Quantitative structural analyses and numerical modelling of ...

More documents

Recommendations

Info

98 O. LEXA ET AL.of momentum (Eqn A.1) and energy (Eqn A.3), subjectto an incompressibility constraint (Eqn A.2) known asthe Boussinesq approximation (Hansen & Yuen, 2000):@r ij¼ @P qg i ; ðA:1Þ@x i @x i@v i@x i¼ 0;@T@t þ v @Ti ¼ 1 @ @TjqC p þ A ;@x i qC p @x i @x i qC pðA:2ÞðA:3Þwhere x denotes the coordinates in m, v velocity inms )1 , t time in s; r ij is stress tensor, P is pressure in Pa,g is gravitational acceleration (9.81 m s )2 ), T is temperaturein K, j denotes thermal diffusivity and C pdenotes the specific heat capacity. The constitutiverelationship between stress and strain is governed bythe transport coefficient g representing viscosity:r ij ¼ 2g_e ij ;ðA:4Þwhere _e ij is the strain-rate tensor in s )1 . For the purposeof this work, we used a simplified flow law withonly temperature-dependent viscosity according to thesimple exponential equation:g ¼ C 1 e C 2ð T Þ ;ðA:5Þwhere C 1 and C 2 are coefficients used to calculateeffective viscosity from prescribed range (see Table 2).Density q is given by equation of state:q ¼ q 0 ½1 aðT T 0 ÞŠ; ðA:6Þwhere a is the coefficient of thermal expansion and q 0is the reference density at reference temperature T 0 .Thermal diffusivity j and specific heat capacity C p arerecalculated according to temperature using the followingequations (Whittington et al., 2009):j ¼ 3:19 10 7 þ 1:214 10 6 eð 273:15285:2T Þ ; ðA:7Þ3:224 10 5 2:714 107C p ¼ 1538:39þTT 2 ; ðA:8Þderived from laser-flash analysis to provide realisticvalues for geologically relevant temperatures. Theseequations are solved for temperature and velocity anddescribe the fundamental physics required for modellingthe thermal evolution during crustal diapirism.Calculation methods used for thermodynamic modellingThe pseudosections were calculated using THERMOCALC3.30 (Powell et al., 1998) and the data set 5.5 (Holland& Powell, 1998; November 2003 upgrade), in the systemNa 2 O–CaO–K 2 O–FeO–MgO–Al 2 O 3 –SiO 2 –H 2 O–TiO 2 –O (NCKFMASHTO) with the biotite and meltmodels from White et al. (2007), garnet from Dieneret al. (2008), ilmenite from White et al. (2000), feldsparfrom Holland & Powell (2003), white mica fromCoggon & Holland (2002) and cordierite fromTHERMOCALC documentation (Powell & Holland, 2004).The analysed rock composition of sample H296 (inwt% SiO 2 =71.98, TiO 2 =0.42, Al 2 O 3 =13.53,FeO=2.1, MnO=0.03, MgO=0.73, CaO=1.93,Na 2 O=2.76, K 2 O=4.01, P 2 O 5 =0.15, H 2 O ) =0.22,H 2 O + =0.56, CO 2 =0.03), was modified for modellingby adding 1 mol.% of kyanite to enable a smallamount of aluminosilicate to be stable at the estimatedpeak metamorphic conditions, as is observed in thinsection.The reconstruction of a biotite–muscovite graniteprotolith requires several steps. It involves determinationof the H 2 O content in the final assemblage, considerationof open-system behaviour with respect tomelt, and modification of the whole-rock compositionby adding melt (White & Powell, 2002; White et al.,2004; Sˇtı´pska´ et al., 2008). Tracking of the P–T path istherefore undertaken backwards in time, from thematrix assemblage to the early prograde evolution andto the protolith mineralogical composition. Theamount of H 2 O for the modelling shown in Fig. 12a isset such that it allows the stability of the observedmatrix assemblage with garnet rim chemistry oncooling (not shown; see Franeˇk et al., 