exchange thermometry be phase, then the KD is exponentially related to T used reliably. Workers have attempted to and may be used as a thermometer if experi- correct various exchange thermometers for the mental or thermodynamic data are available for effects of additional components. For instance, the reaction. Most exchange thermometers are empirical corrections to the garnet-biotite formulated in terms of InKD versus lIT(K), thermometer have been proposed by Perchuk which can be extrapolated linearly to lower T & Aranovich (1984) for F in biotite, by Indares only if InKv is also a linear function of lIT. & Martignole (1985a) for AI and Ti in biotite, A variety of isovalent element exchange ther- and by Hoinkes (1986) for Ca in garnet. These mometers have been proposed for various substitutions occur simultaneously in many Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 7 highgrade garnet-biotite assemblages, and it is solutions in micas and chlorites; octahedral Li difficult to sort out the effects of each exchange. substitutions in staurolites and micas). Never- theless, when this procedure has been checked with more complete analyses for Fe3+/Fe 2+ Errors in normalizing mineral formulae and/or H20, it has yielded accurate formulae Normalization procedures can be a serious for biotites and hornblendes (Bohlen et al. 1980, problem for complex minerals incompletely Edwards and Essene 1988, Cosca et al. 1989). characterized by microprobe analyses (e.g. After an acceptable cation normalization is ob- amphiboles, micas, chlorites, staurolites). Am- tained, limits may be placed on Fe3+/Fe 2+ based biguities in Fe3+/Fe 2+ or in light elements (H, on charge balance, although the substitution Be, Li, B, F) not routinely detected by the Fe z+. OH = Fe 3+. O may be constrained only microprobe preclude accurate calculation of the with direct analyses of Fe3+/Fe 2+ and H2 by amount of oxygen and prevent normalizations accurate wet-chemical and Mossbauer analyses. about anions. Replacement of OH by O in Once the Fe z+ is measured or estimated, a Kc) hydrous silicates prevents accurate normaliz- for Mg/Fe 2+ exchange may be calculated that is ations about oxygen on an anhydrous basis, not biased by inclusion of Fe 3+ with Fe 2+ even though this practice is widely used to (Powell 1985). obtain formulae for hornblende and biotite. Potential vacancies in larger cation sites (especially VIII to XII coordinated sites) often Effect of cation order~disorder in minerals and prevents straightforward normalizations about synthetic phases total cations. As a provisional solution, it is The effect of cation disorder on thermobaro- recommended that cation normalizations of metry is often ignored. For instance, Charlu et microprobe analyses be made consistently on al. (1975) documented differences of c. 40 kJ the smaller cations (SC): Si, Ti, AI, Fe 3+, Fe 2+, mo1-1 in AH~6s between natural and synthetic Mg (+ Mn, Ca, Na), assuming that the SC are sapphirine. Unless natural sapphirine has or- present in stoichiometric numbers on octa- dered upon cooling, synthetic sapphirine must hedral (VI) and tetrahedral (IV) sites for most have substantially increased disorder compared Fe-bearing minerals, e.g.: to its natural analogue. This implies that experimental data on the stability of synthetic SC= 2 for ilmenite-group minerals; sapphirine (e.g. Hensen 1971, Hensen & Green SC= 3 for spinel-group minerals; 1971, 1973, Seifert 1974, Ackermand et al. SC= 4 for pyroxenes (including Mn, Na, Ca); 1975) may apply to metastably disordered SC= 8 for garnets and epidotes (including sapphirine, which would overconstrain its stab- Mn, Ca); ility. Until these difficulties are resolved, re- SC= 10 for chlorites; actions involving sapphirine should not be used SC= 12 for dioctahedral micas (excluding K, Na, Ca); for quantitative thermobarometry. For feldspars, one must select the appropriate SC= 13 for Na and Ca amphiboles (excluding AI-Si ordering state for the calculations of K, Na, Ca); interest. As yet, the exact P-T interval over SC= 14 for trioctahedral micas (excluding K, which disordering occurs in feldspars is uncer- Na, Ca); tain, but albite and K-feldspar probably begin SC= 15 for ferromagnesian amphiboles (ex- to disorder at 400-450°C and are fully disor- cluding K, Na, Ca). dered at 500-600°C in metamorphic rocks. One is obliged to include all cations for il- Thus, the selection of the appropriate ordering menites, spinels, pyroxenes and chlorites be- state of albite and K-feldspar is clear for low- cause only VI and IV sites are available, and for grade rocks such as the greenschist and blue- garnets and epidotes because Fe and Mn (with schist facies, and for high-grade rocks such as 2+ and/or 3+ valencies) may occupy both VIII the upper amphibolite and granulite facies, but and VI sites. Without further modifications, the exact degree of disorder is uncertain in cation normalizations are inadequate for hydro- intermediate-grade metamorphites. Unfortu- garnets (Valley et al. 1983). Cation normaliz- nately, the equilibrium amount of disorder in ation requires no a priori information about intermediate plagioclases in medium- and high- Fe3+lFe2+ or O/OH, but still contains certain grade rocks is uncertain because plagioclases potential flaws (e.g. Mn, Fe z+ for Ca in calcian forming even at high temperatures are not to- amphiboles; Ca, Na for Mg, Fe 2+ in ferro- tally disordered. At present, one can only pre- magnesian amphiboles; REE and vacancy sub- sume that experimental and thermodynamic stitutions in epidotes; di/trioctahedral solid models for 'high' plagioclase solid solutions Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

8 E.J. Essene

(Orville 1972, Newton et al. 1980) are appro- pidly, thus preserving peak metamorphic priate for natural plagioclase at T > 600°C, but MgCO3 contents in calcite (Essene 1983). further work is needed on the equilibrium tem- A solvus potentially applicable to many meta- perature dependence of AI-Si ordering in feld- pelitic rocks is that involving paragonite and spars. Characterization of the present degree of muscovite, even though the miscibility limit has order in intermediate- and high-grade feldspars not been experimentally reversed by unmixing only places a constraint on the minimum amount a homogeneous mica solid solution inside the of disorder in feldspars because of the common solvus to form two macroscopic phases (Essene reordering generally occurring upon cooling. In 1982). Although the binary solvus has been very low-grade rocks such as the zeolite and repeatedly investigated experimentally and portions of the pumpellyite facies, feldspars elaborately treated thermodynamically (e.g. may initially form as disordered structures and Eugster et al. 1972, Blencoe 1974, Chatterjee & once formed, may persist indefinitely. Froese 1975, Pascal & Roux 1985, Chatterjee & Robie et al. (1978) increased the S~ of micas Faux 1986, Green & Usdansky 1986a), the re- by 17-K J mol -I and decreased their AG~ by sults must be regarded with scepticism because 0.017-T kJ mol -~ based on crystal-structure of the lack of demonstrated equilibrium. Ap- refinements consistent with complete long-range plication to rocks with coexisting muscovite- disorder of A1-Si. However, thermodynamic paragonite may nevertheless limit maximum calculations of dehydration equilibria for di- temperatures, because the solvus is constrained octahedral micas do not fit experimental re- to temperatures below the inferred gap. How- versals unless this contribution is removed ever, complexities resulting from phengite (paragonite, Holland (1979a); margarite, and other solid solutions, and from submicro- Perkins et al. (1980); muscovite, Schramke et al. scopic interlayering of micas and chlorite (Ahn (1987)). If micas contain substantial short-range et al. 1985, Franceschelli et al. 1986b) suggest order of tetrahedral Si and AI, the assumed that this system is unlikely to be reliable as a zero-point entropy contribution is inappro- geothermometer. priate. Nuclear magnetic resonance measure- Solvi among feldspars continue to be used for ments are needed to test the short-range model thermometry in metamorphic rocks. Bohlen & on a variety of natural and synthetic micas Essene (1977) were among the first to apply the as the available data suggest substantial short- plagioclase-K-feldspar thermometer to high- range order (Kinsey et al. 1985). In any case, grade rocks with exsolved alkali feldspars. Most the calculations imply that the thermodynamic workers now use the calibration of Haselton et data in Robie et al. (1978) for micas may have al. (1983) for plagioclase-K-feldspar ther- to be corrected back to the ordered structure as mometry. This model does not fully correct for a better approximation to the thermodynamic the effects of high-temperature ternary solu- properties of experimental and synthetic micas. tions, and the treatment of Fuhrman & Lindsley (1988) should be used for ternary feldspars. Based on presumed equilibrium data from natural plagioclases spanning the peristerite Applications of solvus thermometry gap, Maruyama et al. (1983) have proposed a strong pressure dependence of the peristerite Many of these thermometers have been dis- solvus that has occasionally been used as a cussed by Essene (1982), but a few comments thermobarometer. Unfortunately, the available follow on solvus systems that continue to be volume data for plagioclase solid solutions do used. The calcite-dolomite soivus may be not support their model, and it should be criti- useful for rocks metamorphosed to 300-600°C, cally re-evaluated with respect to the possibility but the magnesium content of calcite is com- of metastable structure states and/or compo- monly reduced by retrograde exsolution of sitions forming in low-temperature plagioclases. dolomite and/or recrystallization (Essene 1983). The gap between microcline and low albite Anovitz & Essene (1987a) compiled available (Bachinski & Muller 1971) is potentially of use experimental reversals to obtain an internally in blueschist- and greenschist-facies rocks using consistent solvus. Microprobe analyses rather the pressure correction of Goldsmith & Newton than XRD determinations of the MgCO3 con- (1974). The assemblage albite-microcline is tent of the calcite are necessitated by the widespread in low-grade metapelites and meta- (sub)microscopic exsolution of dolomite pro- mafites but has seldom been applied as a ther- duced in calcite upon cooling. The calcite- mometer. At temperatures between c. 450 and dolomite thermometer is most useful in contact 650°C the system KAISi~Os-NaAISi308 is metamorphic rocks that cooled relatively ra- complicated by anorthite solid solution and Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 9 by intermediate and continuously variable kyanite = sillimanite = andalusite (6) degrees of order/disorder that have not been Al2SiO5 = AI2SiO5 adequately modelled thermodynamically; thus, (Holdaway 1971, Robie & Hemingway the microcline-albite solvus should not be used 1984, Salje 1986) as a thermometer at T > 450°C. (7) The miscibility gap between orthopyroxene aragonite = calcite and clinopyroxene has continued to draw atten- CaCO3 = CaCO3 (Crawford & Fyfe 1965, Johannes & tion. Davidson & Lindsley (1985) combined experimental data on the solvus between quad- Puhan 1971) rilateral pyroxenes to derive a two-pyroxene led to the first modern thermobarometry of thermometer. While their thermometer should various metamorphic facies (e.g. Miyashiro be applicable primarily to higher temperature 1961, Winkler 1965, Turner 1968). Reactions igneous and mantle rocks that equilibrated on (1)-(7) provide first-order thermobarometric the temperature range (900-1300°C) of most information and are powerful especially when experiments, Davidson & Lindsley noted good combined with other thermobarometers. agreement with other thermometers when Other simple reactions useful for thermo- applied to granulite-facies rocks. Nickel & Brey barometry involve dehydration and/or decar- (1984), Carlson (1986, 1988), Saxena et al. bonation. In order to apply these equilibria, (1986) and Carlson & Lindsley (1988) reported knowledge of PH2o/Ps for dehydration reac- additional data on quadrilateral and aluminous tions, Pco,/Ps for decarbonation reactions, pyroxenes that could be useful in another re- and PH2o/Pco2/Ps for reactions involving both vision of the two-pyroxene thermometer. Any fluid species is required (cf. Greenwood 1962, version of the two-pyroxene thermometer is Kerrick et al. 1974, Flowers & Helgeson 1983). highly sensitive to analytical errors and cor- At the lowest grades, Pf may be significantly rections for non-quadrilateral components, and less than Ps as a result of vertical movement of is insensitive to variations in temperatures of fluids, especially for shallowly buried rocks, and most metamorphic rocks because of the steep- PCH4 may become a significant part of Pf. In ness of the limbs of the solvus at T < 800°C. the upper amphibolite and granulite facies, The solvus between monticellite and forsterite Pn2o may become significantly less than P~ may be a useful thermometer for high- through loss of the fluid phase into a H20- temperature dolomitic marbles and some ultra- undersaturated melt or by dilution with CO2. mafic rocks. Davidson & Mukopadhyay (1984) Under amphibolite-facies conditions, Pe can be combined experimental data on the solvus for less than P~ within dry igneous rocks that are quadrilateral olivines with thermodynamic sufficiently competent to minimize recrystalliz- modelling to obtain the temperature depen- ation and deny access of significant amounts dence with composition. Adams & Bishop of external fluids. The petrologist should not (1985) relocated the forsterite-monticellite assume a priori some relation between a fluid solvus with closely reversed experiments. Their species and total pressure (e.g. PH,O = P~ for model of a-X relations for forsterite-monti- all metapelites, Pco2 = Ps for all metacarbon- cellite has brought solid-solid experiments in ates, Pf = 1/3-Ps for hydrothermal metamor- the system CaO-MgO-Si02 into good agree- phism, or Pf = Ps for the eclogite or granulite ment with calculated curves (Sharp et al. 1986). facies). The rarity of rocks with two olivines and the In spite of these complications, some reac- insensitivity of the system below 750°C suggest tions that occur in simple chemical systems may that few successful applications of this thermo- provide useful limits for thermobarometry. meter will be made except in high-temperature Equilibria with particular petrogenetic signifi- rocks. Other solvi are reviewed in Essene cance are given below for different systems. (1982). MgO-SiO2-n20 antigorite + brucite = (8) Thermobarometry with simple forsterite + water vapour reactions Mg3Si2Os(OH)4 + Mg(OH)2 = 2MB2SiO4 + 3H20 (Chernosky et al. 1985, Day et al. 1985, The use of simple univariant reactions for thermobarometry has long been recognized. Early Berman et al. 1986) calibrations of reactions (1)-(4), and others antigorite = forsterite + talc + (9) such as: water vapour Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

10 E. J. Essene

5Mg3Si2Os(OH)4 = 6Mg2SiO4 + (Perkins et al. 1980, Nitsch et al. 1981, Mg3Si4Ol0(OH)2 + 9H20 Jenkins 1984) (Chernosky et al. 1985, Day et al. 1985, prehnite = grossular + zoisite + (18) Berman et al. 1986) quartz + water vapour 5Ca2AI2Si3010(OH)2 = 2Ca3A12Si3012 + Al203-SiO2-H20 2Ca2AI3Si3012(OH) + 3SIO2 + 4H20 (Liou 1971a, Perkins et al. 1980) kaolinite = pyrophyllite + water vapour (10) A12Si2Os(OH)4 + 2SIO2 = Al2Si4Oi0(OH)2 + prehnite = grossular + lawsonite + (19) H20 quartz (Thompson 1970a, Haas & Holdaway 2CazAlzSi3Ol0(OH)2 = Ca3AI2Si3OI2 + 1973, Hemley et al. 1980) CaAI2Si207(OH)2-H20 + SiO2 (Perkins et al. 1980) pyrophyllite = aluminosilicate + (11) quartz + water vapour zoisite + kyanite + quartz = anorthite + (20) water vapour Al2Si4010(OH)2 = Al2SiO5 + 3SIO2 + H20 (Haas & Holdaway 1973, Hemley et al. 1980) 2Ca2AI3Si3OI2(OH) + AI2SiO5 + SiO2 = 4CaA12Si208 + H20 (Jenkins et al. 1983, 1985) CaO- Si02- CO 2 clinozoisite + kyanite + quartz - (21) calcite + quartz = wollastonite + (12) anorthite + water vapour carbon dioxide 2Ca2AI3Si3OI2(OH ) + AIzSiO5 + SiO2 = CaCO3 + SiO2 = CaSiO3 + CO 2 4CaA12Si208 + H20 (Greenwood 1967b, Tanner et al. 1985) (Jenkins et al. 1983,1985) wollastonite + calcite = tilleyite + (13) lawsonite + quartz + water vapour = (22) carbon dioxide laumontite 2CaSiO3 + 3CACO3 = Ca5Si207(CO3)2 + CaAI2Si207(OH)2-H20 + 2SIO2 + 2H20 = CO2 CaAI2Si4012" 4H20 (Treiman & Essene 1983) (Thompson 1970b, Liou 1971b)

mgO-Al203-SiO2-H20 FeO-AI203- SiO2- H20 clinochlore = forsterite + (14) almandine + sillimanite + quartz + (23) enstatite + spinel + water vapour water vapour = Fe-cordierite MgsA12Si3010(OH)8 = Mg2SiO4 + 2MgSiO3 2FeaA12Si3012 + 4A12SIO5 + 5SIO2 + + MgAl204 + 4H20 nH20 = 3Fe2Al4SisOls"nH20 (Fawcett & Yoder 1966, Staudigel & (Richardson 1968, Weisbrod 1973) Schreyer 1977) Mg-chloritoid + quartz = talc + (15) kyanite + water vapour Na20-AI203- SiO2- H20 3MgAI2SiOs(OH)4 + 4SIO2 = Mg3Si4O10(OH)2 + 3A12SIO5 + 5H20 paragonite + quartz = albite + (24) (Schreyer & Seifert 1969, Seifert 1974, aluminosilicate + water vapour Chopin & Schreyer 1983) NaAl3Si3010(OH)2 + SiO2 = Al2SiO5 + NaAISi308 + H20 (Chatterjee 1972) CaO-A1203-SiO2-H20 jadeite + kyanite + quartz + (25) margarite + quartz = anorthite + (16) water vapour = paragonite aluminosilicate + water vapour NaAISi206 + Al2SiO5 + SiO2 + H20 = CaAl4Si2Ol0(OH)2 + SiO2 = CaAl2Si208 + NaAlaSi3010(OH)z Al2SiO5 + H20 (Holland 1979a) (Chatterjee 1976) analcime + quartz = albite + (26) margarite + quartz -- zoisite + kyanite + (17) water vapour water vapour NaAISi206. H20 + SiO2 = NaAISi308 + 4CaAI4Si2OH~(OH)2 + 3SiO 2 = H20 2Ca2AI3Si3O12(OH) + 5A12SIO5 + 3H20 (Liou 1971c, Thompson 1971) Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 11 jadeite + water vapour = analcime (27) morphic rocks. Reaction (23) controls the upper NaAISi206 + H20 = NaAISi206. H20 pressure limit of Fe-cordierite and has been (Newton & Kennedy 1968, Manghnani 1970) located by experiments for PH~O = P~, but the effects of variable PH~O and Pco, on the equilibria have not yet been evaluated experimen- K20-A1203-SiO2-H20 tally, and the thermodynamic models advanced muscovite + quartz = aluminosilicate (28) to assess variable fluid pressure are unsupported + sanidine + water vapour by hard experimental data. This is a serious KAl3SiaOl0(OH)2 + SiO2 = Al2SiO5 + shortcoming for a reaction commonly applied KAISi308 + H20 in low-pressure rocks of the upper amphibolite (Storre & Karotke 1971, Kerrick 1972, and granulite facies where H20 activities are Day 1973, Schramke et al. 1987) locally variable. Cordierite equilibria should not be used for quantitative barometry until additional experiments adequately constrain the FeO-Fe203-SiO2-H20 effects of various fluids, order/disorder, and grunerite -- ferrosilite + quartz + (29) non-ideal a-X relations. Most of the other water vapour reactions have specific petrological significance Fe7SisO22(OH)2 = 7FeSiO3 + SiO2 + H20 that will be considered below (or see Winkler (Miyano & Klein 1986) 1979, Turner 1981).

CaO- MgO- SiO 2-1-120- CO 2 tremolite + calcite + quartz = diopside + (30) Thermobarometry with solid fluid solutions CazMgsSisO22(OH)2 + 3CACO3 + 2SIO2 = 5CaMgSi206 + H20 + 3CO2 While simple univariant reactions are generally (Slaughter et al. 1975, Eggert & Kerrick 1981) easy to apply to rocks, they usually provide P-T limits only because a univariant assem- diopside + forsterite + calcite = (31) blage is rarely preserved. Apparent univariant monticellite + carbon dioxide (or invariant) assemblages are often produced CaMgSi206 + Mg2SiO4 + 2CaCO 3 = by disequilibrium reaction processes during 3CaMgSiO4 + 2CO2 retrogression that may be difficult to interpret (Sharp et al. 1986) (e.g. Lal 1969). Alternatively, reactions may be These reactions are all well located by exper- strongly influenced by solid solutions that must iment and/or thermodynamic calculation and be considered for adequate thermobarometry. may be combined with solid-solid reactions to Solid solutions are often beneficial for thermo- form a well-determined petrogenetic grid of barometry because the assemblage is preserved great use in first-order subdivisions of meta- over a significant P-T range. The importance morphic facies. The upper stability of kaolinite of continuous reactions for quantitative ther- + quartz, reaction (10), and analcime + quartz, mometry and barometry of metamorphic rocks reaction (26), mark the upper P-T limit of was emphasized in a little-referenced paper by the zeolite facies, although the stabilities of Strens (1970), who also pointed out their sig- analcime or kaolinite may contract to lower nificance for the inference of geothermal gradi- temperatures in hydrothermal environments if ents and other geophysical implications. The PH20 < Ps, or if asio2 > 1 in solutions super- widely used garnet-aluminosilicate-silica- saturated with silica or in equilibrium with plagioclase (GASP) barometer (e.g. Ghent 1976, amorphous silica. The upper stability of pyro- 1977, Aranovich & Podlesskii 1980, Newton & phyllite, reaction (11), at c. 350-400°C, marks Haselton, 1981, Koziol & Newton 1988a) serves the approximate initiation of the biotite or gar- as an example; other systems will be discussed net zones of the greenschist facies. However, below under the sections on individual facies. despite the inferences of Winkler (1965, 1979), The assemblage garnet-plagioclase- pyrophyllite is a relatively uncommon mineral Al2SiOs-quartz (GASP) is widespread in in the greenschist facies (cf. Frey 1978, Phillips metapelites ranging from the greenschist to the 1987), because of its instability with feldspars or granulite facies. If the a-X relations are known alkali metal ions. Equilibria involving kaolin or for grossular in garnet and anorthite in plagio- pyrophyllite remain more useful in constraining clase as a function of temperature, the shift in the conditions of hydrothermal alteration zones reaction (1) from the end-member curve may rather than delimiting P-T for most meta- be calculated as: Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

12 E. J. Essene

fAVsdP = R- T. InK = complex equilibria, e.g. staurolite reactions re plagioclase x3t_garnet 1 R- T- In l[aCaAi2Si20~) /t/Ca3Ai2Si3Oi2l in metapelites. However, undue confidence is often placed in the use of n-component (n > For convenience, isopleths of log,0K may be 4) nets for quantitative thermobarometry with- contoured on a P-T diagram (Fig. 2). If one is out evaluation of the effects of variable PH2O able to convert chemical analyses of the plagio- and/or additional components. Semi-quanti- clase and garnet to the activities of the respective tative petrogenetic grids involving Mg/Fe loops Ca end-members with appropriate solution have been constructed by many workers from models, then log,0K may be calculated and a field and topological constraints, e.g. Thomp- P- T line located for a given K. This technique son (1976a, b) for metapelites, as well as is the basis of Ghent's (1977) barometer. Quite Abbott (1982), Liou et al. (1985), and Spear & apart from integration of the volume term, Rumble (1986) for metabasites. Additional proper application requires knowledge of a-X calibrated equilibria are needed in the systems relations of solid solutions at pressure and tem- K20-MgO-FeO-AI203-SiO2-H20 for perature. If one chooses to use previously pub- metapelites and Na20-CaO-MgO-FeO- lished contours of log~0K on a P-T diagram AI203-SiO2-H20 for metabasites in order to rather than rederiving the relation, the same better calibrate realistic univariant reactions volume data (and in some cases, activity models) that combine to become quantitative petro- must be used that were employed in deriving genetic nets. Such experiments must be con- the logl0K plots. The more useful thermo- ducted over a wide range of compositions to barometers relying on solid solutions are pre- permit full evaluation of the effects of various sented in the discussions below of individual solid solutions and are difficult to interpret in facies. terms of equilibrium. Full quantification of P- T-X phase equilibria in such systems is not expected in the near future. Use of petrogenetic grids

