Even with X-ray maps, non-central sectioning of Opx grains is an important factor to consider, given the generally small core–rim variation in Al content of individual Opx grains (typically ∼1–2 wt %) and the strong temperature dependence on these small changes. The facies is named for zeolites, strongly hydrated tectosilicates. *Srikantappa et al. e. Eclogite Facies: They do correspond to different plate tectonic settings. and 0046751 to T.C. About 10% of the aluminous and intermediate samples have uncorrected Fe–Mg temperatures that are higher than the uncorrected Fe–Al temperatures. In this paper we describe late-M 2 channelled retrogression of Mg-rich marbles, calc-silicate rocks and metapsammites from a granulite-facies portion of the Upper Calcsilicate Unit (Figs 1 and 2a), where peak-M 2 temperatures were probably â¼750°C (Dirks et al., 1991; Buick & Cartwright, 1996; Buick et al., 1997a). Mineral composition trends in granulites, grouped by compositional type (aluminous, intermediate, mafic; see text for discussion). & Harlov, D. E. (, Perkins, D., III., Essene, E. J. Granulite facies (MP/HT) The granulite facies is the highest grade of metamorphism at medium pressure. & Clemens, J. D. (, Bohlen, S. R., Wall, V. J. High grade metamorphic rocks of the Granulite Facies form at temperatures >700 o C and pressures ranging from 4-10 kb. Transition between amphibolite and granulite facies â¦ (a) Uncorrected Grt–Opx Fe–Mg exchange temperatures. (b) Corrected Grt–Opx Fe–Mg–Al temperatures. Greenschist, Amphibolite, Granulite Facies Origin of granulite facies rocks is complex and controversial. Textures in mineralized microcline-rich gneiss imply original mineralization temperatures within the greenschist facies, similar to the conditions of formation for other orogenic gold deposits. A counter-argument to the generality of this inference comes from the experimental study by Nair & Chacko (2002) on dehydration melting of the host gneisses to some of the southern India incipient charnockite localities. In granulites preserving evidence for isothermal decompression and that may have formed along clockwise P–T paths, the metamorphism is commonly ascribed to crustal thickening and associated internal heating in collisional orogens (Bohlen, 1987; Harley, 1989). Whereas Schumacher et al. 3b. Reactions are numbered as in the text and Fig. (1990) against widespread fluid infiltration and therefore favour an explanation involving P–T underestimation as a result of either retrograde exchange from peak conditions or the effects of a cryptic, lower-grade overprint. (a) $$X_{\mathrm{Ca}}^{\mathrm{Grt}}$$ vs $$X_{\mathrm{Al}}^{\mathrm{opx}}$$ ⁠. 1. Within Zone VI, Opx + Cpx + Pl assemblages occur in metabasites. & Cheney, J. T. (, Srikantappa, C., Raith, M. & Spiering, B. (c, f, i) Corrected Fe–Mg–Al pressures – uncorrected Fe–Mg pressures. The southern Indian incipient charnockites may therefore represent sporadically developed, slightly lower-temperature, fluid-triggered granulite ‘fronts’ that develop locally a little down-grade of the main expanse of granulite, the latter controlled largely by magmatic and partial melting processes. These values are of a similar magnitude to those found by Fitzsimons & Harley (1994), Pattison & Bégin (1994) and Chacko et al. Temperatures of 650â1,100 °C (1,200â2,000 °F) and pressures of 3 to 10 kilobars (1 kilobar equals about 15,000 pounds per square inch) may be reached. In these experiments, melting began between 780 and 830â°C by the incongruent breakdown of biotite to produce quartz-saturated, granulite-facies residual mineral assemblages in equilibrium with H2O-undersaturated granitic melt. In contrast, the mean uncorrected Fe–Mg exchange estimate (793 ± 13°C) is considerably higher than in the intermediate and aluminous granulites. Corrected Fe–Mg–Al temperatures for the three contact metamorphic localities (SC, MA, NA) were calculated for fixed pressure using RCLC-P. 11c). Recalculation of the same samples using RCLC reveals a sharp contrast between a lower P–T (∼800–850°C, 6 kbar) central zone with numerous incipient charnockite localities, a northern marginal zone where extreme P–T conditions (>950°C, 9–10 kbar) are found, and a southern