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112 L. BARATOUX ET AL.Quantitative textural analysisGrain size distributionThe average grain sizes are presented as medianvalues of the Ferret diameter and the grain sizespread is expressed by the difference of thirdand first quartile (Q3- Ql). The statisticalvalues of the quantitative microstructural andgrain size analyses are summarized in Table 4.Plagioclase. Plagioclase in XZ section of theprotomylonitic stage in the eastern metagabbrobelt is characterized by an average grain size of45 ixm (El) (Fig. l la). Matrix grains in mylonitesare marked by an increase of the averagegrain size, reaching 74 pore in less (E2-pll) and58 Ixm in more (E2-p12) strained domains.Grain coarsening in the mylonite is consistentwith the syndeformational growth of grains originatedfrom subgrain rotation in the protomyloniticstage. This is supported by a greater amountof larger grains in grain size frequency histograms.The grain size is reduced to ~45 Ixm inthe ultramylonite (E3).Plagioclase grains in the augen mylonite ofthe western metagabbro belt (W1) are 43 Ixmon average, which is the statistical valueTable 4, Statistical values of the quantitative textural analysisEastern beltWestern beltProtomyl. Mylonite Mylonite Ultramyl. Augen myl. Banded myl. Banded myl.pl amp, pll p12 amp, pl amp, pl amp, pll p12GBPO Pl-pl 1.23 1.30 1.58 1.44 1.39 1.24 1.59Eigenvalue Amp-amp 2.50 3.53 2.26 1.96r = el/e2 Amp-plt 1.41 1.94 2.60 2.18 1.55 1.50Eigenvector V1 Pl-pl 7 24 23 17 3 - 3 5Orientation (~ Amp-amp 11 2 4 - 2Amp-pl * 16 12 18 7 -5 1SPO P1 1.45 1.46 1.73 1.85 1.86 1.38 1.64Eigenvalue Amp 1.83 4.40 2.89 2.21r = el/ea Amp t 1.81 2.67 3.43 3.26 1.96 1.76Eigenvector V1 P1 - 14 21 22 8 1 2 8Orientation (~ Amp 16 2 8 - 2Amp t 18 9 21 8 - 1 9Aspect ratio P1 1.59 1.56 1.82 1.84 1.68 1.50 1.72(median) Amp 4.46 3.79 2.36 2.12Amp ~ 2.67 2.59 3.02 3.00 2.28 1.84Grain size-Ferret diameterMedian (Ixm) P1 45 74 58 45 43 92Amp 49 41 119 94Amp t 49 39 43 33 59 50Q1 (~m) P1 33 52 43 30 30 57Amp 36 30 62 61Amp t 38 29 31 24 34 35Q3 (~m) P1 63 103 80 72 63 147Amp 68 62 211 142Amp t 64 52 60 44 102 74Q3 - QJ (~m) P1 30 51 37 42 32 90Amp 33 32 150 81Amp t 26 23 29 20 68 39Skewness "+ PI 1.44 - 0.34 - 0.08 - 0.09 1.15 0.01Amp 0.62 0.25 0.02 0.36Kurtosis * P1 7.30 2.86 2.77 2.53 6.99 2.98Amp 4.86 3.12 2.43 2.74R 2 P1 0.9151 0.9909 0.9979 0.9951 0.9442 0.9977correlation Amp 0.9768 0.9942 0.9899 0.9883coef.*Positive values are oriented anticlockwise with respect to the horizontal line.tin plagioclase domains.*The R 2 values, skewness close to zero, and kurtosis close to 3 signify well-fitted lognormal distribution.264725010656
' ~'-----2~--~----TEXTURES OF NATURALLY DEFORMED METAGABBROS 113b)Amphibole~.. ~ Amphibole in plagioclase domainsAmphibole,~ Amphibole in plagioclase domains\ A0 50 100 150Grain size - Ferret diameter (pm)9 Protomylonite- E1"~ A Mylonite- E2-pllLU z~ Mylonite- E2-pl2/x Ultramylonite- E39 ~ 9 Augen mylonite- Wlr o Banded mylonite- W2-pllo Banded mylonite- W2-p12Plagioclaseo50200 181614~8'Plagioclase ~ East ' "2Em Protomylonite - E1I. ~ Mylonit~- E2ttl [~ Ultramylonite- E36420fill L.. Plagioclase - West~21]il-grained plagioclasedlllllllllllllllilLlUL J~nn n~l][]nlIJ]n~Amphibole - Eastt 3~I ~ Mylonite- E2b9 11~ I I Ultramylonite- E3llilJLAmphibole - Westm Augen mylonite W1- [~ Banded mylonite- W250 100 150 200 250 3000 50 100 150 200 250 300 350 400Grain size - Ferret diameter (~m)Grain size - Ferret diameter (p.m)Fig. 11. Grain size evolution in the eastern (triangles) and western (circles) metagabbros. Degree of defomlationincreases from dark to white colour. (a) Calculated medians and standard deviations. (b) Histograms showing thecharacteristic frequencies of grain size for each deformational stage.representing the size of the recrystallized matrixgrains. Plagioclase grain size is substantiallyhigher in the coarse-grained domain (W2-pll)of the banded mylonite (92 ~zm). The grain sizeis reduced to 72 ~m on average in the highstraindomain (W2-p12).The grain size distributions (Fig. 1 lb) in protomylonitesof the eastern belt (El) show slightlybimodal distribution due to presence of largeporphyroclasts surrounded by small recrystallizedgrains. A higher amount of large grainscharacterizes the western banded mylonite(W2) compared to the augen mylonite (W1)and eastern mylonites (El-E3). Lognormal distributionscorrelate with intensity of deformationin both belts.Amphibole. The amphibole grain size is 49 p~min the eastern metagabbro mylonite (E2) and41 ~m in the ultramylonite (E3). However, thegrain size spread is always lower than that ofplagioclase in the same rock.The size of amphibole grains included withinplagioclase domains decreases systematicallywith increasing deformation, from 49 ~m in theleast deformed sample (El) to 39 ~m and43 ~m in the mylonite (E2-pll and E2-p12,respectively) and 33 p~m in the ultramylonite(E3). The grain sizes are always slightly lowerthan those of amphibole matrix grains in thesame thin section.Amphibole grain size in the western