Petrogenetic grids may be useful for thermobarometry if the minerals are well approximated Practical procedures for by reactions of the grid and if the specific effects thermobarometry of fluid versus solid pressure are considered. Some chemical systems closely match rock In the practice of thermobarometry, one should chemistries, e.g. MgO-SiO2-H20-C02 for apply well-calibrated systems that have been metamorphosed ultramafites (e.g. Greenwood shown to be successful by other researchers 1967a) and CaO-MgO-SiO2-H20- CO 2 working on the same metamorphic grades, lith- for metamorphosed siliceous dolomites and ologies and assemblages. One should examine marbles (e.g. Eggert & Kerrick 1981). Unfor- many polished thin-sections of all lithologies tunately, adequate representation of pelite and with transmitted and reflected optical as well as mafite chemistries requires at least six or seven electron imaging techniques in order to evaluate components, even if one may safely ignore F2, textures that may distinguish retrograde from Fe203, TiO2 and CO2. While pelitic subsystems preserved equilibrium assemblages. Accessory have been the subject of much experimental minerals should be identified, because these investigation [e.g. reactions (1), (6), (10), (11), often ignored minerals may fix important equi- (15)-(17), (22)-(28)], reversed equilibria are libria. If possible, textures and assemblages not as yet available in systems of more than five should be tied to structural evidence that may or six components. Documentation of com- indicate the relative timing of various sequential positional reversals is rather difficult when tectonic processes. Assemblages that do not phases contain more than binary solid solutions involve large dilutions should be preferred to and when six or eight phases are present. It is those that may involve large dilutions of the generally safer to select an experimentally re- component(s) sensitive to P-T variations. One versed univariant equilibrium in a chemical sub- should evaluate thermobarometers for the ef- system that is buffered by mineral assemblages fects of variable Fe3+/Fe 2+, normalization in the rock under study, and to correct the schemes and other analytical imprecisions by equilibrium for the effects of additional solid processing reasonable errors and evaluating the solutions, than to rely quantitatively on complex changes involved in the resultant P-T. Several petrogenetic grids. Many petrologists, for different thermobarometers should be evalu- example, place more weight on the P-T lo- ated in the same or nearby rocks in order to cation of the AI2SiO5 isograds than on more gain insights as to the reliability of the P-T Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 13 estimates. A necessary but not sufficient con- 1981, 1987, Frey 1987). Petrogenetic grids dition of accuracy is that two or more ther- based on the stability of zeolites and prehnite mometers or barometers happen to give the may be useful (e.g. Liou, 1971a, b), although same results. Thermometers that are reset uncertainties in the chemistry and order/ during retrogression may affect inferences from disorder relations of the natural and synthetic barometers with a significant temperature de- phases have not been fully considered. In ad- pendence. Zoning of refractory minerals such dition, the locations of these dehydration equi- as garnets must be carefully evaluated if one is libria may be strongly affected by PH~O < Ps to separate the effects of retrograde versus pro- due to open fracture systems, involvement of grade reactions. If other workers have criticized highly saline fluids, and high PCH~ in carbon- the bases or results of a given thermobarometer, aceous lithologies metamorphosed at low it should be applied with great caution, or grades. In order to relate anchimetamorphic errors may ensue. Thermobarometric results terrains to exact metamorphic facies, more should not be averaged by combination of ques- attention should be given to assemblages in tionable systems with ones in which greater intercalated metamafites that are responsive to confidence is placed. With careful application, metamorphic grade at low temperatures (Liou thermobarometry can often be precise to +50°C et al. 1987). and +1 kbar if several well-calibrated systems Researchers have applied 'thermometers' are applied to rocks metamorphosed at the such as illite crystallinity (e.g. Kisch, 1980a, b, same conditions. 1981, 1987, Frey et al. 1980, Thompson & Frey 1984), vitrinite reflectance (e.g. Bostick 1974, Kisch, 1980a, b, 1981, 1987, Frey et al. 1980, Teichmuller 1987), and conodont colour in- Recommendations for individual dex (e.g. Rejebian et al. 1987) to studies of metamorphic facies diagenesis, hydrothermal systems, and low- temperature metamorphites (Frey, 1987). The choice of optimal thermobarometers varies These thermometers involve poorly under- widely from facies to facies. Definitions of in- stood, rate-dependent, non-isochemical, dis- dividual facies follow Turner (1981). Low- equilibrium reactions best evaluated with temperature metamorphites contain abundant, kinetic or irreversible thermodynamic models. complex, low-symmetry hydrous silicates for Although primarily controlled by time- which few acceptable thermodynamic and temperature relations, these systems should experimental data are available. Moderate- also be sensitive to fluid/rock ratios as well as temperature metamorphic rocks often preserve the chemistry of the fluid phase and the ratio vestiges of a complex metamorphic P-T-t his- Pf/Ps. Reactions forming and destroying illite tory rich with information but complicated by are non-isochemical, may include reaction with complex zoning patterns in refractory minerals feldspars or alkali metal ions, and probably in- such as garnet, amphibole and epidote. High- volve disequilibrium phases such as smectite, temperature metamorphites, composed largely illite and detrital high-temperature feldspars of relatively simple anhydrous silicates (and (Ahn & Peacor 1986). The process of graphitiz- complex hydroxyl-silicates, e.g. hornblende ation of vitrinite produces coexisting carbon- and biotite), seldom preserve the prograde aceous phases with different ordering and metamorphic history, but are often affected by structure states and progressive variations in retrograde processes that obscure inference of bulk properties, such as powder X-ray diffrac- peak metamorphic conditions. tion measurements or reflectance, will reflect modal variations in the coexisting phases rather than a homogeneous, monotonic transformation to ordered graphite (Buseck & Huang Zeolite facies 1985, Okuyama-Kusunose & Itaya 1987). The Thermobarometry has been evaluated in the degree of graphitization is accelerated by defor- zeolite facies by some workers (Frost 1980, mation at low temperatures, retarded in con- Kisch 1980a, b, 1981, 1987, Frey et al. 1980, tact aureoles relative to regional metamor- Padan et al. 1982, Evarts & Schiffman 1983, phites, and is correlated with modal carbon, Thompson & Frey 1984, Liou et al. 1985, 1987, methane fugacities and permeability (Itaya Cho et al. 1986, Frey 1987, Bevins & Merriman 1981, Wintsch et al. 1981, Okuyama-Kusunose 1988). Anchimetamorphic conditions have not & Itaya 1987). Bostick (1974), who applied his been well defined, but probably include both phytoclast reflectance analysis to jadeite- the zeolite and pumpellyite facies (Kisch 1980b, bearing Franciscan metagreywackes, concluded Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

14 E. J. Essene

that they attained only 120-150°C, at least upper stability of prehnite. Calculations of the 100°C less than that estimated from petrological locus of reaction (18) (Perkins et al. 1980) devi- and stable isotopic thermobarometry. The ate with increasing pressure from the reversed documented complexities of the natural graphi- experiments on this reaction (Liou 1971b). The tization process have implications for the frac- reasons for this discrepancy are still unknown. tionation of carbon isotopes (Valley & O'Neil Reaction (19) marks the upper pressure limit 1981), but do not bode well for these systems of prehnite, and calculations of Perkins et al. as geothermometers or as monitors of tem- (1980) place this curve close to the aragonite- perature-time history. Similar concerns exist calcite transition, although grossular-law- for the conodont colour index thermometer sonite-quartz has not been reported yet in the (Rejebian et al. 1987). Suffice it to say here that blueschist facies. these systems must be questioned as quanti- Liou et al. (1983) obtained experimental data tative until the details of the mechanisms and on epidote-prehnite equilibria that apply to rates of transformations are much better under- low-temperature metamorphic systems. The stood (Essene 1982). Thermometry may be reaction: obtained from stable isotopic fractionations of prehnite + haematite = (32) minerals in low-grade metamorphic rocks (e.g. epidote + water vapour Friedman & O'Neil 1977, Bottinga & Javoy 1987), although one needs to evaluate the 2Ca2AIESi3010(OH)e + Fe~O3 = 2CaaAleFe3+Si3012(OH) + H20 possibilities of disequilibrium fractionations encountered in rapidly growing phases and of can be derived from their experiments. This erroneous extrapolations to low temperatures equilibrium is appealing as a thermometer be- from experimental or theoretical calibrations of cause of its simplicity and the widespread occur- the fractionations. Estimates of total pressure rence of prehnite-haematite in the pumpellyite in some contact metamorphic rocks may also be facies. Unfortunately, the experimental data on obtained from reconstructions of overburden. epidote need further evaluation, because syn- If one confines the zeolite facies by the stab- thetic and rapidly grown natural epidotes may ility of analcime + quartz, reaction (26), the contain metastably disordered Fe 3+ (Burns & thermal limit of this facies may be taken as Strens 1967, Bird et al. 1988). The disorder 180°C based on the experiments of Liou (1971c) could have a profound effect on the a-X re- and Thompson (1971). Many zeolites are still lations inferred, from experimental data, on stable within the pumpellyite facies, especially the stability of epidote. The zoning common- at reduced activities of SIO2. However, the ly found in epidote will also interfere with effects of compositional and structural com- order/disorder measurements and complicate plexities on the location of reaction (26) have thermobarometry. not yet been fully evaluated for experimental The stability of iron-pumpellyite is given by and natural analcimes and albites. the reactions: iron-pumpellyite + oxygen = epidote + (33) Pumpellyite facies water vapour 4Ca4Fe2+Fe3+AI4Si602,~(OH)3 .2H20 + 02 For succinctness and convenience, this new = 8Ca2AI2Fe3+Si3012(OH) + 10H20 facies name is here defined to include both the prehnite-pumpellyite and pumpellyite- iron-pumpellyite + oxygen = prehnite + (34) actinolite facies. Pumpellyite is also stable in haematite + water vapour portions of the blueschist facies, but this should + 02 offer no bar to this definition, because several 4Ca4Fe2+Fe3+AI4Si6023(OH)3.2H20 zeolites are stable outside the limits of the zeolite = 8Ca2AI2SiaOlo(OH)2 + 4Fe203 + 6H20 facies. Metamorphism in the pumpellyite facies Reaction (34) is obtained from combination of has been described by many workers (e.g. Brand reaction (32) and reaction (33), and it has not 1980, Offler et al. 1980, 1981, Mevel 1981, previously been proposed, to the writer's knowl- Nakajima 1982, Levi et al. 1982, Evarts & edge. Other simple reactions may also be bal- Schiffman 1983, Liou et al. 1983, 1985, 1987, anced with grossular-andradite solid solution. Ishizuka 1985, Maruyama & Liou 1985, Cho & Liou (1979) estimated the location of reaction Liou 1987). Few systems provide useful thermo- (33) to lie at 250-300°C for P of c. 5 kbar on barometers for the pumpellyite facies, although the haematite-magnetite buffer, but Schiffman calcite-dolomite and stable isotope thermom- & Liou (1983) were unable to obtain exper- etry may provide useful thermometric infor- imental reversals on reaction (33). Other ex- mation. Reactions (18) and (19) govern the periments on pumpellyite-chlorite-epidote Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 15

-actinolite equilibria (Nitsch 1971) are unre- ionic, multi-site mixing model for the silicates. versed and appear to have quite different dP/dT This model ignores crystal-chemical evidence slopes than those determined by calculation on the importance of local charge balance (Schiffman & Liou 1980). The upper stability of in multivalent exchanges in solid solutions natural Mg-Fe2+-AI-Fe 3+ pumpellyite must (Kerrick & Darken 1975). The barometer involve complex reactions with solid solutions needs to be re-evaluated with a locally charge- of chlorite, actinolite and epidote (Brown balanced solution model and with inclusion of 1977b, Nakajima 1982, Liou et al. 1985, 1987, the experimental data of Massonne & Schreyer Cho & Liou 1987) that are not likely to be easily (1987). The location of the end-member reac- amenable to experimental study. However, re- tion is uncertain in P- Tspace, and the resultant actions (32)-(34) should eventually be useful barometry may involve substantial systematic for quantitative thermometry once reliable errors (Hodges & Spear 1982). As yet, few a-X relations become available for prehnite, reliable entropy and/or free energy data are pumpellyite and epidote at 200-400°C, and available for biotite and chlorite (cf. Helgeson the end-member reactions are more accurately et al. (1978) and Hemingway et al. (1984) for located. The P-T limits of the pumpellyite the available data). In addition, correction for facies remain poorly defined, but the writer's the effect of solid solutions (e.g. Mg/Fe 2+, prejudice is that these facies span the range (K + AI)/Si, (R 3+ + O)/(R 2+ + OH) remains of c. 200-300°C at < 5 kbar. uncertain for any sheet silicate. Biotite and chlorite should also be examined by TEM to evaluate the possibility of submicroscopic inter- Greenschist facies layering of separate phases. Several workers Thermobarometric studies of the greenschist have applied the Powell & Evans barometer facies (Ferry 1980, 1984, Phillips 1980, 1987, (reaction (35)) to rocks without critical evalu- Wintsch et al. 1981, Zen 1981, Yardley 1982, ation, even though Powell & Evans emphasized Hodges & Spear 1982, Nesbitt & Essene the preliminary nature of their calibration. 1982, Bucher-Nurminen et al. 1983, Graham Thermobarometry of the greenschist facies et al. 1983, Hudson 1985, Watkins 1985, reveals T of c. 300-500°C, but the P/T limit re- Di Pisa et al. 1985, Franceschelli et al. 1986a, b, lative to the pumpellyite and the bluechist facies Wang et al. 1986, Klaper & Bucher-Nurminen remains quantitatively ill-defined. Depending 1987) are less common than those of higher on the placement of the epidote-amphibolite grade metamorphic rocks. Other than the (sub)facies, the greenschist- amphibolite- thermometers based on garnet-biotite (e.g. facies boundary may vary between 450 and Ferry & Spear 1978, Ferry 1980, 1984, Hodges 550°C. & Spear 1982) or calcite-dolomite (e.g. Ferry 1979, Nesbitt & Essene 1982, Di Pisa et al. 1985, Anovitz & Essene 1987a), few thermo- Amphibolite facies barometers have been calibrated adequately for Modern petrological work on the amphibolite use in this facies, and applications of stable facies using thermobarometry is extensive (e.g. isotope thermometers are necessary to better Ferry 1980, 1983, Gole & Klein 1981, Sharma & establish temperature limits of this facies. Un- MacRae 1981, Hodges & Spear 1982, Nesbitt & fortunately, simple dehydration reactions are Essene 1982, Ghent et al. 1982, 1983, Chamber- seldom applicable in greenschist-facies rocks lain & Lyons 1983, Mohr & Newton 1983, because of the rarity of the reactant or pro- Leonard 1984, St-Onge 1984, 1987, Ghent & duct assemblages. Isograds in this facies are Stout 1984, Graham & Powell 1984, Hodges & highly complex and are not yet amenable to Royden 1984, Royden & Hodges 1984, Sel- thermobarometric analysis. verstone et al. 1984, Baker 1985, Dempster Powell & Evans (1983) proposed a barometer 1985, Droop 1985, Hudson 1985, Karabinos based on the reaction: 1985, McLellan 1985, Moles 1985, Treloar 1985, Barber & Yardley 1985, Bowman & Ghent phengite + chlorite = muscovite + (35) 1985, Lang & Rice 1985a, b; Selverstone & phlogopite + quartz + water vapour Spear 1985, Chamberlain 1986, Hoinkes 1986, 8K2MgAI3Si7AIO20(OH)4 + Ferguson & AI-Ameen 1986, Spear & Rumble, 2MgsA12Si3OI0(OH)8 = 1986, Stout et al. 1986, Klaper & Bucher- 5K2AI4Si6A12020(OH)4 + Nurminen 1987, Steltenpohl & Bartley 1987, St- 3K2Mg6Si6AI2020(OH)4 + 14SIO2 + 8H20 Onge & King 1987, Thompson & LeClair 1987, Their calibration was based on the experiments Phillips & de Nooy 1988, Peterson & Essene of Velde (1965) in combination with an ideal 1989). The biotite-garnet thermometer of Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

16 E. J. Essene

Ferry & Spear (1978) is best designed for this Kml3Si3Olo(OH)2 = 3CaA12Si208 + facies because the compositions of the natural KMg3Si3AIO10(OH)2 and synthetic phases are similar, although the almandine + grossular + muscovite = (37) role of Fe3+/Fe 2+ and O/OH in biotite needs anorthite + annite greater attention. Calcite-dolomite thermo- Fe3Al2Si3012 + Ca3Al2Si3Ol2 + metry may record near-peak metamorphic tem- KAI3Si3OI0(OH)2 = 3CaAI2Si2Os + peratures, especially at the lower end of this KFe3Si3AIO10(OH)2 facies (Essene 1983). However, most of the thermometers and barometers applicable at Ghent & Stout calibrated reactions (36) and higher grades are not readily extrapolated to the (37) using the thermodynamic data of Helgeson lower and middle amphibolite facies because of et al. (1978). Their location of these reactions is the non-linear and unknown temperature de- unlikely to be accurate as the thermodynamic pendence of a-X relations of most silicate solid data for almandine has since been revised sub- solutions at T less than 600-650°C. stantially, and our knowledge of the thermo- Hodges & Spear (1982) estimated the activity dynamics of annite remains inadequate for coefficient for CaAIESi208 in sodic plagioclases such calculations. In addition, the garnet- to be about 2.0 using Ghent's (1976) location of muscovite-plagioclase- biotite barometer suf- reaction (2) and a constant AVs. Their activity fers from many of the same deficiencies for coefficient for sodic plagioclase is considerably the garnet- aluminosilicate-quartz- plagioclase larger than that obtained from extrapolation of barometer, including the low grossular con- the plagioclase model of Newton et al. (1980) to tent of most pelitic garnets and uncertainties in these temperatures, which is not surprising as the mixing models for garnet, plagioclase and this mixing model is expressly intended for biotite at amphibolite-facies temperatures plagioclases with substantial disorder (Hodges (Essene 1982). The applications of Ghent & & Spear 1982). Ghent (1976) and Hodges & Stout (1981), Hudson (1985) and Moles (1985) Spear (1982) assumed that AVs is constant, show good agreement with the GASP bar- and correction for compressibility and expan- ometer, but it should be recalibrated with new sion will shift the calculated equilibrium by thermodynamic data. +1 kbar at 500°C, and reduce the calculated Various workers considered use of a bar- activity coefficient of the anorthite component ometer involving muscovite-almandine- to 1.5 following the calculation of Hodges & annite-sillimanite (MABS), involving the Spear (1982). These calculations are all predi- reaction cated on an accurate activity coefficient for the almandine + muscovite = annite + (38) grossular component in almandine at 500°C, sillimanite + quartz but this is also suspect at these temperatures. FesA12Si3012 + KAIsSisOlo(OH)2 = Nevertheless, if Holdaway's (1971) triple point KFe3Si3AIOI0(OH)2 + 2A12SIO5 + SiO2 is close to correct, the Hodges & Spear (1982) model of mixing for garnets and plagioclases Reaction (38) may be obtained from algebraic will yield reasonable results for similar com- combination of reaction (37) and GASP, reac- position mineral assemblages equilibrated near tion (1), and therefore contains no information the aluminium silicate triple point, because they not already implicit in the calibration and ap- forced a field calibration to fit with the thermo- plication of the other barometers. Spear & dynamics. Therefore, their model is provision- Selverstone (1983) and Robinson (1983) esti- ally recommended for GASP barometry mated the approximate location of MABS reac- involving garnet and plagioclase of similar tion. Holdaway et al. (1988) calculated the compositions at upper greenschist- and lower locus of reaction (38) empirically against the amphibolite-facies conditions, even though can- andalusite-sillimanite equilibrium, garnet- celling errors may be involved in their mixing biotite thermometry, and calculations of micro- models. probe data using ideal mixing for micas and Ghent & Stout (1981) developed alterna- Ganguly & Saxena's (1984) model for garnet tive barometers for the amphibolite facies solutions. While one may question the assump- based on the assemblage garnet-muscovite- tions in the mixing models for these silicates, plagioclase-biotite. The end-member reactions the major shortcoming of this barometer is re- are: lated to its near indifference to changes in P and T caused by its very small A V and AS. The pyrope + grossular + muscovite = (36) location of the end-member equilibrium has anorthite + phlogopite correspondingly greater uncertainty, and appli- Mg3AI2Si3012 + Ca3AI2Si3OI2 + cation of the barometer is highly sensitive to the Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 17 specific activity models chosen for garnet, biotite the experiments would be applicable to the and muscovite. This barometer is therefore abundant tholeiitic metabasalts. However, it is inappropriate even for comparative barometry exceedingly difficult to know whether these in a single region, but an excellent choice for experiments represent equilibrium, as structur- testing activity models for natural micas and ally complex solid solutions involving many garnets over a wide range of temperatures. phases are produced in the experiments. Bio- Because of the inapplicability of many ther- pyriboles and other metastably disordered mobarometers to the amphibolite facies, petrol- phases (feldspars, epidotes, sheet silicates) may ogists have relied on P- T information garnered be produced in experiments at T < 700°C and from specific dehydration reactions, exper- relatively short experimental durations. The iments involving common rock compositions, detailed experimental stabilities, compositions and/or petrogenetic nets constructed for meta- and crystal structures of many important rock- pelites and metabasites. The use of dehydration forming minerals in this facies are still uncertain, equilibria for thermobarometry is suspect, as for instance, staurolite (Holdaway et al. 1986a, the implicit assumption that Prt,o=Ps needs b), biotite (e.g. Bohlen et al. 1980) and horn- _ additional testing in the upper amphibolite blende (Hawthorne 1982, Gilbert et al. 1982). facies where in situ partial melting is initiated. Given the difficulties in nucleation and growth Calculations evaluating PH~o relative to Ps (e.g. of amphiboles (Greenwood 1963, Skippen & Phillips 1980, Bohlen et a-l. 1980, Ferry 1983, McKinstry 1985), experiments on complex rock Chamberlain & Lyons 1983, Nesbitt & Essene compositions may yield metastable assem- 1983, Lamb & Valley 1984, 1985, Peterson & blages, and they should not be used for quanti- Essene 1989) suggest that PH,o approximates tative thermobarometry. Petrogenetic grids are Ps for graphite-free metapelites of the low- to widely used to aid in estimations of P- T in the mid-amphibolite facies. On the other hand, amphibolite (and other) facies. They often pro- rocks of the upper amphibolite and granulite vide the researcher insights into the actual iso- facies may record water pressures significantly gradic reactions of the rocks under study, and if less than total pressures (e.g. Phillips 1980, compared with other thermobarometers may Edwards & Essene 1988). provide tests of the grids. Pressures in the amphibolite facies may be Thermobarometry of rocks in the amphibolite estimated by a comparison of prograde index facies indicates that they form in the approxi- minerals of metapelites relative to key invariant mate T range of 500-700°C and at pressures points on a petrogenetic grid, which may be ranging from 3 to 12 kbar. The relations of the mappable as bathograds (Carmichael 1978). amphibolite to the blueschist and greenschist Additional pressure estimates may be obtained facies at high P/T remain obscure. by application of biotite-garnet K D thermometry compared to isograds involving Al2SiO5 Granulite facies minerals. Temperatures may often be obtained by comparison of assemblages including chlor- Quantitative thermobarometry based on ite, chloritoid, garnet, staurolite, anthophyllite, displaced equilibrium curves has been more grunerite, gedrite, talc, and/or cordierite, with successful in the granulite facies than in any experimentally calibrated dehydration equi- other metamorphic facies (Ellis 1980, 1987, libria in the systems FeO-Al203-SiO2-H20 Nesbitt 1980, Phillips 1980, Bohlen & Essene (e.g. Richardson 1968, Ganguly 1969a, b, 1980, Glassley & Sorenson 1980, Grew 1981, Hoschek 1969, Rao & Johannes 1979, Pigage & Harris 1981, Bohlen & Boettcher 1981, Perkins Greenwood 1982, Holdaway et al. 1986b) and & Newton 1981a, Johnson & Essene 1982, MgO-A1203-SiO2-H20 (e.g. Schreyer & Newton & Perkins 1982, Harris et al. 1982, Siefert 1969, Siefert 1974). Unfortunately, the Janardhan et al. 1982, Bohlen et al. 1983a, b, c, a-X relations involving Mg/Fe (as well as Mn, 1985, 1986a, b, Newton 1983, Percival 1983, Zn) remain unknown for ferromagnesian phases Kay & Kay 1983, Johnson et al. 1983, 1984, in the amphibolite facies, and even these sys- ?erchuk et al. 1983, 1985, Harley 1984c, 1985, tems are difficult to apply to most rocks except 1987, Medaris 1984, Schenk 1984, Vielzeuf for the simplified chemical systems well rep- 1984, Harris & Holland 1984, Indares & resented by whiteschists and iron formations. Martignole 1984, 1985a, b, 1988, Lamb & An alternate approach to thermobarometry Valley 1984, 1985, Ellis & Green 1985, Perkins involves comparison of assemblages with those & Chipera 1985, Powers & Bohlen 1985, obtained by experiments on basaltic compo- Avchenko 1986, Waters 1986, Bhattacharya sitions (e.g. Apted & Liou 1983, Moody et al. & Sen 1986, Miyano & Klein 1986, Sandiford & 1983). This is attractive at first glance because Powell 1986, Schreurs & Westra 1986, Tella & Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