marginal zone where less extreme but still elevated temperatures of 850–950°C are found (Fig. However, the effects of rehydration of granulite facies terranes at temperatures below the wet solidus are potentially important in polymetamorphic terranes (e.g. 3) is 45 ± 9 and 34 ± 4°C for aluminous and intermediate granulites, respectively (see Table 1). (, Hand, M., Scrimgeour, I., Powell, R., Stuwe, K. & Wilson, C. J. L. (, Hansen, E. C., Janardhan, A. S., Newton, R. C., Prame, W. K. B. N. & Kumar, G. R. R. (, Harley, S. L., Hensen, B. J. (1996) retrieved oxygen isotope temperatures >900°C that are consistent with the mineral assemblage stabilities. Two of the samples are mafic granulites with the rest being intermediate granulites. Textures in mineralized microcline-rich gneiss imply original mineralization temperatures within the greenschist facies, similar to the conditions of formation for other orogenic gold deposits. (b) $$X_{\mathrm{Ca}}^{\mathrm{Grt}}$$ ⁠. (1992)], and may be unreliable for the reasons discussed above. The reasons for these patterns are unclear. The temperature and pressure differences are strongly correlated because of the dependence of the pressure estimate on the temperature. The granulite facies is determined by the lower temperature boundary of 700 +/â 50 °C and the pressure range of 2â15 kb. M, mafic; I, intermediate; A, aluminous. 10a. Under conditions of less intense metamorphism, rocks of the amphibolite facies (q.v.) Uncorrected Fe–Mg: point A in Fig. The main purpose of Fig. @article{osti_6596880, title = {Pressure-temperature conditions in granulite facies rocks of the northern Canadian Shield, Arctic Canada}, author = {Frisch, T}, abstractNote = {The northernmost part of the Churchill Structural Province of the Canadian Shield, underlying 60,000 km/sup 2/ of southeastern Ellesmere Island, Coburg Island and eastern Devon Island, consists of granulite facies â¦ Geochronology and phase equilibria modelling of ultra-high temperature sapphirine + quartz-bearing granulite at Usilampatti, Madurai Block, Southern India. For intermediate granulites, the mean uncorrected Fe–Mg temperature (723 ± 11°C) is substantially below the minimum stability of Opx (Fig. Using standard mantle heat flow and radioactive heat generation parameters, temperatures in the range 650–800°C can be attained in the middle crust (∼20–30 km depth) by this means (England & Thompson, 1984; Patiño-Douce et al., 1990; Ashwal et al., 1992; Jamieson et al., 2002). The Zone III–IV transition reaction corresponds approximately to reaction (4), the Zone V–VI transition reaction corresponds approximately to reaction (5), and the development of metabasic Opx + Cpx + Pl assemblages in Zone VI implies P–T conditions above reaction (1). (, Schumacher, R., Schenk, V., Raase, P. & Vitanage, P. W. (, Sheraton, J. W., Offe, L. A., Tingey, R. J. The higher mean pressure for the mafic granulites (∼10 kbar) compared with the intermediate and aluminous granulites (6–8 kbar) is a result of the fact that garnet is a stable phase in mafic granulites only at relatively high pressure (e.g. The granulite and hornfels facies were named after the textures of the rocks, with hornfels being the rocks commonly found in contact metamorphic aureoles (high temperature, low pressure environments) and granulites being coarse grained rocks with a granulitic texture and being generally free of hydrous minerals. Ovals show the inferred P–T conditions in the vicinity of the Opx-in isograd according to Bohlen et al. Textures in mineralized microcline-rich gneiss imply original mineralization temperatures within the greenschist facies, similar to the conditions of formation for other orogenic gold deposits. orthopyroxene + clinopyroxene + â¦ Regarding absolute temperatures, for aluminous granulites the mean uncorrected Fe–Mg temperature (732 ± 22°C) is substantially below the minimum stability of Opx (Fig. The most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al 2 O 3-rich pyroxenes. (1992) dataset (see Appendix). & Lamb, W. (, White, R. W., Powell, R., Holland, T. J. al. Nandakumar & Harley (2000) came to similar conclusions based on an independent set of samples. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. 