Quantitative structural analyses and numerical modelling of ...

More documents

Recommendations

Info

B10210ZÁVADA ET AL.: EXTREME DUCTILITY OF FELDSPAR AGGREGATESB10210Table 1. Microstructural Analysis Data From Digitized ThinSections a Ferret, mm Axial RatioKfs Pl Qtz Kfs Pl QtzB108 0.32 0.25 0.47 1.40 1.44 1.51B13 0.30 0.26 0.42 1.48 1.42 1.49B109-2 0.26 0.17 0.47 1.42 1.45 1.65B109 0.12 0.09 0.90 1.43 1.49 1.58Q 3 –Q 1 , mmSPOKfs Pl Qtz Kfs Pl QtzB108 0.21 0.16 0.35 1.20 1.18 1.14B13 0.22 0.18 0.23 1.30 1.21 1.08B109-2 0.20 0.15 0.25 1.17 1.07 1.12B109 0.07 0.05 0.93 1.18 1.13 1.45a The grain size represented by the Ferret diameter is the diameter ofcircles with the same area as the measured grain. SPO is the eigenvalueratio of the shape preferred orientation tensor. Q 3 –Q 1 designates grain sizespread quantified as the difference between third and first quartile.the shape preferred orientation tensor [Lexa et al., 2005].These are important parameters when determining thedeformation mechanisms in deformed rocks [Kruse et al.,2001; Schmid et al., 1999; Ulrich et al., 2002].[11] Crystallographic preferred orientation (CPO) of quartz,plagioclase and K-feldspar was determined using the electronbackscattered diffraction method (EBSD using the CHAN-NEL5 software) in manual mode. Each thin section wascalibrated by a silicone monocrystal and only measurementswith mean angular deviation below 1 were accepted and saved.The output data were plotted in pole figures (ftp://www.gm.univ-montp2.fr/mainprice//CareWare_Unicef_Programs/) andpresented on lower hemisphere stereographic projections inwhich the trace of foliation is oriented in E-W direction. In caseof K-feldspar and plagioclase, pole figures of published slipplanes and slip directions [Tullis, 1983;Kruse et al., 2001]were plotted in order to select and present possible operativeslip systems.4.1. Microstructural Analysis[12] Microscopic observations, grain size and shape characteristicsare described below for three different typesmarked by increasing degree of strain intensity. The type1 (metagranite) and type 2 (banded orthogneiss) revealcompletely recrystallized equigranular mineral aggregateswith similar shapes of mineral grains without relics oforiginal magmatic porphyroclasts. Quartz aggregates consistof large grains with highly lobate mutual quartz boundariesand numerous ‘‘left-over grains’’ [Jessell, 1987]. Grainboundaries with neighboring feldspars as well as feldsparinclusions in quartz exhibit cuspate-lobate phase boundaries,typical for diffusional mass transfer along interphaseboundaries in high-temperature quartzo-feldspathic rocks[Gower and Simpson, 1992; Martelat et al., 1999]. Monomineralicfeldspar ribbons are composed of equidimensionalrecrystallized grains marked by straight grain boundariesshowing 120° triple point junctions. Average grain size,expressed as geometrical mean, ranges between 0.26 and0.32 mm for K-feldspar and between 0.17 and 0.26 mm forplagioclase. Grain size distribution of these minerals ismarked by low grain size spread (K-feldspar 0.2–0.21mm and plagioclase 0.15–0.18 mm) quantified as thedifference between third and first quartile (Table 1). Quartzexhibits average grain size ranging between 0.42 and 0.47mm and significantly larger grain size spread (Q 3 –Q 1 =0.23–0.35 mm) in comparison with feldspars. Axial ratio ofall mineral phases is very low in conjunction with low SPO(see Table 1).