18 E. J. Essene

Eade 1986, Moecher et al. 1986, 1988, Osanai volume change and cannot be reset on decom- et al. 1986, Raase et al. 1986, Bohlen 1987, pression without removing some material or Gasparik 1987, Santosh 1987, Cartwright & increasing the rock volume, unless retrograde Barnicoat 1987, Harley & Black 1987, Kienast deformation is operative. Most thermometers & Ouzegane 1987, Sills & Rollinson 1987, have a small volume change and are easily reset Ackermand et al. 1987, Hanson et al. 1987, by exsolution and/or recrystallization without Pownceby et al. 1987, Sanders et al. 1987, increasing volume. Most barometers involve Sanders 1988, Nzenti et al. 1988, Pin & Vielzeuf garnet and tend to preserve thermobarometric 1988, Paria et al. 1988, Anovitz & Essene 1989). information because of its refractory nature. The dominance of anhydrous minerals in the Partial melting is common in many rocks of the granulite facies--including garnets, pyroxenes, granulite (and upper amphibolite) facies, lead- feldspars, olivines--and the availability of ing to the presence of a (liquid) phase that mixing data for these phases (see previous cannot be quenched, and which, upon crystal- section on thermodynamic data base) provides lization during early retrogression, may re- the requisite information to allow correction for lease dissolved volatiles and contribute to the reduced activities of end-member com- retrogressive resetting. ponents in minerals with significant solid Reactions (1), (2), (5) and (6) are widely solution. applicable as barometers in the granulite facies, Successful thermometers for the granulite as well as the following: facies were discussed by Essene (1982) and only a few additional comments are necessary ferrosilite = fayalite + quartz (39) here. The magnetite-ilmenite thermometer of Fe2Si206 = Fe2SiO4 + SiO2 Buddington & Lindsley (1964) has been re- (Bohlen & Boettcher 1981) worked by Anderson & Lindsley (1988). Only almandine + sillimanite = hercynite + (40) occasionally does reintegration of oxide exsol- quartz ution lamellae recapture peak metamorphic temperature (e.g. Bohlen & Essene 1977, Fe3AI2Si3012 + 2A12SIO5 = 3FeAI204 + 5SIO2 Jansen et al. 1985, Anovitz & Essene 1989), and (Bohlen et al. 1986b) these oxides are clearly easily reset during retrogression. The garnet-clinopyroxene KD ther- almandine + corundum = hercynite + (41) mometer has been experimentally reversed sillimanite by Pattison & Newton (1988) at lower P and Fe3AIzSi3012 + 5A1203 = 3FeAI204 + T than by previous investigators. Their ap- 3A12SIO5 plications appear to suggest that garnet- (Bohlen et al. 1986a) clinopyroxene pairs have generally been reset grossular + almandine = anorthite + (42) during retrogression to upper amphibolite- fayalite facies temperatures. Harley (1984b), Sen & Bhattacharya (1984) and Lee & Ganguly Ca3AI2Si3012 + 2Fe3AI2Si3012 = 3CaAI2Si2Os + 3Fe2SiO4 (1988) constructed garnet-orthopyroxene KD (Bohlen et al. 1983b,c) thermometers for garnet-clinopyroxene. While their models should be updated with newer grossular + almandine + quartz = (43) mixing data for garnet and orthopyroxene, they anorthite + ferrosilite appear to give results approximately compar- Ca3AI2Si2012 + 2Fe3AI2Si3012 + 3SIO2 able with the other thermometers (Sen & Bhat- = 3CaA12Si208 + 3FezSi206 tacharya 1984, Harley 1984c, 1985, Anovitz & (GAFS, Bohlen et al 1983b, c; Fig. 4) Essene 1989). Haselton et al. (1983) and Brown grossular + pyrope + quartz = (44) & Parsons (1985) reformulated the two-feldspar anorthite + enstatite thermometer with different thermodynamic mixing parameters for the feldspars. This Ca3Al2Si3Ot2 + 2Mg3A12Si3O12 + 3SIO2 thermometer may record temperatures ap- = 3CaA12Si208 + 3Mg2Si206 (GAES, Newton & Perkins 1982, Perkins proaching 800°C when exsolved alkali feldspars & Chipera 1985; Fig. 5) are carefully reintegrated (Bohlen & Essene 1977, Mora & Valley 1985, Edwards & Essene grossular + pyrope + quartz = (45) 1988, Anovitz & Essene 1989). Few other anorthite + diopside thermometric systems (e.g. exchange thermo- 2Ca3AI2Si3O12 + Mg3AI2Si3012 + 3SiO meters) preserve peak prograde temperatures = 3CaAI2Si2Os + 3CaMgSi206 in the granulite facies. (GADS, Newton & Perkins 1982, Most barometric equilibria have a substantial Moecher et al. 1988; Fig. 6) Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 19 grossular + almandine + quartz = (46) Additional reactions may also be obtained with anorthite + hedenbergite titanite instead of rutile or ilmenite (e.g. Ghent 2Ca3A12Si3012 + Fe3AI2Si3Ot2 + 3SIO2 & Stout 1984, Essene & Bohlen 1985), but = 3CaA12Si208 + 3CaFeSi206 additional calculations (Moecher pers. comm. (GAHS, Moecher et al. 1988; Fig. 7) 1987) suggest that direct experiments are needed grossular + almandine + rutile = (47) before such equilibria can be used for quantitative barometry. anorthite + ilmenite + quartz A number of workers refined the pyroxene- Ca3A12Si3012 + 2Fe3A12Si3012 + 6TIO2 = garnet barometer, initially proposed by Boyd 3CaA12Si208 + 6FeTiO3 + 3SIO2 (GRIPS, Bohlen & Liotta 1986; Fig. 8) (1973), Wood & Banno (1973) and MacGregor (1974), because of the wide interest in this pyrope + diopside + quartz = (48) barometer for garnet peridotites. Lane & enstatite + anorthite Ganguly (1980), Perkins & Newton (1981b), Mg3AI2Si3OI2 + CaMgSi206 + SiO2 = Harley (1984a, c), Brey et al. (1986), Carlson 2Mg2Si206 + CaAI2SizO8 (1986), Arima (1987), and Lee & Ganguly (Paria et al. 1988) (1988) all reversed the Tschermak's component almandine + hedenbergite + quartz = (49) of pyroxene in equilibrium with garnet at high ferrosilite + anorthite pressures and temperatures. The barometer has been applied to crustal granulites, but it is in- Fe3A12Si3012 + CaMgSi206 + SiO2 = accurate at crustal pressures because of the low 2Fe2Si206 + CaAI2Si208 (Paria et al. 1988) Tschermak's component in pyroxenes of most quartz-saturated crustal rocks and the uncertain Reactions (1), (5) and (43)-(47) have been re- effect of octahedral site exchange of Fe 3+ for calculated with a self-consistent thermodynamic AI in pyroxene. data base and presented in Figs 2-8 for use by Other barometers are potentially available the reader. Chemical analyses of the appro- for granulites that involve sapphirine and cordi- priate mineral assemblages followed by cal- erite, but available calibrations yield disparate culation of a-X relations and the appropriate results (e.g. Currie 1971, Henson & Green 1971, Ks allows utilization of these curves without 1973, Henson 1972, 1987, Newton 1972, Froese further input. Several of these barometers may 1973, Holdaway & Lee 1977, Lee & Holdaway often be applied simultaneously in the same 1977, Newton & Wood 1979, Lonker 1981, rock, allowing tests of the reliability of the Martignole & Sisi 1981, Aranovich & Podlesskii barometers (Perkins & Chipera 1985, Bohlen & 1983, Perchuk & Lavrent'eva 1983, Perchuk et al. Liotta 1986, Anovitz & Essene 1989, Moecher 1983, Bhattacharya & Sen 1985, Bhattacharya et al. 1988). Pressures are best calculated with et al. 1988). Until the roles of H20, CO2 and the unmixed garnet curve for reactions (42)-(47) other fluid constituents are better understood, and with the same garnet mixing model used to cordierite equilibria must be regarded as calculate the unmixed curve (Anovitz & Essene tentative at best. The large thermodynamic 1987b). When tested internally, most of the difference between natural and synthetic barometers yield similar pressures (to + 1 kbar). sapphirine (Charlu et al. 1975) suggests that Reaction (41) provides an excellent thermo- the synthetic phase is a poor analogue to the barometer for corundum-bearing metapelites natural mineral. More experimental and crystal- (Bohlen et al. 1986a,b). Reactions (48) and (49) chemical work is needed on cordierite and may be obtained from algebraic combination of sapphirine before they should be used for (1), (43) and (44). However, they were calcu- thermobarometry. lated by Paria et al. (1988) from the thermo- While mineral equilibria in many granulite- dynamic data in Helgeson et al. (1978). While a facies terranes record pressures between 6 and complete analysis of these barometers is under- 8 kbar for temperatures between 700 and 850°C way, the use of outdated data for almandine (Perkins & Newton 1981a, Newton 1983, has led to an erroneous location and slope for Bohlen et al. 1983a, b, c, Bohlen 1987, Moecher reaction (49) by Paria et al. (1988). et al. 1988), some have been well documented Additional barometers involving corundum to have attained pressures as high as 10-12 may be obtained from reactions involving alumi- kbar (O'Hara & Yarwood 1978, Sanders et al. nosilicates by adding the AG for AI2SiO5 = 1987, Anovitz & Essene 1989) or as low as 4-6 A1203 + SiO2 so as to eliminate quartz (Harris kbar (Phillips 1980, Schreurs & Westra 1986, 1981, Bohlen 1986). These reactions involving Anovitz & Essene 1989), or temperatures of corundum should be tested systematically in a 900-1000°C (O'Hara & Yarwood 1978, Ellis variety of corundum-bearing garnet granulites. 1980, Harley 1987). Orthopyroxene-bearing Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

20 E. J. Essene

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22 E. J. Essene assemblages may occur at low H20 activities in phlogopite) have widely been reported in eclo- the amphibolite facies, and many amphibolites gite samples, it is often unclear whether they are stable at high H20 activities in the granulite are part of the eclogitic assemblage or were facies, but thermometry generally shows that produced during subsequent retrograde events. the granulite facies forms at higher temperatures The garnet-clinopyroxene KD thermometer than the amphibolite facies. is clearly apropos for eclogites if retrograde resetting is evaluated through careful studies of Eclogite facies mineral zonations. New versions of this thermometer have been presented by Krogh (1988) Many researchers have evaluated the P-T and Pattison & Newton (1988). Experiments or conditions of eclogites (e.g. Krogh 1980, thermodynamic measurements need to be con- Maresch & Abraham 1980, Carpenter 1981, ducted on appropriate mineral chemistries for Carpenter & Smith 1981, Laird & Albee P-T at which the eclogites equilibrated. The 1981a, b, Lippard 1983, Franz & Spear 1983, reversed experiments by Pattison & Newton Matthews et al. 1983, Medaris 1984, Ridley (1988) are more directly designed for granulites 1984, Dobretsov & Sobolev 1984, Monk 1985, than for eclogites. Shortcomings of the garnet- Pognante 1985, Sautter 1985, Austrheim & clinopyroxene thermometer were reviewed by Griffin 1985, Gil Ibarguchi & Ortega Girones Essene (1982) and Koons (1984); for many 1985, Agrinier et al. 1985, Baldelli et al. 1985, eclogites, the most serious difficulty resides Bocchio et al. 1985, Robert et al. 1985, Koons in the cation ordering involved with many 1986, Newton 1986, Schliestedt 1986, Barnicoat omphacites that have 1/3 < Xjd < 2/3 (e.g. & Fry 1986, Brown & Forbes 1986, Pognante & Carpenter 1981, Rossi et al. 1983). Most low Kienast 1987, Ghent et al. 1987, Krogh 1988). and moderate temperature eclogitic omphacites The transitions between granulite, garnet- are ordered. Carpenter (1981) concluded from granulite and eclogite have been reasonably TEM and thermal annealing studies that P2/n well determined at high T (c. 1100-1200°C) for omphacites grow as ordered structures. Holland various basaltic compositions (Ringwood & (1983) determined the lower pressure limit of Green 1964, 1966, Green & Ringwood 1967, ordered omphacite in an assemblage with quartz 1972, Ito & Kennedy 1971). Unfortunately, the and high albite, but extrapolation to lower tem- dry transitions remain uncertain at metamorphic peratures requires adjustment for ordering in T (< 800°C) (cf. Green & Ringwood (1972) albite. Experiments on the Mg/Fe exchange of versus Kennedy & Ito (1972)). The transitions disordered omphacite with garnet are inappro- from amphibolite to garnet amphibolite to priate for ordered omphacite (Essene 1982, eclogite remain poorly constrained in nature, Koons 1984, Carpenter & Putnis 1986). Appli- but have been located experimentally just below cations to higher temperature and low-sodium the wet solidus at 675-700°C and 15-25 kbar eclogites are probably more reliable as these for Primo = P~ (Essene et al. 1970). Thus, the eclogites generally have low-sodium (C2/c) transition to eclogite mineralogy (garnet- clinopyroxenes closer in chemistry, structure clinopyr0xene) for rocks of basaltic composition and equilibration P-T to the experimental is strongly dependent on PH~o, and none of materials. _ these experiments is necessarily relevant to Few other thermometers applicable for eclo- eclogites where H20 activities are uncertain, gites are available that do not involve a priori even though several workers supported high assumptions of PH,o. However, stable isotope H20 activities for crustal eclogites (Essene & thermometers offer an underexplored system Fyfe 1967, Holland 1979a, b, Newton 1986). that may not reset for type C and perhaps some Other thermobarometers not dependent on type B eclogites. Desmons & O'Neil (1978) assumptions of H20 activities are needed for a used the partitioning of oxygen isotopes among complete understanding of the conditions of quartz, rutile, and phengite of type C eclogites eclogite equilibration. from the Sesio zone to estimate equilibration Most eclogite assemblages have few minerals temperatures of c. 540°C. Matthews et al. other than garnet, clinopyroxene and rutile, (1983) calibrated stable isotope thermometers although kyanite, zoisite and quartz are com- involving garnet, pyroxene and zoisite that are mon in crustal eclogites. Only rarely has coesite appropriate for many eclogitic assemblages and been reported in eclogites from mantle nodules inferred equilibration temperatures of 430- (Sobolev et al. 1976, Smyth & Hatton 1977) and 480°C for blueschist eclogites (type C) and from crustal settings (Chopin 1984, Smith 1984). 480-650°C for amphibolite eclogites (type B). Although amphiboles (glaucophane, barroisite, Using stable isotope measurements, Robert et hornblende) and micas (phengite, paragonite, al. (1985) obtained temperatures of 470°C for Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 23 quartz-pyroxene from a type C eclogite from Blueschist facies the Sesia-Lanzo zone of Italy, and Agrinier et al. (1985) found T of 650-870°C for quartz- Many workers applied thermobarometry in the rutile, quartz-pyroxene and quartz-garnet blueschist facies (e.g. Aiba 1980, Okay 1980, pairs of type B eclogites from the Western Carpenter 1981, Laird & Albee 1981a, b, Gneiss Region of Norway. These data are in Mposkos & Perdikatzis 1981, Wood 1982, Brown & O'Neil 1982, Lippard 1983, Brown & good agreement with temperatures estimated from petrological studies (Newton 1986), and Ghent 1983, Moore 1984, Dobretsov & Sobolev oxygen isotopic thermometry seems to be a 1984, Koons & Thompson 1985; Maruyama & promising technique for crustal eclogites. Liou 1985, 1987, 1988, Maruyama et al. 1985, Most barometers are inapplicable to eclogites Evans, 1986; Sakakibira 1986, Schliestedt 1986, because of the typical high-variance assem- Takayama 1986, Barnicoat & Fry 1986, Franz et blages. However, limits may often be placed on al. 1986, Massonne & Schreyer 1987, Pognante pressure with reactions (1), (3), (5) and (40)- & Kienast 1987, Ghent et al. 1987, Pognante et (49) (cf. Figs 2-8), as well as: al. 1987, 1988, Gillet & Goffe 1988). The blueschist facies was originally distinguished as a jadeite + lawsonite = zoisite + (50) high-pressure equivalent of the greenschist paragonite + quartz + water vapour facies on the basis of the presence of the dense, high-pressure minerals jadeite, glaucophane NaAISi206 + 4CaAI2SizO7(OH)2. H20 = and/or lawsonite rather than the more volumin- 2Ca2AI3Si3012(OH) + NaA13Si3Olo(OH)2 + ous chemical equivalents, such as albite, chlor- SiO2 + 6H20 (Holland 1979a) ite, epidote and/or laumontite. This conclusion was reinforced when experimentation confirmed the high pressures of the reaction jadeite + Application of these equilibria requires mixing quartz = albite. Although concerns have been models for garnet, clinopyroxene and plagio- raised about the stabilizing effects of solid sol- clase (for the fictive feldspar in the limit- utions in jadeite, this involves a negligible ing reactions). If dehydration reactions with (clino)zoisite or paragonite are used, one must shift (< 1 kbar) for 10-20% NaFeSi206 or CaMgSi206 in pyroxenes (Essene & Fyfe 1967, apply non-ideal corrections for Fe/AI exchange in (clino)zoisite and (K + Ca)/Na in paragonite Newton & Smith 1967, Essene 1969, Popp & Gilbert 1972, Holland 1983). Other significant to constrain minimum pressures for Pn,o = Ps. blueschist equilibria include reactions (19), (22), For eclogites with accessory kyanite,-quartz, (23), (28) and (50), as well as: rutile, zoisite, paragonite and/or corundum, pressures have been bracketed to 15 _ 5 kbar (Newton 1986). Two reports of coesite in crustal lawsonite + albite = zoisite + (51) eclogite and associated crustal rock (Chopin paragonite + quartz + water vapour 1984, Smith 1984) indicate pressures in excess 4CaAIaSi207(OH)2-H20 + NaAISi308 = of 25 kbar (reaction (4), Fig. 1). These pressures 2Ca2AI3Si3012(OH ) + NaAI3Si3OH)(OH)2 + approach those needed for the formation of 2SIO2 + 6H20 diamond (Kennedy & Kennedy 1976), and this (Heinrich & Althaus 1980) mineral should be systematically sought in these associations. Additional experimental and Reactions (50) and (51) separate lawsonite- thermodynamic work is still needed on eclogitic albite/jadeite from paragonite-zoisite/clino- thermobarometers, particularly with Mg/Fe ex- zoisite blueschists at about 400-500°C and change reactions involving ordered omphacite. provide useful thermometers for blueschist- Barometry of crustal (type B and C) eclogites facies rocks. suggests that most formed at c. 12-18 kbar, Aragonite is widespread in blueschists of the significantly higher than the minimum pressures Franciscan terrane (sensu lako) of California inferred for the eclogite facies by Turner (1981). (Carlson 1980) but is uncommon in other blue- These high pressures are compatible with but schists of the world (cf. Gillet & Goffe 1988), do not require relatively high water pressures. even if they contain jadeite indicating that they The remarkable finds of coesite in crustal associ- reached the stability field of aragonite. Studies ations require pressures in excess of 25 kbar. of the kinetics of the aragonite-calcite tran- The survival of such high-pressure assemblages sition show that the back-reaction of aragonite requires that the rock remains dry and implies to calcite is exceedingly rapid in the presence of rapid transport to the surface. These uplift rates H20 and that aragonite is unlikely to be pre- could be quantified if the kinetics of transfor- served even in dry rocks if the retrograde path mation of coesite to quartz were known. intersects the aragonite-calcite boundary at Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