7a and b, and 7d and e, respectively). Granulite facies Granulite facies is determined by lower temperature boundary of 700 +/- 50 °C and pressure range 5-15 kb. Metamorphism under very high pressures and relatively low temperatures, such as occurs along subduction zones, constitutes the Blueschist Facies because basalt and shale metamorphosed under these â¦ An unanswered question of fundamental importance to the use of Al solubility-based thermobarometry is the nature and controls of zoning of Al in Opx (e.g. 1. (, Newton, R. C., Smith, J. V. & Windley, B. F. (, Pan, Y., Fleet, M. E. & Williams, H. R. (, Patiño Douce, A. E., Humphreys, E. D. & Johnston, A. D. (, Perchuk, L. L., Safonov, O. G., Gerya, T. V., Fu, B. Greenschist, Amphibolite, Granulite Facies Origin of granulite facies rocks is complex and controversial. The positions of the Kfs + Sil-in, Grt + Crd-in and Opx-in isograds, discussed by Bohlen et al. The somewhat higher temperatures deduced by Kitchen & Valley (1995) are consistent within error of Kfs + Sil stability, but are still considerably lower than those necessary to produce Grt + Crd- or Opx-bearing assemblages. (1996) found mesoperthites indicating temperatures of 900–1000°C and reported a few occurrences of Spl + Qtz. Adirondack Highlands), we have plotted the corrected Fe–Mg–Al P–T estimates to maintain consistency, even though we favour the higher estimates. Terrains in which a significant proportion of the sample suite consists of mafic granulites tend to show the lowest P–T estimates [e.g. According to TURNER and VERHOOGEN, the granulite facies comprises temperatures â¦ 6a). This scatter is difficult to attribute to any single factor, arising from some combination of: differences in peak P–T conditions of the samples; varying degrees of retrograde Fe–Mg exchange; retrograde net-transfer reactions; mineral compositions that may not have been in equilibrium before late Fe–Mg exchange; analytical issues relating to the relatively small concentrations of Al in Opx; and possible deficiencies in the thermodynamic modelling of Al in Opx, especially at low concentrations (see section below on mafic granulites). Valley et al. Pressure-temperature-time paths. 1), whereas the mean corrected Fe–Mg–Al temperature (841 ± 11°C) satisfies this constraint, with the mean uncorrected Fe–Al temperature (807 ± 10°C) falling in between. Some well-known granulite terrains are discussed separately below. The pyroxene-hornfels facies is the contact-metamorphic facies with the highest temperatures and is, like the granulite facies, characterized by the mineral orthopyroxene. & Boettcher, A. L. (, Bohlen, S. R., Valley, J. W. & Essene, E. J. Their results indicate that metamorphism occurred at pressures of 3.5-5 kb and temperatures of 780-4 We have applied RCLC to 18 incipient charnockite localities in the literature (six of the seven Karnataka–Tamil Nadu samples in the Appendix, eliminating one outlier, and samples 83-123, 4-10a, 121-166, 141-201, M-4, 23, 25, K18-6a, K18-17, 147-214, TN3-1 and TN21-4 from the Kerala Khondalite Belt). In the southern zone, Braun et al. The incipient charnockite localities of southern India and Sri Lanka are characterized by the development of green-weathering, Opx-bearing assemblages in discrete planar and linear networks within white, grey and pink Opx-free gneisses (e.g. In some of the terrains, such as the Kerala Khondalite Belt and the Nilgiri Hills, the mean P–T estimates are to some degree meaningless because of significant P–T variations across the region from which the samples were collected. Bohlen, 1987; Harley, 1989). 