metagabbrobelt is highest in the sample including porphyroclasts(W1), reaching 119 Fm on average.Very high variance is typical of this mylonite,which is due to a relatively low number of newgrains and a high number of large porphyroclasts.In the banded mylonites (W2), grain sizedecreases to 94 Fm on average.In the eastern belt, amphibole grain size distributions(Fig. 11 b) are similar to those of plagioclase.They are characterized by well-developedlognormal distribution in both mylonite andultramylonite stages. In contrast, the distributionof amphibole grain size in the western belt exhibitsweaker fits of lognormal distribution withincreasing deformation, which is attributed to ahigher number of large grains of variable size(Table 4).Shape preferred orientationPIagioclase. Recrystallized plagioclase grainsin the protomylonite of the eastern belt (El)and mylonite (E2-pll) have aspect ratio (AR)of 1.59 and 1.56, respectively (Fig. 12a). Bothaspect ratio (AR = 1.82) and SPO increase inthe analysed high-strain plagioclase aggregateadjacent to the rigid amphibole porphyroclastin mylonite (E2-pl2). The ultramylonite (E3)exhibits further strengthening of the SPO andsimilar high aspect ratios (AR = 1.84).265
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“It strikes me that all our knowl
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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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3. Quantitative analyses of metamor
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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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Journal of Structural Geology 23 20
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JOURNAL OF GEOPHYSICAL RESEARCH, VO
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DTD 5ARTICLE IN PRESSJournal of Str
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DTD 5ARTICLE IN PRESSL. Baratoux et
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Table 1Statistical values of the qu
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Table 2Summary of parameters derive
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J. metamorphic Geol., 2008, 26, 273
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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 285a
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EXHUMATION IN LARGE HOT OROGEN 287w
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EXHUMATION IN LARGE HOT OROGEN 289T
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EXHUMATION IN LARGE HOT OROGEN 291O
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EXHUMATION IN LARGE HOT OROGEN 293r
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EXHUMATION IN LARGE HOT OROGEN 295B
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EXHUMATION IN LARGE HOT OROGEN 297R
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Author's personal copyK. Schulmann
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J. metamorphic Geol., 2011, 29, 79-
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HEAT SOURCES AND EXHUMATION MECHANI
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EXTRUSIONOFLOWERCRUSTINVARISCANOROG
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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 37(a)Pl
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ORIGIN OF FELSIC MIGMATITES 39Grain
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ORIGIN OF FELSIC MIGMATITES 41(a)(b
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ORIGIN OF FELSIC MIGMATITES 43(a)(b
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ORIGIN OF FELSIC MIGMATITES 45Fig.
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ORIGIN OF FELSIC MIGMATITES 47produ
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ORIGIN OF FELSIC MIGMATITES 49stron
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ORIGIN OF FELSIC MIGMATITES 51Cmı
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ORIGIN OF FELSIC MIGMATITES 53easte
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104 J. FRANĚK ET AL.in terms of th
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106 J. FRANĚK ET AL.Fig. 2. Struct
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108 J. FRANĚK ET AL.(a)perthite po
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110 J. FRANĚK ET AL.(a)(b)(c) (d)
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112 J. FRANĚK ET AL.Table 1. Repre
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114 J. FRANĚK ET AL.at these P-T c
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116 J. FRANĚK ET AL.(a)(b)Fig. 10.
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124 J. FRANĚK ET AL.Fig. 16. Inter
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126 J. FRANĚK ET AL.development of
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128 J. FRANĚK ET AL.Behrmann, J.H.
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130 J. FRANĚK ET AL.Southern Bohem
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