24 E. J. Essene

T > 180°C (Carlson 1980). Thus, the preser- To completely characterize reactions (52) vation of aragonite in blueschists may constrain and (53), one must evaluate Tschermak's ex- the retrograde path, and the occurrence of change in chlorite and phlogopite, as well as calcite cannot be assumed to limit prograde phengite, tri/dioctahedral solid solutions and pressures. other vacancy-related substitutions in micas Thermometers applicable to blueschist assem- (Wang & Banno 1987). Unfortunately, Massonne blages are far less commonly available. Use of & Schreyer (1987) estimate only the phengite petrogenetic grids constrain blueschist tempera- and trioctahedral substitutions as inferred from tures to 250-450°C. Chlorite-phengite KD unit cell data. The experiments of Velde (1965) thermometry could ultimately prove useful in and Massonne & Schreyer (1987) for the con- blueschists. Stable isotope systematics offer tinuous reaction (53) on phengite stability a potentially powerful and as yet largely un- mostly include metastable phases and assem- explored alternative to conventional petro- blages in their experimental starting materials logical approaches for blueschist thermometry. and run products. Additional experiments Brown & O'Neil (1982) calculated temperatures involving only phengite-clinochlore-quartz- from measured oxygen isotope fractionations microcline (reaction (52)) and phengite- for quartz-magnetite pairs from Shuksan blue- phlogopite-quartz-microcline (reaction (53)), schists of north-west Washington and obtained and carefully documented compositional re- T of 320-410°C, in good agreement with versals with the sheet silicates are still requisite available P-T information from petrological for this system. Correction of the phengite equi- constraints. The presence of strong chemical libria for additional solid solutions in natural zoning in many blueschist minerals such as phengite is uncertain (Massonne & Schreyer amphiboles, epidotes, pyroxenes and garnets 1987), and reversed experiments with iron- suggests that oxygen isotopes may be similarly bearing assemblages should also be obtained zoned, and the possible implications for stable before this barometer is applied to most rocks. isotope thermometry must be evaluated (Wada Bucher-Nurminen (1987) calculated the logl0K 1988). for reaction (53a) based on Massonne & Additional barometers applicable to blue- Schreyer's (1987) experiments and using an schists include those involving phengite: ideal ionic model for celadonite activity in phengite. He appears to obtain more accurate phengite = K-feldspar (52) estimates of pressures with his version of phen- + chlorite + quartz + water vapour gite equilibria, but the experimental data base 3K2MgaAIzSisO20(OH)4 = 6KAISi308 + (52a) and modelling of solid solutions must be ques- Mg6Si4010(OH)8 + 2SIO2 + 2H20 tioned. The possibility of a submicroscopic 5K2MgAl3Si7AIOz0(OH)4 -- (52b) phase interlayering in fine-grained micas and Mg5AI2Si3OIo(OH)s + 2K2AI6Si602o(OH)4 + chlorites should also be considered. Massonne 6KAISi30 s + 2SiO/+ 2H20 & Schreyer's (1987) and Bucher-Nurminen's (Velde 1965) (1987) phengite barometers need further testing phengite = K-feldspar (53) against other barometers in greenschists and + phlogopite + quartz + water vapour blueschists before they should be accepted as 3K2MgzA12Si802o(OH)4 = 4KAISi308 + (53a) dependable. K2Mg6Si6AI202o(OH)4 + 6SIO2 + 4H20 In a related barometer, Sassi (1972) and Sassi 6K/MgAI3Si7AIO2o(OH)4 = & Scolari (1974) used the average contraction K2Mg6Si6AI2020(OH)4 + of the bo cell dimension of phengite as an 3K2A16Si6020(OH)4 + 4KAISi308 + empirical index of increasing pressures. Appli- 6SIO2 + 4H20 cations of Sassi's phengite barometer (e.g. (Velde 1965, Bucher-Nurminen 1987, Guidotti & Sassi 1976, 1986) usually involve Massonne & Schreyer 1987) unbuffered assemblages lacking K-feldspar. The amount of phengite solution is therefore con- At least two reactions may be used simul- trolled only by the rock chemistry and by Kt) taneously to describe the stability of phengite exchange reactions with other ferromagnesian solution in equilibrium with quartz, chlorite and silicates such as amphibole or chlorite. These K-feldspar. Reaction (52a) relates the end- effects are unlikely to be pressure dependent member celadonite component to the Al-free and it is unclear why Sassi's barometer should component in chlorite, while reaction (52b) is yield apparently reasonable results (Massonne controlled by the ratio of phengite to muscovite & Schreyer 1987). Perhaps the rock chemistry activity relative to that of ideal clinochlore. of pelites in high-pressure terrains is systemati- Similar relations are involved for reaction (53). cally different than lower pressure rocks. Sassi's Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 25 system has also been applied to anchimetamor- (involving other amphibole solutions) and/or phic rocks (Padan et al. 1982) and greenschists structure (pyribole or biopyribole) may grow (Guidotti & Sassi 1986) where submicroscopic under the relatively short times involved in layering is common in micas and where co- experiments. Maruyama et al. (1986) reported herency effects may perturb the value for bo. experimental reversals on reaction (58) using Given these caveats, it seems prudent to avoid natural mineral seeds and using SEM/EDA to the use of Sassi's phengite barometer for characterize experimental products. Reactions thermobarometry. (57) and (58) are complicated by the presence Nitsch (1980) calibrated the cymrite/celsian of additional phases whose chemistry and struc- reaction: ture before and after the experiments needs additional documentation, and the glaucophane cymrite = celsian + H20 (54) may deviate from the ideal composition by solid BaAI2Si207(OH)2-H20 = BaAI2Si208 + solutions such as tschermakite, richterite, or 2H20 actinolite during the experiment. Cotkin (1987) The experiments of Nitsch suggest that cym- corrected reaction (58) of Maruyama et al. rite is truly an index mineral of the blueschist (1986) with an ideal model for the solid solutions facies. Natural cymrite and/or celsian should be reported and obtained P- Testimates consistent checked for solid solutions involving Na, K, Ca with other thermobarometers for blueschists of and Sr before applying the end-member reaction the Klamath mountain range. Holland (1988) (Essene 1967, Reinecke 1982). measured the high-temperature heat capacity Applications of glaucophane equilibria, in- of a Tauern glaucophane and estimated its cluding: other thermodynamic properties. He also calculated phase equilibria for reactions involving glaucophane + quartz = albite + talc (55) glaucophane, including reaction (58). While Na2MgaA12SisO22(OH)2 + 2SIO2 = the calculations of Cotkin (1987) and Holland 2NaAISi3Os + Mg3Si4Olo(OH)2 (1988) are encouraging, any thermobarometry (Koons 1982) involving glaucophane must remain speculative glaucophane = jadeite + talc (56) until a-X relations for synthetic and natural Na2Mg3AI2SisO22(OH)2 = 2NaAISi206 + sodic amphiboles are adequately delineated. Mg3Si4010(OH)2 Brown (1977a) empirically correlated the Na (Essene et al. 1970, Carman & Gilbert 1983) content in the M4 site of low-grade amphiboles buffered by albite + quartz + chlorite + glaucophane + lawsonite -- clinozoisite + (57) epidote + iron oxide with increasing pressure. chlorite + albite + quartz + water vapour This assemblage is closely related to that re- 5NaEMgaAI2SisO22(OH)2 + quired for reactions (57) and (58). Brown's 12CaAI2Si207(OH)2- H20 = buffer system involves oxidation as well as de- 6Ca2AI3Si3OI2(OH) + 3MgsAl2Si3Oi0(OH)8 + hydration and cannot be expected to operate as 10NaAISi3Os + 7SIO2 + 14H20 a pure barometer. In addition, different nor- (uncalibrated) malizations of electron microprobe data on glaucophane + clinozoisite + quartz + (58) amphiboles yield different partitioning of Na water vapour = tremolite + chlorite + albite between the M4 and A sites, which will affect 25Na2Mg3AI2Si8022(OH)2 + the calculated pressures. This barometer is un- 6Ca2AI3Si3012(OH) + 7SIO2 + 14H20 = likely to yield reliable pressures and should not 6Ca2MgsSi8022(OH)2 + be relied on for precise work. The glaucophane 9Mg5Al2Si3010(OH)8 + 50NaAISi3Os barometer of Maruyama et al. (1986) needs to (Maruyama et al. 1986, Cotkin 1987, be tested on a variety of blueschists---especially Holland 1988) those containing pyroxene-albite-quartz as an independent barometer. are difficult to apply as thermobarometers. The From the available thermobarometry, it is experiments of Ernst (1961), Maresch (1977), clear that many blueschists equilibrated in the Koons (1982), Carman & Gilbert (1983) and range of 250-450°C, and some may extend to T Maruyama et al. (1986) are heroic efforts on an as low as 200°C while others may have attained exceedingly difficult problem of nucleation and 500°C. Pressures typically vary from 5 to 12 growth of ordered glaucophane. Even with natu- kbar and some may have attained as much as ral glaucophane seeds in the experiments, it is 12-16 kbar in rocks transitional to the eclogite necessary (but difficult) to document the growth facies (e.g. Koons 1986). These results suggest of new ordered amphibole of glaucophane that the blueschist-eclogite facies boundary is chemistry and structure. A metastable chemistry nearer 15 kbar rather than 10 kbar, although Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

26 E. J. Essene

the location of the boundary should depend on Well-calibrated thermobarometers are avail- PH,o/Ps. able for high-temperature contact metamorphic rocks. Systems involving Ca-silicates and Ca-Mg-silicates contain many thermally sensitive phase equilibria appropriate to high- Contact metamorphic facies temperature thermal aureoles (Goldschmidt In these facies, thermobarometry has been re- 1911, Winkler 1965, Turner 1968). Reactions ported by a number of workers (e.g. Williams- in the systems CaO-SiO2-CO2-H20 (e.g. Jones 1981, Novak & Holdaway 1981, Labotka Treiman & Essene 1983) and CaO-MgO- et al. 1981, Bowman & Essene 1982, 1984, Berg Si02-C02-H20 (e.g. Skippen 1974, Slaughter & Docka 1983, Wada & Suzuki 1983, Morikiyo et al. 1975, Eggert & Kerrick 1981, Sharp et al. 1984, Evans & Speer 1984, Okuyama-Kusunose 1986) provide a variety of well-calibrated ther- 1985, Droop & Charnley 1985, Pattison & Harte mometers and CO2 barometers useful for cal- 1985, Grapes 1986, Docka et al. 1986, Kerrick careous rocks. Total pressures are more difficult 1987, Pattison 1987, Speer 1987, van Bosse & to estimate in contact metamorphic environ- Williams-Jones 1988, Holdaway et al. 1988). ments, and the equilibrium grossular + quartz = Many of the geothermometers useful for these anorthite + wollastonite, reaction (2), is of facies are identical to those of the thermally critical importance in this regard. The end- equivalent regional metamorphic facies, i.e. member reaction is well located, and some albite-epidote hornfels versus greenschist, experimental data are now available on the hornblende hornfels versus amphibolite, pyr- effects of Fe3+/AI (Huckenholz et al. 1981) oxene hornfels or sanidinite versus granulite. and 4H/Si in grossular (Huckenholz & Fehr The immediate difficulty for contact meta- 1982). Garnet- quartz- plagioclase- wollastonite morphic thermobarometry is the virtual absence assemblages are widespread in the pyroxene- of pyralspite garnet so valuable in thermo- hornfels facies and provide excellent thermobarometry of regional metamorphic rocks. Use- barometers if the reduced activities of anorthite ful thermometers in lower temperature contact in plagioclase and grossular in garnet are metamorphites include calcite-dolomite and corrected for properly. It is important to seek oxygen isotope systems. The MgCO3 content of textural evidence supporting an equilibrium calcite equilibrated with dolomite is well cali- assemblage, as late garnet commonly overgrows brated between 300 and 600°C and is often well feldspar or wollastonite in calc-silicate rocks. preserved in intermediate-temperature con- The four-phase assemblage is rare in skarns, tact metamorphic environments (Essene 1983, though limiting pressure data are often available Wada & Suzuki 1983, Morikiyo 1984, Anovitz from the assemblage garnet-quartz. & Essene 1987a). Few applications using stable Alternative geobarometers are available in isotopic thermometers have been published for the system K20-AI203-SiO2-H20 from the contact metamorphites, and further applications intersection of the muscovite-quartz dehy- should be made. dration, reaction (29), with the thermal limit of Other quantitative thermobarometers that andalusite = sillimanite, reaction (6). Careful are useful for lower grade contact metamor- application involves correction of the equilibria phites are difficult to find. Petrogenetic grids for the effects of: primarily based on dehydration and/or decarbonation reactions are widely used as ther- 1 reduced activity of H20 by CO2, NaCl, etc.; mometers in such rocks, but their precision is 2 albite and paragonite solution (Thompson critically dependent on the inferred pressures, 1974, Chatterjee & Froese 1975); especially at low pressures where volatiliz- 3 other solid solutions (e.g. F, CI, Mg, Fe, ation reactions increase their curvature in P-T O/OH) on muscovite stability; space. A promising system involves the Mg/Fe 2÷ 4 Mn, Fe, Ti, Cr on AI2SiO5 equilibria (Strens exchange between chlorite and muscovite, 1968, Grambling & Williams 1985, Kerrick although careful calibration must account for & Speer 1988); substitutions of Fe3+/Fe 2+ and/or O/OH for 5 fibrolite rather than sillimanite (Holdaway each phase in experimental and natural assem- 1971, Salje 1986, Kerrick 1987); blages. The submicroscopic interlayering com- 6 order/disorder changes in muscovite and K- mon in low-temperature micas and chlorites feldspar. (e.g. Lee et al. 1984, Ahn et al. 1985) must be evaluated before accepting electron microprobe Pelitic rocks metamorphosed to the sanidinite analysis (with > 1 ~m 3 analytical volume) as facies may contain two other univariant reac- representative of phase compositions. tions of thermobarometric potential: Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 27 corundum + sillimanite = mullite (59) These facies seldom preserve a record of their A1203 + 2A12SIO5 = 3A1203. 2SIO2 prograde history. In contrast, the intermediate- grade facies (greenschist and amphibolite facies) sillimanite = mullite + tridymite (60) preserve the richest history of prograde and 3A12SIO5 = 3A1203.2SIO2 + SiO2 retrograde events. This makes quantitative These equilibria have not been calibrated well thermobarometry complex, yet will ultimately experimentally, and, in the opinion of the provide the most information as to the P-T author, their best location remains the thermo- history of the terrain. Approximate temperature dynamic calculations of Holm & Kleppa (1966). ranges for the metamorphic facies are as follows: While mullite (+SIO2) is occasionally reported zeolite facies < 200°C; pumpellyite facies, in buchites (Grapes 1986, Cosca et al. 1989a), it 200-300°C; greenschist facies, 300-500°C; is difficult to distinguish from sillimanite using amphibolite facies, 500-700°C; granulite facies, optical or X-ray methods. Quantitative electron 700-900°C and occasionally extending to microprobe analysis should be used to confirm 1000°C. The blueschist facies ranges from 200 mullite, and Fe 3÷ substitution and other solid to 500°C and crustal eclogites between 500 and solutions can also be determined. Order/dis- 800°C. These conclusions agree well with the order (Deer et al. 1982) and microstructural interpretations of Turner (1968). complexities (Wenk 1983) may also influence Geobarometry is able to sort out low-pressure mullite equilibria. Before these reactions can facies (< 4 kbar: zeolite, pumpellyite and contact be used quantitatively, experimental data that metamorphic facies) from the amphibolite and evaluate the effects of AI/Si solution and order/ granulite facies (at 4-12 kbar). The blueschist disorder are essential. Once calibrated, these facies ranges from c. 6 to 14 kbar. Transitions to equilibria should be useful as thermobarometers the eclogite facies appear to be in the range of for contact metamorphic rocks. 12-16 kbar. These high pressures will permit Contact metamorphic rocks span a wide range the transitions to occur at relatively high PH~O. of Tfrom 200 to 1000°C. If one includes buchites With thermobarometry now yielding more and clinkers, then maximum temperatures may precise results, much more effort can now be approach 1150-1250°C. Most contact aureoles devoted to obtaining data on partial pressures form at P < 2 kbar; at P > 4-5 kbar they are of various fluid species in terrains with carefully usually indistinguishable from regional meta- evaluated pressures and temperatures. More morphites. If passage of magmas or occurrence care should be taken to evaluate the potential of subjacent plutons is important in forming the errors of activity models for solids, particularly granulite facies, then these rocks are in some at lower temperatures. However, thermo- sense contact metamorphic, and in any case one barometry can yield estimates of peak pressure should expect a continuum of occurrences from to +1 kbar and temperatures to +50°C for most contact to regional metamorphic facies. metamorphites if a variety of lithologies is available that allows simultaneous application of several systems.

Conclusions ACKNOWLEDGEMENTS: The writer benefited from many discussions with colleagues at the University of It is difficult to obtain precise thermometry on Michigan and elsewhere. Careful reviews by L. M. the lowest grade metamorphites (blueschist, Anovitz, S. R. Bohlen, D. M. Carmichael, R. A. zeolite and pumpellyite facies) because of the Cliff, M. A. Cosca, J. S. Daly, E. D. Ghent, D. M. Kerrick, K. Mezger, D. P. Moecher, Z. D. Sharp and lack of thermometers that are well calibrated B. W. D. Yardley greatly improved the manuscript at low temperatures. Thermometry on high- and are much appreciated. S. Fast and D. P. Moecher grade metamorphites (granulite and pyroxene- are thanked for help in preparation of the figures. hornfels facies) is plagued by partial resetting Support for this paper was provided by the IUGC through exsolution and diffusional processes. and NSF grants EAR-84-08169 and EAR-88-05083.

References

ABBOTT, R. N. 1982. A petrogenetic grid for medium Instability of sapphirine at high pressure. Contri- and high grade metabasites. American Mineral- butions to Mineralogy and Petrology, 50, 79-92. ogist, 67, 865-76. -- , HERD, R. K., REINHARDT,M. & WINDLEY, B. ACKERMAND, D., SEIFERT, F. & SCHREVER, W. 1975. F. 1987. Sapphirine parageneses from the Caraiba Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

28 E. J. Essene

complex, Bahia, Brazil: the influence of Fe z+ mation and eclogite formation within granulite- -Fe 3+ distribution on the stability of sapphirine facies anorthosites of the Bergen Arcs, western in natural assemblages. Journal of Metamorphic Norway. Chemical Geology, 50, 261-81. Geology, 5, 323-39. AVCHENKO, O. V. 1986. Interpreting pressure and ADAMS, G. E. & BISHOP, F. C. 1985. An experimental temperature estimates derived from mineral investigation of thermodynamic mixing prop- assemblages and from geothermobarometers. erties of forsterite-monticellite solid solutions. International Geology Review, 28, 1269-77. American Mineralogist, 70, 714-22. BACHINSKi, S. W. & MULLER, G. 1971. Experimental AGRINIER, P., JAVOY, M., SMITH, D. C. & PINEAU, F. determinations of the microcline-albite solvus. 1985. Carbon and oxygen isotopes in eclogites, Journal of Petrology, 12, 329-56. amphibolites, veins and marbles from the West- BAKER, A. J. 1985. Pressures and temperatures of ern Gneiss Region, Norway. Chemical Geology, metamorphism in the eastern Dalradian. Journal 52, 145- 62. of the Geological Society, London, 142, 137-46. AHN, J. H. & PEACOR, D. R. 1986. Transmission and BALDELLI, C., DAL PIAZ, G. V. & LOMBARDO, B. analytical electron microscopy of the smectite-to- 1985. Ophiolite eclogites from Verres Val illite transition. Clays and Clay Minerals, 34, d'Aosta, western Alps, Italy. Chemical Geology, 165-79. 50, 87-98. , & ESSENE, E. J. 1985. Coexisting BARBER, J. P. & YARDLEY, B. W. D. 1985. Conditions paragonite-phengite in blueschist eclogite: a of high grade metamorphism in the Dalradian of TEM study. American Mineralogist, 70, Connemara, Ireland. Journal of the Geological 1193- 204. Society, London, 142, 87-96. AIBA, K. 1980. Sanbagawa metamorphism of BARNICOAT, A. C. & FRY, N. 1986. High-pressure the Nakatsu-Nanokawa district, west central metamorphism of the Zermatt Saas ophiolite, Shikoku. Journal of the Geological Society of Switzerland. Journal of the Geological Society, Japan, 88, 875-85. London, 143, 607-18. ANDERSON, D. J. & LINDSLEY, D. L. 1988. Internally BARTON, P. B. JR. & SKINNER, B. J. 1979. Sulfide consistent solution models for Fe-Mg-Mn-Ti mineral stabilities. In: BARNES, H. L. (ed.) Geo- oxides: Fe-Ti oxides. American Mineralogist, chemistry of Hydrothermal Ore Deposits, 2nd 73, 714-26. edn. pp. 278-403, Wiley & Sons, New York. ANOVITZ, L. M. & ESSENE, E. J. 1987a. Phase equi- BERG, J. H. & DOCKA, J. A. 1983. Geothermometry libria in the system CaCO3-MgCO3-FeCO3. in the Kiglapait contact aureole, Labrador. Journal of Petrology, 28, 389-414. American Journal of Science, 283, 414-34. -- & ~ 1987b. Compatibility of geobarometers BERMAN, R. G. 1988. Internally-consistent ther- in the system CaO-FeO-AI203-SiO2-TiO2 modynamic data for minerals in the sys- (CFAST): implications for garnet mixing models. tem KxO-Na20-CaO- MgO-FeO-Fe203- Journal of Geology, 95, 635-45. AIzO3-SiO2-TiO2-H20-CO2. Journal of & -- 1989. Thermobarometry and pressure- Petrology, 29, 445-522. temperature paths in the Grenville Province of , ENGI, M., GREENWOOD, H. J. & BROWN, Ontario. Journal of Petrology, in press. T. H. 1986. Derivation of internally consistent AerED, M. J. & LIOU, J. G. 1983. Phase relations thermodynamic data by the technique of math- among greenschist, epidote amphibolite and ematical programming: a review with application amphibolite in a basaltic system. American to the system MgO-SiOe-H20. Journal of Journal of Science, 283-A, 328-54. Petrology, 27, 1331-64. ARANOVICH, L. YA. & KOSYAKOVA, N. A. 1987. BERTRAND, P., SOTIN, C., GAULIER, J.-M. & MERCIER, The cordierite = orthopyroxene + quartz equi- J.-C. 1987. La solubilite d6 I'aluminium dans librium: laboratory data and thermodynamics l'orthopyroxene. Inversion globale des donn6es of ternary Fe-Mg-AI orthopyroxene solid experimentales du systeme MgO-Al203-SiO2. solutions. Geochemistry International, 24(3), Bulletin de la SocieM Gdologique de France, 8, 111-30. 821-32. & PODLESSKII, K. K. 1980. The garnet- BEVINS, R. E. & MERRIMAN, R. J. 1988. Com- plagioclase barometer. Doklady, Earth Science positional controls on coexisting prehnite-ac- Sections, 251, 101-3. tinolite and prehnite-pumpellyite facies as- & 1983. The cordierite-garnet- semblages in the Tal y Fan metabasite intrusion, sillimanite-quartz equilibrium: experiments and North Wales: implications for Caledonian meta- applications. In: SAXENA,S. K. (ed.)Advances in morphic field gradients. Journal of Metamorphic Physical Geochemistry, Kinetics and Equilibrium Geology, 6, 17-40. in Mineral Reactions, 3, pp. 172-98, Springer- BHAITACHARYA, A. & SEN, S. K. 1985. Energetics of Verlag, New York. hydration of cordierite and water barometry in ARIMA, M. 1987. Phase equilibria in the system cordierite granulites. Contributions to Mineralogy MgSiO3-Al203-Fe203 at high temperatures and Petrology, 89, 370-8. and pressures with special reference to the solu- -- & -- 1986. Granulite metamorphism, fluid bility of AI203 and Fe203 in enstatite. Journal of buffering and dehydration melting in the Madras the Faculty of Sciences, Hokkaido University, 18, charnockites and metapelites. Journal of Pet- 305-38. rology, 27, 1119-41. AUSTRHEIM, H. & GRIFFIN, W. L. 1985. Shear defor- -- , MAZUMDAR, A. C. & SEN, S. K. 1988. Fe-Mg Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 29

mixing in cordierite: constraints from natural cance in water barometry. American Mineral- data and implications for cordierite-garnet ogist, 65, 55-62. geothermometry in granulites. American Miner- ~, WALL, V. J. & BOETrCHER, A. L 1983a. Exper- alogist, 73, 338-44. imental investigations and geologic applications BIRCH, F. 1966. Compressibility: elastic constants. of equilibria in the system FeO-TiO2-AI2Oa- /n: CLARK, S. P. JR (ed.) Handbook of Physi- SiO2-H20. American Mineralogist, 68, 1049- cal Constants, Geological Society of America 58.