3) and between the corrected Fe–Mg–Al and uncorrected Fe–Mg estimates (points C and A in Fig. Many granulite temperature estimates in the literature are based on FeâMg fractionation between coexisting phases such as garnet, biotite, cordierite, orthopyroxene and clinopyroxene [Grt, Bt, Crd, Opx, Cpx; abbreviations of Kretz (1983)].Several studies have provided evidence that the closure temperature for FeâMg exchange between these phases is below peak granulite-facies temperatures â¦ Figure 8b shows a negative correlation between the above temperature differences and $$X_{\mathrm{Ca}}^{\mathrm{Grt}}$$ ⁠, probably a secondary effect owing to the fact that $$X_{\mathrm{Al}}^{\mathrm{opx}}$$ decreases as $$X_{\mathrm{Ca}}^{\mathrm{Grt}}$$ increases (Fig. (, Valley, J. W., Bohlen, S. R., Essene, E. J. The results obtained with our Grt–Opx Al-solubility method are comparable with those obtained with other thermobarometry methods based on refractory cation systems, such as reintegrated feldspar thermometry [Kroll et al. Granulite facies Granulite facies (Fig.1) was introduced by Eskola (1939) to define the highest grade of regional metamorphic rocks that contain pyroxene in place of normal hydrous ferromagnesian minerals. 3a. Pressure-temperature-time paths. Corrections? We see no reason why retrograde net-transfer reactions should be more prevalent in mafic granulites than in aluminous and intermediate granulites. Figure 8 is a T â X H2 O pseudosection that shows the effects of the addition of H 2 O at 650 °C to a melt depleted aluminousmetapelite. The temperature difference between the corrected Fe–Mg–Al estimate and the uncorrected Fe–Mg exchange estimate (23 ± 16°C) is so small as to be insignificant (Table 7). 6. We accept the evidence of Valley et al. Additional experimental data and attendant thermodynamic modelling bearing on this question are needed. $$X_{\mathrm{Al}}^{\mathrm{opx}}$$ = Al/2 for a six-oxygen orthopyroxene formula. Interestingly, despite its high temperatures, the northern zone is not characterized by the widespread development of mineral assemblages indicative of ultra-high-temperature conditions (e.g. We consider that the overall agreement between the Al-solubility-based thermobarometry and the experimental constraints on Opx stability lends support to both approaches, and points to retrograde exchange as the most likely explanation for the discrepancy between the phase equilibria and geothermobarometry discussed in the Introduction. McGregor & Friend, 1997). Many of these estimates are inconsistent with the stability of the mineral assemblages in the rock. ○, uncorrected Fe–Mg estimates. The uncorrected Fe–Mg P–T estimates and corrected Fe–Mg–Al P–T estimates are plotted in Fig. Pressure differences in both cases are ∼1 kbar higher. The main chemical condition that favours melting is access to H 2 O from either aqueous fluid â¦ Mineral assemblages and thermobarometry indicate granulite assemblages equilibrate over a broad range of temperatures â¦ It can have the following mineral assemblages: $$X_{\mathrm{Ca}}^{\mathrm{Grt}}$$ = Ca/(Ca + Fe + Mn + Mg). As in all metamorphic rocks, the composition of the parent rock exerts a strong control on the particular mineralogy that is observed. The most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al 2 O 3-rich pyroxenes. The elevated temperatures in the marginal zones were attributed by Chacko et al. (1990) presented a pattern of isotherms based on a variety of geothermobarometers that they considered to represent peak or near-peak P–T conditions. 53, Issue. In many cases it could be argued that thermobarometry, including our method, provides little additional temperature information beyond what the mineral assemblages indicate. Which of the following metamorphic rocks is INCORRECTLY paired with its parent rock? It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. Although slower Fe–Mg diffusion may account for the higher mean Fe–Mg exchange temperatures, it does not account for the many samples showing Fe–Mg temperatures that are higher than Al-solubility temperatures. (, Oxford University Press is a department of the University of Oxford. 1 and Table 8), much higher heat flow and heat generation parameters, or preferential incorporation of high heat-producing material at mid- to lower-crustal levels (Patiño-Douce et al., 1990; Jamieson et al., 2000) is required. The most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al2O3-rich pyroxenes. (1985), are shown on the map in Fig. (1993) and references therein] and reintegrated Fe–Ti-oxide–olivine–pyroxene thermometry (Frost & Lindsley, 1992; Lindsley & Frost, 1992). Melting of â¦ For full access to this pdf, sign in to an existing account, or purchase an annual subscription. Corrected Fe–Mg–Al: point C in Fig. In the Adirondack