[13] The microstructure of type 3 sample shows alternatingbands of feldspars and quartz. Elongate quartz aggregatesand one-grain thick ribbons consist of large quartzgrains with gently curved to straight mutual boundariesperpendicular to ribbon boundaries. Both feldspars formmonomineralic bands with polygonal mosaic of feldspargrains with a triple junction network similar to microstructureof types 1 and 2. Grain size of both minerals hasconsiderably decreased to 0.12 mm and 0.9 mm for K-feldspar and plagioclase in comparison with type 1 and 2samples. The grain size spread also decreased (from averageQ 3 –Q 1 = 0.21–0.07 mm for K-feldspar and from averageQ 3 –Q 1 = 0.16 mm to 0.05 mm for plagioclase) and the axialratio together with SPO remain low (Table 1). In contrast,quartz exhibits significant increase in grain size (from0.47 mm in type 2 to 0.9 mm in type 3), grain size spread(from average 0.28 in types 1 and 2 to 0.93 in type 3) andSPO (Table 1).4.2. Crystallographic Preferred Orientations[14] The crystallographic preferred orientation of grainsof all mineral phases was measured in two samples; amoderately deformed type 2 banded orthogneiss and ahighly strained type 3 mylonite using the EBSD method.Only quartz texture in sample B13 (type 2) was measuredusing the U stage.[15] K-feldspar and plagioclase in type 2 sample exhibitweak CPO that do not show any coincidence with publishedslip systems [Kruse et al., 2001; Tullis, 1983] (Figure 3).The only exception can be seen in case of K-feldspar thatshows maxima compatible with the activity of [110](001)slip system [Willaime et al., 1979]. C axes pattern of quartzis characterized by incomplete crossed girdles with twomaxima distributed along the periphery of the diagramhaving mutual distance of 90° and weak central submaximum.This type of quartz CPO corresponds to type I crossgirdle pattern of Lister and Hobbs [1980] that is typical forcombination of basal hai and prism hai slip systems active athigh-temperature plane strain deformation [Lister andDornsiepen, 1982; Morgan and Law, 2004]. The form ofquartz c axes pattern is consistent with the shape ofmeasured plane strain ellipsoid of quartz aggregates(Figure 2b) [Passchier and Trouw, 1996].[16] K-feldspar in the type 3 sample shows crystallographicpreferred orientation marked by [100] directionsforming weak maximum close to the lineation (Figure 4).This slip direction operates on (010) planes [Willaime et al.,1979] that exhibit weak maximum in the YZ plane at anangle of 30° with respect to Y axis of the specimen’scoordinate system. Inspection of K-feldspar CPO patternrevealed that [001](120) slip system can be also active[Willaime and Gandais, 1977]. Plagioclase grains showweak CPO and reveal some activity of three slip directions,namely, [201], [100] and [101] on the (010) slip planereported by Marshall and McLaren [1977] and Olsen andKohlstedt [1984]. Quartz CPO is characterized by two broadvertical parallel girdles of c axes indicating again combined4of15282
B10210ZÁVADA ET AL.: EXTREME DUCTILITY OF FELDSPAR AGGREGATESB10210Figure 3. CPO data for K-feldspar, plagioclase and quartz from the type 2 (banded orthogneiss) sample(B13). Contoured at multiples of uniform distribution, lower hemisphere, equal-area projection. X and Zdesignate direction of lineation and pole to the foliation, respectively. Mineral abbreviations are afterKretz [1983].Figure 4. CPO data for K-feldspar, plagioclase, and quartz from the type 3 (mylonite) sample (B109).Contoured at multiples of uniform distribution, lower hemisphere, equal-area projection. X and Zdesignate direction of lineation and pole to the foliation, respectively. Mineral abbreviations are afterKretz [1983].5of15283
Page 3:
“It strikes me that all our knowl
Page 8 and 9:
Contentsviii4.7 Schulmann, Konopás
Page 11:
Dedicated to my wife Markéta, daug
Page 14 and 15:
Foreword 2First topic “Quantitati
Page 16 and 17:
Foreword 4source and freely availab
Page 18 and 19:
1. Quantitative analysis of deforma
Page 20 and 21:
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 31 and 32:
Chapter 2Mechanisms of lower crusta
Page 33 and 34:
2. Mechanisms of lower crustal flow
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Chapter 3Quantitative analyses ofme
Page 43 and 44:
3. Quantitative analyses of metamor
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51:
Page 54 and 55:
Bibliography 42Culshaw, N., Beaumon
Page 56 and 57:
Bibliography 44sources and trigger
Page 58 and 59:
Bibliography 46Skrzypek, E., Štíp