Memoir, 97, 97-173. -- & 1983b. Experimental investigation BIRD, D. K. & Helgeson, H. C. 1980. Chemical inter- and application of garnet granulite equilibria.

actions of aqueous solutions with epidote-feld- Contributions to Mineralogy and Petrology, 83, spar mineral assemblages in geologic systems. I. 52-61.

Thermodynamic analysis of phase relations in -- & 1983c. Geobarometry in granulites. the system CaO-FeO-FeaO2-AI203-SiO2- In: SAXENA, S. K. (ed.) Kinetics and Equilibrium H20-CO 2. American Journal of Science, 280, in Mineral Reactions, Advances in Physical Geo- 907-41. chemistry, 3, pp. 141-72. Springer-Verlag, New

-- , CHO, M., JANIK, C. J. LIou, J. G. & CARUSO, York. L. J. 1988. Compositional, order/disorder, and ~, VALLEY, J. W. & ESSENE, E. J. 1985. Meta- stable isotopic characteristics of AI-Fe epidote, morphism in the Adirondacks. I. Pressure and state 2-14 drill hole, Salton sea geothermal temperature. Journal of Petrology, 26, 971-92. system. Journal of Geophysical Research, 93, ~, DIETZ, J. M., ZEC, C. P. & Governale, R. C. 1315-44. 1986a. Thermobarometer for corundum-bearing BLENCOE, J. G. 1974. An experimental study of pelites. Geological Society of America Abstracts muscovite-paragonite stability relations. Ph.D. with Programs, 18, 545. thesis, Stanford University, 281 pp. ~, DOLLASE, W. A. & WALL, V. J. 1986b. 1977. Molal volumes of synthetic paragonite- Calibration and application of spinel equilibria muscovite micas. American Mineralogist, 62, in the system FeO-AI203-SiO2. Journal of 1200-15. Petrology, 27, 1143-56.

-- , MERKEL, G. A. & SELL, M. K. 1982. Thermo- Bos~cK, N. H. 1974. Phytoclasts as indicators of dynamics of crystal-fluid equilibria, with appli- thermal metamorphism, Franciscan assemblage cations to the system NaAISi3Os-CaA12SieOs- and Great Valley sequence, California. Geo- NaCI-CaCI2-H20. In: SAXENA, S. K. (ed.) logical Society of America Special Paper, 153, Advances in Physical Chemistry, 2, pp. 191-222, 1-17. Springer-Verlag, New York. BOTI'INGA, Y. & JAVOY, M. 1987. Comments of stable BOCCHlO, R., LmORIO, G. & MOTrAr~A, A. 1985. isotope geothermometry: the system quartz- Petrogenesis of the eclogites from Soazza, South- water. Earth and Planetary Science Letters, 84, west Lepontine Alps. Chemical Geology, 50, 406-14. 47-63. BOWMAN, J. R. & ESSENE, E. J. 1982. P-T-X(CO2) BOHLEN, S. R. 1986. Instability of the assemblage conditions of contact metamorphism in the Black corundum + quartz. Los (Transactions of the Butte Aureole, EIkhorn, Montana. American American Geophysical Union), 67, 1280. Journal of Science, 282, 311-40. 1987. Pressure-temperature-time paths and a & 1984. Contact skarn formation at tectonic model for the evolution of granulites. Elkhorn, Montana: I. P-T-component activity Journal of Geology, 95, 617-32. conditions of early skarn formation. American & BOETrCHER, A. L. 1981. Experimental investi- Journal of Science, 284, 597-651. gations and geological applications of ortho- -- & GHEt~'r, E. D. 1985. Oxygen and hydrogen pyroxene geobarometry. American Mineralogist, isotope studies of minerals from metapelitic 66, 951-64. rocks, staurolite to sillimanite zones, Mica Creek, & 1982. The quartz-coesite transfor- British Columbia. Journal of Metamorphic mation: a precise determination and the effects Geology, 4, 131-42. of other components. Journal of Geophysical BovD, F. R. 1973. The pyroxene geotherm. Geo- Research, 87, 7073- 8. chimica et Cosmochimica Acta, 37, 2533-46. & ESSENE, E. J. 1977. Feldspar and oxide BRAND, R. 1980. Die niedriggradige Metamor- thermometry of granulites in the Adirondack phose einer Diabas-Assoziation im Gebiet von Highlands. Contributions to Mineralogy and Berg und Frankenwald. Neues Jahrbuch fur Petrology, 62, 153-69. Mineralogie, Abhandlungen, 139, 82-101. & ~ 1980. Evaluation of coexisting garnet- BREY, G. P., NICKEL, K.G. & KOGARKO, L. 1986. biotite, garnet-clinopyroxene and other Mg-Fe Garnet-pyroxene equilibria in the system exchange thermometers in Adirondack granu- CaO-MgO-Al203-SiO2 (CMAS); prospects lites. Geological Society of America Bulletin, 91, for simplified ('T-independent') Iherzolite bar- 685-719. ometry and an eclogite barometer. Contributions -- & L1OTrA, J. J. 1986. A barometer for garnet to Mineralogy and Petrology, 92, 448-55. amphibolites and garnet granulites. Journal of BROWt~, E. H. 1977a. The crossite content of Ca- Petrology, 27, 1025-56. amphibole as a guide to pressure of metamor- , PEACOR, D. R. & ESSENE E. J. 1980. Crystal phism. Journal of Petrology, 18, 53-72.

chemistry of metamorphic biotite and its signifi- -- 1977b. Phase equilibria among pumpellyite, law- Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

30 E. J. Essene

sonite, epidote and associated minerals in low- metamorphic uplift and erosion on the regional grade metamorphic rocks. Contributions to scale. American Journal of Science, 278,769-97. Mineralogy and Petrology, 64, 123-36. CARPENTER, M. A. 1981. Omphacite microstructures & FoRays, R. B. 1986. Phase petrology of as time-temperature indicators of blueschist- eclogitic rocks in the Fairbanks district, Alaska. and eclogite-facies metamorphism. Contributions Geological Society of America Memoir, 164, to Mineralogy and Petrology, 78, 441-51. 155 -67...... & FERRY, J. M. 1984. Constraints on the thermo- -- & GHENT, E. D. 1983. Mineralogy and phase dynamic mixing properties of plagioclase feld- relations in the blueschist facies of the Black spars. Contributions to Mineralogy and Petrology, Butte and Ball Rock areas, northern California 87, 138-48. Coast Ranges. American Mineralogist, 68, & PUTNIS, A. 1986. Cation order and disorder 365-72. during crystal growth: some implications for & O'NEIL, J. R. 1982. Oxygen isotope geother- natural mineral assemblages. In: THOMPSON, A. mometry and stability of lawsonite and pumpel- H. & RUBLE, D. C. (eds) Metamorphic Reactions, lyite in the Shuksan Suite, North Cascades, Kinetics, Textures and Deformation, pp. 1-26, Washington. Contributions to Mineralogy and Springer-Verlag, New York. Petrology, 80, 240-4. & SMITH, D. C. 1981. Solid solution and cation BROWN, W. L. & PARSONS, I. 1985. Calorimetric and ordering limits in high-temperature sodic pyr- phase diagram approaches to two-feldspar geo- oxenes from the Nybo eclogite pod. Mineral- thermometry: a critique. American Mineralogist, ogical Magazine, 44, 37-44. 70, 356-61. CARTWRIGHT, I. & BARNICOAT, A. C. 1987. Petrology BUCHER-NURMINEN, K. 1987. A recalibration of of Scourian supracrustal rocks and orthogneisses the chlorite-biotite-muscovite geobarometer. from Stoer, NW Scotland: implications for the Contributions to Mineralogy and Petrology, 96, geological evolution of the Lewisian complex. 519-22. In: Park, R. G. & Tarney, J. (eds) Evolution of , FRANK, E. & FREY, M. 1983. A model for the the Lewisian and Comparable PreCambrian High progressive regional metamorphism of margarite- Grade Terrains, Geological Society Special bearing rocks in the Central Alps. American Publication No. 27, pp. 93-107. Journal of Science, 283-A, 370-95. CHAMBERLAIN, C. P. 1986. Evidence for the repeated BUDDINGTON, A. F. & LINDSLEY, D. H. 1964. Iron- folding of isotherms during regional metamor- titanium oxide minerals and their synthetic equiv- phism. Journal of Petrology, 27, 63-89. alents. Journal of Petrology, 5, 310-57. -- & LYONS, J. B. 1983. Pressure, temperature and BURNHAM, C. W., HOLLOWAY,J. R. & DAVIS, N. F. metamorphic zonation studies of pelitic schists in 1969. Thermodynamic properties of water to the Merrimack synclinorium, south-central New 1000°C and 10,000 bars. Geological Society of Hampshire. American Mineralogist, 68, 530-40. America Special Paper, 132, 96 pp. CHARLU, T. V., NEWTON, R. C. & KLEPPA, O. J. BURNS, R. G. & STRENS, R. G. J. 1967. Structural 1975. Enthalpies of formation at 970 K of com- interpretation of polarized spectra of epidote. pounds in the system MgO-Al203-SiO2 from Mineralogical Magazine, 36, 204-26. high temperature solution calorimetry. Geo- BUSECK, P. & HUANG, B.-J. 1985. Conversion of chimica et Cosmochimica Acta, 39, 1487-97. carbonaceous material to graphite during meta- CHASE, M. W. JR., DAVIS, C. A., DOWNEY, J. R. JR., morphism. Geochimica et Cosmochimica Acta, FRURIP, D. J., MCDONALD, R. A. & SYVERUD,A. 49, 2003-16. N. 1985. JANAF Thermochemical Tables, 3rd CARLSON, W. D. 1980. The calcite-aragonite equi- edn, Journal of Physical and Chemical Reference librium: effects of Sr substitution and anion orien- Data, 14, Supplement 1, 1856 pp. tational disorder. American Mineralogist, 65, CHATFERJEE, N. O. 1972. The upper stability limit of 1252-62. the assemblage paragonite+quartz and its natural 1986. Reversed pyroxene phase equilibria in occurrences. Contributions to Mineralogy and CaO-MgO-SiO2 from 925 to 1175°C at one Petrology, 34, 288-303. atmosphere. Contributions to Mineralogy and 1976. Margarite stability and compatibility re- Petrology, 92, 218-24. lations in the system CaO-AI203-SiO2-H20 -- 1988. Subsolidus phase equilibria on the forsterite- as a pressure-temperature indicator. American saturated join Mg2Si206-CaMgSi206 at atmos- Mineralogist, 61,699-709. pheric pressure. American Mineralogist, 73, & FAUX, S. 1986. Thermodynamic mixing prop- 232-41. erties of muscovite-paragonite crystalline sol- -- & LINDSLEY, D. L. 1988. Thermochemistry of utions at high temperatures and pressures, and pyroxenes on the join Mg2SieO6-CaMgSi206. their geological applications. Journal of Pet- American Mineralogist, 73, 242-52. rology, 27, 677-93. CARMAN, J. H. & GILBERT, M. C. 1983. Experimental -- & FROESE, E. 1975. A thermodynamic study of studies on glaucophane stability. American the join muscovite-paragonite in the system Journal of Science, 283-A, 414-37. KAISi3Os- NaAISi3Os- A1203 - SiO2 - H20. CARMICHAEL, D. M. 1978. Metamorphic bathozones American Mineralogist, 60, 985-93. and bathograds: a measure of the depth of post- --, JOHANNES, W. & LEISTNER, H. 1984. The system Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 31

CaO- A1203- SiO2- H20: new phase equilibria, DAVIDSON, P. M. & LINDSLEY, D. H. 1985. Thermo- some calculated phase relations, and their petro- dynamic analysis of quadrilateral pyroxenes. Part logical applications. Contributions to Mineralogy II. Model calibration from experiments and appli- and Petrology, 88, 1-13. cations to geothermometry. Contributions to CHERNOSKY, J. V., DAY, H. W. & CARUSO, L. J. 1985. Mineralogy and Petrology, 91,390-404. Equilibria in the system MgO-SiO2-H20: -~ • MUKHOPADHYAY, D. K. 1984. Ca-Fe-Mg experimental determination of the stability of olivines: phase relations and a solution model. Mg-anthophyllite. American Mineralogist, 70, Contributions to Mineralogy and Petrology, 86, 223-36. 256-63. CHO, M. & LIou, J. G. 1987. Prehnite-pumpellyite DAY, H. W. 1973. The high temperature stability of to greenschist facies transition in the Karmutsen muscovite plus quartz. American Mineralogist, metabasites, Vancouver Island, B. C. Journal of 58, 255-62. Petrology, 28, 417-43. , CHERNOSKY, J. V. & KUMIN, H. J. 1985. Equi- , -- & MARUYUMA, S. 1986. Transition from libria in the system MgO-SiO2-HeO: a thermo- the zeolite to prehnite-pumpellyite facies in dynamic analysis. American Mineralogist, 70, the Karmutsen metabasites, Vancouver Island, 237-48. British Columbia. Journal of Petrology, 27, DEER, W. A., HOWIE, R. A. & ZUSSMAN, J. 1982. 467-94. Orthosilicates, Rock-Forming Minerals, 1A, CHOPIN, C. 1984. Coesite and pure pyrope in high- Longman, London, 919 pp. grade blueschists of the western Alps: a first DEMPSTER, T. J. 1985. Garnet zoning and meta- record and some consequences. Contributions to morphism of the Barrovian type area, Scotland. Mineralogy and Petrology, 58, 255-62. Contributions to Mineralogy and Petrology, 89, -- & SCHREYER, W. 1983. Magnesiocarpholite and 30-8. magnesiochloritoid: two index minerals of pelitic DESMONS, J. & O'NEILL, J. R. 1978. Oxygen and blueschists and their preliminary phase relations hydrogen isotopic composition's of eclogites and in the model system MgO-AI203-SiOe-H20. associated rocks from the eastern Sesia zone American Journal of Science, 283-A, 72-96. (Western Alps, Italy). Contributions to Min- CLARK, S. P. JR. (ed.) 1966. Handbook of Physical eralogy and Petrology, 67, 79-85. Constants, Geological Society of America DI PISA, A., FRANCESCHELLI, M., LEONI, L. d~: Memoir, 97, 587 pp. MECCHERI, M. 1985. Regional variation of the COSCA, i. A., MOECHER, D. R. & ESSENE, E. J., metamorphic transect across the Tuscanid I Unit 1986. Activity-composition relations for the join and its implications on the alpine metamorphism grossular-andradite and application to calc- (Apuan Alps, North Tuscany). Neues Jahrbuch silicate assemblages. Geological Society of fur Mineralogie, Abhandlungen, 151, 197-211. America Abstracts with Program, 18, 572. DOBRETSOV, N. L. & SOBOLEV, N. V. 1984. Glauco- , ESSENE, E. J. & BOWMAN, J. R. 1988. Com- phane schists and eclogites in the folded systems plete chemical analysis of metamorphic horn- of Northern Asia. Ofioliti, 9, 401-24. blendes with implications for amphibole normal- DOCKA, J. A., BERG, J. H. & KLEWIN, K. H. 1986. izations and calculated H20 activities. Los Geothermometry in the Kiglapait aureole. II. (Transactions of the American Geophysical Evaluation of exchange thermometry in a well- Union), 69, 1519. constrained setting. Journal of Petrology, 27, , ESSENE, E. J., GEISSMAN, J. W., SIMMONS, 605-26. W. B. & COATES, D. A. 1989. Pyrometamorphic DROOP, G. T. R. 1985. Alpine metamorphism in the rocks associated with naturally burned coal south-east Tauern Window, Austria. 1. P-T seams, Powder River Basin, Wyoming. American variations in space and time. Journal of Meta- Mineralogist, 74, 85-100. morphic Geology, 3, 371-402. COTKIN, S. J. 1987. Conditions of metamorphism in -- & CHARNLEY, N. R. 1985. Comparative geo- an Early Paleozoic blueschist, Schist of Skookum barometry of pelitic hornfelses associated with Gulch, northern California. Contributions to the Newer Gabbros: a preliminary study. Journal Mineralogy and Petrology, 96, 192-200. of the Geological Society, London, 142, 53-62. COTKIN, S. J., VALLEY, J. W. & ESSENE, E. J. 1988. EDWARDS, R. L. & ESSENE, E. J. 1988. Pressure, Petrogenesis of a margarite-bearing meta- temperature and C-O-H fluid fugacities across anorthosite from the Western Gneiss region of the amphibolite-granulite facies transition, NW Norway: P-T constraints of Caledonian retro- Adirondack Mtns., NY. Journal of Petrology, grade metamorphism. Lithos, 21, 117-28. 29, 39-72. CRAWFORD, W. A. & FYFE, W. S. 1965. Calcite- EGGERT, R. G. & KERRICK,D. M. 1981. Metamorphic aragonite equilibria at 100°C. Science, 144, equilibria in the siliceous dolomite system: 1569-70. 6 kbar experimental data and geologic impli- CURRIE, K. L. 1971. The reaction 3 cordierite = 2 cations. Geochimica et Cosmochimica Acta, 45, garnet + 4 sillimanite + 5 quartz as a geological 1039-49. thermometer in the Opinicon Lake Region, ELLIS, D. J. 1980. Osumilite-sapphirine-quartz Ontario. Contributions to Mineralogy and Pet- granulites from Enderby Land, Antarctica: P-T rology, 33, 215-26. conditions of metamorphism, implications for Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

32 E. J. Essene

garnet-cordierite equilibria and the evolution of EVARTS, R. C. & SCHIFFMAN, P. 1983. Submarine the deep crust. Contributions to Mineralogy and hydrothermal metamorphism of the Del Puerto Petrology, 74, 201 - 10. ophiolite, California. American Journal of -- 1987. Origin and evolution of granulites in nor- Science, 283, 289-340. mal and thickened crusts. Geology, 15, 167-70. FAWCETr, J. J. & YODER, H. S. JR. 1966. Phase -- & GREEN, D. H. 1985. Garnet-forming reactions relationships of chlorite in the system MgO- in mafic granulites from Enderby Land, A12Oa-SiO2-H20. American Mineralogist, 51, Antarctica--implications for thermobarometry. 353-80. Journal of Petrology, 26, 633-62. FERGUSON, C. C. & AL-AMEEN, S. I. 1986. Geo- ENO, M. 1983. Equilibria involving AI-Cr spinel: I. chemistry of Dalradian pelites from Connemara, Mg-Fe exchange with olivine: experiments, Ireland: new constraints on kyanite genesis and thermodynamic analysis and consequences for conditions of metamorphism. Journal of the Geo- geothermometry and barometry. American logical Society, London, 143, 237-52. Journal of Science, 283-A, 29- 71. FERRY, J.M. 1979. A map of chemical potential dif- & WERSIN, P. 1987. Derivation and appli- ferences within an outcrop. American Mineral- cation of a solution model for calcic garnet. ogist, 64, 966- 85. Schweizer Mineralogische und Petrographische 1980. A comparative study of geother- Mitteilungen, 67, 53-73. mometers and geobarometers in pelitic schists ERNST, W. G. 1961. Stability relations of glaucophane. from southern-central Maine. American Mineral- American Journal of Science, 259, 735-65. ogist, 65, 720- 32. ESSENE, E. J. 1967. An occurrence of cymrite in the 1983. Regional metamorphism of the Vassalboro Franciscan Formation, California. American Formation of south-central Maine, USA; a case Mineralogist, 52, 1885-90. study of the role of fluid in metamorphic petro- 1969. Relatively pure jadeite from a siliceous genesis. Journal of the Geological Society, Corsican gneiss. Earth and Planetary Science London, 140, 551-76. Letters, 5,270-2. -- 1984. A biotite isograd in south-central Maine, -- 1982. Geologic thermometry and barometry. In: USA: mineral reactions, fluid transfer and heat FERRY, J. M. (ed.) Characterization of Meta- transfer. Journal of Petrology, 25, 871-93. morphism Through Mineral Equilibria, Reviews & SPEAR, F. S. 1978. Experimental calibration of in Mineralogy, 10, pp. 153-206, Mineralogical the partitioning of Fe and Mg between biotite Society of America. and garnet. Contributions to Mineralogy and Pet- 1983. Solid solutions and solvi among metamor- rology, 66, 113- 7. phic carbonates with applications to geologic FLOWERS, G. C. & HELGESON, H. C. 1983. Equilib- thermometry. In: REEDER, R. J. (ed.) Car- rium and mass transfer during progressive bonates: Mineralogy and Chemistry, Reviews in metamorphism of siliceous dolomites. American Mineralogy, I l, pp. 77- 96. Mineralogical Society Journal of Science, 283, 230-86. of America. FRANCESCHELLI,M., LEONI, I., MEMMI, I & PUXEDDU, -- & BOHLEN, S. R. 1985. New garnet barometers M. 1986a. Distribution of aluminum silicates in the system CaO-FeO-Al203-SiO2-TiO2 and metamorphic zonation in the low grade (CFAST). Los (Transactions of the American Verrucano metasediments from the northern Geophysical Union), 66, 386. Apennines, Italy. Journal of Metamorphic Ge- -- & FYFE, W. S. 1967. Omphacite in California ology, 4, 309-21. metamorphic rocks. Contributions to Mineralogy --., MELLINI, M., MEblMI, I. & RICCI, C. A. 1986b. and Petrology, 15, 1-23. Fine-scale chlorite-muscovite association in low- , HENSEN, B. J. & GREEN, D. H. 1970. Exper- grade metapelites from Nurra (NW Sardinia), imental study of amphibolite and eclogite stab- and the possible misidentification of metamorphic ility. Physics of the Earth and Planetary Interiors, vermiculite. Contributions to Mineralogy and 3, 378-84. Petrology, 93, 137-43. EUGSTER, H. P., ALBEE, A. L., BENCE, A. E., FRANZ, G. & SPEAR, F. S. 1983. High pressure meta- THOMPSON, J. B. JR. & WALDBAUM,D. R. 1972. morphism of siliceous dolomites from the central The two-phase region and excess mixing prop- Tauern Window, Austria. American Journal of erties of paragonite-muscovite crystalline sol- Science, 283-A, 396-413. utions. Journal of Petrology, 13, 147-79. , THOMAS, S. & SMn'H, D. C. 1986. High-pressure EVANS, B. W. 1986. Reactions among sodic, calcic, phengite decomposition in the Weissenstein and ferromagnesian amphiboles, sodic pyroxene, eclogite, Munchberger Gneiss Massif, Germany. and deerite in high-pressure metamorphosed Contributions to Mineralogy and Petrology, 92, ironstone, Siphnos, Greece. American Mineral- 71-85. ogist, 71, 1118-25. FREY, M. 1978. Progressive low grade metamorphism EVANS, N. H. & SPEER, J. A. 1984. Low-pressure of a black shale formation, Central Swiss Alps, metamorphism and anatexis of Carolina Slate with pyrophyllite and margarite bearing assem- Belt phyllites in the contact aureole of the blages. Journal of Petrology, 19, 95-135. Lilesville pluton, North Carolina, USA. Contri- -- (ed.) 1987. Low Temperature Metamorphism, butions to Mineralogy and Petrology, 87, Blackie, Glasgow, 351 pp. 297-309. , TEICHMULLER, M., TEICHMULLER, R., MULLIS, Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 33

J., KUNZE, B., BREITSCHMID,A., GRUNER, U. & quartz. In: GREENWOOD, H. J. (ed.)Application SCHWIZER, B. 1980. Very low-grade metamor- of Thermodynamics to Petrology and Ore De- phism in external parts of the Central Alps: illite posits, Short Course Handbook, 2, pp. 99-108, crystallinity, coal rank and fluid inclusion data. Mineralogical Association of Canada, Evergreen Eclogae Geologicae Helvetiae, 73, 173-203. Press, British Columbia. FRIEDMAN, I. and O'NEIL, J. R. 1977. Compilation & STOUT, M. Z. 1981. Geobarometry and geo- of stable isotope fractionation factors of geothermometry of plagioclase-biotite-garnet- chemical interest. Data of Geochemistry, 6th edn, muscovite assemblages. Contributions to Miner- United States Geological Survey Professional alogy and Petrology, 76, 92-7.