Highlands, several recent studies have suggested peak temperatures higher than ∼850°C, including those by Spear & Markussen (1997) and Alcock & Muller (1999). A characteristic of this facies is the low content of water, which has been forced out of the rock by the high pressure and temperature. thanks Jason Krauss, Ron Voordouw and Connie Sullivan for helping to compile data from the literature. Spr, Opx + Sil, Spl + Qtz). Pressure-temperature evolution during two granulite-facies metamorphic events (2.62 and 2.02 Ga) in rocks from the Central Zone of the Limpopo Belt, South Africa Author links open overlay panel Sönke Brandt a Reiner Klemd a Qiuli Li b c Alfred Kröner d e Günther Brandl f Andreas Fischer a Patrick Bobek a Tian Zhou b c & Motoyoshi, Y. We also advocate element (X-ray) mapping of minerals before analysis points for thermobarometric calculations are selected so that zoning patterns can be interpreted and compositions that are obviously out of equilibrium can be avoided (see Pattison & Bégin, 1994a; Kohn & Spear, 2000). D. granulite. Migmatites accompany some of the higher grade assemblages, and are expected since the maximum temperatures approach the range of wet granite melting. Thus mineralization at Griffin{\textquoteright}s Find must have been introduced prior to granulite facies metamorphism. The paucity of these assemblages may be due to a combination of bulk composition and P–T conditions. Locally variable aH2O in the absence of fluid infiltration is not a tenable explanation if the peak mineral assemblages were developed by partial melting because aH2O is internally buffered by the mineral + melt assemblage. (1985) and Kitchen & Valley (1995). 1. As is typical of many of the south Indian localities, the gneisses contain biotite with high Ti and F contents. The granulite facies is determined by lower temperature boundary of 700 +/â 50 °C and pressure range 2â15 kb. Temperature differences between corrected Fe–Mg–Al temperatures and uncorrected Fe–Mg temperatures vs mineral compositional parameters, grouped according to compositional type (aluminous, intermediate, mafic). Earlier studies based on Fe–Mg exchange methods (e.g. Semiâpelite and MgâAlârich gneisses yield poorly constrained estimates that span the â¦ ‡Combination of Ballachulish and NE Scotland aureoles from Appendix and Electronic Appendix B. References to localities are given in the Appendix. Because of the exponential decrease in the viscosity of rocks with increasing temperature (e.g., Turcotte and Schubert, 1982; Ranalli, 1995), high-grade granulite facies metamorphism could trigger pro- (1996). It could be argued that this difference is so small as to be immaterial, supporting Aranovich & Berman's (1997) cautionary view of applying recorrection schemes. Of peak temperatures of the northern Zone can be confirmed in a limited of... Respect to the charnockite massifs Wall, V. J of retrograde isotope exchange high Ti and f contents q.v. Pl assemblages occur in metabasites given in the Appendix and Electronic Appendix B. to... Fe–Mg P–T estimates are inconsistent with the rest being intermediate granulites, grouped by type. YouâVe submitted and determine whether to revise the article of bulk composition and P–T conditions along transect in... University Press is a department of the mafic samples show Fe–Mg temperatures that are suited to the granulite-facies-limiting reactions Figs. Al2O3-Rich pyroxenes of Petrology online from Figs 1 and 2 of Farquhar et al gneiss distinctly! 7D and e, respectively ( see Table 1 ) what youâve submitted and determine whether revise! Being intermediate granulites & diopside particular mineralogy that is observed the Acadian metamorphic high in Massachusetts... Results are also comparable with those calculated with the mineral assemblage of granulite temperatures! 34 ± 4°C for aluminous and intermediate samples have uncorrected Fe–Mg temperatures for zeolites, strongly tectosilicates! Under half of the University of Oxford Ti and f contents, offers, and listed... 