Page 61 and 62:
Journal of Structural Geology 23 20
Page 63 and 64:
J. KonopaÂsek et al. / Journal of
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
JOURNAL OF GEOPHYSICAL RESEARCH, VO
Page 83 and 84:
SCHULMANN ET AL.: STRAIN DISTRIBUTI
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95:
Page 98 and 99:
5 - 2 LEXA ET AL.: COLLISION IN WES
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
5 - 10 LEXA ET AL.: COLLISION IN WE
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
156O. Lexa et al. / Journal of Stru
Page 116 and 117:
Page 118 and 119:
Page 121 and 122:
DTD 5ARTICLE IN PRESSJournal of Str
Page 123 and 124:
DTD 5ARTICLE IN PRESSL. Baratoux et
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Table 1Statistical values of the qu
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Table 2Summary of parameters derive
Page 143 and 144:
Page 145 and 146:
J. metamorphic Geol., 2008, 26, 273
Page 147 and 148:
EXHUMATION IN LARGE HOT OROGEN 275m
Page 149 and 150:
Probabi l irequencyProbabi l ireque
Page 151 and 152:
EXHUMATION IN LARGE HOT OROGEN 279y
Page 153 and 154:
EXHUMATION IN LARGE HOT OROGEN 281N
Page 155 and 156:
EXHUMATION IN LARGE HOT OROGEN 283w
Page 157 and 158:
EXHUMATION IN LARGE HOT OROGEN 285a
Page 159 and 160:
EXHUMATION IN LARGE HOT OROGEN 287w
Page 161 and 162:
EXHUMATION IN LARGE HOT OROGEN 289T
Page 163 and 164:
EXHUMATION IN LARGE HOT OROGEN 291O
Page 165 and 166:
EXHUMATION IN LARGE HOT OROGEN 293r
Page 167 and 168:
EXHUMATION IN LARGE HOT OROGEN 295B
Page 169:
EXHUMATION IN LARGE HOT OROGEN 297R
Page 172 and 173:
Author's personal copyK. Schulmann
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 193 and 194:
J. metamorphic Geol., 2011, 29, 79-
Page 195 and 196:
HEAT SOURCES AND EXHUMATION MECHANI
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
J. metamorphic Geol., 2011, 29, 53-
Page 219 and 220:
EXTRUSIONOFLOWERCRUSTINVARISCANOROG
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244: J. metamorphic Geol., 2005, 23, 649
Page 245 and 246: CONTRASTING TEXTURAL RECORD OF TWO
Page 261 and 262: Contrasting microstructures and def
Page 263 and 264: TEXTURES OF NATURALLY DEFORMED META
Page 273 and 274: 1.0--0.9__Mg~(Mg2++Fe2+)9 Core of p
Page 277 and 278: ' ~'-----2~--~----TEXTURES OF NATUR
Page 289: TEXTURES OF NATURALLY DEFORMED META
Page 292 and 293: B10210ZÁVADA ET AL.: EXTREME DUCTI
Page 307 and 308: ClickHereforFullArticleJOURNAL OF G
Page 309 and 310: B10406SCHULMANN ET AL.: RHEOLOGY OF
Page 327 and 328: J. metamorphic Geol., 2008, 26, 29-
Page 329 and 330: ORIGIN OF FELSIC MIGMATITES 31Ó 20
Page 331 and 332: ORIGIN OF FELSIC MIGMATITES 33durin
Page 333 and 334: ORIGIN OF FELSIC MIGMATITES 35(a)Ty
Page 335 and 336: ORIGIN OF FELSIC MIGMATITES 37(a)Pl
Page 337 and 338: ORIGIN OF FELSIC MIGMATITES 39Grain
Page 339 and 340: ORIGIN OF FELSIC MIGMATITES 41(a)(b
Page 341 and 342: ORIGIN OF FELSIC MIGMATITES 43(a)(b
Page 343 and 344: ORIGIN OF FELSIC MIGMATITES 45Fig.
Page 345 and 346:
ORIGIN OF FELSIC MIGMATITES 47produ
Page 347 and 348:
ORIGIN OF FELSIC MIGMATITES 49stron
Page 349 and 350:
ORIGIN OF FELSIC MIGMATITES 51Cmı
Page 351:
ORIGIN OF FELSIC MIGMATITES 53easte
Page 354 and 355:
104 J. FRANĚK ET AL.in terms of th
Page 356 and 357:
106 J. FRANĚK ET AL.Fig. 2. Struct
Page 358 and 359:
108 J. FRANĚK ET AL.(a)perthite po
Page 360 and 361:
110 J. FRANĚK ET AL.(a)(b)(c) (d)
Page 362 and 363:
112 J. FRANĚK ET AL.Table 1. Repre
Page 364 and 365:
114 J. FRANĚK ET AL.at these P-T c
Page 366 and 367:
116 J. FRANĚK ET AL.(a)(b)Fig. 10.
Page 368 and 369:
Page 370 and 371:
120 J. FRANĚK ET AL.Table 2. Quant
Page 372 and 373:
Page 374 and 375:
124 J. FRANĚK ET AL.Fig. 16. Inter
Page 376 and 377:
126 J. FRANĚK ET AL.development of
Page 378 and 379:
128 J. FRANĚK ET AL.Behrmann, J.H.
Page 380:
130 J. FRANĚK ET AL.Southern Bohem
show all

Quantitative structural analyses and numerical modelling of ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?