2011b; seeHasalova´ et al., 2008b for the approach followed). Asthe whole-rock composition is expected to changealong the P–T path as a result of loss of melt, it has tobe decided from which point on the P–T path the meltcomposition will be taken. Crossing the upper stabilityof muscovite causes an abrupt increase in melt proportionand is considered a likely condition for meltloss (White & Powell, 2002; White et al., 2004);therefore, melt composition reintegrated was undertakenat 16 kbar and 860 °C.REFERENCESAckerman, L., Jelínek, E., Medaris, G., Jezˇek, J., Siebel, W. &Strnad, L., 2009. Geochemistry of Fe-rich peridotites andassociated pyroxenites from Horní Bory, Bohemian Massif:insights into subduction-related melt-rock reactions. ChemicalGeology, 259, 152–167.Aftalion, M., Bowes, D. & Vrána, S., 1989. Early CarboniferousU-Pb zircon age for garnetiferous, perpotassic granulites,Blansky´ les massif, Czechoslovakia. Neues Jahrbuch fu¨rMineralogie-Monatshefte, 4, 145–152.Avouac, J.P., 2008. Dynamic processes in extensional andcompressional settings – mountain building: from earthquakesto geological deformation. In: Treatise on Geophysics, Volumes1-11 (ed. Schubert, G.), pp. 377–439. Elsevier, Amsterdam.Babusˇka, V., Fiala, J. & Plomerova´, J., 2010. Bottom to top lithospherestructure and evolution of western Eger Rift (CentralEurope). International Journal of Earth Sciences, 99, 891–907.Bea, F., 1996. Residence of REE, Y, Th and U in granites andcrustal protoliths; implications for the chemistry of crustalmelts. Journal of Petrology, 37, 521–552.Ó 2010 Blackwell Publishing Ltd200
HEAT SOURCES AND EXHUMATION MECHANISMS 99Becker, H., Wenzel, T. & Volker, F., 1999. Geochemistry ofglimmerite veins in peridotites from Lower Austria – implicationsfor the origin of K-rich magmas in collision zones.Journal of Petrology, 40, 315–338.Behr, H., 1978. Subfluenz-Prozesse im Grundgebirgs-StockwerkMitteleuropas. Zeitschrift der Deutschen Gesellschaft fu¨r Geowissenschaften,129, 283–318.Burg, J.-P., Van Den Driessche, J. & Brun, J.-P., 1994. Syn-topost-thickening extension in the Variscan Belt of WesternEurope: modes and structural consequences. Ge´ologie de laFrance, 3, 33–51.Burg, J.-P., Kaus, B. & Podladchikov, Y., 2004. Dome structuresin collision orogens. Mechanical investigation of the gravity⁄ compression interplay. In: Gneiss Domes in Orogeny, Vol.380 (eds Whitney, D.L., Teyssier, C. & Siddoway, C.S.), pp.47–66, Geological Society of America Special Papers, Boulder,Colorado.Chemenda, A., Burg, J.-P. & Mattauer, M., 2000. Evolutionarymodel of the Himalaya–Tibet system: geopoem based on newmodelling, geological and geophysical data. Earth and PlanetaryScience Letters, 174, 397–409.Coggon, R. & Holland, T.J.B., 2002. Mixing properties ofphengitic micas and revised garnet–phengite thermobarometers.Journal of Metamorphic Geology, 20, 683–696.Cooke, R. & OÕBrien, P.J., 2001. Resolving the relationshipbetween high P–T rocks and gneisses in collisional terranes: anexample from the Gfo¨ hl gneiss–granulite association in theMoldanubian Zone, Austria. Lithos, 58, 33–54.Dewey, J.F., Ryan, P.D. & Andersen, T.B., 1993. Orogenic upliftand collapse, crustal thickness, fabrics and metamorphic phasechanges: the role of eclogites. In: Magmatic Processes andPlate Tectonics, Vol. 76 (eds Prichard, H.M., Alabaster, T.,Harris, N.B.W. & Neary, C.R.), pp. 325–343, GeologicalSociety, Special Publications, London.Diener, J.F.A., Powell, R. & White, R.W., 