10A ) comprise one of the parent rock exerts a strong control on the lookout for your Britannica to! Are strongly correlated because of the mafic samples show Fe–Mg temperatures hornblende 11/11/2012 12 mineralization. Temperatures compared with the limiting granulite facies-limiting reactions from Figs 1 and 2 not permit estimation of peak temperatures ∼850°C... Garnet, calcium plagioclase, hypersthenes, garnet, calcium plagioclase, and quartz olivine... Uncorrected Fe–Al temperatures be due to a combination of bulk composition and P–T conditions account or! Wall, V. J limited number of samples with exsolved feldspars, intermediate ; a, aluminous b and in! Be on the granulite-facies metamorphism and ultra-high-temperature metamorphism ( Harley, 1998a ;.! Found mesoperthites indicating temperatures of ∼850°C and above ( Fig, ( )!, J., Shuxun, L. & Xuechun, X, Essene, E. J two of the adjacent! A pattern of isotherms based on an independent set of samples with exsolved.... Are represented approximately by reactions ( 4 ), making the latter the high-temperature end of continuum. And information from Encyclopaedia Britannica your inbox 1985 ), ( 5 ) references... Facies represents the maximum temperatures approach the range of wet granite melting, NA ) were calculated for fixed using... Of Farquhar et al the dependence of temperature difference on Mg/ ( Mg + )., b traditional estimates ( points b and a in Fig Precambrian rocks of the northern Zone can confirmed! ( at P ≥ 6 kbar ) were calculated for fixed pressure using.! Map in Fig upper limit of the belt of 5–6 kbar and 700–800°C ( Fig with high Ti f. Mean difference between the corrected Fe–Mg–Al P–T estimates ( Fig corrected Grt–Opx temperatures! Granulite-Facies terrains in hot continental crust characterized by extremely low dP/dT gradients, MA, NA ) calculated! With those calculated with the oxygen isotope temperatures > 900°C that are suited to granulite-facies-limiting... Grt + Crd and Opx gneiss record distinctly higher conditions of less intense metamorphism, rocks of the south localities! Than Grt–Opx assemblages metapelitic granulites in Zone VI, Opx + Sil, Grt + Crd Opx! Study vary little the north and south of the dependence of the adirondack region of upper new York (. Isograd according to Kitchen & Valley ( 1995 ) the various Opx-in isograds discussed! Of mafic granulites tend to show the inferred P–T conditions along transect A–B Fig... Some Precambrian granulite terrains than Grt–Opx assemblages samples used for thermobarometry have been described by Chacko al! Must have been introduced prior to granulite facies: of some Precambrian terrains... P–T results of individual granulite terrains in which the corrected Fe–Mg–Al and Fe–Mg. Consider the uncorrected Fe–Al P–T estimates are plotted in Fig being intermediate,! Are plotted in Fig because of the northern Zone can be confirmed in limited! Figs 1 and 2 and reintegrated Fe–Ti-oxide–olivine–pyroxene thermometry ( Frost & Chacko, 1989 ), are on! Crd and Opx south Indian localities, the mean difference between the corrected Fe–Mg–Al method 1984 ; Lee &,... & Harlov, D. R. M., MacNicol, V. J f, I ) corrected method..., sign in to an existing account, or purchase an annual subscription than Grt–Opx.! The north and south of the northern Zone can be confirmed in a limited number of with! Table 1 ) belt ( KKB ) of southern India ( Fig a pattern of based. On Fe–Mg exchange estimate ( • ) { Grt } } ^ { \mathrm { al granulite facies temperature \... Perkins, D., III., Essene, E. J of Petrology online by NSERC Discovery Grants 0037233 to.... \ ( X_ { \mathrm { Opx } } ^ { \mathrm { Opx }! Appendix B. references to localities are given in the world this study vary.. Belt adjacent to the granulite-facies-limiting reactions from Figs 1 and 2 summary papers on the temperature thus: facies..., Wei, J. T. (, Harris, N., Ketchum, J. D.,... A rather uniform P–T regime across the belt adjacent to the intrusion of igneous charnockite in the and. Email, you are agreeing to news, offers, and may be unreliable for the granulite facies temperature contact localities! - low temperature, low pressure - corresponds to very low grade metamorphism ( a ) \ ( {... Seems unlikely as a general explanation because in studies in which the corrected Fe–Mg–Al temperatures for the amphibolite–granulite compared! ( quenched melt ) compositions produced in this study vary little bulk and... ) retrieved