Paper. No. 440KK, 61 pp. -- & -- 1984. TiO2 activity in metamorphosed FROESE, E. 1973. The oxidation of almandine and pelitic and basic rocks: principles and applications iron cordierite. Canadian Mineralogist, 11, to metamorphism in southeastern Canadian 991-1002. Cordillera. Contributions to Mineralogy and FROST, B. R. 1980. Observations on the boundary Petrology, 86, 248-55. zone between zeolite facies and prehnite- --, KNrlTER, C. C., RAESIDE, R. P. & STOUT, M. Z. pumpellyite facies. Contributions to Mineralogy 1982. Geothermometry and geobarometry of and Petrology, 73, 365-73. pelitic rocks, upper kyanite and sillimanite zones, FUHRMAN, M. L. & LINDSLEY, D. H. 1988. Ternary Mica Creek area, British Columbia. Canadian feldspar modeling and thermometry. American Mineralogist, 20, 295-305. Mineralogist, 73, 201-15. , RAESIDE, R. P. & STOUT, M. Z. 1983. GANGULY, J. 1969a. Chloritoid stability and related Plagioclase- clinopyroxene- garnet- quartz eq- parageneses: theory, experiments and appli- uilibria and the geobarometry and geother- cations. American Journal of Science, 267, mometry of garnet amphibolites from Mica 910-44. Creek, British Columbia. Canadian Journal of 1969b. Staurolite stability and related para- Earth Sciences, 20, 699-706. geneses: theory, experiments and applications. ~, STOUT, M. Z., BLACK, P. M. & BROTHERS, R. N. Journal of Petrology, 13, 335-65. 1987. Chloritoid-bearing rocks associated with t~ SAXENA, S. K. 1984. Mixing properties blueschists and eclogites, northern New of aluminosilicate garnets: constraints from natu- Caledonia. Journal of Metamorphic Geology, 5, ral and experimental data and applications to 239-54. geothermo-barometry. American Mineralogist, GmORSO, M. S. 1984. Activity/composition relations 69, 88-97. in the ternary feldspars. Contributions to Min-

-- & -- 1987. Mixtures and mineral reactions. eralogy and Petrology, 87, 282-96. In: A. EL. GORESY & VON ENGELHARDT, W. GILBERT, M. C., HELZ, R. T., PoPP, R. K. & Spear, (eds) Minerals and Rocks, 19, Springer-Verlag, F. S. 1982. Experimental studies of amphibole Berlin. stability. In: VEBLEN, D. R. & RIBBE, P. H. GASPARIK, T. 1984. Experimental study of subsolidus (eds) Amphiboles: Petrology and Experimental phase relations and mixing properties of pyroxene Phase Relations, Reviews in Mineralogy, 9B, in the system CaO-AI203-SiO2. Geochimica et pp. 229-354, Mineralogical Society of America. Cosmochimica Acta, 48, 2537-46. GIL IBARGUCH1, J. I. & ORTEGA GIRONES 1985. Pet- -- 1985. Experimental study of subsolidus phase rology, structure and geotectonic implications of relations and mixing properties of pyroxene and glaucophane-bearing eclogites and related rocks plagioclase in the system Na20-CaO-AI203- from the Malpica-Tuy (MT) unit, Galicia, north- SiO2. Contributions to Mineralogy and Petrology, west Spain. Chemical Geology, 50, 145-62. 89, 346-57. GILLET, P. & GOFFE, B. 1988. On the significance

-- 1986. Experimental study of subsolidus phase of aragonite occurrences in the Western Alps. relations and mixing properties of clinopyr- Contributions to Mineralogy and Petrology, 99, oxene in the silica-saturated system CaO- 70-81. MgO-AI203-SiO2. American Mineralogist, 71, GLASSLEY, W. E. & SORENSON, K. 1980. Constant 686-93. P- T amphibolite to granulite facies transition in 1987. Orthopyroxene thermobarometry in Agto (West Greenland) metadolerites. Journal simple and complex systems. Contributions to of Petrology, 21, 69-105. Mineralogy and Petrology, 96, 357-70. GOLDSCHMIDT, V. M. 1911. Die Kontaktmeta- GEIGER, C. A., NEWTON, R. C. & KLEPPA, O. J. 1987. morphose im Kristiangebiet. Oslo Videnskaps Enthalpy of mixing of synthetic almandine- Skrifter Matematisk-Naturvidenskapelig Klasse, grossular and almandine-pyrope garnets from Skrifter, 11,483 pp. high-temperature solution calorimetry. Geo- GOLDSMITH, J. R. 1980. Melting and breakdown reac- chimica et Cosmochimica Acta, 51, 1755-63. tions of anorthite at high pressures and tempera- GHENT, E. D. 1976. Plagioclase-garnet-Al~SiOs- tures. American Mineralogist, 65, 272-84. quartz: a potential geobarometer-geothermo- 1987. Aluminum/silicon interdiffusion in albite: meter. American Mineralogist, 61,710-4. effect of pressure and the role of hydrogen. - 1977. Applications of activity-composition Contributions to Mineralogy and Petrology, 95, relations to displacement of a solid-solid equi- 311-21. librium anorthite = grossular + kyanite + & NEWrON, R. C. 1974. An experimental Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

34 E. J. Essene

determination of the alkali feldspar solvus. Jahrbuch fur Mineralogie, Abhandlungen, 153, In: MacKenzie, W. S. and Zussman, J. (eds) 363-80. The Feldspars, Manchester University Press, HAAS, H. • HOLDAWAY, M. J. 1973. Equilibria in Manchester. the system A1203-SiOE-H20 involving the stab- GOLE, M. J. & KLEIN, C. 1981. High-grade metamor- ility limits of pyrophyllite, and the thermo- phic Archaean banded iron-formations, Western dynamic data of pyrophyllite. American Journal Australia: assemblages with coexisting pyroxenes of Science, 273, 449-64. +/-fayalite. American Mineralogist, 66, 87-99. HANSEN, E. C., JANARDHAN, A. S., NEWTON, R. C., GRAHAM, C. M. & POWELL, R. 1984. A garnet- PRAME, W. K. B. N. & RAVINDRA KUMAR, G. R. hornblende geothermometer and application to 1987. Arrested charnockite formation in southern the Peloma Schist, southern California. Journal India and Sri Lanka. Contributions to Mineralogy of Metamorphic Geology, 2, 13-32. and Petrology, 96, 225-44. --, GREIG, K. M., SHEPPARD, S. M. F. & TURI, B. HARLEY, S. L. 1984a. The solubility of alumina in 1983. Genesis and mobility of the H20-CO2 orthopyroxene coexisting with garnet in FeO- fluid phase during regional greenschist and epi- MgO-AI20 3- SiO 2 and CaO- FeO-MgO- dote amphibolite facies metamorphism: a study AI203-SiO 2. Journal of Petrology, 25, 665-96. in the Scottish Dalradian. Journal of the Geo- 1984b. An experimental study of the partitioning logical Society, London, 140, 577-99. of Fe and Mg between garnet and orthopyroxene. GRAMBLING, J. A. & WILLIAMS, M. L. 1985. The Contributions to Mineralogy and Petrology, 86, effects of Fe 3+ and Mn 3÷ on aluminum silicate 359-73. phase relations in north-central New Mexico, 1984c. Comparison of the garnet-orthopy- U.S.A. Journal of Petrology, 26, 324-54. roxene geobarometer with recent experimental GRAPES, R. H. 1986. Melting and thermal reconsti- studies, and applications to natural assemblages. tution of pelitic xenoliths, Wehr Volcano, East Journal of Petrology, 25, 697-712. Eifel, West Germany. Journal of Petrology, 27, -- 1985. Garnet-orthopyroxene bearing granulites 343-96. from Enderby Land, Antarctica: metamorphic GREEN, D. H. & RINGWOOD, A. E. 1967. An exper- pressure-temperature-time evolution of the imental investigation of the gabbro to eclogite Archaean Napier Complex. Journal of Petrology, transformation and its petrological applications. 26, 819-56. Geochimica et Cosmoschimica Acta, 31, -- 1987. A pyroxene-bearing meta-ironstone and 767-833. other pyroxene-granulites from Enderby Land, -- & -- 1972. A comparison of recent exper- Antarctica: further evidence for very high tem- imental data on the gabbro-garnet granulite- perature (> 980°C) Archaean regional meta- eclogite transition. Journal of Geology, 80, morphism in the Napier Complex. Journal of 277-88. Metamorphic Geology, 5, 341-56. GREEN, N. L. & USDANSKY, S. I. 1986a. Toward a -- & BLACK, L. P. 1987. The Archaean geological practical plagioclase-muscovite thermometer. evolution of Enderby Land, Antarctica. In: American Mineralogist, 71, 1109-17. PARK, R. G. & TARNEY, J. (eds) Evolution of the -- & 1986b. Ternary feldspar mixing relations Lewisian and Comparable PreCambrian High and thermobarometry. American Mineralogist, Grade Terrains, Geological Society Special 71, 1100-08. Publication No. 27, pp. 285-96. GREENWOOD, H. J. 1962. Metamorphic reactions HARRIS, N. B. W. 1981. The application of spinel involving two mineral components. Carnegie bearing metapelites to P/T determinations: an Institute of Washington Yearbook, 61, 82-5. example from south India. Contributions to Min- -- 1963. The synthesis and stability of anthophyllite. eralogy and Petrology, 76, 229-33. Journal of Petrology, 4, 317-51. -- & HOLLAND, T. J. B. 1984. The significance -- 1967a. Mineral equilibria in the system MgO- of cordierite-hypersthene assemblages from SiO2-H20-CO 2. In: ABELSON, P. E. (ed.) Re- the Beitbridge region of the Central Limpopo searches in Geochemistry, pp. 542-67, Wiley Belt: evidence for rapid decompression in the and Sons, New York. Archean? American Mineralogist, 69, 1036-49. 1967b. Wollastonite: stability in H20-CO2 --, HOLT, R. W. & DRURY, S. A. 1982. Geobar- mixtures and occurrence in a contact metamor- ometry, geothermometry, and late Archaean phic aureole near Salmo, British Columbia. geotherms from the granulite facies terrain in American Mineralogist, 52, 1669-80. South India. Journal of Geology, 90, 509-27. GREW, E. S. 1981. Granulite facies metamorphism at HASELTON, H. T. JR, HOVIS, G. L., HEMINGWAY,B. S. Molodezhnaya Station, East Antarctica. Journal & ROBIE, R. A. 1983. Calorimetric investigation of Petrology, 22, 297-336. of the excess entropy of mixing in analbite- GUIDOTrl, C. V. & SASSl, F. P. 1976. Muscovite as a sanidine solid solutions: lack of evidence for Na, petrogenetic indicator mineral in pelitic schists. K short range order and implications for two- Neues Jahrbuch fur Mineralogie, A bhandlungen, feldspar thermometry. American Mineralogist, 127, 97-112. 68, 398-413. -- & -- 1986. Classification and correlation of HAWTHORNE, F. C. 1982. Crystal chemistry of the metamorphic facies series by means of muscovite amphiboles. In: VEaLEN, D. R. (ed). Amphiboles bo data from low-grade metapelites. Neues and Other Hydrous Pyriboles, Reviews in Miner- Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 35

alogy, 9A, pp. 1-102, Mineralogical Society and the aluminum silicate phase diagram. of America. American Journal of Science, 271, 97-131.

HAZEN, R. M. & FINGER, L. W. 1982. Comparative -- 1980. Chemical formulae and activity models Crystal Chemistry, Wiley, New York, 281 pp. for biotite, muscovite and chlorite and appli- HEINRICH, W. & ATHAUS, E. 1980. Die obere Stab- cation to pelitic metamorphic rocks. American ilitatsgrenze von Lawsonit plus Albit bzw. Jadeit. Mineralogist, 60, 711-9. Fortschritte der Mineralogie, 58, 49-50. -- & LEE, S. M. 1977. Fe-Mg cordierite in high HELGESON, H. C., DELANY, J. M., NESBITr, H. W. & grade pelitic rocks based on experimental and BIRD, D. K. 1978. Summary and critique of the natural observations. Contributions to Miner- thermodynamic properties of rock-forming min- alogy and Petrology, 63, 175-98. erals. American Journal of Science, 278-A, --, DUTROW, B. L., BORTHWICK, J., SHORE, P., 1-229. HARMON, R. S. & HINTON, R. W. 1986a. H HEMINGWAY, B. S., ROBIE, R. A., KIIq'RICK, J. A., content of staurolite as determined by H extrac- GREW, E. S., NELEN, J.A. & LONDON, D. 1984. tion line and ion microprobe. American Mineral- The heat capacity of osumilite from 298.15 to ogist, 71, 1135-41. 1000 K, the thermodynamic properties of two & SHORE, P. 1986b. A model for the natural chlorites to 500 K, and the thermody- crystal chemistry of staurolite. American Miner- namic properties of petalite to 1800 K. American alogist, 71, 1142-59. .mineralogist, 69, 701-10. & HINTON, R. W. 1988. Devonian and HEMLEY, J. J., MONTOYA, J. W., MARENKO, J. W. & Carboniferous metamorphism in west-central LUCE, R. W. 1980. Equilibrium in the system Maine: the muscovite-almandine geobarometer A1203-SiO2-H20 and some general impli- and the staurolite problem revisited. American cations for alteration mineralization processes. Mineralogist, 73, 20-47. Economic Geology, 75, 210-28. HOLLAND, T. J. B. 1979a. Experimental determi- HENSEN, B. J. 1971. Theoretical phase relations in- nation of the reaction paragonite=jadeite+ volving cordierite and garnet in the system MgO- kyanite+H20 and thermodynamic data for part FeO-Al203-SiO2. Contributions to Mineralogy of the system Na20-A1203-SiO2-H20, with and Petrology, 33, 191-214. application to eclogites and blueschists. Contri- 1972. Cordierite-garnet equilibrium as a butions to Mineralogy and Petrology, 68, function of pressure, temperature, and iron- 293-301. magnesium ratio. Carnegie Institute of Washing- 1979b. High water activities in the generation of ton Yearbook, 71,418-21. high-pressure kyanite eclogites of the Tauern

-- 1987. P-T grids for silica-undersaturated granu- Window, Austria. Journal of Geology, 87, 1-27.

lites in the systems MAS (n+4) and FMAS -- 1980. The reaction albite=jadeite+quartz deter- (n+3)--tools for the derivation of P- T paths of mined experimentally in the range 600-1200°C. metamorphism. Journal of Metamorphic Ge- American Mineralogist, 65, 129-34. ology, 5, 255-71. 1983. The experimental determination of ac-

-- & GREEN, D. H. 1971. Experimental study of tivities in disordered and short-range ordered the stability of cordierite and garnet in pelitic jadeitic pyroxenes. Contributions to Mineralogy composition. I. Compositions with excess alumi- and Petrology, 82, 214-20. nosilicate. Contributions to Mineralogy and Pet- 1988. Preliminary phase relations involving rology, 33, 309-30. glaucophane and applications to high pressure

-- & 1973. Experimental study of the stability petrology: new heat capacity and thermodynamic of cordierite and garnet in pelitic compositions at data. Contributions to Mineralogy and Petrology, high pressures and temperatures. III. Synthesis 99, 134-42. of experimental data and geological applications. HOLM, J. L. & KLEPPA, O. J. 1966. The thermo- Contributions to Mineralogy and Petrology, 38, dynamic properties of the aluminum silicates. 151-66. American Mineralogist, 31, 1608-22. HODGES, K. V. & ROYDEN, R. L. 1984. Geologic HOSCHEK, G. 1969. The stability of staurolite and thermobarometry of retrograded metamorphic chloritoid and their significance in metamor- rocks: an indication of the uplift trajectory of a phism of pelitic rocks. Contributions to Min- portion of the northern Norwegian Caledonides. eralogy and Petrology, 22, 208-32. Journal of Geophysical Research, 89, 7077-90. HUCKENHOLZ, H. G. & FEHR K. T. 1982. Stability -- & SPEAR, F. S. 1982. Geothermometry, geo- of grossular+quartz+wollastonite+anorthite: the barometry and the AI2SiO5 triple point at Mt. effect of grandite-hydrograndite. Neues Jahrbuch Moosilauke, New Hampshire. American Min- fur Mineralogie, Abhandlungen, 145, 1-33. eralogist, 67, 1118- 34. , LINDHUBER, W. & FEHR, K. T. 1981. Stability of HO1NKES, G. 1986. Effect of grossular-content on the grossular + quartz+ wollastonite+anorthite: the partitioning of Fe and Mg between garnet and effect of andradite and albite. Neues Jahrbuch biotite. An empirical investigation on staurolite- fur Mineralogie, Abhandlungen, 142, 223-47. zone samples from the Austroalpine Schneeberg HUDSON, N. F. 1985. Conditions of Dalradian meta- complex. Contributions to Mineralogy and Pet- morphism in the Buchan area, NE Scotland. rology, 92, 393-9. Journal of the Geological Society, London, 142, HOLDAWAY, M. J. 1971. Stability of andalusite 63-76. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

36 E. J. Essene

HULTGREN, R., DESAI, P. D., HAWKINS, D. T., aibite breakdown reaction. Contributions to GLEISER, M. & KELLEY, K. K. 1973. Selected Mineralogy and Petrology, 32, 24-38. Values of the Thermodynamic Properties of JOHNSON, C. A. & ESSENE, E. J. 1982. The formation Binary Alloys, American Society of Metals, of garnet in olivine-bearing metagabbros from Metals Park, Ohio, 1435 pp. the Adirondacks. Contributions to Mineralogy HYNDMAN, D. W. 1985. Petrology of Igneous and and Petrology, 81,240-51. Metamorphic Rocks, 2nd edn, McGraw-Hill, --, BOHLEN, S. R. & ESSENE, E. J. 1983. An New York, 786 pp. evaluation of garnet-clinopyroxene geother- INDARES, A. & MARTIGNOLE, J. 1984. Evolution of mometry in granulites. Contributions to Min- P-T conditions during high-grade metamor- eralogy and Petrology, 84, 191-8. phism in the Maniwaki area, Grenville Province. KARABINOS, P. 1985. Garnet and staurolite producing Canadian Journal of Earth Sciences, 21,853-63. reactions in a chlorite-chloritoid schist. Contri- -- & -- 1985a. Biotite-garnet geothermometry butions to Mineralogy and Petrology, 90,262-75. in the granulite facies: the influence of Al and Ti KAWASAKI, T. • MATSUI, Y. 1984. Thermodynamic in biotite. American Mineralogist, 70, 272-8. analyses of equilibria involving olivine, orthopyr- -- & -- 1985b. Biotite-garnet geothermometry oxene and garnet. Geochimica et Cosmochimica in granulite facies rocks: evaluation of equilib- Acta, 47, 1661-79. rium criteria. Canadian Mineralogist, 23, 187-3. KAY, S. M. & KAY, R. W. 1983. Thermal history of -- & 1988. P- T variations across the Grenville the deep crust inferred from granulite xenoliths, Province of Quebec in a transect away from the Queensland, Australia. American Journal of Grenville Front. Tectonophysics, in press. Science, 283-A, 486-513. ISHIZUKA, H. 1985. Prograde metamorphism of the KENNEDY, C. S. & KENNEDY, G. C. 1976. The equi- Horokanai ophiolite in the Kamuikotan zone, librium boundary between graphite and diamond. Hokkaido, Japan. Journal of Petrology, 26, Journal of Geophysical Research, 81, 2467- 70. 391-417. KENNEDY, G. C. & ITO, K. 1972. Comments on "A ITAYA, T. 1981. Carbonaceous material in pelitic comparison of recent experimental data on the schists of the Sanbagawa metamorphic belt in gabbro-garnet granulite-eclogite transition." Central Shikoku, Japan. Lithos, 14, 215-24. Journal of Geology, 80, 288-92. ITO, K. & KENNEDY, G. C. 1971. An experimental KERRICK, D. M. 1972. Experimental determination of study of the basalt-garnet granulite-eclogite muscovite + quartz stability with Pri2o

Thermobarometry in metamorphic rocks 37

London, 137, 271-88. Gunflint Trail, Minnesota. American Mineral-

-- 1980b. Illite crystallinity and coal rank associ- ogist, 66, 70-86. ated with lower grade metamorphism of the LAIRD, J. & ALBEE, A. L. 1981a. High-pressure meta- Taveyanne greywacke, Helvetic zone, Swiss morphism in mafic rocks from northern Vermont. Alps. Eclogae Geologisches Helvetica, 75, American Journal of Science, 281,735-67.

753-77. & -- 1981b. Pressure, temperature and time

-- 1981. Coal rank and illite crystaUinity associ- indicators in mafic schist: their application to ated with the zeolite facies of Southland and the reconstructing the polymetamorphic history of pumpellyite-bearing facies of Otago, southern Vermont. American Journal of Science, 281, New Zealand. New Zealand Journal of Geology 127-75. and Geophysics, 24, 349-60. LAL, R. K. 1969. Retrogression of cordierite to kyan- 1987. Correlation between indicators of very low ite and andalusite at Fishtail Lake, Ontario grade metamophism. In: FREY, M. (ed.) Low Canada. Mineralogical Magazine, 37, 466-71. Temperature Metamorphism, pp. 227-300, LAMB, W. M. & VALLEY,J. W. 1984. Metamorphism Blackie, Glasgow. of reduced granulites in low-CO2, vapor-free KLAPER, E. M. and BUCHER-NURMINEN, K. 1987. environments. Nature, 312, 56-8.