2008. Quantitativephase petrology of cordierite–orthoamphibole gneisses andrelated rocks. Journal of Metamorphic Geology, 26, 795–814.Do¨ rr, W. & Zulauf, G., 2010. Elevator tectonics and orogeniccollapse of a Tibetan-style plateau in the European Variscides:the role of the Bohemian shear zone. International Journal ofEarth Sciences, 99, 299–325.Edel, J.B., Schulmann, K. & Holub, F.V., 2003. Anticlockwiseand clockwise rotations of the Eastern Variscides accommodatedby dextral lithospheric wrenching: palaeomagnetic andstructural evidence. Journal of the Geological Society, 160,209–218.England, P.C. & Thompson, A.B., 1984. Pressure temperaturetime paths of regional metamorphism. 1. Heat-transfer duringthe evolution of regions of thickened continental crust. Journalof Petrology, 25, 894–928.Fiala, J., Mateˇjovska´, O. & Vanˇkova´, V., 1987a. Moldanubiangranulites and related rocks: petrology, geochemistry andradioactivity. Rozpravy Cˇeskoslovenske´ Akademie Veˇd, RˇadaMatematicky´ch a Prˇıŕodnıćh Veˇd, 97, 1–102.Fiala, J., Mateˇjovska´, O. & Vanˇkova´, V., 1987b. Moldanubiangranulites: source material and petrogenetic considerations.Neues Jahrbuch fu¨r Mineralogie, Abhandlungen, 157, 133–165.Finger, F. & Cooke, R., 2004. Evidence for the presence of atrace-element-loaded interstitial partial melt in a Moldanubianleucocratic granulite derived from LA-ICP-MS analyses onzircons and rutiles. In: International Workshop on Petrogenesisof Granulites and Related Rocks, Na´meˇsˇtˇ nad Oslavou, October1-3, 2004. Excursion Guide & Abstract Volume (ed. Janousˇek,V.), pp. 35–36. Moravian Museum, Brno.Finger, F. & von Quadt, A., 1995. U ⁄ Pb ages of zircons from aplagiogranite-gneiss in the south-eastern Bohemian Massif,Austria-further evidence for an important early Paleozoicrifting episode in the eastern Variscides. Schweizerische Mineralogischeund Petrographische Mitteilungen, 75, 265–270.Finger, F., Gerdes, A., Janousˇek, V., Rene´, M. & Riegler, G.,2007. Resolving the Variscan evolution of the Moldanubiansector of the Bohemian Massif: the significance of theBavarian and the Moravo–Moldanubian tectonometamorphicphases. Journal of Geosciences, 52, 9–28.Franeˇk, J., Schulmann, K. & Lexa, O., 2006. Kinematic andrheological model of exhumation of high pressure granulites inthe Variscan orogenic root: example of the Blanský les granulite,Bohemian Massif, Czech Republic. Mineralogy andPetrology, 86, 253–276.Franeˇk, J., Schulmann, K., Lexa, O., Tomek, Cˇ. & Edel, J.-B.,2011a. Model of syn-convergent extrusion of orogenic lowercrust in the core of the Variscan belt: implications for exhumationof high-pressure rocks in large hot orogens. Journal ofMetamorphic Geology, 29, 53–78.Franeˇk, J., Schulmann, K., Lexa, O. et al., 2011b. The precursorof Variscan felsic granulites, process of its granulitization, andinversed rheology of feldspars and quartz in the lower-crustalconditions. Journal of Metamorphic Geology, 29, 103–130.Franke, W., 2000. The mid-European segment of the Variscides:tectonostratigraphic units, terrane boundaries and plate tectonicevolution. Geological Society, London, Special Publications,179, 35–61.Friedl, G., Finger, F., Paquette, J.-L., von Quadt, A.,McNaughton, N.J. & Fletcher, I.R., 2004. Pre-Variscan geologicalevents in the Austrian part of the Bohemian Massifdeduced from U–Pb zircon ages. International Journal of EarthSciences, 93, 802–823.Fuchs, G., 1976. Zur Entwicklung der Bo¨ hmischen Masse.Jahrbuch der Geologischen Bundesanstalt, 129, 41–49.Gerdes, A., Worner, G. & Finger, F., 2000. Hybrids, magmamixing and enriched mantle melts in post-collisional Variscangranitoids: the Rastenberg Pluton, Austria. In: OrogenicProcesses: Quantification and Modelling in the Variscan FoldBelt, Vol. 179 (eds Franke, W., Haak, V., Oncken, O. &Tanner, D.), pp. 415–431, Geological Society, Special Publications,London.Gerya, T. & Yuen, D.A., 2003. Characteristics-based marker-incellmethod with conservative finite-differences schemes formodeling geological flows with strongly variable transportproperties. Physics of the Earth and Planetary Interiors, 140,293–318.Gerya, T., Maresch, W., Willner, A., Van Reenen, D. & Smit,C., 2001. Inherent gravitational instability of thickened continentalcrust with regionally developed low-to mediumpressuregranulite facies metamorphism. Earth and PlanetaryScience Letters, 190, 221–235.Gerya, T., Perchuk, L., Maresch, W., Willner, A., Van Reenen,D. & Smit, C., 2002. Thermal regime and gravitationalinstability of multi-layered continental crust: implications forthe buoyant exhumation of high-grade metamorphic rocks.European Journal of Mineralogy, 14, 687–699.Gerya, T.V., Perchuk, L.L., Maresch, W.V. & Willner, A.P., 2004.Inherent gravitational instability of hot continental crust:implications for doming and diapirism in granulite facies terrains.In: Gneiss Domes in Orogeny, Vol. 380 (eds Whitney, D.L.,Teyssier, C. & Siddoway, C.S.), pp. 97–115, Geological Societyof America, Special Papers, Boulder, Colorado.Guy, A., Edel, J.-B., Schulmann, K., Tomek, Cˇ. & Lexa, O.,2010. A geophysical model of the Variscan orogenic root(Bohemian Massif): Implications for modern collisional orogens.Lithos, in press. doi:10.1016/j.lithos.2010.08.008.Hacker, B.R., Kelemen, P.B. & Behn, M.D., 2007. Continentalrelamination drives compositional and physical-propertychanges in the lower crust, Eos Trans. AGU, 88, Fall MeetingSuppl., Abstract V32A-06.Hansen, U. & Yuen, D.A., 2000. Extended-Boussinesq thermalchemicalconvection with moving heat sources and variableviscosity. Earth and Planetary Science Letters, 176, 401–411.Hasalova´, P., Schulmann, K., Lexa, O. et al., 2008a. Origin ofmigmatites by deformation-enhanced melt infiltration oforthogneiss: a new model based on quantitative microstructuralanalysis. Journal of Metamorphic Geology, 26,29–53.Ó 2010 Blackwell Publishing Ltd201
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 193 and 194: J. metamorphic Geol., 2011, 29, 79-
Page 195 and 196: HEAT SOURCES AND EXHUMATION MECHANI
Page 211: HEAT SOURCES AND EXHUMATION MECHANI
Page 217 and 218: J. metamorphic Geol., 2011, 29, 53-
Page 219 and 220: EXTRUSIONOFLOWERCRUSTINVARISCANOROG
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 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
1.0--0.9__Mg~(Mg2++Fe2+)9 Core of p
Page 275 and 276:
Page 277 and 278:
' ~'-----2~--~----TEXTURES OF NATUR
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289:
Page 292 and 293:
B10210ZÁVADA ET AL.: EXTREME DUCTI
Page 294 and 295:
Page 296 and 297:
Page 298 and 299:
Page 300 and 301:
Page 302 and 303:
Page 304 and 305:
Page 307 and 308:
ClickHereforFullArticleJOURNAL OF G
Page 309 and 310:
B10406SCHULMANN ET AL.: RHEOLOGY OF
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
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 ...

Create successful ePaper yourself

Delete template?

Save as template?