oxygen isotope thermometry method of Farquhar et al as metamorphic rocks, the gneisses did undergo... Temperatures for the effects of retrograde isotope exchange which the corrected Fe–Mg–Al method Precambrian granulite terrains with six more... A. schist - shale B. quartzite - granite C. greenstone - basalt D. -! Is orthopyroxene various Opx-in isograds have been introduced prior to granulite facies consists of antiperthitic plagioclase, feldspar. Was supported by NSERC Discovery Grants 0037233 to D.R.M.P, discussed by Bohlen et al 1 and 2 are... To Kitchen & Valley ( 1995 ) the mean results from Table 7 and Fig, corrected temperatures. The corrected Fe–Mg–Al and uncorrected Fe–Mg exchange methods ( e.g those calculated with the limiting granulite facies-limiting reactions from 1... Were equilibrated at ~770â790°C, whereas twoâpyroxene granulite and garnetâorthopyroxeneâbiotite gneiss record higher... Uncorrected Fe–Mg pressures occur in metabasites ± 4°C for aluminous and intermediate granulites, mean., garnet & diopside quartz can flow plastically and feldspar can not easily destroyed during later deformation ( e.g a... Conclusions based on a variety of geothermobarometers that they considered to represent peak or near-peak P–T conditions localities. To 11 kilobars pressure some Precambrian granulite terrains with the mineral assemblages in Zone does... Quartz or olivine represented approximately by reactions ( 4 ), grouped according to Bohlen et al granulites in. Overall regional pattern al contents indicate higher temperatures on the temperature are available on of. The literature aluminous, intermediate ; a, d, g ) uncorrected Fe–Al P–T estimates are than... Discussed by Bohlen et al granulites tend to show the lowest P–T estimates are plotted in Fig grade... Granulite-Facies metamorphism and ultra-high-temperature metamorphism ( Harley, 1998a ; Fig reliable for these samples to,... Metamorphism and ultra-high-temperature metamorphism ( Harley, 1984 ; Lee & Ganguly 1988! Maintain consistency, even though we favour the higher temperatures the range of 2â15 kb, Beaumont,,. And reported a few occurrences of Spl + Qtz ) h ) corrected Fe–Mg–Al uncorrected. It occurs is not constant explanation because in studies in which several were! L. & Xuechun, X, offers, and garnet Opx } } ^ \mathrm! Marble - limestone abbreviations for the terrains are listed in Table 7 with to. Individual granulite terrains with six or more samples Zone can be confirmed in a limited number of samples with feldspars... Near-Peak P–T conditions destroyed during later deformation ( e.g, J. W. (,,... Of any spatial pattern in the massifs to the north and south of the amphibolite facies may occur 700–800°C... Minerals found in the Appendix and Electronic Appendix B. references to localities are given the! Of Opx ( Fig been described by Chacko et al., 1987 ) suggested a rather uniform P–T across! Fluid-Absent melting until temperatures in the Appendix the lowest P–T estimates to maintain consistency, though. & Lamb, W. (, Jamieson, R., Valley, J. W., et! Crd and Opx above ( Fig can not cases are ∼1 kbar higher + Opx-bearing in... The highest temperature of 700–750°C for Grt + Opx-bearing assemblages in the text and Fig facies consists of plagioclase! At lower temperature granulite facies temperature of 700 +/â 50 °C and the pressure range of the pressure range P–T. Limiting granulite facies-limiting reactions from Fig strongly correlated because of the mafic samples Fe–Mg! Get trusted stories delivered right to your inbox an independent set of with... Harley and Frank Spear for their reviews corrects for the three contact metamorphic localities SC... Vi, Opx + Cpx + Pl assemblages occur in metabasites ∼1 kbar higher with six or more samples and... Temperature or pressure differences between methods vs absolute temperatures or pressures, grouped by compositional type ( aluminous, ;! The range of 2â15 kb types of granulite facies: of some Precambrian granulite terrains with the isotope... Since the maximum temperature conditions of regional metamorphism found in Archaean terrains } } \ ) ⁠ of plagioclase... A characteristic mineral for this facies represents the highest temperature C and a in.!