Alpine metamorphism of pelitic schists in the -- & -- 1985. C-O-H fluid calculations and Nufenen Pass area, Lepontine Alps. Journal of granulite genesis. In: Tom, A. C. & TOURET, J. Metamorphic Geology, 5, 175-94. L. R. (eds) The Deep Proterozoic Crust in the Koot~s, P. O. 1982. Experimental investigation of the North Atlantic Provinces, pp. 119-31, D. Reidel, behavior of amphibole in the system Na20- Dordrecht. MgO-AI203-SiO2-H20 at high pressures. LANE, D. L. & GANGULY,J. 1980. AI20 3 solubility in Contributions to Mineralogy and Petrology, 79, orthopyroxene in the system MgO-AI203- 258-67. SiO2: a reevaluation and a mantle geotherm. 1984. Implications to garnet-clinopyroxene Journal of Geophysical Research, 85B, 6963-72. geothermometry of non-ideal solid solution in LANG, H. M. & RICE, J. M. 1985a. Regression model- jadeitic pyroxenes. Contributions to Mineralogy ling of metamorphic reactions in metapelites, and Petrology, 88, 340-47. Snow Peak, northern Idaho. Journal of Pet-

-- 1986. Relative geobarometry from high-pressure rology, 26, 857-87. rocks of quartzofeidspathic composition from the -- & -- 1985b. Geothermometry, geobarometry Sesia Zone, Western Alps, Italy. Contributions and T-X (Fe-Mg) relations in metapelites, to Mineralogy and Petrology, 93, 322-34. Snow Peak, northern Idaho. Journal of Pet- -- & THOMeSON, A. B. 1985. Non-mafic rocks in rology, 26, 889-924. the greenschist, blueschist and eclogite facies. LEAKE, B. E. 1968. A catalog of analyzed calciferous Chemical Geology, 50, 3-30. and sub-calciferous amphiboles together with KOTEL'NIKOV, A. R., BYCHKOV,A. M. & CHENAVINA, their nomenclature and associated minerals. N. I. 1981. The distribution of calcium between Geological Society of America Special Paper, 98, plagioclase and a water-salt fluid at 700°C and 210 pp. Pfl = 1000 kg/cm 2. Geochemistry International, LEE, H. Y. & GANGULY, J. 1988. Equilibrium com- 18(3), 61-75. positions of coexisting garnet and orthopyroxene: KOZiOL, A. M. & NEWTON, R. C. 1988a. Redeter- reversed experimental determinations in the sys- mination of the garnet breakdown reaction tem FeO-MgO-Al203-SiO2 and applications. and improvement of the plagioclase-garnet- Journal of Petrology, 29, 93-114. Al2SiOs-quartz geobarometer. American Min- LEE, J. H., PEACOR, D. R., LEWIS, D. D. & WINTSCH, eralogist, 73, 216-23. R. P. 1984. Chlorite-illite/muscovite interlayer-

-- & -- 1988b. Experimental determination of ing and interstratified crystals: a TEM/STEM almandine-grossular and (Ca, Mg, Fe) ternary study. Contributions to Mineralogy and Pet- garnet solid solution relations. Eos (Transactions rology, 88, 372-85. of the American Geophysical Union), 69, 498. LEE, S. M. & HOLDAWAY,M. J. 1977. Significance of KRETZ, R. 1983. Symbols for rock-forming minerals. Fe-Mg-cordierite stability relations on tem- American Mineralogist, 68, 277-9. perature, pressure, and water pressure in cordi- KROGH, E. J. 1980. Compatible P-T conditions erite granulites. In: HEACOCK, J. G. (ed.) The for eclogites and surrounding gneisses in the Earth's Crust, American Geophysical Union Kristiansund area, western Norway. Contri- Monograph Series, 20, 559-88. butions to Mineralogy and Petrology, 75,387-93. LEHMAN, J. & Roux, J. 1984. Calculation of activity- 1988. The garnet-clinopyroxene Fe-Mg composition relations in multi-site solid solutions: geothermometer--a reinterpretation of existing the example of AB204 spinels. Contributions to experimental data. Contributions to Mineralogy Mineralogy and Petrology, 87, 328-36. and Petrology, 99, 44-8. LEONARD, R. 1984. Metamorphism, structure and KUREPIN, V. A. 1988. Thermodynamics and biotite stratigraphy around the Blackman gneiss, British stability. Fe-Mg-KAISi3Os-O-H. Geochemis- Columbia. Geological Survey of Canada Paper, try International, 25(4), 103-12. 1984-1A, 121-7. LABOTKA, T. C., PAPIKE, J. J., VANIMAN, D. T. & LEVI, B., AGOmRE, L. & NYSTROM, J. O. 1982. Meta- MOREY, G. B. 1981. Petrology of contact metamorphic gradients in burial metamorphosed morphosed argillite from the Rove formation, vesicular lavas: comparison of basalt and spilite Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

38 E. J. Essene

in Cretaceous basic flows from central Chile. & 1988. Petrology of Franciscan metabasites Contributions to Mineralogy and Petrology, 80, along the jadeite-glaucophane type facies series, 49-58. Cazadero, California. Journal of Petrology, 29, Lmu, J. G. 1971a. Synthesis and stability relations of 1-37. prehnite, Ca2AIzSi3OIo(OH)2. American Min- -- & SUZUKI, K. 1983. The peristerite gap in eralogist, 56, 507-31. iow-grade metamorphic rocks. Contributions to -- 1971b. P- T stabilities of laumontite, wairakite, Mineralogy and Petrology, 81,268-76. lawsonite and related minerals in the system ~, CHO, M. & Lmu, J. G. 1985. Low-temperature CaAI2Si2Os-SiO2-H20. Journal of Petrology, recrystallization of Franciscan graywackes from 12, 379-411. Pacheco Pass, California. Mineralogical Maga- -- 1971c. Analcime equilibria. Lithos, 4, 389-402. zine, 49, 345-55. -- 1973. Synthesis and stability relations of epidote, -- & -- 1986. Experimental investigations Ca2AIzFeSi3OI2(OH ). Journal of Petrology, 14, of blueschist-greenschist transition equilibria: 381-413. pressure dependence of AI20 3 contents in sodic -- 1979. Zeolite facies metamorphism of basaltic amphiboles--a new geobarometer. Geological rocks from the east Taiwan ophiolite. American Society of America Special Paper, 164, 1-16. Mineralogist, 64, 1-14. MASSONNE, H. J. d~. SCHREYER, W. 1987. Phengite , KIM, H. S. & MARUYAMA, S. 1983. Prehnite- geobarometry based on the limiting assemblage epidote equilibria and their petrologic appli- with K-feldspar, phlogopite and quartz. Contri- cations. Journal of Petrology, 24, 321-42. butions to Mineralogy and Petrology, 96, 212-24. , MARUYAMA,S. ~¢, CHO, M. 1985. Phase equilibria MATTHEWS, A., GOLDSMITH, J. R. & CLAYTON,R. N. and mineral parageneses of metabasites in low- 1983. Oxygen isotope fractionations involving grade metamorphism. Mineralogical Magazine, pyroxenes: the calibration of mineral pair geo- 49, 321-33. thermometers. Geochimica et Cosmochimica , & CHO, M. 1987. Very low-grade meta- A cta, 47, 631 - 44. morphism of volcanic and volcaniclastic rocks-- MATrlOLI, G. S., WOOD, B. J. ~ CARMICHAEL,I. S. E. mineral assemblages and mineral facies. In: 1987. Ternary-spinel volumes in the system FREY, M. (ed.) Low Temperature Metamorphism, MgAl204-Fe304-yFeev304: implications for pp. 59-114, Blackie, Glasgow. the effect of P on intrinsic fo~ measurements of LIPPARD, S. J. 1983. Cretaceous high pressure meta- mantle-xenolith samples. .,(merican Mineral- morphism in NE Oman and its relationship to ogist, 72, 468-80. subduction and ophiolite nappe emplacement. MCLELLAN, E. 1985. Metamorphic reactions in the Journal of the Geological Society, London, 140, kyanite and sillimanite zones of the Barrovian 97-104. type area. Journal of Petrology, 26, 789-818. LONKER, S. W. 1981. The P-T-X relations of MEDARIS, L. G. JR. 1984. A geothermobarometric the cordierite - garnet- quartz equilibrium. investigation of garnet peridotite in the Western American Journal of Science, 282, 1056-90. Gneiss Region of Norway. Contributions to MACGREGOR, I. D. 1974. The system MgO-AI203- Mineralogy and Petrology, 87, 72-86. SiO2: solubility of A1203 in enstatite for spinel MEVEL, C. 1981. Occurrence of pumpellyite in hydro- and garnet peridotite compositions. American thermally altered basalts from the Vema fracture Mineralogist, 59, 110-9. zone (Mid-Atlantic Ridge). Contributions to MANGHNANI, M. H. 1970. Analcite-jadeite phase Mineralogy and Petrology, 76, 386-93. boundary. Physics of the Earth and Planetary MILLS, K. C. 1974. Thermodynamic Data for In- Interiors, 3, 456-61. organic Sulphides, Selenides and Tellurides. MARESCH, W. V. 1977. Experimental studies of Butterworths, London, 845 pp. glaucophane an analysis of present knowledge. MIRWALD, P. W. & MASSONNE, H.-J. 1980. Quartz = Tectonophysics, 43, 109-25. coesite transition and the comparative frictional -- & ABRAHAM, J. 1980. Petrography, mineralogy, measurement in piston-cylinder apparatus using and metamorphic evolution of an eclogite from talc-alsimag-glass (TAG) and NaCI high- the Island of Margarita, Venezuela. Journal of pressure cells: a discussion. Neues Jahrbuch fur Petrology, 22, 337-62. Mineralogie Monatshefte, 1980, 469-77. MART1GNOLE, J. t~ SIsl, J.-C. 1981. Cordier- MIYANO, T. & KLEIN, C. 1986. Fluid behavior ite-garnet-H20 equilibrium: a geological and phase relations in the system Fe-Mg-Si- thermometer, barometer and water fugacity in- C-O-H and applications to high grade meta- dicator. Contributions to Mineralogy and Pet- morphism of iron formations. American Journal rology, 77, 38-46. of Science, 286, 540-75. MARUYAMA, S. & LIOU, J. G. 1985. The stability MIYASHIRO, A. 1961. Evolution of metamorphic belts. of Na-Ca pyroxene in low-grade metabasites Journal of Petrology, 2, 277-318. of high pressure intermediate facies series. MOECHER, D. P., PERKINS, D. III, LEIER- American Mineralogist, 70, 16-29. ENGLEHARDT, P. J. & MEDARIS, L. G. JR. 1986. -- & -- 1987. Clinopyroxene--a mineral tele- Metamorphic conditions of late Archean high- scoped through the processes of blueschist facies grade gneisses, Minnesota River Valley, USA. metamorphism. Journal of Metamorphic Ge- Canadian Journal of Earth Sciences, 23,633-45. ology, 5, 529-52. -- ANOVITZ, L. M. & ESSENE, E. J. 1988. Calcu- Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 39

lation of clinopyroxene-garnet-plagioclase- 1972. The experimental determination of the quartz geobarometers and application to high high-pressure stability limits of magnesian cordi- grade metamorphic rocks. Contributions to erite under wet and dry conditions. Journal of

Mineralogy and Petrology, 100, 92-106. Geology, 80, 398-420.

MOHR, D. W. & NEWTON, R. C. 1983. Kyanite- -- 1983. Geobarometry of high-grade metamorphic staurolite metamorphism in sulfidic schists of the rocks. American Journal of Science, 283-A, 1-28.

Anakeesta formation, Great Smoky Mountains, -- 1986. Metamorphic temperatures and pressures North Carolina. American Journal of Science, of Group B and C eclogites. Geological Society 283, 97-134. of America Special Paper, 164, 17-30. MOLES, W. R. 1985. Metamorphic conditions NEWTON, R. C. & HASELTON. H. T. 1981. Thermo- and uplift history in central Perthshire: evidence dynamics of the garnet-plagioclase-Al2SiOs- from mineral equilibria in the Foss celsian- quartz geobarometer. In: NEWTON, R. C., barite-sulphide deposit. Journal of the Geo- NAVROTSKY, A. & WOOD, B. J. (eds) Thermo- logical Society, London, 142, 39-52. dynamics of Minerals and Melts, pp. 129-45, MOODY, J. B., MEYER, D. & JENKINS, J. E. 1983. Springer-Verlag, New York. Experimental characterization of the green- & PERKINS D., III 1982. Thermodynamic schist/amphibolite boundary in mafic systems. calibration of geobarometers based on the as- American Journal of Science, 283, 48-92. semblage garnet- plagioclase-orthopyroxene- MOORE, D. E. 1984. Metamorphic history of a high- clinopyroxene-quartz. American Mineralogist, grade blueschist exotic block from the Franciscan 67, 203-22.

Complex, California. Journal of Petrology, 25, -- & SMITH, J. V. 1967. Investigations concerning 126-50. the breakdown of albite at depth in the earth. MORA, C. I. & VALLEY,J. W. 1985. Ternary feldspar Journal of Geology, 75,268-86. thermometry in granulites from the Oaxacan -- & WOOD, B. J. 1979. Thermodynamics of water Complex, Mexico. Contributions to Mineralogy in cordierite and some petrologic consequences and Petrology, 89, 215-25. of cordierite as a hydrous phase. Contributions to MORIKIYO, Z. 1984. Carbon isotopic study on coexist- Mineralogy and Petrology, 68, 391-405. ing calcite and graphite in the Ryoke meta- --, SMITH, J. V. • WINDLEY, B. F. 1980. Carbonic morphic rocks, northern Kiso district, central metamorphism, granulites, and crustal growth. Japan. Contributions to Mineralogy and Pet- Nature, 288, 45-50. rology, 87, 251-9. NICKEL, K. G. & BREY, G. 1984. Subsolidus ortho- MORK, M. B. E. 1985. A gabbro to eclogite tran- pyroxene-clinopyroxene systematics in the sys- sition on FlemsOy, Sunnmore, western Norway. tem CaO-MgO-SiO2 to 60 kb: a reevaluation Chemical Geology, 50, 283-310. of the regular solution model. Contributions to MPOSKOS, E. & PERDIKATZIS,V. 1981. Die Paragonit- Mineralogy and Petrology, 87, 35-42.

Chloritoid fuhrenden Schiefer des sudwestlichen NITSCH, K.-H. 1971. Stabilitatsbereichungen von Bereiches des Kerkis auf Samos (Griechenland). Prehnit und Pumpellyit-haltigen Parageneses. Neues Jahrbuch fur Mineralogie, Abhandlungen, Contributions to Mineralogy and Petrology, 30, 142, 292-308. 240-60.

MUELLER, R. F. & SAXENA, S. K. 1977. Chemical -- 1980. Reacktion von Bariumfeldspat (Celsian) Petrology with Applications to the Terrestrial mit HzO zu Cymrite unter metamorphen Planets and Meteorites, Springer-Verlag, New Bedingungen. Fortschritte der Mineralogie, 58, York, 394 pp. 98-9. NAKAJ~MA, T. 1982. Phase relations of pumpellyite- --, STORRE, B. & TOPFER, U. 1981. Experimentelle actinolite metabasites in the Sanbagawa meta- Bestimmung der Gleichgewichtsdaten der Reak- morphic belt in central Shikoku, Japan. Lithos, tion 1 Margarit + 1 Quartz = 1 Anorthit + 15, 267-80. Andalusit/Disthen + 1 H~O. Fortschritte der NESBIYr, B. E. & ESSENE, E. J. 1982. Metamorphic Mineralogie, 59, 139-40. thermometry and barometry of a portion of the NOVAK, J. M. & HOLDAWAY,M. J. 1981. Metamorphic Southern Blue Ridge Province. American Journal petrology, mineral equilibria and polymeta- of Science, 282, 701-29. morphism in the Augusta Quadrangle, south- -- & -- 1983. Metamorphic volatile equilibria in central Maine. American Mineralogist, 66, a portion of the Southern Blue Ridge province. 51-69. American Journal of Science, 283, 135-65. NZENTI, J. P., BARBEY, P., MACAUDIERE, J. & NESBIYr, H. W. 1980. Genesis of the New Quebec SOBA, J. 1988. Origin and evolution of the late and Adirondack granulites: evidence for their Precambrian high-grade Yaonde gneisses production by partial melting. Contributions to (Cameroon). Precambrian Research, 38, 91-109. Mineralogy and Petrology, 72, 303-10. OFFLER, R., AGU1RRE, L., LEVI, B. & CHILD, S. 1980. NEWTON, M. S. & KENNEDY, G. C. 1968. Jadeite, Burial metamorphism in rocks of the western analcite, nepheline and albite at high tempera- Andes of Peru. Lithos, 13, 31-42. tures and pressures. American Journal of Science, --, BAKER, C. K. & GAMBLE, J. 1981. Pumpellyite 266, 728-35. in two low-grade metamorphic terranes north of NEWTON, R. C. 1966. Some calc-silicate equilibria. Newcastle, NSW, Australia. Contributions to American Journal of Science, 264, 204-22. Mineralogy and Petrology, 76, 171 - 8. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

40 E. J. Essene

O'HARA, M. J. & YARWOOD, G. 1978. High pressure- in epidote-group minerals. American Mineral- temperature point on an Archaean geotherm, ogist, 73, 838-42. magma genesis by crustal anatexis, and con- PERCHUK, L. L. & ARANOVICH, L. YA. 1984. Improve- sequences for garnet-pyroxene thermobar- ment of biotite-garnet thermometer: correction ometry. Philosophical Transactions of the Royal for fluorine content in biotite. Doklady Akademie Society, London. Series A, 288, 441-56. Nauk SSSR, 277, 131-5. OKA, Y., STEINKE, P. & CHATI'ERJEE, N. D. & LAVRENT'EVA, I. V. 1983. Experimental 1984. Thermodynamic mixing properties of investigation of exchange equilibria in the system Mg(AI, Cr)20 4 spinel crystalline solution at high cordierite-garnet-biotite. In: SAXENA, S. K. temperatures and pressures. Contributions to (ed) Kinetics and Equilibrium in Mineral Reac- Mineralogy and Petrology, 87, 196-204. tions, Advances in Physical Geochemistry, 3, OKAY, A. I. 1980. Lawsonite zone blueschists and pp. 199-239, Springer-Verlag, New York. a sodic amphibole producing reaction in the --, ARANOVICH, L. YA. & PODLESSKII, K. K. Tavsanli region, north-west. Turkey. Contri- 1983. Biotite- Garnet- Cordierite Equilibria and butions to Mineralogy and Petrology, 75,179-86. Metamorphic Evolution, Nauka Press, Moscow, OKUYAMA-KUSUNOSE, Y. • ITAYA, T. 1987. Meta- 197 pp. (in Russian). morphism of carbonaceous material in the Tono --, ARANOVICH, L. YA., PODLESSKII, K. K., contact aureole, Kitakami Mountains, Japan. LAVRENT'EVA, I. V., GERASIMOV, V. Yu., Journal of Metamorphic Geology, 5, 121-39. FED'KIN, V. V., KITSUL, V. I., KARSAKOV,L. P. O'NEILL, H. ST.C. & NAVROTSKY, A. 1984. Cation & BERDNJKOV, N. V. 1985. Precambrian granu- distributions and thermodynamic properties of lites of the AIdan shield, Eastern Siberia, USSR. binary spinel solutions. American Mineralogist, Journal of Metamorphic Geology, 3, 265-310. 69, 733-53. PERCIVAL, J. A. 1983. High-grade metamorphism in ORVILLE, P. M. 1972. Plagioclase cation exchange the Chaplau-Foleyet area, Ontario. American equilibria with aqueous chloride solution: results Mineralogist, 68, 667-86. at 700°C and 2000 bars in the presence of quartz. PERKINS, D., III & CHIPERA, S. J. 1985. Garnet- American Journal of Science, 272, 234-72. orthopyroxene- plagioclase- quartz barometry: OSANAI, Y., ARITA, K. & MITSUTAKA, B. 1986. P-T refinement and application to the English River conditions of granulite facies rocks from the subprovince and the Minnesota River Valley. Hidaka metamorphic belt, Hokkaido, Japan. Contributions to Mineralogy and Petrology, 89, Journal of the Geological Society of Japan, 92, 69-80. 793-808. -- & NEWTON, R. C. 1981a. Charnockite geobar- PADAN A., KISCH, H. J. & SHAGAM, R. 1982. Use of ometers based on coexisting garnet-pyroxene- the lattice parameter bo of dioctahedral illite/ plagioclase-quartz. Nature, 292, 144-6. muscovite for the characterization of P/T gradi- -- & -- 1981b. The compositions of coexisting ents of incipient metamorphism. Contributions to pyroxenes and garnets in the system CaO- Mineralogy and Petrology, 79, 85-95. MgO-AI203-SiO2 at 900-1100°C and high PANKRATZ, L. B. 1982. Thermodynamic properties of pressure. Contributions to Mineralogy and Pet- elements and oxides. United States Bureau of rology, 75, 291-300. Mines Bulletin, 672, 589 pp. , WESTRUM, E. F. JR. & ESSENE, E. J. 1980. The PARIA, P., BHATI'ACHARYA, A. & SEN, A. 1988. The thermodynamic properties and phase relations of reaction garnet + clinopyroxene + quartz = 2 some minerals on the system CaO-AI203- orthopyroxene + anorthite: a potential geobar- SiO2-H20. Geochimica et Cosmochimica Acta, ometer for granulites. Contributions to Miner- 44, 61-84. alogy and Petrology, 99, 126-33. PETERSON, E. U. & ESSENE, E. J. 1989. Geobarometry PASCAL, M. L. tg, Roux, J. 1985. K-Na exchange and geothermometry of the Manitouwadge equilibria between muscovite solid solution and greenstone belt, Ontario, Canada. Journal of hydrothermal chloride solutions. Mineralogical Metamorphic Geology, 7, in press. Magazine, 49, 515-21. PHILLIPS, G. N. 1980. Water activity changes across PAI~rlSON, D. R. M. 1987. Variations in Mg/ an amphibolite-granulite facies transition, (Mg + Fe) and (Fe,Mg)Si = 2Al in pelitic Broken Hill, Australia. Contributions to Min- minerals in the Bailachulish thermal aureole, eralogy and Petrology, 75, 377-86. Scotland. American Mineralogist, 72, 255-72. -- 1987. Metamorphism of the Witwatersrand gold & HARTE, B. 1985. A petrogenetic grid for fields: conditions during peak metamorphism. pelites in the Ballachulish and other Scottish Journal of Metamorphic Geology, 5, 307-22. thermal aureoles. Journal of the Geological -- & DE NooY, D. 1988. High-grade metamorphic Society, London, 142, 7-28. processes which influence Archaean gold deposits -- & NEWTON, R. C. 1988. Reversed experimental with reference to Big Bell, Australia. Journal of calibration of the garnet-clinopyroxene Ko Metamorphic Geology, 6, 95-114. (Fe-Mg) exchange thermometer. Contributions PIGAGE, L. C. & GREENWOOD, H. J. 1982. Internally to Mineralogy and Petrology, in press. consistent estimates of pressure and temperature: PEACOR, D. R. & DUNN, P. J. 1988. Dollaseite-(Ce): the staurolite problem. American Journal of magnesium orthite redefined. Structure refine- Science, 282, 943-69. ment and implications for F-M 2+ substitutions PIN, C. & VIELZEUF, D. 1988. Les granulites de Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 41

