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656 O. LEXA ET AL.Table 2. Summarized compositions of minerals used for thermobarometry.Sample Rock type Locality Grt Pl Amp Cpx Bt IlmXMg Alm Py Grs Sps An Compositional name a XMg Si (pfu) XMg XMg XIlmSamples associated with D1 Cambro-Ordovician structureLAC4a Grt-amphibolite 66 g 0.16–0.18 62–65 12–14 11–21 4–5 31–33 Ts, Fe-Ts 0.47–0.54 6.27–6.37 – – –LAC4b Cpx-amphibolite S149c – – – – – 44–50 Mg-Hbl, Ts, Ed, Prg 0.59–0.68 6.36–6.71 0.67 b – –LAC4c Melt patche within amphibolite S149f – – – – – 38–43 Ts 0.63–0.74 6.25–6.50 – – –TG1a Tonalitic migmatite S24-1b 0.10–0.11 55 (51) 7 (8) 28 (29) 6 (13) 33–35 Fe-Prg, Hs 0.34–0.37 5.8–6.2 – 0.34–0.36 –TG1b Tonalitic migmatite S24-5a 0.11–0.12 58 (50) 8 (6) 25 (31) 9 (14) 31–34 Fe-Prg, Hs 0.25–0.40 5.8–6.2 – 0.33–0.35 –TG1c Melt patche within migmatite S24-6e – – – – – 32–35 Fe-Prg, Hs 0.34–0.38 5.95–6.25 – 0.32–0.33 –MP1 Metapelite Heg3 0.15 (0.26–0.28) b 75 (69) 15 (26) 4 (4) 5 (1) 24–26 – – – – 0.50–0.53 0.95–0.98– – –6.1–6.37.7–7.96.0–6.35.30.46–0.670.48–0.500.82–0.880.64Samples associated with D2 Variscan structureGAHT Grt-amphibolite S33b 0.15 (0.05) 70 (57) 12 (3) 15 (27) 3 (12) 15–27 (15) Fe-Ts, TsCum– – –GHT3 Metagabbro S151 – – – – – 37–60 Ts,CumGLT2 Metagabbro S130 – – – – – 48–62 (25) Mg-Hbl, Ts 0.74–0.88 6.24–6.64 – – –T3 Granodiorite – – – – – 34–37 Mg-Hbl, Ts 0.54–0.64 6.3–6.7 – – –Values in brackets represent core compositions of zoned minerals. Notes: Alm ¼ 100 · Fe 2+ /(Mg + Ca + Mn + Fe 2+ ), An ¼ 100 · Ca/(Ca + Na + K), XMg ¼ Mg/(Mg + Fe 2+ ).a Amphibole compositional name from classification of Leake et al. (1997): Prg, pargasite; Ts, tschermakite; Ed, edenite; Hs, hastingsite; Tr, tremolite; Mg-Hbl, magnesio-hornblende.b XMg ¼ Mg/(Mg + Fe tot ).tine from the core to the rim (i.e. Alm 57 fi 70Grs 2 fi 15 Py 3 fi 12 Sps 12 fi 3 ; X Mg ¼ 0.05 fi 0.15).A relic magmatic assemblage in the eastern myloniticmetagabbro is represented by Pl + Hbl ±Cpx ± Ttn ± Ilm. Magmatic plagioclase (0.5–5 mm)shows zoning marked by a rimward increase ofanorthite from 50 to 60%, whereas recrystallization ofthe plagioclase (0.05–0.1 mm) is accompanied by adecrease in anorthite content (i.e. An 45 ). Magmaticamphibole (0.5–5 mm) with pyroxene relics in thecores is magnesiohornblende (6.8–7.0 Si p.f.u., X Mg ¼0.72–0.77). Recrystallized grains (0.02–0.1 mm) correspondto magnesiohornblende with a slightly lowercontent of Si and X Mg (6.6–6.7 Si p.f.u., X Mg ¼ 0.69–0.74) in comparison with original grains.P–T conditions of Variscan metamorphismThe pressure of crystallization of the granodiorite (T3)was calculated as 6.5–7.0 kbar using the Al-content ofamphibole (Schmidt, 1992) at a temperature of 670–725 °C inferred from the Pl–Hbl thermometer ofHolland & Blundy (1994). In the western mylonitemetagabbro the temperature was estimated as770 ± 50 °C using the thermometer by Holland &Blundy (1994) in metagabbro (GHT3), while in garnetamphibolitethe temperature was estimated as 710–740 °C (GAHT). A similar temperature of 750 ±50 °C is reported by Baratoux et al. (2005) for 40amphibole–plagioclase couples. Pressure conditionsbetween 8 and 10 kbar were calculated only in Qtzbearinggarnet-amphibolite by means of the Kohn &Spear (1990) barometer. Based on 30 amphibole–plagioclase couples from the eastern mylonite metagabbro,Baratoux et al. (2005) estimated temperatureas 650 ± 50 °C using the Pl–Hbl thermometer ofHolland & Blundy (1994). The pressure could not becalculated because of the lack of garnet.Mineral textures and mineral compositions of rocks of thebanded amphibolite complexMineral assemblages and selected mineral compositionsof all study rocks are given in Table 1 and summarizedin Table 2, respectively.Banded amphibolites are characterized by the mineralassemblage Amp + Pl + Qtz ± Cpx ± Grt ±Mag ± Ilm. Three types of microstructures marked bystraightened grain boundaries without indications ofdynamic recrystallization are distinguished: (1) Equigranularaggregates (grain size 0.05–1.0 mm) ofamphibole, plagioclase and quartz (Fig. 5a); (2)amphibole-rich layers alternating with elongateaggregates (grain size 0.05–1.0 mm) of quartz andplagioclase; and (3) coarse-grained aggregates (grainsize 1–5 mm) of randomly distributed plagioclaseand quartz sometimes with amphibole occur in meltpatches. In types (1) and (2) the mineral grains arealigned and elongated parallel to the compositionalÓ 2005 Blackwell Publishing Ltd238
CONTRASTING TEXTURAL RECORD OF TWO METAMORPHIC EVENTS 657Table 3. Representative electron probe analyses of garnet.Garnet analyses recalculated to 12 oxygenEvent C-O Varis.Sample/analyses TG1a/grt23-rim TG1a/grt44-core TG1b/grt27-rim LAC4a/grt43-rim MP1/grt379-core a MP1/grt313-rim a GAHT/grt5-15-core GAHT/grt114-rimSiO 2 37.96 37.65 37.44 37.95 37.69 36.79 37.14 37.47TiO2 0.06 0.13 0.14 0.07 0.08 0.08 0.07 0.04Al 2 O 3 20.64 20.53 20.77 20.46 21.21 20.82 21.17 20.98FeO 26.47 24.70 27.05 30.02 32.60 35.12 25.97 32.46MnO 4.28 5.78 5.19 1.84 0.56 2.25 6.15 1.25MgO 1.80 1.54 1.75 3.06 6.54 3.62 0.85 3.12CaO 10.05 10.28 8.31 7.34 1.33 1.33 9.92 5.28Total 101.26 100.61 100.65 100.74 100.01 100.01 101.27 100.60Si 2.99 2.98 2.98 3.00 2.97 2.97 2.94 2.97Ti 0.00 0.08 0.01 0.00 0.00 0.00 0.00 0.00Al 1.92 1.92 1.95 1.90 1.97 1.98 1.98 1.96Fe 3+ 0.10 0.11 0.09 0.09 0.00 0.00 0.13 0.09Fe 2+ 1.65 1.53 1.71 1.89 2.15 2.37 1.59 2.07Mn 0.29 0.39 0.35 0.12 0.04 0.15 0.41 0.08Mg 0.21 0.18 0.21 0.36 0.77 0.44 0.10 0.37Ca 0.85 0.87 0.71 0.62 0.11 0.12 0.84 0.45a Fe 3+ not calculated.Table 4. Representative electron probe analyses of amphibole.Amphibole analyses recalculated after Holland & Blundy (1994)Event C-O Varis.Sample/analyses LAC4a/amp37 LAC4b/amp16 LAC4c/amp482 TG1a/amp45 TG1b/amp12-6 TG1c/amp64 GAHT/amp115 GAHT/cum6-7 a GHT3/amp48 GLT2/amp-102 T3/amp18SiO 2 42.06 45.27 42.58 39.82 39.12 39.38 41.64 51.85 43.34 45.11 43.59TiO 2 1.59 1.47 1.75 0.91 1.05 0.94 0.53 0.05 0.20 0.61 1.26Al2O3 11.58 9.68 11.73 12.96 13.51 13.40 12.42 1.35 17.66 13.94 11.85FeO 20.83 15.88 17.00 23.31 23.52 23.46 22.17 27.34 11.03 9.82 16.03MnO 0.12 0.32 0.24 0.57 0.54 0.46 0.46 0.59 0.13 0.18 0.24MgO 7.87 11.69 10.54 5.66 5.45 5.55 7.28 13.95 12.09 13.98 10.89CaO 10.62 11.34 10.68 11.13 11.41 11.31 10.57 2.51 11.29 12.42 11.05Na2O 2.11 1.50 1.86 1.45 1.33 1.39 1.77 0.18 1.95 1.71 1.25K 2 O 0.07 0.55 0.78 1.47 1.65 1.63 0.23 0.01 0.27 0.32 1.48Total 96.85 97.70 97.16 97.28 97.58 97.52 97.07 97.83 97.95 98.09 97.64Si 6.38 6.65 6.34 6.16 6.05 6.09 6.30 7.75 6.15 6.43 6.44Ti 0.18 0.16 0.20 0.11 0.12 0.11 0.06 0.01 0.02 0.07 0.14Al 2.07 1.68 2.06 2.36 2.46 2.44 2.22 0.24 2.95 2.34 2.07Fe 3+ 0.58 0.50 0.61 0.66 0.70 0.67 0.91 0.19 0.70 0.34 0.51Fe 2+ 2.06 1.45 1.50 2.36 2.34 2.36 1.90 3.23 0.61 0.83 1.47Mn 0.02 0.04 0.03 0.08 0.07 0.06 0.06 0.08 0.02 0.02 0.03Mg 1.78 2.56 2.34 1.30 1.26 1.28 1.64 3.11 2.56 2.97 2.40Ca 1.73 1.79 1.70 1.84 1.89 1.87 1.71 0.40 1.72 1.90 1.75Na 0.62 0.43 0.54 0.44 0.40 0.42 0.52 0.05 0.54 0.47 0.36K 0.01 0.10 0.15 0.29 0.33 0.32 0.04 0.00 0.05 0.06 0.28a Cummingtonite recalculated on the basis of 23 oxygen and 15 cations + Na + K.layering. Regardless of textural type, the minerals arenot zoned. Almandine-rich garnet reveals flat chemicalprofiles (Alm 62)65 Grs 11)21 Py 12)14 Sps 4)5 ; X Mg ¼ 0.16–0.18; Fig. 7a). Amphibole is magnesiohornblende ortschermakite, rarely edenite or pargasite. Plagioclase isandesine (An 30)50 ) and X Mg of rare clinopyroxeneequals 0.65–0.67.Tonalitic migmatitic gneiss is made up ofQtz + Pl + Bt + Amp ± Grt. Its structure is characterizedby alternations of leucosome, mesosome andmelanosome layers several mm to 1 cm in thickness.Weak layering is defined by amphibole–plagioclaseaggregates alternating with quartz-rich domains(Fig. 4b). Plagioclase and amphibole are elongated(length 0.2–3 mm) in the leucosome and restitic layers,whereas plagioclase is isometric (up to 3 mm). Biotite(0.2–1 mm) is oriented parallel to the foliation togetherwith amphibole in melanosome. Garnet porphyroblasts(0.3 mm) occur in mesosome and melanosome. Largecoarse-grained quartz aggregates occurs in leucosome.Chemical profiles across garnet show slight zoning withcores being more spessartine-rich; the X Mg ratio is constant(0.10–0.12) (Fig. 7c). Amphibole is homogeneousferropargasite or hastingsite, regardless of the texturalposition and type of aggregate. X Mg in biotite rangesbetween 0.32 and 0.36, and the Ti content between 0.14and 0.22 p.f.u. The composition of plagioclase in boththe leucosome and melt patches is An 31)35 andesine.Ó 2005 Blackwell Publishing Ltd239
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Contentsviii4.7 Schulmann, Konopás
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Dedicated to my wife Markéta, daug
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Foreword 2First topic “Quantitati
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Foreword 4source and freely availab
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1. Quantitative analysis of deforma
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Chapter 2Mechanisms of lower crusta
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2. Mechanisms of lower crustal flow
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Chapter 3Quantitative analyses ofme
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Bibliography 42Culshaw, N., Beaumon
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Bibliography 44sources and trigger
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Bibliography 46Skrzypek, E., Štíp
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Table 1Statistical values of the qu
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Table 2Summary of parameters derive
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EXHUMATION IN LARGE HOT OROGEN 275m
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Probabi l irequencyProbabi l ireque
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EXHUMATION IN LARGE HOT OROGEN 279y
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EXHUMATION IN LARGE HOT OROGEN 281N
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EXHUMATION IN LARGE HOT OROGEN 283w
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EXHUMATION IN LARGE HOT OROGEN 295B
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EXHUMATION IN LARGE HOT OROGEN 297R
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ORIGIN OF FELSIC MIGMATITES 31Ó 20
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ORIGIN OF FELSIC MIGMATITES 33durin
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ORIGIN OF FELSIC MIGMATITES 35(a)Ty
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ORIGIN OF FELSIC MIGMATITES 39Grain
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ORIGIN OF FELSIC MIGMATITES 45Fig.
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ORIGIN OF FELSIC MIGMATITES 49stron
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ORIGIN OF FELSIC MIGMATITES 51Cmı
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