haute-pression d'Europe moyenne temoins d'une RICItARDSON, S. W. 1968. Staurolite stability in a part subduction eo-hercynienne. Implications sur of the system Fe-AI-Si-O-H. Journal of Pet- l'origine des groupes leptyno-amphiboliques. rology, 9, 467-88. Societd Gdologique de France Bulletin, 1988, RID LEY, J. 1984. Evidence of a temperature- 13-20. dependent blueschist to eclogite transformation POGNANTE, U. 1985. Coronitic reactions and ductile in high-pressure metamorphism of metabasic shear zones in eclogitised ophiolite metagabbro, rocks. Journal of Petrology, 25, 852-70. western Alps, north Italy. Chemical Geology, 50, RIN.3WOOD, A. E. & GREEN, D. H. 1964. Exper- 99-109. imental investigations bearing on the nature of -- & KIENAST, J.-L. 1987. Blueschist and eclogite the Mohorovic discontinuity. Nature 201, transformations in Fe-Ti gabbros: a case from 566-7. the western Alps ophiolites. Journal of Petrology, ~- & -- 1966. An experimental investigation of 28, 271-92. the gabbro-eclogite transformation and some , TALARICO, F., RASTELLI, N. & FERRATI, N. geophysical implications. Tectonophysics, 3, 1987. High pressure metamorphism in the nappes 383-427. of the Valle dell'Orco traverse (western Alps ROBERT, C., JAVOY, M. & KIENAST, J.-R. 1985. Co- collisional belt). Journal of Metamorphic Ge- efficients de distribution et mesures isotopiques ology, 5, 397-414. ~SO/~60: comparaisons thermometriques et bar- , -- & BENNA, P. 1988. Incomplete blueschist ometriques sur quelques eclogites et micaschistes re-crystallization in high-grade metamorphics de la zone Sesia-Lanzo (Alpes italiennes). from the Sesis-Lanzo unit (Vasario-Sparone Bulletin de Mineralogie, 108, 699-711. subunit, Western Alps): a case history of meta- ROi~IE, R. A. & HEMINGWAY,B. S. 1984. Entropies of stability. Lithos, 21, 129-42. kyanite, andalusite, and sillimanite: additional PoPP, R. K. & GILBERT, M. C. 1972. Stability constraints on the pressure and temperature of of acmite-jadeite pyroxenes at low pressure. the AI2SiO5 triple point. American Mineralogist, American Mineralogist, 57, 1210-31. 69, 298-306. POWELL, R. 1985. Geothermometry and geobar- ~-, BETHKE, P. M. TOULMIN, M. S. & EDWARDS, J. ometry: a discussion. Journal of the Geological L. 1966. X-ray crystallographic data, densities Society, London, 142, 29-38. and molar volumes of minerals. In: CLARK, S. P. -- & EVANS, J. A. 1983. A new geobarometer for JR. (ed.) Handbook of Physical Constants, Geo- the assemblage biotite-muscovite-chlorite- logical Society of America Memoir, 97, 27-74. quartz. Journal of Metamorphic Geology, 1, ---, HEMINGWAY, B. S. & FISHER, J. R. 1978. Ther- 331-6. modynamic properties of minerals and related -- & HOLLAND, T. J. B. 1985. An internally con- substances at 298.15 K and 1 bar (105 Pascals) sistent thermodynamic dataset with uncertainties pressure and at higher temperatures. United and correlations: I. Methods and a worked States Geological Survey Bulletin, 1452, 456 pp. example. Journal of Metamorphic Geology, 3, ROF;INSON, G. R. JR. 1983. Calibration of the 327-42. muscovite- biotite- quartz- aluminosilicate geo- POWERS R. E. & BOHLEN S. R. 1985. The role of barometer. Los (Transactions of the American synmetamorphic igneous rocks in the metamor- Geophysical Union), 64, 351. phism and partial melting of metasediments, ---, HAAS, J. L. JR., SCHAFER, C. M. & northwest Adirondacks. Contributions to Min- HASELTON, H. T. JR. 1982. Thermodynamic and eralogy and Petrology, 90, 401-9. thermophysical properties of selected phases in POWNCEBY, M. I., WALL, V. J. & O'NEILL, H. ST.C. the MgO- SiO 2- H20- CO 2, CaO- AI203- 1987. Fe-Mn partitioning between garnet and SIO2-H20-CO2, and Fe-FeO-Fe203-SiO2 ilmenite: experiments and applications. Contri- chemical systems with special emphasis on the butions to Mineralogy and Petrology, 97, 116- 26. properties of basalts and their mineral com- RAASE, P., RAITH, M., ACKERMAND,D. & LAL, R. K. ponent. United States Geological Survey Open- 1986. Progressive metamorphism of the mafic file Report, 83-79, 429 pp. rocks from greenschist to granulite facies in the ROHNSON, P., SPEAR, F. S., SCHUMACHER, J. C., Dharwar Craton of South India. Journal of Ge- LAIRD, J., KLEIN, C., EVANS, B. W. & DOOLAN, ology, 94, 261-82. B. L. 1982. Phase relations of metamorphic RAO, B. B. & JOHANNES, W. 1979. Further data on amphiboles: natural occurrence and theory. In: the stability of staurolite + quartz and related VEBLEN, D. R. & RIBBE, P. n. (eds) Amphiboles: assemblages. Neues Jahrbuch fur Mineralogie, Petrology and Experimental Phase Relations, Monatshefte, 1979, 437-47. Reviews in Mineralogy, 9B, pp. 1-228, Mineral- REINECKE, T. 1982. Cymrite and celsian in manganese- ogical Society of America. rich rocks from Andros Island/Greece. Contri- Rosst, G., SMITH, D. C., UNGARE'ITI, L. & butions to Mineralogy and Petrology, 79, 333-6. DOMENEGHEITI, M. C. 1983. Crystal-chemistry REJEBIAN, V. A., HARRIS, A. G. & HUEBNER, S. 1987. and cation ordering in the system diopside- Conodont color and textural alteration: an index jadeite: a detailed study by crystal structure to regional metamorphism, contact metamor- refinement. Contributions to Mineralogy and Pet- phism, and hydrothermal alteration. Geological rology, 83, 247-58. Society of America Bulletin, 99, 471-9. ROVDEN, R. L. & HODGES, K. V. 1984. A technique Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

42 E. J. Essene

for analyzing the thermal and uplift histories of SCHENK, V. 1984. Petrology of felsic granulites, meta- eroding orogenic belts: a Scandinavian example. pelites, metabasics, ultramafics and metacar- Journal of Geophysical Research, 89, 7091 - 106. bonates from Southern Calabria (Italy); prograde SACK, R. O. 1980. Some constraints on the thermo- metamorphism, uplift and cooling of a former dynamic mixing properties of Fe-Mg ortho- lower crust. Journal of Petrology, 25, 255-98. pyroxenes and olivines. Contributions to Miner- SCHIFFMAN, P. t~ Llou, J. G. 1980. Synthesis and alogy and Petrology, 71,257-69. stability of Mg-Al pumpellyite. Journal of Pet- 1982. Spinels as petrologic indicators: activity- rology, 21,441-74. composition relations at low pressure. Contri- & 1983. Synthesis of Fe-pumpellyite and its butions to Mineralogy and Petrology, 79, 169-86. stability relations with epidote. Journal of Meta- ST.-ONGE, M. R. 1984. Geothermometry and geo- morphic Geology, 1, 91-102. barometry in pelitic rocks of north-central SCHLIESTEDT, M. 1986. Eclogite-blueschist relation- Wopmay Orogen (early Proterozoic), Northwest ships as evidenced by mineral equilibria in the Territories, Canada. Geological Society of high-pressure metabasic rocks of Sifnos (Cycladic America Bulletin, 95, 196-208. Islands), Greece. Journal of Petrology, 27,

-- 1987. Zoned poikioblastic garnets: P-T paths 1437-59. and syn-metamorphic uplift through 30 km of SCHRAMKE, J. A., KERRICK, D. M. & LASSAGA, A. C. structural depth, Wopmay Orogen, Canada. 1987. The reaction muscovite + quartz = Journal of Petrology, 28, 1-21. andalusite + K-feldspar + water. Part 1. Kinetics

-- & KING, J. E. 1987. Thermo-tectonic evolution and mechanisms. American Journal of Science, of a metamorphic internal zone documented by 287, 517-59. axial projections and petrological P-T paths, SCHREYER, W. & SEIFERT, F. 1969. Compatibility re- Wopmay orogen, Northwest Canada. Geology, lations of the high pressure phases in the system 15, 155-8. MgO-Al203-SiO2-H20. American Journal of SAKAKmARA, M. 1986. A newly discovered high- Science, 267, 371-85. pressure terrane in Eastern Hokkaido, Japan. SCHREURS, J. & WESTRA, L. 1986. The thermotectonic Journal of Metamorphic Geology, 4, 401-8. evolution of a Proterozoic, low pressure, granulite SALJE, E. 1986. Heat capacities and entropies dome, SW Finland. Contributions to Mineralogy of andalusite and sillimanite: the influence of and Petrology, 93, 236-50. fibrolitization on the phase diagram of the SEIFERT, F. 1974. Stability of sapphirine: a study of AI2SiO5 polymorphs. American Mineralogist, 71, the aluminous part of MgO-AI203-SiO2-H20. 1366-71. Journal of Geology, 82, 173-204. SANDERS, I. S. 1988. Plagioclase breakdown and re- SELVERSTONE, J. & SPEAR, F. S. 1985. Metamorphic generation reactions in Grenville kyanite eclogite P- T paths from pelitic schists and greenstones in at Glenelg, Scotland. Contributions to Miner- the southwest Tauern Window, Eastern Alps. alogy and Petrology, 98, 33-9. Journal of Metamorphic Geology, 3, 439-66. --, DALY, J. S. & DAVIES, G. R. 1987. Late --, --, FRANZ, G. & MORTEANI, G. 1984. High- Proterozoic high-pressure granulite facies meta- pressure metamorphism in the SW Tauern morphism in the north-east Ox inlier, north-west Window, Austria: P-T paths from hornblende- Ireland. Journal of Metamorphic Geology, 5, kyanite-staurolite schists. Journal of Petrology, 69-85. 25, 501-31. SANDIFORD, M. & POWELL, R. 1986. Pyroxene ex- SEN, S. t~ BHATrACHARYA, A. 1984. An orthopyr- solution in granulites from Fyfe Hills, Enderby oxene-garnet thermometer and its application Land, Antarctica: evidence for 1000°C metamor- to the Madras charnockites. Contributions to phic temperatures in Archean continental crust. Mineralogy and Petrology, 88, 64-71. American Mineralogist, 71,946-54. SHARMA, R. S. t~ MACRAE, N. D. 1981. Paragene- SANTOSH, M. 1987. Cordierite gneisses of Kerala, tic relation in garnet-cordierite-staurolite- India: petrology, fluid inclusions and implications biotite-sillimanite-kyanite gneisses at Ajitpura, for crustal uplift history. Contributions to Min- Rajasthan, India. Contributions to Mineralogy eralogy and Petrology, 96, 343-56. and Petrology, 78, 48-60. SASSi, F. P. 1972. The petrologic and geologic signifi- SHARP, Z. D., ESSENE, E. J., ANOVITZ, L. M., METZ, cance of bo value of potassium white micas in G. W., WESTRUM, E. F., JR., HEMINGWAY, B. S. low-grade metamorphic rocks. An application to & VALLEY, J. W. 1986. The heat capacity of the Eastern Alps. Tschermaks Mineralogie Petro- monticellite and phase equilibria in the system graphie Mitteilungen, 18, 105-13. CaO-MgO-SiO2-CO2. Geochimica et Cosmo- -- t~ SCOLARI, A. 1974. The bo value of the potass- chimica Acta, 50, 1475-84. ium white micas as a barometer in low-grade SHULTERS, J. C. • BOHLEN, S. R. 1987. Hercynite- metamorphism of pelitic schists. Contributions to gahnite solution properties. Los (Transactions of Mineralogy and Petrology, 45, 143-52. the American Geophysical Union), 68, 1528. SAUTrER, V. 1985. An eclogite paragenesis from SILLS, J. D. & ROLUNSON, H. R. 1987. Metamorphic the Aleksod basement, central Hoggar, south evolution of the mainland Lewisian complex. In: Algeria. Chemical Geology, 50, 331-47. PARK, R. G. & TARNEY, J. (eds) Evolution of the SAXENA, S. K., SYKES, J. & ERIKSSON, G. 1986. Phase Lewisian and Comparable PreCambrian High equilibria in the pyroxene quadrilateral. Journal Grade Terrains, Geological Society Special Pub- of Petrology, 27, 843-52. lication No. 27, pp. 81-92. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

Thermobarometry in metamorphic rocks 43

SKINNER, B. J. 1966. Thermal expansion. In: CARK, 1970. Application of geothermometry and S. P. JR. (ed.) Handbook of Physical Constants, geobarometry to the determination of the Geological Society of America Memoir, 97, palaeogeothermal gradient and palaeogravity. 75-96. In: RUNCORN, S. K. (ed.) Palaeogeophysics, SKIPPEN, G. B. 1974. An experimental model for low pp. 377-86, Academic Press, London. pressure metamorphism of siliceous dolomitic TAKAYAMA, M. 1986. Mode of occurrence and signifi- marble. American Journal of Science, 274, cance of jadeite in the Kamikatan metamorphic 487-509. rocks, Hokkaido, Japan. Journal of Metamorphic & MCKINSTRY, B. W. 1985. Synthetic and Geology, 4, 445-54. natural tremolite in equilibrium with forsterite, TANNER, S. B., KERRICK, D. M. & LASAGA, A. C. enstatite, diopside, and forsterite. Contributions 1985. Experimental kinetic study of the reaction

to Mineralogy and Petrology, 89, 256-62. calcite + quartz-wollastonite + carbon dioxide SLAUGHTER, J., KERRICK, D. M. & WALL, V. J. 1975. from 1 to 3 kbar and 500 to 850°C. American Experimental and thermodynamic study of equi- Journal of Science, 285, 577-60. librium in the system CaO-MgO-SiO2-H20- TEICHMULLER, M. 1987. Organic material and very CO2. American Journal of Science, 275,143-62. low grade metamorphism. In: FREY, M. (ed.) SMITH, D. C. 1984. Coesite in clinopyroxene in Low Temperature Metamorphism, pp. 114-61, the Caledonides and its implications for geo- Blackie, Glasgow. dynamics. Nature, 310, 641-4. TELLA, S. t~ LADE, K. E. 1986. Occurrence and SMVTH, J. R. & HA~ON, C. J. 1977. Coesite-sanidine possible tectonic significance of high-pressure grospydite from the Roberts Victor kimberlite. granulite fragments in the Tulemalu fault zone, Earth and Planetary Science Letters, 34, 284-90. District of Keewatin, NWT, Canada. Canadian SOBELEV, N. V., YEFtMOVA, E. S., KOPTIL, V. I., Journal of Earth Sciences, 23, 1950-62. LAVRENT'YEV, YU. G. & SOBOLEV, V. S. 1976. THOMPSON, A. B. 1970a. A note on the kaolinite- Coesite, garnet and omphacite inclusions in pyrophyllite equilibrium. American Journal of Yakutia diamonds--first finding of coesite Science, 268, 454-8. parageneses. Doklady Akademii Nauk SSSR, 1970b. Laumontite-albite equilibria at low tem- 230, 1442-4. peratures. American Journal of Science, 269, SPEAR, F. S. & RUMBLE, D. M., III 1986. Pressure, 267-75.

temperature and structural evolution of the -- 1971. Analcite-albite equilibria at low tempera- Ordfordville belt, west-central New Hampshire. tures. American Journal of Science, 271, 79-92.

Journal of Petrology, 27, 1071-93. -- 1974. Recalculation of muscovite-paragonite- & SELVERSTONE,J. 1983. Quantitative P-T paths alkali feldspar relations. Contributions to Min- from zoned minerals: theory and tectonic appli- eralogy and Petrology, 44, 173-94.

cations. Contributions to Mineralogy and Pet- -- 1976a. Mineral reactions in pelitic rocks. I. rology, 83, 348-57. Prediction of P-T-X (Fe-Mg) phase relations. SPEER, J. A. 1987. Metamorphism of the pelitic rocks American Journal of Science, 276, 401-24.

of the Snyder Group in the contact aureole of the -- 1976b. Mineral reactions in pelitic rocks. II. Kiglapait layered intrusion, Labrador. Canadian Calculation of some P-T-X (Fe-Mg) phase Journal of Earth Sciences, 19, 1888-909. relations. American Journal of Science, 276, SPENCER, K. J. & LINDSLEY, D. H. 1981. A solution 425-54.

model for coexisting iron-titanium oxides. -- & FREY, M. 1984. lllite 'crystallinity' in the American Mineralogist, 66, 1189-201. Western River Formation and its significance STAUDIGEL, H. & SCHREYER, W. 1977. The upper regarding the regional metamorphism of the early thermal stability of clinochlore, MgsAI[AISi301o] Proterozoic Goulburn Group, District of (OH)8 at 10-35 kb PH2O. Contributions to Min- Mackenzie. In: Current Research, Part A, Geo- eralogy and Petrology, 61,187-98. logical Survey of Canada Paper 84-1A, STELTENPOHL, M. G. & BARTLEY,J. M. 1987. Thermo- pp. 409-14. barometric profile through the Caledonian nappe & LECLA1R, A. D. 1987. Chloritoid-hornblende stack of Western Lofoton, North Norway. Con- assemblages in pelitic rocks of the Central Meta- tributions to Mineralogy and Petrology, 96, sedimentary Belt, Grenville Province, Canada. 93-103. Journal of Petrology, 5, 415-36. STORRE, B. & KAROTKE, E. 1971. An experimental TREIMAN, A. H. & ESSENE, E. J. 1983. Phase equilibria determination of the upper stability limit of in the system CaO-SiO2-CO2. American muscovite + quartz in the range 7-20 kb water Journal of Science, 283-A, 97-120. pressure. Neues Jahrbuch fur Mineralogie, TRELOAR, P. J. 1985. Metamorphic conditions in cen- Monatshefte, 1971, 237-40. tral Connemara, Ireland. Journal of the Geo- STOUT, M. Z., CRAWFORD, M. L. & GHENT, E. D. logical Society, London, 142, 77-86. 1986. Pressure-temperature and evolution of TURNER, F. J. 1968. Metamorphic Petrology, 1st edn. fluid compositions of Al2SiOs-bearing rocks, McGraw-Hill, New York. Mica Creek, B. C., in light of fluid inclusion data 1981. Metamorphic Petrology, 2nd edn. and mineral equilibria. Contributions to Miner- McGraw-Hill, New York, 524 pp. alogy and Petrology, 92, 236-47. VAIDYA, S. N., BAILEY, S., PASTERNACK, T. STRENS, R. G. J. 1968. Stability of AI2SiO5 solid KENNEDY, G. C. 1974. Compressibilities of fifteen solutions. Mineralogical Magazine, 36, 839-49. Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021

44 E. J. Essene

minerals to 45 kbars. Journal of Geophysical WATKINS, K. P. 1985. Geothermometry and geobar- Research, 78, 6893-8. ometry of inverted metamorphic zones in the VALLEY, J. W. & O'NEIL, J. R. 1981. '3C/~2C exchange west-central Scottish Dalradian. Journal of the between calcite and graphite: a possible ther- Geological Society, London, 142, 157-66. mometer in Grenville marbles. Geochimica et WEISBROD, A. 1973. Refinements of the equilibrium Cosmochimica Acta, 45, 411-9. conditions of the reaction Fe-cordierite = PETERSEN, E. U., ESSENE, E. J. & garnet + sillimanite + quartz (+H20). Carnegie BOWMAN, J. R. 1982. Fluorphlogopite and fluor- Institute of Washington Geophysical Laboratory tremolite in Adirondack marbles and calculated Yearbook, 72, 515-22. C-O-H-F fluid compositions. American Min- WENK, H.-R. 1983. Mullite-sillimanite intergrowths eralogist, 67, 545-57. from pelitic inclusions in Bergell tonalite. Neues , ESSENE, E. J. & PEACOR, D. R. 1983. Fluorine- Jahrbuch fur Mineralogie, Abhandlungen, 146, bearing garnets in Adirondack calc-silicates. 1-14. American Mineralogist, 68, 444-8. WILLIAMS-JONES, A. E. 1981. Thermal metamorphism VAN BOSSE, J. Y. & WILLIAMS-JONES, A. E. 1988. of siliceous limestone in the aureole of Mount Chemographic relationships of biotite and cordi- Royal, Quebec. American Journal of Science, erite in the McGerrigle thermal aureole, Gaspe, 281,673-96. Quebec. Journal of Metamorphic Geology, 6, WINKLER, H. G. F. 1965. Petrogenesis of Metamorphic 65-76. Rocks, 1st edn, Springer-Verlag, Berlin, 237 pp. VELDE, B. 1965. Phengite micas: synthesis, stability -- 1979. Petrogenesis of Metamorphic Rocks, 5th and natural occurrence. American Journal of ed. Springer-Verlag, New York, 348 pp. Science, 263, 886-913. WINTSCH, R. P., O'CONNELL, A. F., RANSON, B. L. VIELZEUF, D. 1984. Relations de phases dans le facies WIECHMANN, M. J. 1981. Evidence for the granulite et implications geodynamique. influence of fCH4 on the crystailinity of dissemi- L'example des granulites des Pyrenees. Annales nated carbon in greenschist facies rocks, Rhode Scientifique de L'Universitd de Clermont-Ferrand Island, USA. Contributions to Mineralogy and H, 79, 288 pp. Petrology, 77, 50-73. WADA, H. 1988. Microscale isotopic zoning in calcite WOOD, B. J. & BANNO, S. 1973. Garnet-ortho- and graphite crystals in marble. Nature, 331, pyroxene and orthopyroxene-clinopyroxene 61-3. relationships in simple and complex systems. -- & SuzuKI, K. 1983. Carbon isotope thermometry Contributions to Mineralogy and Petrology, 42, calibrated by dolomite-calcite solvus tempera- 109-24. tures. Geochimica et Cosmochimica Acta, 47, WOOD, R. M. 1982. The Laytonville quarry 697-706. (Mendocino County, California) exotic block: WAN~, G.-F. & BANNO, S. 1987. Non-stoichiometry iron-rich blueschist-facies subduction-zone meta- of interlayer cations in micas from low- to middle- morphism. Mineralogical Magazine, 45, 87-99. grade metamorphic rocks in the Ryoke and the YARDLEY, B. W. D. 1982. The early metamorphic Sanbagawa belts, Japan. Contributions to Min- history of the Haast schists and related rocks of eralogy and Petrology, 97, 313-9. New Zealand. Contributions to Mineralogy and -- & TAKEUCHI, K. 1986. Reactions to define Petrology, 81,317-27. the biotite isograd in the Ryoke metamorphic ZEN, E-AN 1981. Metamorphic mineral assemblages belt, Kii Peninsula, Japan. Contributions to Min- of pelitic rocks in and around the Taconic eralogy and Petrology, 93, 9-17. allochthon, southwestern Massachusetts and WATERS, D. J. 1986. Metamorphic history of adjacent Connecticut and New York. United sapphirine-bearing and related magnesian States Geological Survey Professional Paper, gneisses from Namaqualand, South Africa. 1113, 128 pp. Journal of Petrology, 27, 541-65.

E. J. ESSENE, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA.