Vojte ÿch Janous ÿek, Fritz Finger, Malcolm Roberts, Jir ÿõ« Fry … · 2017-06-30 ·...

Deciphering the petrogenesis of deeply buriedgranites whole-rock geochemical constraints onthe origin of largely undepleted felsic granulitesfrom the Moldanubian Zone of the BohemianMassif

Vojtech Janousek Fritz Finger Malcolm Roberts Jirı FrydaChristian Pin and David Dolejs

ABSTRACT The prominent felsic granulites in the southern part of the Bohemian Massif (GfohlUnit Moldanubian Zone) with the Variscan (w340 Ma) high-pressure and high-temperatureassemblage garnet+quartz+hypersolvus feldsparkyanite correspond geochemically to slightlyperaluminous fractionated granitic rocks Compared to the average upper crust and most granitesthe U Th and Cs concentrations are strongly depleted probably because of the fluid andor slightmelt loss during the high-grade metamorphism (900ndash1050(C 1middot5ndash2middot0 GPa) However the rest of thetrace-element contents and variation trends such as decreasing Sr Ba Eu LREE and Zr withincreasing SiO2 and Rb can be explained by fractional crystallisation of a granitic magma Low Zrand LREE contents yield w750(C zircon and monazite saturation temperatures and suggestrelatively low-temperature crystallisation The granulites contain radiogenic Sr (87Sr86Sr340=0middot7106ndash0middot7706) and unradiogenic Nd (340

Nd =4middot2 to 7middot5) indicating derivation from an oldcrustal source The whole-rock RbndashSr isotopic system preserves the memory of an earlier probablyOrdovician isotopic equilibrium

Contrary to previous studies the bulk of felsic Moldanubian granulites do not appear to representseparated syn-metamorphic Variscan HPndashHT melts Instead they are interpreted as metamor-phosed (partly anatectic) equivalents of older probably high-level granites subducted to continentalroots during the Variscan collision Protolith formation may have occurred within an EarlyPalaeozoic rift setting which is documented throughout the Variscan Zone in Europe

KEY WORDS Austria Czech Republic high-grade metamorphism Nd isotopes partial meltingSr isotopes Variscan orogeny

Felsic garnetkyanite-bearing high-pressure and high-temperature (HPndashHT) granulites with broadly granitic com-positions are prominent constituents in the central part of theEuropean Variscides (eg Pin amp Vielzeuf 1983 OrsquoBrien ampRotzler 2003) These light-coloured SiO2ndashrich rocks areknown from many places of the Bohemian Massif namelyfrom the Moldanubian (Lower Austria and southern CzechRepublic Fig 1) and the Saxothuringian zones (the SaxonianGranulite Massif and Erzgebirge Romer amp Rotzler 2001Rotzler amp Romer 2001 OrsquoBrien amp Rotzler 2003) Since theMoldanubian granulites may provide insights into processesrelated to deep subduction and subsequent exhumation of thecontinental crust research over the past 40 years has focusedmainly on constraining their precise pressurendashtemperaturendashtime (PndashTndasht) paths (for reviews see OrsquoBrien 2000 OrsquoBrien ampRotzler 2003) However their pre-metamorphic history hasbeen largely neglected

Concerning the protolith the felsic granulites were con-sidered as former rhyolites or granites which acquired theirhigh-grade metamorphic character during the course of theVariscan collision (Fiala et al 1987a b Vellmer 1992) Basedon existing PndashT estimates and fluid-absent melting models forcrustal rocks Roberts amp Finger (1997) proposed that theyprobably experienced a certain degree of partial melting andmelt persisted during much of their metamorphic historyOther authors (Vrana amp Jakes 1982 Vrana 1989 Jakes 1997

Kotkova amp Harley 1999) went further and suggested that thegranulites actually represent high-pressure granitic magmaswhich formed during the Variscan metamorphic cycle

Clearly the problem of granulite genesis cannot be resolvedwithout involving additional aspects of granite petrologyand geochemistry constraining the protolith formation andmetamorphic reworking The present paper characterises thecompositional variation of the felsic Moldanubian granulitesand provides their petrogenetic interpretation The authorsdemonstrate that most if not all of their whole-rockgeochemical signature may be related to a pre-existing EarlyPalaeozoic igneous-rock suite whereas the Variscan high-pressure metamorphism could have been nearly isochemical

1 Geological setting and petrology

11 Moldanubian ZoneThe Moldanubian Zone represents remnants of the crystallinecore of the Variscan orogen in central Europe (eg Dallmeyeret al 1995) In the southern part of the Bohemian Massifshared by the Czech Republic and Austria the MoldanubianZone consists of several crustal segments with contrasting agesand complex polyphase deformational histories intruded bynumerous mainly post-tectonic granitic masses (Dallmeyeret al 1995 OrsquoBrien 2000 and references therein) It has been

Transactions of the Royal Society of Edinburgh Earth Sciences 95 141ndash159 2004

subdivided into a structurally lower mainly metasedimentaryamphibolite-facies Drosendorf Assemblage and an overlyinghigher-grade allochtonous Gfohl Assemblage (eg Matteet al 1990 Fiala et al 1995 Franke 2000)

The lower part of the Drosendorf Assemblage consists ofthe Monotonous Unit (Ostrong Unit) made up mainlyof cordieritendashbiotitendashsillimanite paragneisses which are partlymigmatitic and contain intercalations of orthogneisses andminor amphibolites The upper part termed the Varied (orVariegated) Unit consists of paragneisses orthogneissesamphibolites carbonate rocks calc-silicate gneisses quartzitesand graphite schists

The lower parts of the Gfohl Assemblage include mainlyanatectic orthogneisses (Gfohl gneiss) The higher are domi-nated by granulites associated with minor bodies of garnet

and spinel peridotites pyroxenites dunites and eclogites(Fuchs amp Matura 1976 Fiala et al 1995)

12 Granulite bodiesSeveral granulite massifs occur in the Waldviertel region ofLower Austria These are interpreted as the isolated klippenof an original regionally extensive nappe (Tollmann 1995)From SW to NE these are the Yspertal PochlarnndashWieselburgDunkelsteiner Wald St Leonhard and Blumau massifs (Fuchsamp Matura 1976 Fig 1) In the southern Czech Republic thegranulite bodies tend to be roughly oval-shaped and dome-like The largest is the Blansky les Massif (244 km) followedby Kristrsquoanov Prachatice Lisov Krasejovka and othernumerous small occurrences (Fig 1) In southwest Moravia

Figure 1 Geological sketch of the Moldanubian Zone in southern Bohemia south-western Moravia and LowerAustria (simplified from the Czech Geological Survey map 1500 000) The numbers of felsic granulite samplesfrom larger massifs (totalnew determinations) are shown

142 VOJTECH JANOUSEK ET AL

the most prominent are the Namestrsquo and Bory bodies (Fialaet al 1987a b)

13 PetrologyThe individual massifs consist of a heterogeneous blend ofhigh-pressure crustal and upper mantle rocks assembled andexhumed in course of the Variscan orogeny Felsic granuliteswith granitic compositions are by far the most abundant andoccur in all the main massifs accounting for more than75ndash80 vol (Fiala et al 1987a Vellmer 1992) In comparisonmaficndashintermediate pyroxene-bearing and sedimentary-derivedtypes are rather rare

The typical felsic granulites are characterised by the high-pressure assemblage of garnet kyanite quartz and hypersolvusfeldspar Rutile zircon apatite ilmenitemonazite are thecommon accessories (Fiala et al 1987a Carswell 1991 Vellmer1992 OrsquoBrien amp Rotzler 2003) The estimated peak metamor-phic conditions are 900ndash1050(C and 1middot5ndash2middot0 GPa (OrsquoBrien ampRotzler 2003 and references therein)

Following the high-pressure metamorphic peak the rockswere exhumed along a steep decompression path to mid-crustal levels and subjected to a medium-pressure overprint(0middot8ndash1middot2 GPa 800ndash900(C Cooke 2000) Further evolution wascharacterised by near isobaric cooling (0middot8ndash0middot5 GPa) variableretrogression of the original assemblages and intense deforma-tion reflecting the effects of stacking and subsequent exhuma-tion of the Moldanubian nappe pile (Carswell amp OrsquoBrien 1993Cooke 2000) These processes resulted in the breakdown ofsome garnet to a secondary biotite kyanite to sillimanite orgarnet with kyanite to hercynitendashplagioclase coronas (Owen ampDostal 1996 OrsquoBrien amp Rotzler 2003) Most of the granuliteswere mylonitised and recrystallised with pronounced folia-tions of platy quartz and fine K-feldsparndashplagioclase mosaicsRegional differences in the metamorphic style do exist insouthern Bohemia (eg Prachatice and Blansky les massifs)the effects of a low-P high-T overprint that led to thecrystallisation of cordierite and the formation of partial meltpatches can be observed (OrsquoBrien 2000)

14 Geochronology141 Carboniferous granulite-facies metamorphism subse-

quent cooling and uplift The numerous UndashPb zircon andmonazite ages clustering around 340 Ma are interpreted bymost authors as reflecting the granulite-facies metamorphicclimax (van Breemen et al 1982 Schenk amp Todt 1983 Kroneret al 1988 Aftalion et al 1989 Wendt et al 1994 Kroner et al2000 Friedl et al 2003 Kotkova et al 2003) In contrastRoberts amp Finger (1997) proposed that much of the zirconcould have crystallised only on a retrogression path Svojtkaet al (2002) concluded based on SmndashNd ages for garnet coreswith prograde zoning that the HPndashHT metamorphic peakmay have been even c 10ndash15 Ma older than the retrogradeevent

However it is worth noting that many of the dated zirconswere enclosed in high-pressure phases (garnet and formerhypersolvus feldspar Aftalion et al 1989 Kroner et al 2000)The metamorphic peak was probably short-lived as demon-strated by diffusion modelling of garnet zoning (Medaris et al1990 2003) The exhumation rate was high since the granulitepebbles already occur in Upper Visean conglomerates (severalmm year1 Vrana amp Novak 2000 Kotkova et al 2003)Rapid uplift and cooling is compatible with the fact thatzircons enclosed in late cordierite-bearing decompression meltpockets also gave ages of c 340 Ma (Kroner et al 2000)Taken together the age of the high-grade metamorphism isnot likely to differ substantially from 340 Ma

142 Pre-Carboniferous ages Devonian ages (c 360ndash370 Ma) were obtained from some prismatic zircons as well ascores of multifaceted metamorphic grains (Wendt et al 1994Kroner et al 2000) However the SHRIMP dating of Kroneret al (2000) and Friedl et al (2003 2004) revealed abundantoscillatory zoned zircon cores with concordant Ordovician(Fig 2) as well as less prominent older ages Friedl et al (20032004) assumed a c 450-Ma-old igneous protolith for theirsample from the Dunkelsteiner Wald

The early RbndashSr whole-rock dating of Austrian felsic granu-lites also yielded Ordovician ages (48611 and 45030 MaArnold amp Scharbert 1973 recalculated with the accepted decayconstants of Steiger amp Jager 1977) Similar whole-rock RbndashSrages (w470 Ma) were obtained for felsic granulites fromBlansky les (present work and A Arnold unpublished dataquoted by Kodym et al 1978) RbndashSr thin slab dating of theSt Leonhard Massif yielded a somewhat younger age of42816 Ma (Frank et al 1990) The significance of thesepre-Variscan ages will be addressed below

2 Whole-rock geochemistry

21 The databaseThe present authors have assembled a database in which newanalyses supplement critically selected literature data in orderto assess the overall whole-rock geochemical variability of theMoldanubian granulites Data management recalculationplotting and statistical evaluation were facilitated usingGCDkit (Janousek et al 2003a)

In this database over 20 new samples complemented 93previously published Austrian whole-rock analyses (Vellmer1992 Becker 1997 Becker et al 1999 Cooke 1999) Severalgranulite quarries show a striking alternation of darker andlighter bands sometimes tightly folded (Fig 3a b) Thebanding could have formed by the Variscan metamorphicsegregation or migmatisation Alternatively it may representolder pre-Variscan heterogeneities (enclaves dykes) flattenedand obscured by the strong deformation In order to verifythe presence of isotopic (dis-) equilibria sample pairs werecollected from adjacent darker (denoted by suffix D) andlighter (L) bands (Popp-DL Ost-DL and Ysp-DL)Petrographic sample descriptions are given in Appendix 1

The database includes 50 new and w180 old Czech whole-rock analyses (Kodym et al 1978 Slaby 1983 Cadkova et al1985 Strejcek 1986 Fiala et al 1987a Gurtlerova et al 1997)Peculiar K-feldsparndashgarnet perpotassic granulites documentedfrom a single small body within the Blansky les Massif (Vrana1989) were not considered Many of the new samples came

Figure 2 Histogram of frequencies for the 206Pb238U SHRIMPzircon ages from the Moldanubian granulites Data taken fromKroner et al (2000 five samples from Prachatice and twofrom Blansky les massifs) and Friedl et al (2004 sampleSt Dunkelsteiner Wald)

GRANULITES OF THE MOLDANUBIAN ZONE BOHEMIAN MASSIF 143

from the borehole H-1 drilled in the Blansky les Massif(Appendix 1)

As noted above caution should be taken to separate indi-vidual granulite groups with potentially distinct origin (Fialaet al 1987a) For instance the major-element binary plots donot follow simple patterns but are characterised by inflectionsor discontinuities at SiO2 w60 andor SiO2 w70 wt (Vellmer1992) The present paper focuses on a rather coherent group ofmost common felsic garnetkyanite granulites defined on thebasis of geochemical variation diagrams as having SiO2

gt70 wt In addition they needed to be devoid of ortho-pyroxene since the rare charnockitic types are suspected offorming a distinct geochemical and petrogenetic suite In totalsome 200 analyses of the felsic granulites were evaluated(Fig 1)

22 Major elementsAll Moldanubian granulites span a wide range of felsic(granitic) to mafic (gabbroic) compositions as shown by themulticationic diagram PndashQ (Debon amp Le Fort 1983 Fig 4) Itis worth stressing that the sampling is strongly biased towardsthe less-common basic types All the rocks are subalkaline anddefine a calc-alkaline trend in the Na2O+K2OndashFeOtndashMgOternary diagram (AFM Irvine amp Baragar 1971 Fig 5a) Asnoted already by Fiala et al (1987b) the granulites can be

characterised as medium- (mafic and transitional) to high-K(felsic) calc-alkaline rocks on the basis of the SiO2ndashK2O plot ofPeccerillo amp Taylor (1976) (Fig 5b)

The major-element composition of the felsic granulites isvery silicic (SiO2=74middot42middot3 wt median1 Table 1)slightly peraluminous (ACNK=1middot110middot08) K-rich (K2ONa2O=1middot540middot37) and with Fe prevailing strongly over Mg(FeOt=1middot940middot71 wt MgO=0middot470middot35 wt mg w30)At given SiO2 contents CaO (1middot030middot48 wt) is rather highwhile Al2O3 is low (13middot280middot91 wt) The Harker variationdiagrams (Fig 6) show strong negative correlations of SiO2

with TiO2 Al2O3 FeOt MgO CaO and mg In contrastalkalis and the alumina saturation index (ACNK not shown)are scattered potentially implying some metamorphicmobility

23 Trace elements231 LILE All the Moldanubian granulites including the

mafic types have typical crustal KRb ratios (ie betweenc 120 and 500 Shaw 1968 Rudnick et al 1985) (Fig 7aTable 1) and thus are not significantly depleted in Rb (seealso Fiala et al 1987a b Vellmer 1992) The felsic types showwide range of Rb contents (28ndash362 ppm 16459 ppm)and RbSr ratios (0middot5ndash16middot5 median=2middot9) The SiO2ndashRb plot ischaracterised by a scattered positive trend (Fig 6) The RbCs

Figure 3 (a) Folded distinctly banded felsic granulite Yspertal quarry (b) Detail of the hand specimen of a felsicgranulite with dark bands rich in biotite and strong mylonitic fabric Plesovice quarry Blansky les Massif(c) Photomicrograph of felsic granulite Popp-L (Krug St Leonhard Massif) Garnet porphyroclasts are set in afine-grained feldsparndashquartz matrix Plain polarised light (d) Photomicrograph of dark facies of the samplefrom Osterberg PochlarnndashWieselburg (Ost-D) A large garnet porphyroclast encloses a subhedral grain ofmesoperthite The strongly recrystallised feldsparndashquartz matrix contains streaks of biotite Plain polarised light


ratios for the felsic granulites (11ndash1100 median=122) arehigher than the average continental crust (RbCs=30 Tayloramp McLennan 1985 or even 23 Wedepohl 1995) Strontiumand in particular Ba vary over a wide range Both show goodcovariation and sharp decrease with increasing silica (Figs 6 amp7 bndashc)

232 U and Th While many of the felsic Moldanubiangranulites have ThU (0middot2ndash39 median=3middot1) corresponding tonormal igneous rocks (Rudnick amp Presper 1990) a significantoverall depletion of both elements exists (Fiala et al 1987a)down to less than 0middot05 times the concentration of averageupper crust (Taylor amp McLennan 1985)

233 REE Chondrite-normalised REE plots resembletypical patterns of fractionated granitic rocks showing mod-erate to weak enrichment in LREE (CeNYbN=1middot5ndash7middot2 CeNSmN=1middot3ndash3middot4 Fig 8) and negative Eu anomalies (EuEu=0middot14ndash0middot62 Eu=SmNGdN) the magnitude of whichincreases with increasing silica (see also Vellmer 1992 Jakes1997) There is a sharp decrease in LREE and MREE contentswith increasing SiO2 while the HREE contents remain rela-tively constant (Figs 6 amp 8) Such variation is a commonfeature in felsic granitic magmas which have undergone frac-tional crystallisation particularly at monazite saturation(Miller amp Mittlefehldt 1982 1984 Ayres amp Harris 1997) Giventhe siliceous and slightly peraluminous nature of the studiedrocks the presence of monazite as a main LREE carrier islikely (Watt amp Harley 1993 Broska et al 2000) If one assumes

that the whole-rock compositions correspond to those ofmonazite-saturated melt the calculated crystallisation tem-peratures (Montel 1993) would be close to 750(C (Fig 9a)

234 Zr Zirconium concentrations in the felsic granu-lites are generally low (8650 ppm) These decrease withincreasing SiO2 to less than 50 ppm (Fig 6) which iscompatible with zircon fractionation The zircon saturationtemperatures (Watson amp Harrison 1983) of 74048(C arecomparable to those obtained from the monazite saturationmodel (Fig 9b)

235 Spiderplots Spiderplots for the felsic granulites(Fig 10a) normalised to the average upper crust are charac-terised by conspicuous troughs in Nb Sr Hf Zr and Ti Asimilar feature is also seen for U and Th in most cases Someelements tend to be variously depleted starting with apparentcrustal values (eg Ba P and Nd) Rubidium and K seem to bein the range of the upper crust (if not somewhat higher)together with HREE and Y In contrast the LREE tend to beslightly lower than upper crustal values With notable excep-tion of U and Th the patterns resemble those of felsic granitesvariably modified by fractional crystallisation

Figure 4 Frequency plots of Moldanubian granulites in the multi-cationic diagram PndashQ (Debon amp Le Fort 1983) P represents theproportion of K-feldspar to plagioclase and Q the quartz contentPlotting symbols represent individual granulite massifs Filled lettersstand for felsic granulite (FG) samples dealt with in detail in the textThe frequency of all available analyses is expressed by various shadesof grey

Figure 5 (a) AFM diagram (A=Na2O+K2O F=FeOt M=MgOIrvine amp Baragar 1971) illustrating the calc-alkaline trend shown bythe Moldanubian granulites (b) SiO2ndashK2O plot with the discrimi-nation boundaries between the tholeiitic calc-alkaline high-K calc-alkaline and shoshonitic rocks after Peccerillo amp Taylor (1976)Symbols as in Figure 4


Table 1 Selected whole-rock geochemical data for the (mostly felsic) Moldanubian granulites

Popp-D Popp-L Ost-D Ost-L St Du Ysp-D Ysp-L 1059 1062 1064 1074 1076 1078

Locality 1 1 2 2 3 4 5 5 1146 1178 1312 1372 1381 1405 mMassifdagger StL StL PW PW DW DW Yt Yt BL BL BL BL BL BL

SiO2 71middot69 74middot82 63middot90 77middot55 76middot94 70middot14 76middot03 75middot84 70middot43 73middot87 75middot54 76middot54 76middot02 70middot78TiO2 0middot47 0middot21 0middot78 0middot09 0middot12 0middot50 0middot20 0middot15 0middot35 0middot27 0middot12 0middot07 0middot08 0middot32Al2O3 14middot53 12middot95 17middot89 11middot90 12middot30 13middot97 12middot66 12middot36 14middot36 13middot53 12middot58 12middot10 12middot16 13middot92FeOt 2middot95 1middot72 3middot66 1middot52 1middot66 4middot05 1middot84 1middot64 4middot01 2middot22 1middot72 1middot56 1middot54 2middot79MnO 0middot05 0middot04 0middot03 0middot04 0middot04 0middot07 0middot05 0middot03 0middot05 0middot03 0middot02 0middot03 0middot02 0middot04MgO 0middot83 0middot51 2middot82 0middot17 0middot21 0middot94 0middot40 0middot24 1middot54 0middot55 0middot58 0middot28 0middot31 0middot93CaO 1middot63 0middot84 3middot02 0middot69 0middot73 3middot22 0middot82 0middot67 2middot50 1middot69 1middot41 0middot78 0middot95 1middot68Na2O 3middot12 2middot37 5middot20 3middot49 3middot20 3middot69 2middot95 3middot16 3middot94 3middot64 4middot21 2middot66 2middot78 3middot34K2O 4middot65 5middot40 2middot74 3middot82 4middot32 2middot85 4middot45 4middot98 2middot36 4middot06 3middot13 4middot85 4middot94 4middot31P2O5 0middot18 0middot16 0middot21 0middot10 0middot15 0middot12 0middot16 0middot14 0middot08 0middot07 0middot03 0middot13 0middot15 0middot18H2O+LOI 0middot57Dagger 0middot20Dagger 0middot51Dagger 0middot22Dagger 0middot44Dagger 0middot27Dagger 0middot49Dagger 0middot30Dagger 0middot27 0middot08 0middot27 0middot12 0middot14 0middot64F ndash ndash ndash ndash ndash ndash ndash ndash 0middot05 0middot03 0middot06 0middot05 0middot04 0middot03

Total 100middot67 99middot22 100middot76 99middot59 100middot11 99middot82 100middot05 99middot51 99middot94 100middot04 99middot67 99middot17 99middot13 98middot96

mg 33middot4 34middot6 57middot9 16middot6 18middot4 29middot3 27middot9 20middot7 40middot7 30middot7 37middot6 24middot3 26middot4 37middot3ACNK 1middot11 1middot15 1middot05 1middot07 1middot09 0middot93 1middot13 1middot05 1middot06 1middot01 0middot98 1middot10 1middot04 1middot05K2ONa2O 1middot49 2middot28 0middot53 1middot09 1middot35 0middot77 1middot51 1middot58 0middot60 1middot12 0middot74 1middot82 1middot78 1middot29

(ppm)Rb 145 168 201 331 288 48 220 180 66 126 92 241 216 153Sr 96 73 158 35 34 71 61 58 79 70 73 35 46 108Ba 612 398 402 58 139 565 371 357 496 601 476 114 190 586Nb 7middot5 4middot9 11middot1 bd 4middot8 4middot3 6middot3 4middot1 7middot4 5middot1 2middot9 bd 3middot3 8middot9Zr 115 105 120 16 38 108 102 74 135 112 29 50 66 106Hf 3middot8 1middot5 2middot4 bd 2middot1 2middot1 2middot7 1middot0 2middot1 1middot7 0middot9 bd 0middot6 1middot7Ga 19 18 26 20 18 18 18 17 19 17 18 17 16 19Th 2middot1 2middot8 bd 2middot6 3middot7 bd 3middot2 bd 5middot0 3middot8 bd 3middot4 2middot4 5middot6U 2middot2 2middot9 bd 2middot3 2middot7 bd 5middot2 3middot0 3middot8 1middot6 1middot0 3middot0 2middot2 2middot7Cr 41 61 120 11 11 75 22 18 ndash ndash ndash ndash ndash ndashCo 5middot9 2middot4 7middot1 1middot2 2middot2 13middot5 4middot6 2middot7 10middot7 4middot8 5middot4 3middot4 3middot4 6middot8Pb 1middot3 6middot7 bd bd 4middot1 bd 5middot5 4middot7 bd 0middot9 4middot4 4middot3 7middot2 4middot3Zn 48 23 24 15 17 59 37 26 59middot8 27middot6 28middot2 22middot5 23middot4 43middot3La 32middot2 22middot0 22middot0 9middot0 11middot6 37middot0 17middot4 14middot1 21middot1 13middot5 ndash 9middot4 12middot1 24middot1Ce 69middot3 50middot4 48middot6 19middot3 27middot0 74middot6 40middot0 32middot1 47middot0 39middot4 ndash 23middot6 30middot5 56middot0Pr ndash ndash ndash ndash ndash ndash ndash ndash 6middot02 4middot86 ndash 2middot38 3middot82 6middot67Nd 28middot9 19middot2 22middot7 6middot3 11middot5 29middot2 17middot4 13middot3 24middot2 20middot8 ndash 10middot6 14middot2 26middot8Sm 6middot67 4middot42 5middot51 1middot61 3middot05 5middot35 4middot16 3middot48 5middot05 4middot72 ndash 2middot67 3middot41 5middot67Eu 0middot91 0middot42 0middot93 0middot09 0middot17 1middot00 0middot34 0middot23 0middot89 0middot54 ndash 0middot25 0middot38 0middot89Gd 7middot30 4middot72 5middot35 2middot28 3middot58 4middot88 4middot30 3middot70 5middot43 5middot93 ndash 3middot15 3middot92 6middot38Tb ndash ndash ndash ndash ndash ndash ndash ndash 1middot2 1middot2 ndash 0middot83 0middot96 1middot24Dy 7middot93 6middot07 5middot68 4middot38 5middot76 3middot71 6middot06 6middot00 5middot5 7middot84 ndash 5middot47 6middot73 7middot51Ho ndash ndash ndash ndash ndash ndash ndash ndash 0middot99 1middot73 ndash 1middot15 1middot50 1middot45Er 4middot43 3middot92 3middot47 3middot25 3middot51 1middot98 3middot8 3middot81 3middot53 5middot54 ndash 4middot07 4middot92 4middot35Tm ndash ndash ndash ndash ndash ndash ndash ndash 0middot33 0middot55 ndash 0middot52 0middot60 0middot49Yb 4middot21 4middot06 3middot94 3middot82 3middot78 1middot89 3middot97 4middot12 3middot25 4middot84 ndash 4middot11 4middot57 3middot31Lu 0middot62 0middot57 0middot60 0middot52 0middot49 0middot28 0middot52 0middot56 0middot5 0middot7 ndash 0middot58 0middot65 0middot44Y 45middot8 38middot7 34middot7 30middot3 35middot6 19middot9 36middot8 38middot0 34middot1 50middot2 11middot2 36middot2 44middot9 48middot6

EuEu 0middot40 0middot28 0middot52 0middot14 0middot16 0middot60 0middot25 0middot20 0middot52 0middot31 ndash 0middot26 0middot32 0middot45CeNYbN 4middot3 3middot2 3middot2 1middot3 1middot9 10middot2 2middot6 2middot0 3middot7 2middot1 ndash 1middot5 1middot7 4middot4CeNSmN 2middot5 2middot8 2middot1 2middot9 2middot1 3middot4 2middot3 2middot2 2middot2 2middot0 ndash 2middot1 2middot2 2middot4

KRb 265middot5 266middot5 113middot3 95middot9 124middot4 490middot8 167middot6 229middot3 299middot1 266middot9 284middot0 167middot0 189middot9 233middot4RbSr 1middot5 2middot3 1middot3 9middot5 3middot6 8middot5 3middot1 0middot7 0middot8 1middot8 1middot3 7middot0 4middot7 1middot4

Localities (1) Naturstein Popp Krug (2) Osterberg (3) Steinaweg (4) Lindwurmkreuz (5) Gleisen The rest Holubov borehole H-1 (with depthindicated) Mafic sample CharnockitedaggerMassifs (Fig 1) (StL) St Leonhard (PW) PochlarnndashWieselburg (DW) Dunkelsteiner Wald (Yt) Yspertal (BL) Blansky les Dagger Loss on ignition(bd) below detection limit (ndash) not determined


24 Radiogenic isotopes241 Neodymium The 340

Nd values for the felsic granulitesare distinctly negative (4middot2 to 7middot5 median=6middot1 Table 2amp Fig 11a) This is reflected by rather high mean crustal

residence ages (TDMNd two-stage depleted-mantle Nd model

ages Liew amp Hofmann 1988) of 1middot39ndash1middot64 Ga (Fig 11a)which corresponds to derivation from mature continentalcrust The systematic shift in Nd isotopic compositions

Figure 6 Binary plots of SiO2 versus major-element oxides (wt) mg and selected trace elements (ppm) forfelsic Moldanubian granulites from Austria (filled symbols) and the Czech Republic (empty symbols)

Figure 7 (a) Rb (ppm) versus K (wt) diagram for all the Moldanubian granulites Symbols as in Figure 4FG felsic granulites Depletion trend for granulites with KRb gt 500 is taken from Jahn (1990) (b) Sr versus Baand (c) Sr versus Rb plots (ppm) for the felsic granulites from Austria (filled symbols) and Czech Republic(empty symbols) Labelled vectors correspond to up to 50 fractional crystallisation of the main rock-formingminerals Trace-element distribution coefficients are from Hanson (1978 Kfs Amp Rb in Pl) Icenhower ampLondon (1995 Bt and Ms) and Blundy amp Shimizu (1991 Sr in Pl assuming 750(C An15 and An50)


between adjacent lighter (more negative 340Nd) and darker facies

(less negative 340Nd) of the samples Popp (7middot06middot1) and Ost

(7middot55middot7) rules out closed-system differentiation during theVariscan metamorphism Small-scale isotopic disequilibriumwas also evidenced by previous SmndashNd (and UndashPb) garnetndashwhole-rock ages which show considerable scatter (470 tolt330 Ma Janousek et al 1996 Becker 1997 Chen et al 1998Prince et al 2000) Conversely granulites Ysp-D and Ysp-Lhave nearly the same 340

Nd values (6middot26middot4) in accordancewith their mutually comparable major- and trace-elementcompositions

242 Strontium The newly measured Sr isotopic ratiosshow pronounced variations (87Sr86Sr340 w0middot711ndash0middot770Fig 11b) The ratios demonstrate strong isotopic dis-equilibrium between adjacent lighter and darker samples Popp(0middot7300middot719) Ost (0middot7530middot715) and Ysp (0middot7710middot738) at340 Ma (Fig 11b)

If one assumes an initial equilibrium state the individualpairs would all give Early Palaeozoic ages in line with theresults of the previous RbndashSr dating (Arnold amp Scharbert1973 Frank et al 1990) Similarly the Blansky les granulitesdefine an Ordovician isochron (4698 Ma 2 87Sr86Sri

w0middot706 Fig 12a) Sample 1078 which is not included in theregression could have been derived along with 1076 from a

Figure 8 Chondrite-normalised plot for REE in felsic granulites Thisnew diagram (lsquospider boxplotrsquo) represents a combination of the morecommon chondrite-normalised REE plot with box and whiskers plots(boxplots) For each element the box represents 50 of the population(being delimited by two quartiles) the horizontal line inside is themedian and the lsquowhiskersrsquo show the total range without outliers(denoted by small circles) The solid black arrows indicate trends withrising silica if applicable Normalisation values are from Boynton(1984)

Figure 9 Monazite and zircon saturation calculations for felsic Mold-anubian granulites (a) Boxplot of monazite saturation temperatures(Montel 1993) (b) Boxplot of zircon saturation temperatures (Watsonamp Harrison 1983) (c) Binary plot of M=100 (Na+K+2Ca)AlSiversus Zr (ppm) for the felsic granulites (see Fig 4 for legend)Boxplots at the axes portray the statistical distribution of bothparameters The isotherms of Zr saturation levels were calculatedusing the model of Watson amp Harrison (1983) The arrows indicate theeffects of increasing zircon inheritance and (hypothetical) alkali lossboth of which would produce slight temperature overestimates

Figure 10 Average upper crust normalised (Taylor amp McLennan1985) lsquospider boxplotsrsquo for felsic granulites (a) and acid metaigneousrocks from Fichtelgebirge (SiO2 gt70 Siebel et al 1997) (b) In thelatter plot stars denote three samples of Gfohl gneiss given by Vellmer(1992) An identical field corresponding to 50 of the felsic granulitesis outlined in both diagrams The solid black arrows indicate trendswith increasing SiO2


domain with a somewhat higher 87Sr86Sri (w0middot709 Fig 12a)Alternatively it may have been partly influenced by the nearbyVariscan granitic dykes (Appendix 1) Nevertheless the boot-strap spectrum for all the samples seems to confirm theOrdovician age (Fig 12b)

Five thin-slab and one whole-rock RbndashSr isotopic analysesfrom the St Leonhard Massif were re-evaluated for compari-son (Frank et al 1990 without feldspar fraction and sample 1rejected by the original authors because of substantial alter-ation M Thoni pers comm 2004) The age obtained(42519 Ma MSWD=5middot8) seems to be distinctly youngerthan that for the Blansky les set Again the bootstrap spec-trum (Fig 12c) despite skewness shows no ages lower than400 Ma and the w430 Ma maximum remains rather welldefined

Furthermore on the 87Sr86Sr340ndash340Nd plot (Fig 11c) the

granulites from the Czech Republic and Austria form broadly

subparallel partly overlapping fields They run diagonallyfrom less to more radiogenic SrndashNd isotopic compositionsreaching 87Sr86Sr340 values gt0middot77 which are clearly above theinitial ratios typical of common granitic rocks The easiestexplanation is that the data are not sufficiently age-correctedand that isotopic equilibrium during the Variscan was notattained This agrees with the fact that the 340

Nd values becomeless negative with increasing silica along with the SmNdratios

The significance of the individual RbndashSr whole-rock agesshould not be overrated since the system is known to beprone to resetting by metamorphism Nonetheless it is clearthat most of the Sr isotopic ratios of the felsic granuliteswhen corrected to Early Palaeozoic ages (see also Fig 2)would yield 87Sr86Sri isotopic ratios expected for normalslightly-peraluminous crustally-derived granites (Fig 11bTable 2)

Table 2 Selected whole-rock SrndashNd isotopic data for the (mostly felsic) Moldanubian granulites

Popp-D Popp-L Ost-D Ost-L St Du Ysp-D Ysp-LLaboratorydagger CNRS CNRS CNRS CNRS CNRS CNRS CNRS CNRS

Rb (ppm) 162 209 212 288 260 72 249 284Sr (ppm) 97 65 137 37 34 99 43 3087Rb86Sr 4middot85 9middot36 4middot49 22middot9 22middot5 2middot11 16middot9 27middot987Sr86Sr 0middot74240 0middot77558 0middot73679 0middot86389 0middot86499 0middot72075 0middot81994 0middot905742 se 3 3 3 3 3 3 3 387Sr86Sr340 0middot71893 0middot73026 0middot71506 0middot75322 0middot75625 0middot71055 0middot73796 0middot77059Sm (ppm) 7middot64 5middot53 5middot6 1middot88 3middot29 6middot34 4middot59 3middot53Nd (ppm) 34middot0 23middot8 24middot8 7middot03 12middot1 35middot2 18middot5 13middot6147Sm144Nd 0middot1358 0middot1402 0middot1363 0middot1617 0middot1640 0middot1090 0middot1501 0middot1571143Nd144Nd 0middot512142 0middot512200 0middot512119 0middot512266 0middot512291 0middot512073 0middot512218 0middot5122242 se 7 7 11 8 9 8 8 11143Nd144Nd340 0middot511840 0middot511888 0middot511816 0middot511906 0middot511926 0middot511830 0middot511884 0middot511874340

Nd 7middot0 6middot1 7middot5 5middot7 5middot4 7middot2 6middot2 6middot4T Nd

DM (Ga) 1middot60 1middot53 1middot64 1middot50 1middot47 1middot62 1middot54 1middot5587Sr86Sr470 0middot70993 0middot71287 0middot70672 0middot71076 0middot71453 0middot70664 0middot70651 0middot71875470

Nd 6middot0 5middot2 6middot5 5middot2 4middot8 5middot8 5middot4 5middot7

1059 1062 1064 1074 1076 1078Laboratorydagger CGS CGS CGS CGS CGS CGS

Rb (ppm) 72 134 99 254 230 158Sr (ppm) 72 63 66 26 39 10287Rb86Sr 2middot65 5middot84 4middot04 26middot4 16middot1 4middot3087Sr86Sr 0middot72398 0middot74516 0middot73349 0middot8784 0middot81717 0middot738022 se 20 5 8 11 8 887Sr86Sr340 0middot71117 0middot71691 0middot713932 0middot75045 0middot73926 0middot71722Sm (ppm) 6middot7 5middot1 0middot7 2middot8 4middot7 4middot3Nd (ppm) 33middot0 20middot9 2middot20 10middot0 20middot8 19middot1147Sm144Nd 0middot1227 0middot1475 0middot19235 0middot1693 0middot1366 0middot1361143Nd144Nd 0middot512087 0middot512206 0middot512335 0middot512301 0middot512277 0middot5121992 se 21 14 40 19 15 19143Nd144Nd340 0middot511814 0middot511878 0middot511907 0middot511924 0middot511973 0middot511896340

Nd 7middot5 6middot3 5middot7 5middot4 4middot4 5middot9T Nd

DM (Ga) 1middot64 1middot55 1middot50 1middot48 1middot4 1middot5287Sr86Sr470 0middot70626 0middot70607 0middot70643 0middot70137 0middot70936 0middot70924470

Nd 6middot3 5middot5 5middot7 4middot9 3middot4 4middot9

Subscripts indicate the age to which were isotopic ratios corrected 340 Ma (granulite-facies metamorphism Kroner et al 2000 and referencestherein) and 470 Ma (estimated protolith age) i

Nd values were calculated using the Bulk Earth parameters given by Jacobsen amp Wasserburg (1980)T Nd

DM are two-stage Nd model ages based on Liew amp Hofmann (1988) Mafic sample (SiO2=63middot90 wt see Table 1) CharnockitedaggerCNRS Universite Blaise Pascal Clermont-Ferrand analytical techniques described by Pin et al (1990) and Roberts et al (2000) CGS CzechGeological Survey PraguendashBarrandov Sm and Nd concentrations determined by isotope dilution Rb and Sr by XRF (Harvey amp Atkin 1981)Isotopic ratios were measured in static mode on a Finnigan MAT 262 spectrometer in the CGS In both laboratories the 143Nd144Nd ratios werecorrected for mass fractionation by normalisation to 146Nd144Nd=0middot7219 while 87Sr86Sr ratios were normalised to 86Sr88Sr=0middot1194


3 Discussion

31 Pre-Variscan metagranites or Variscan high-PmeltsThe CIPW-normative compositions of the felsic granulites fallclose to a low-pressure minimum in the AbndashQzndashOr ternarydiagram (Fiala et al 1987a Vrana 1989 Kotkova amp Harley1999) and this demonstrates that they represent magmacompositions with little cumulate or restite component

Indeed most of the authors agreed that they were granitic orrhyolitic magmas at some stage of their evolution (Fiala 1987ab Carswell 1991 Vellmer 1992 Jakes 1997 Kotkova amp Harley1999) Even though there is near consensus on igneous heritageof the felsic Moldanubian granulites it is important to discusswhether (a) the bulk formed and segregated as high-pressuremelts during Variscan subduction (Kotkova amp Harley 1999)or (b) they are merely Early Palaeozoic granites which werenearly isochemically metamorphosed during the Variscan col-lision undergoing no or a negligible degree of partial melting

In the present authorsrsquo view there are several reasons whythe latter model is more realistic

311 Preservation of the pre-Carboniferous RbndashSr whole-rock ages As shown by the variation in the 87Sr86Sr340 ratiosand the preserved OrdovicianSilurian isochron ages thewhole-rock RbndashSr system failed to re-equilibrate even on alocal scale during the Variscan high-grade metamorphismThis leaves little scope for models which interpret the rocks assegregated Variscan granites and indicates that any granulite-facies partial melting did not lead to larger-scale chemicalequilibrium Given the correspondence of the RbndashSr system-atics with the SHRIMP ages for many inherited zircon cores

Figure 11 (a) Two-stage Nd development diagram for the felsic(except for Ost-D) Moldanubian granulites DM=Depleted Mantleevolution lines after Goldstein et al (1984) and Liew amp Hofmann(1988) (b) Strontium isotopic plot UR=Uniform (chondritic) Reser-voir evolution line after Faure (1986) (c) Diagram of (87Sr86Sr)340

versus 340Nd for felsic granulites Tie lines join adjacent sample pairs

from banded granulites (L=lighter D=darker) The plot also includesdata from Vellmer (1992) Valbracht et al (1994) and Becker et al(1999) new analyses are labelled by sample names

Figure 12 (a) Improved isochron diagram (Provost 1990) for RbndashSrisotopic compositions of felsic granulites from the Blansky les Massif(this work and sample 36 of Valbracht et al 1994) (b) Bootstrapspectrum (Diaconis amp Efron 1983 Kalsbeek amp Hansen 1989) obtainedon the basis of 5000 randomly chosen data sets for seven points fromFigure 12a (ie including 1078) (c) Bootstrap spectrum for six RbndashSrisotopic analyses from the St Leonhard Massif (Frank et al 1990feldspar fraction and sample 1 were omitted) The individual ages inboth cases were calculated using the algorithm of York (1969) and theunpublished programme BTRAP


the RbndashSr isotopes seem to have largely maintained memoryof an older igneous protolith The preservation of pre-metamorphic Sr isotopic signatures in high-grade meta-igneous rocks is by no means rare (eg Hradetzky amp Lippolt1993 Kuhn et al 2000) It could have been facilitated by therarity of hydrous fluids or melt immobility and isolationduring the HPndashHT stage coupled with a presumably shortduration of the metamorphic peak

312 Zircon and monazite saturation temperatures If thefelsic granulites represent Variscan hot restite-poor high-PTmelts then they should have acquired Zr contents several timeshigher than observed (Fig 9c) To invoke dramatic Zr-undersaturation (Kotkova amp Harley 1999) seems unrealisticbecause all felsic Moldanubian granulites contain abundantpre-Variscan mainly Ordovician zircon relics (Poschl-Otrel1995 Kroner et al 2000 Friedl et al 2003 2004) For such lowZr concentrations the saturation temperatures tend to berobust to changes in both the bulk magma composition anderrors in the Zr determinations (Fig 9c see also Miller et al2003)

The fact that older zircon grains are usually overgrown byVariscan shells interpreted as having crystallised from meltunder granulite-facies conditions (Roberts amp Finger 1997Friedl et al 2003) rules out the possibility that the inheritanceis merely a result of shielding by restitic minerals Thus anypartial melting during the Variscan high-grade metamorphismmust have been volumetrically limited since considerably morerestitic zircons should have dissolved otherwise

Conversely the observed strong negative SiO2ndashZr correla-tion (Fig 6) seems to be indicative of zircon saturation incourse of the melt fractionation (Chappell et al 1998Hoskin et al 2000) As shown by the zircon saturationcalculations this must have been at temperatures much lowerthan 900ndash1000(C and thus most likely a feature of theprotolith stage As the volume proportion of pre-Ordoviciancores is rather limited (Kroner et al 2000 Friedl et al 20032004) the equivalent zircon and monazite saturation tem-peratures (w750(C) can be interpreted as a rough estimateof the crystallisation temperatures of the Early Palaeozoicprotolith

313 The HREE and Y signature If the felsic granuliteswere essentially restite-depleted HP melts then restite wouldinevitably be rich in garnet and kyanite In such case asignificant HREE+Y depletion should be observed in thegranulite samples but this does not seem to be the case(Figs 8 amp 10) The data of Kotkova amp Harley (1999) indicat-ing that the granulite garnets typically show a decrease ofgarnet-compatible elements (HREE+Y) from core to rim areindeed compatible with a Rayleigh-type fractionation duringthe crystal growth However this observation does not con-strain the proportion of the melt involved (Otamendi et al2002)

32 Nature and origin of the igneous protolith to theMoldanubian granulites

321 Granite typology The protolith to the Moldanubiangranulites has probably corresponded to low-temperaturegranites (Miller et al 2003) The geochemical characteristicsresemble fractionated I-type granite suites as defined in theLachlan Fold Belt in eastern Australia The similarities includehigh concentrations of Y and HREE at low-to-moderate Zr astrongly negative Eu anomaly increasing with SiO2 andgenerally low P2O5 contents (Chappell amp White 1992 Chappell1999) Compared to A-types the FeMg ratios and HFSEcontents (Zr+Nb+Ce+Yw20060 ppm) of the granulitesare too low (cf Whalen et al 1987 Eby 1990) The low Nbcontents (mostly lt10) of the granulites are a typical feature for

granites derived from rather primitive arc-type crustal sources(Pearce et al 1984)

322 Possible source With the assumption of granulitesamples at SiO2 w70 wt to approximate the leastdifferentiated granitic melts this indicates relative paucity inRb (Rb[70] w100 ppm superscript=approximate silica con-tents by weight) and Sr (w100 ppm RbSr[70] w1) togetherwith a high Ba content (600ndash800 ppm)

The whole-rock geochemical character (ACNK w1middot1K2ONa2O w1middot5 high Ba low Rb strongly negative 470

Nd atrelatively unevolved 87Sr86Sr470) argues for a partial meltingof a quartzondashfeldspathic source (orthogneiss or greywackeBarbarin 1996 and references therein) fairly immature interms of its major- and trace-element composition and withrelatively low time-integrated SmNd and RbSr ratios Inaddition metapelitic parentage may be ruled on the basis ofthe high CaONa2O[70] ratios (w0middot6ndash0middot8) fairly low Al2O3TiO2

[70] (w25ndash40) RbBa[70] (w0middot1ndash0middot3) and RbSr[70] (w1)(Sylvester 1998) Apart from low RbSr ratios any significantrole for muscovite dehydration melting can be discountedbased on low SrBa[70]=0middot1ndash0middot2 (Harris amp Inger 1992)

The distinction between melts produced from meta-psammitic parents and derived by anatexis of K-rich ortho-gneisses respectively remains fairly difficult using geochemicalcharacteristics (eg Barbarin 1996 Sylvester 1998)

323 Magmatic evolution Increasing Rb and decreasing Baand Sr with increasing SiO2 of the Moldanubian granulites(Figs 7b c) are best explained by fractional crystallisation andare inconsistent with partial-melting models Mass-balancecalculations (Janousek et al 1997) indicate that unreasonablyhigh degrees of partial melting (Z80) would be required toyield a comparably broad compositional range of partial melts

An origin by large-scale fractionation of more mafic(dioriticndashtonalitic) parents is unlikely given the generallycrustal-like Sr and Nd isotopic compositions of the felsicgranulites Indeed the much rarer more mafic types havenoticeably more primitive isotope compositions (Becker 1997Janousek et al 2003b) In addition mafic granulite types arefairly subordinate at the present surface level

The trends seem to be compatible with fractional crystallis-ation involving K-feldspargtplagioclase from rather siliceous(SiO2 w70 wt) magma Some role for biotiteaccessoryoxide minerals (ilmenite) is apparent in view of falling MgOFeOt (Fig 6) Nb and Zn contents (not shown) The drop in Zrand LREE can be accounted for by zircon and monazitefractionation respectively (Fig 6) The negative correlation ofSr Ba Zr LREE and EuEu with the SiO2 along withenrichment in Rb are considered to be characteristic ofevolved acid igneous rocks crystallising feldspar zircon andmonazite dominated assemblages (Miller amp Mittlefehldt 1984Chappell amp White 1992 Hoskin et al 2000)

33 Geological correlationIt follows from the above that a specific felsic igneous suite ofEarly Palaeozoic age should have been an important con-stituent of the subducted Gfohl terrane In support of this theassociated Gfohl orthogneisses (eg Dudek et al 1974 Cookeamp OrsquoBrien 2001) also show Ordovician protolith ages (Friedlet al 2004) and whole-rock geochemical characteristicsstrongly resembling the felsic granulites (Fig 10b Vellmer1992)

Geochemically similar felsic meta-igneous rocks can befound in the Saxothuringian Zone for example orthogneissesin the OrlicandashSunieznik dome in Poland (Franke amp Z~elazniewicz2000 Turniak et al 2000 Brocker et al 2003) or metagranitesand metarhyolites in the Fichtelgebirge in Germany (Siebelet al 1997 Wiegand 1997) Regrettably detailed comparisons


are hampered by a lack of reliable and sufficiently largewhole-rock geochemical datasets

Of the available data the best characterised seem to be themeta-igneous rocks from the Fichtelgebirge (Siebel et al 1997Wiegand 1997) As follows from Figure 10b their analyseswith SiO2 gt70 match well the overall compositionalspectrum for the felsic granulites in most of the elements saveU and Th Unfortunately there is a dearth of data on Cscontents the median of four samples analysed by Wiegand(1997) was 4middot8 ppm ie slightly lower than the upper crustalaverage of 5middot8 ppm (Wedepohl 1995) The most reliabledata from felsic granulites (Vellmer 1992 Becker et al1999) seem to show that these are markedly Cs-impoverished(0middot1ndash2middot1 ppm median=0middot9)

The meta-igneous rocks from Fichtelgebirge were dated at455ndash480 Ma (Siebel et al 1997 Wiegand 1997 and referencestherein) which falls within the spectrum of inherited agesobserved in the granulites Despite considerable disturbance ofthe RbndashSr isotopic system in many of the Fichtelgebirgesamples some still yield Ordovician ages and initial ratios(Siebel et al 1997) comparing favourably with the mean of thefelsic granulites at that time (w0middot709) Moreover the 480

Ndvalues (orthogneisses 3middot50middot4 metarhyolites 4middot81middot1)also match the mean 480

Nd (4middot91middot9) for the felsic granulitesand overlap with the data for the Gfohl gneiss (4middot4 to 6middot1Vellmer 1992)

34 Geochemical changes during the granulite-faciesmetamorphismMost of the felsic Moldanubian granulites show undepletedLILE contents Unlike in many other granulite terrains aroundthe world (Rudnick et al 1985 Rudnick amp Presper 1990)prograde metamorphism appears to have occurred largelyisochemically This implies that high-pressure melting in felsicgranulites was widely suppressed and small-fraction partialmelts were (mostly) incapable of segregating from theirsource

Nevertheless a chemical feature that needs explanation isthe distinct U Th and Cs depletion compared to the averageupper crust or the otherwise geochemically similar Saxothur-ingian meta-igneous rocks As proposed already by Fiala et al(1987a b) and Vellmer (1992) these elements could have beenstripped out by fluid or small-scale melt during the high-pressure metamorphism The strong Cs impoverishment(Vellmer 1992 Becker et al 1999) is a well-known feature ofmany granulite-facies terrains (Rudnick amp Taylor 1987Rudnick amp Presper 1990) This effect has been ascribed to thefractionation between K-feldspar and meltfluid (Rudnick ampPresper 1990 Hart amp Reid 1991 Morgan amp London 2003)

Minor fluid or melt loss is compatible with the preservationof the nearly pristine high-pressure mineralogy (garnet+kyanite+rutile) in many granulites Otherwise as argued byPowell amp Downes (1990) Clemens amp Droop (1998) Brown(2002) and White amp Powell (2002) the retention of the aqueousfluids (or hydrous melt) should have upon retrograde coolingled to the back-reaction of alumosilicates and garnet to biotiteand muscovite

341 Role of fluids On the basis of the experimental workby Keppler amp Wyllie (1990) a major role for Cl- and CO2ndashrichfluids can be probably discounted since U and Th are almostequally depleted but undecoupled (Fig 10a) Interestingly rareglimmerite veins occurring in Austrian peridotite bodies adja-cent to granulite massifs show high concentrations of LILE Uand Th accompanied by low RbCs and KRb ratios (Beckeret al 1999) These contain Sr and Nd with isotopic com-positions which overlap with the granulites at c 340 MaAccording to Becker et al (1999) high Zn and F low Sr

negative Eu anomaly as well as low HFSE all point to originof glimmerites through crystallisation from a F-bearingaqueous-carbonic fluid released during the high-temperaturehigh-pressure devolatilisation in the granulite massifs

342 Melt loss A melt would be two orders of magnitudemore efficient in partitioning U and Th than a pure H2O-richfluid (Keppler amp Wyllie 1990) The present authors haveconstrained potential metamorphic assemblages partial melt-ing and volatile regimes by pressurendashtemperature andtemperaturendashX(H2O) pseudosections (Powell et al 1998) cal-culated using the internally consistent thermodynamic dataset(Holland amp Powell 1998) and the associated melt model(Holland amp Powell 2001 White et al 2001) Solid-solutionmodels were taken from the following sources (feldspar)Fuhrman amp Lindsley (1988) and Wen amp Nekvasil (1994)(biotite) Powell amp Holland (1999) (garnet and phengite)Coggon amp Holland (2002) and (clinopyroxene) Holland ampPowell (1996) hydrous cordierite was considered idealComputations were performed with the Perplex computersoftware (Connolly amp Petrini 2002) for average granulitecomposition of 81middot03 mol SiO2 0middot209 mol TiO28middot54 mol Al2O3 1middot89 mol FeOt 0middot868 mol MgO1middot113 mol CaO 3middot17 mol Na2O and 3middot19 mol K2O atvariable H2O concentrations

The representative felsic granulite has a relatively mono-tonous and modally insensitive pre-peak mineral assemblagebiotite (4middot5ndash5middot5 vol) white mica (5middot4ndash6middot4 vol) plagioclase(27middot7ndash28middot3 vol) K-feldspar (22middot2ndash23middot0 vol) and quartz(37middot7ndash38middot1 vol) with accessory garnet (0middot2ndash0middot3 vol)ilmenite or rutile (0middot1ndash0middot3 vol) The bulk-rock H2O budgetprior to the mica dehydration reactions is 0middot49ndash0middot51 wtDuring prograde burial breakdown of micas leads to theassemblage feldspar+garnet+kyanite+quartz+rutile+graniticmelt However the fertility of the protolith is severelyrestricted by the low modal abundances of micas The calcu-lated isopleths of melt fraction produced by dehydrationmelting are illustrated in the pressurendashtemperature spacetogether with the available PndashT estimates for the Moldanubiangranulites (Fig 13)

The overall dPdT slope of the melt-fraction isopleths isapproximately parallel to the fluid-absent haplogranitic melt-ing curve (Holtz et al 2001) and shifts to progressively highertemperatures with increasing pressure This explains both theinfertility of the granulites at the presumed metamorphic peakconditions and the irregular distribution of the melt-fractionisopleths (Fig 13) Initial melting limited by mica availabilitydoes not exceed 10 vol for any of the granulite decompres-sion paths Rapid increase of the melt fraction would occuronly at about 1100(C and 1 GPa and 1200(C and 2 GPabecause of the closely approaching fluid-absent haplograniticsolidus

These results are in a very good agreement with estimatedmelt production at the peak PndashT conditions (1000(C and1middot6 GPa) of 5ndash15 vol (Roberts amp Finger 1997) Such lowdegrees of partial melting suggest that granulites have under-gone very limited anatexis It can be argued that the partialmelt would start to escape only following the breakdown of theframework of residual minerals after reaching the Melt EscapeThreshold (gt20ndash25 vol melt) (Vigneresse et al 1996 Sawyer1999) However some authors have suggested that as little as5 vol of melt can be efficiently separated if deformation isinvolved (Rutter amp Neumann 1995) On this basis some degreeof melt loss from the felsic granulites cannot be ruled out

The present authors have estimated the effect of extractionof a small-degree partial melt on the LILE budget of anaverage felsic granulite To their knowledge no suitable Kdsexist for hypersolvus feldspar and hence they have employed


those for K-feldsparrhyolitic melt (Fig 14) Taking intoaccount the considerable scatter in the Kd values some 0middot4ndash12middot5 batch melting would be sufficient to deplete Cs from4middot8 ppm (an average Fichtelgebirge orthogneiss see preced-ing section) to 0middot9 (felsic granulite) On the other hand Sr andBa concentrations would be nearly unaffected by comparablysmall degrees of partial melting (Fig 14) Even for Rbpublished Kds (Leeman amp Phelps 1981 Mahood amp Hildreth1983 Stix amp Gorton 1990 Ewart amp Griffin 1994) suggestmoderately incompatible behaviour Thus Rb depletion wouldbe imperceptible at lower degrees of melting In this respect itis worth noting that several samples seem to have slight excessradiogenic Sr (Fig 11b) compatible with a minor Rb loss incourse of the Variscan high-grade metamorphism However

the real significance of this observation might be doubtful sincethese are the most felsic samples with 87Rb86Sr ratios sensi-tive to small errors in Sr determinations (Jahn et al 2000)

If a protolith composition similar to Fichtelgebirge meta-igneous rocks (Siebel et al 1997) is assumed depletion in asimilar fashion to Cs would need to be invoked for Th(112middot1 ppm) and U (90middot95 ppm) as well Rudnick ampPresper (1990) demonstrated that both elements can stronglypartition into meltfluid especially if the role of UndashTh bearingaccessory phases was limited

In summary additional work is needed to shed more lighton the mechanism of the striking U Th and Cs depletion inthe Moldanubian granulites Given the results of the thermo-dynamic modelling only a small melt fraction was likely to bepresent at the high-grade metamorphic peak and any melt losswould be rather unlikely This still would have little effect onthe whole-rock geochemical signatures including the LILelements other than Cs

35 Geotectonic settingTaken together the Ordovician meta-igneous crust with acomposition resembling that preserved in the Fichtelgebirgecould have yielded rocks similar to felsic Moldanubian granu-lites upon subduction to depths of at least 50ndash60 km (OrsquoBrien2000) This process was accompanied by surprisingly negligiblegeochemical modification

The most appropriate geotectonic setting for the Ordovicianigneous activity widespread throughout Variscan Europe (egPin amp Marini 1993) seems to be an intracontinental orback-arc rift where crustal thinning and heating by upwellingmantle could have led to melting of various crustal lithologies(Siebel et al 1997 Linnemann et al 2000 Franke 2000) Thehigh Nd model ages testify that the source of the Ordovicianigneous rocks parental to the felsic granulites could have beena pre-existing crust possibly Cadomian I-type granodiorites or

Figure 13 Pressurendashtemperature diagram for the Moldanubiangranulites (including both felsic and mafic types) The water-saturatedand dry haplogranite solidi are from Holtz et al (2001) and thepetrogenetic grid from Cooke (2000) Data sources (a) Lower Austria(Carswell amp OrsquoBrien 1993 Cooke 2000) and (b) Blansky les MassifSouthern Bohemia (Vrana 1989 Owen amp Dostal 1996 Kotkova ampHarley 1999 Kroner et al 2000) Isopleths represent the volumefraction of partial melt produced by mica dehydration melting (see textfor calculation procedure)

Figure 14 Modelling effects of slight melt loss on LILE budget(cSc0=change in element concentration of the residue relative to theoriginal source composition) Batch melting estimated residual min-eralogy 45 alkali feldspar+45 Qtz+10 Grt Distribution coeffi-cients K-feldsparrhyolitic melt are from (1) Leeman amp Phelps (1981)(2) Mahood amp Hildreth (1983) (3) Stix amp Gorton (1990) and (4) Ewartamp Griffin (1994) garnet and quartz were assumed to contain noappreciable concentrations of the modelled elements daggerThe concentra-tion in the residue=concentration in the sourcedepletion factor


geochemically undistinguishable immature psammitic (meta-)sediments Such material was readily available at the activeGondwana margin from which the Moldanubian andSaxothuringian crust were derived (eg Nance amp Murphy1996 Linnemann et al 2000 Winchester 2002)

4 Conclusions

1 The majority of the felsic Moldanubian granulites donot seem to represent separated high-pressure Variscansyn-collisional melts The main arguments include+ concentrations of Zr far too low compared to calculated

saturation levels at TR900(C coupled with presence ofsignificant mainly Ordovician zircon inheritance

+ consistently low zircon and monazite saturation tempera-tures

+ preservation of OrdovicianSilurian whole-rock and thinslab RbndashSr ages and

+ high HREE+Y ruling out the presence of largeramounts of garnet in the residue

2 Instead the felsic granulites are interpreted as metamor-phosed (partly anatectic) equivalents of an older igneouscomplex

3 Protoliths for the felsic granulites and Gfohl gneiss werecompositionally similar to some meta-igneous rocks pre-served in the Saxothuringian Zone for instanceOrdovicianndashSilurian metarhyolitesndashorthogneisses fromFichtelgebirge These were probably rift-related rockswhich could have originated by remelting of Cadomiancrust such as I-type granodiorites or immature psammitic(meta-) sediments

4 Trends of rapidly falling Sr Ba Zr LREE and P withslightly increasing Rb and SiO2 characteristic of evolvedgranites crystallising K-feldspargtplagioclase+biotitegtzircon+monazite seem to have been inherited from theigneous stage

5 During the Variscan orogeny the Early Paleozoic acidmeta-igneous crust was subducted to depths of at least50ndash60 km A moderately small melt fraction was presum-ably present during much of the metamorphic history Mostof the geochemical signature was conserved despite theHPndashHT metamorphism which led only to the loss of H2OU Th and Cs

6 The ultimate mechanism of the U Th and Cs depletion isuncertain It could have been caused by fluid loss or byremoval of a small-degree (lt10) partial melt Whileloss of such a small-degree partial melt would strip off mostof the Cs and presumably also U and Th other LILE(in particular Rb Ba and Sr) would be little affected

7 In favourable cases (eg the absence of fluids and the shortduration of the event) the RbndashSr whole-rock system mightbe rather resistant to resetting during granulite-facies meta-morphism

8 Deep burial and HPndashHT metamorphism of infertile crustallithologies such as felsic meta-igneous rocks does not needto cause extensive partial melting The resulting granuliteswould have largely undepleted geochemical signatureand preserve much of geochemical information from theirprotolith

5 Acknowledgements

This work originated during the research stay of V J at theInstitute of Mineralogy University of Salzburg in the frame-work of the FWF Project 15133ndashGEO (FF) This is a con-tinuation of previous FWF projects (M 287 and P 11674)

which funded the research stay of M R in Salzburg from 1995to 1998 Further support from the Czech Grant Agency andthe AustrianndashFrench cooperation programme Amadeus (296and 497b) is gratefully acknowledged The paper benefitedfrom constructive and detailed reviews by P Nabelek and ananonymous reviewer as well as editorial handling by SHarley G Friedl kindly provided her so-far-unpublishedSHRIMP data and M Thoni a table of RbndashSr isotopicanalyses plotted by Frank et al (1990)

We would like to thank J Trnkova along with V KopeckyJ Zeman and C Bosq for technical assistance in the isotopelaboratories of Prague and ClermontndashFerrand V Sixta formajor-element and REE chemical analyses and C Bertoldifor help with preparation of thin sections

Thanks are also due to W Siebel B Wiegand J Konopasekand C Tomek for advice S Vrana for his unbeatable knowl-edge of South Bohemian granulites inspiring discussions andproviding some samples as well as P OrsquoBrien for organising athought-provoking workshop on the (U)HP metamorphicrocks in 2002

6 Appendix 1 Petrography of the studied samples

Popp-DL Quarry of Natursteine Popp E of RamsauSt Leonhard Massif (GR 6892 3894)Ost-DL Roadside exposure at Osterberg on thePochlarnndashZelking road PochlarnndashWieselburg Massif(GR 6873 3399)Sample pairs Ost-LD and Popp-LD represent adjacent lighterand darker granulite bands Characteristic for the darker faciesis the presence of considerable amounts of small biotite flakes(3ndash10) which often define a weak foliation within thefine-grained (lt0middot1 mm) quartzndashorthoclasendashplagioclase matrixAdditionally there is always garnet (lt4 mm) and often somekyanite (lt1 mm) in the darker bands

The lighter varieties are typical felsic massive granuliteswith generally very little biotite They contain c 2ndash5 garnet(0middot2ndash4 mm across) the bigger of which often enclose inclusionsof relict mesoperthite and sometimes show fine exsolved rutileneedles The fine-grained (lt0middot1 mm) matrix consists of roughly30ndash40 quartz 25ndash30 K-feldspar and 25ndash30 sodic plagio-clase A few single elongate kyanite crystals up to 4 mm arepresent as well as accessory brown euhedral rutile (lt1 mm)

Ysp-DL Roadside quarry lsquoan der Gleisenrsquo Yspertal(GR 6530 3422)The granulite at this locality is well banded and associated witha serpentinite body Although sample Ysp-D is of clearlydarker appearance than Ysp-L there is no large compositionaldifference between the two The former contains a smallpercentage of biotite (small evenly distributed flakes) and hasa finer grained mylonitic groundmass On the other handYsp-L is a typical felsic granulite with rare garnets set in aquartzondashfeldspathic matrix Both contain some kyanite grains

Du Small abandoned quarry west of LindwurmkreuzDunkelsteiner Wald (GR 6903 3549)Sample Du is a dark-coloured granulite with a biotite-poorcharnockitic mineral paragenesis (Opx+Cpx+Grt) comingfrom a megaboudin c 1ndash1middot5 km long and up to 9 m thick Thesample contains large amounts of plagioclase (40) and quartz(30) and some K-feldspar (10) All these minerals form afine-grained mosaic


St Road cut near Steinaweg Dunkelsteiner Wald(GR 6953 3593)Leucocratic fine- to medium-grained quartz-rich felsic granu-lite with alternating Grt-free and Grt-bearing layers Withinthe weakly folded matrix numerous dark pinkred garnets arevisible up to 5 mm in diameter Particularly striking featuresare the widespread pale blue kyanite grains up to 4 mm inlength often aligned to the foliation defined by quartz ribbonsand sparse biotite Compared to most of the acidic rocks foundin the Austrian granulite occurrences the peak metamorphicassemblage of Grt+Ky+hypersolvus feldspar+Qtz is remark-ably preserved in this sample a reason why it was chosen for adetailed geochronological study (Friedl et al 2003 2004)Within the matrix abundant mesoperthitic K-feldsparporphyroclasts up to 3 mm across are visible with only minorrecrystallisation around their margins to granoblastic fine-grained K-feldspar and subordinate plagioclase Accessoryphases are rutile apatite zircon and ilmenite

1059ndash1078 Borehole H-1 at Holubov 8 km N of CeskyKrumlov Blansky les MassifThe borehole drilled in 1965 penetrated mainly granuliticrocks with leucogranulites prevailing over more mafic typesThe rest was accounted for by several tectonic slices ofultrabasic rocks and the whole assemblage was cut by infre-quent dykes of Variscan aplitesndashpegmatites While systematicpetrographic account (including 50 modal analyses of stainedgranulite samples) was published by Kodym et al (1978)Fediukova (1978) focused solely on mineralogy and chemistryof mafic phases

The felsic granulites with peak metamorphic assemblagehypersolvus feldspar+quartz+garnet+rutilekyanite showeffects of variable retrogression and mylonitic deformationThese processes resulted mainly in breakdown of garnet to asecondary biotite as well as recrystallisation of the meso-perthite into a K-feldspar and plagioclase mosaic The presentsamples coming from near the bottom of the borehole(c 1100ndash1400 m Fig 15) were selected so that they would beas little affected as possible all having inequigranulargranoblastic texture with only indistinct plane-parallel fabricHowever differences do exist Some (1074 and 1076) containpractically no biotite still preserving large mesoperthiteaugen The others were nearly completely recrystallised to anequilibrated mosaic of two feldspars and quartz (1062) andcontain a large proportion of secondary biotite sometimesaltered to chlorite (1064 and 1078) The replacement of garnetporphyroclasts by lath-shaped biotite started at the marginsand proceeded along cracks (1064) Rarely tiny flakes concen-trated into thin stripes within the matrix defining a weakfoliation (1062)

In all cases the mineral assemblage is dominated by quartzK-feldspar (mesoperthitic microcline) and plagioclase(wAn10ndash20 in less felsic types ranging to wAn30) Theseminerals occur in about equal proportions in more felsic typesbut the plagioclase content increases at the expense of Kfs toc 40 vol in the less felsic ones (1059) Garnet porphyroclasts(up to 7 vol) which are often poikilitic are conspicuousenclosing mainly subhedral perthite grains The contents ofgarnet and rutile drop sharply from less to more silica-richsamples The rutile forms both euhedral prismatic crystals inthe matrix as well as in less felsic samples (1059) a plethora ofunmixed oriented needles in the garnet porphyroclasts (egZhang et al 2003) In the two most felsic granulites there wererather abundant kyanite porphyroclasts (1074 and 1078 up to1 vol) some elongate and subhedral others lobate enclos-ing perthite grains On the other hand the least felsic sample

1059 contained kyanite with hercynite coronas the hostmineral having been sometimes completely consumed In allcases common accessories were ilmenite zircon and apatite

7 References

Aftalion M Bowes D R amp Vrana S 1989 Early CarboniferousUndashPb zircon age of garnetiferous perpotassic granulites Blanskyles massif Czechoslovakia Neues Jahrbuch fur MineralogieMonatshefte 4 145ndash52

Arnold A amp Scharbert H G 1973 RbndashSr Altersbestimmungen anGranuliten der sudlichen Bohmischen Masse in O sterreichSchweizerische mineralogische und petrografische Mitteilungen 5361ndash78

Ayres M amp Harris N 1997 REE fractionation and Nd-isotopedisequilibrium during crustal anatexis constraints fromHimalayan leucogranites Chemical Geology 139 249ndash69

Barbarin B 1996 Genesis of the two main types of peraluminousgranitoids Geology 24 295ndash8

Becker H 1997 SmndashNd garnet ages and cooling history of high-temperature garnet peridotite massifs and high-pressure granulitesfrom Lower Austria Contributions to Mineralogy and Petrology127 224ndash36

Becker H Wenzel T amp Volker F 1999 Geochemistry of glimmeriteveins in peridotites from Lower Austria ndash implications for theorigin of K-rich magmas in collision zones Journal of Petrology40 315ndash38

Blundy J D amp Shimizu N 1991 Trace element evidencefor plagioclase recycling in calcndashalkaline magmas Earth andPlanetary Science Letters 102 178ndash97

Boynton W V 1984 Cosmochemistry of the rare earth elementsmeteorite studies In Henderson P (ed) Rare Earth ElementGeochemistry 63ndash114 Amsterdam Elsevier

Brocker M Lange U Mezger K amp Z~elazniewicz A 2003 Theorthogneisses of the OrlicandashSunieznik dome (West SudetesPoland) SrndashNd isotope characteristics and RbndashSr geochronologyJournal of the Czech Geological Society 48 25ndash6

Broska I Petrık I amp Williams C T 2000 Coexisting monazite andallanite in peraluminous granitoids of the Tribec MountainsWestern Carpathians American Mineralogist 85 22ndash32

Brown M 2002 Retrograde processes in migmatites and granulitesrevisited Journal of Metamorphic Geology 20 25ndash40

Figure 15 Simplified petrographic profile for the sampled part ofborehole H-1 Holubov Blansky les Massif The location of thesamples mentioned in the text as well as SiO2 variations with depth areshown In part after Kodym et al (1978)


Carswell D A 1991 Variscan high PndashT metamorphism and uplifthistory in the Moldanubian Zone of the Bohemian Massif inLower Austria European Journal of Mineralogy 3 323ndash42

Carswell D A amp OrsquoBrien P J 1993 Thermobarometry and geo-tectonic significance of high-pressure granulites examples fromthe Moldanubian zone of the Bohemian Massif in Lower AustriaJournal of Petrology 34 427ndash59

Chappell B W 1999 Aluminium saturation in I- and S-type granitesand the characterization of fractionated haplogranites Lithos 46535ndash51

Chappell B W Bryant C J Wyborn D White A J R ampWilliams I S 1998 High- and low-temperature I-type granitesResource Geology 48 225ndash35

Chappell B W amp White A J R 1992 I- and S-type granites inthe Lachlan Fold Belt Transactions of the Royal Society ofEdinburgh Earth Sciences 83 1ndash26

Chen F Hegner E amp Todt W 1998 Garnet dating of granulitesfrom the Variscan foldbelt in Central Europe evidence for earlyand pre-Variscan high grade metamorphism Acta UniversitatisCarolinae Geologica 42 221ndash2

Clemens J D amp Droop G T R 1998 Fluids PndashT paths and thefates of anatectic melts in the Earthrsquos crust Lithos 44 21ndash36

Coggon R amp Holland T J B 2002 Mixing properties of phengiticmicas and revised garnetndashphengite geothermometers Journal ofMetamorphic Geology 20 683ndash96

Connolly J A D amp Petrini K 2002 An automated strategy forcalculation of phase diagram sections and retrieval of rockproperties as a function of physical conditions Journal ofMetamorphic Geology 20 697ndash708

Cooke R A 1999 The petrology of high-pressure granulites fromthe St Leonhard Granulite Massif Gfohl Unit Lower AustriaUnpublished PhD thesis University of Sheffield

Cooke R A 2000 High-pressuretemperature metamorphism in theSt Leonhard Granulite Massif Austria evidence from inter-mediate pyroxene-bearing granulites International Journal ofEarth Sciences 89 631ndash51

Cooke R A amp OrsquoBrien P J 2001 Resolving the relationshipbetween high PndashT rocks and gneisses in collisional terranesan example from the Gfohl gneissndashgranulite association in theMoldanubian Zone Austria Lithos 58 33ndash54

Cadkova Z Jakes P Hakova M amp Mrazek P 1985 Geochemicalcatalogue of the basic network In Lithogeochemical Database ofthe Czech Geological Survey Prague

Dallmeyer R D Franke W amp Weber K (eds) 1995 Pre-PermianGeology of Central and Eastern Europe Berlin Springer-Verlag

Debon F amp Le Fort P 1983 A chemicalndashmineralogical classificationof common plutonic rocks and associations Transactions of theRoyal Society of Edinburgh Earth Sciences 73 (for 1982) 135ndash49

Diaconis P amp Efron B 1983 Computer-intensive methods instatistics Scientific American 248 96ndash108

Dudek A Matejovska O amp Suk M 1974 Gfohl orthogneiss in theMoldanubicum of Bohemia and Moravia Krystalinikum 1067ndash78

Eby G N 1990 The A-type granitoids a review of their occurrenceand chemical characteristics and speculations on their petro-genesis Lithos 26 115ndash34

Ewart A amp Griffin W L 1994 Application of proton-microprobedata to trace-element partitioning in volcanic rocks ChemicalGeology 117 251ndash84

Faure G 1986 Principles of Isotope Geology Chichester John Wileyamp Sons

Fediukova E 1978 Mafic minerals from granulites of theborehole Holubov (South Bohemian Moldanubicum) Sbornıkgeologickych ved Loziskova geologiendashmineralogie 19 169ndash98

Fiala J Matejovska O amp Vankova V 1987a Moldanubian granu-lites and related rocks petrology geochemistry and radioactivityRozpravy Ceskoslovenske akademie ved rada matematickych aprırodnıch ved 97 1ndash102

Fiala J Matejovska O amp Vankova V 1987b Moldanubian granu-lites source material and petrogenetic considerations NeuesJahrbuch fur Mineralogie Abhandlungen 157 133ndash65

Fiala J Fuchs G amp Wendt J I 1995 Moldanubian Zone ndashstratigraphy In Dallmeyer R D Franke W amp Weber K (eds)Pre-Permian Geology of Central and Eastern Europe 417ndash428Berlin Springer

Frank W Hammer S Popp F Scharbert S amp Thoni M 1990Isotopengeologische Neuergebnisse zur Entwicklungsgeschichteder Bohmischen Masse Osterreichische Beitrage zu Meteorologieund Geophysik 3 185ndash228

Franke W 2000 The mid-European segment of the Variscidestectonostratigraphic units terrane boundaries and plate tectonicevolution In Franke W Haak V Oncken O amp Tanner D(eds) Orogenic Processes Quantification and Modelling in theVariscan Belt 35ndash61 Geological Society London Special Publi-cation 179 London Geological Society

Franke W amp Z~elazniewicz A 2000 The eastern termination of theVariscides terrane correlation and kinematic evolution InFranke W Haak V Oncken O amp Tanner D (eds) OrogenicProcesses Quantification and Modelling in the Variscan Belt63ndash86 Geological Society London Special Publication 179London Geological Society

Friedl G Cooke R Finger F McNaughton N J amp Fletcher A2003 UndashPb SHRIMP dating and trace element investigations onmultiple zoned zircons from a South-Bohemian granulite Journalof the Czech Geological Society 48 51ndash2

Friedl G Finger F Paquette J L von Quadt A McNaughtonN J amp Fletcher I R 2004 Pre-Variscan geological events in theAustrian part of the Bohemian Massif deduced from UPb zirconages International Journal of Earth Sciences 93 802ndash23

Fuchs G amp Matura A 1976 Zur Geologie des Kristallinsder sudlichen Bohmischen Masse Jahrbuch der GeologischenBundesanstalt 119 1ndash43

Fuhrman M L amp Lindsley D H (1988) Ternary-feldspar modelingand thermometry American Mineralogist 73 201ndash15

Goldstein S L OrsquoNions R K amp Hamilton P J 1984 A SmndashNdisotopic study of atmospheric dusts and particulates from majorriver systems Earth and Planetary Science Letters 70 221ndash36

Gurtlerova P Cadek J Cadkova Z Mrazek P Adamova M ampDusek P 1997 Database of analytical determinations on mapsof rock geochemical reactivity 150 000 In LithogeochemicalDatabase of the Czech Geological Survey Prague

Hanson G N 1978 The application of trace elements to thepetrogenesis of igneous rocks of granitic composition Earth andPlanetary Science Letters 38 26ndash43

Harris N B W amp Inger S 1992 Trace element modelling ofpelite-derived granites Contributions to Mineralogy and Petrology110 46ndash56

Hart S R amp Reid M R 1991 RbCs fractionation a link betweengranulite metamorphism and the S-process Geochimica etCosmochimica Acta 55 2379ndash83

Harvey P K amp Atkin B P 1981 The rapid determination of Rb Srand their ratios in geological materials by X-ray fluorescencespectrometry using a rhodium X-ray tube Chemical Geology 32155ndash65

Holland T amp Powell R 1996 Thermodynamics of order-disorder inminerals II Symmetric formalism applied to solid solutionsAmerican Mineralogist 81 1425ndash37

Holland T amp Powell R 1998 An internally consistent thermo-dynamic data set for phases of petrological interest Journal ofMetamorphic Geology 16 309ndash43

Holland T amp Powell R 2001 Calculation of phase relationsinvolving haplogranitic melts using an internally consistentthermodynamic dataset Journal of Petrology 42 673ndash83

Holtz F Becker A Freise M amp Johannes W 2001 The water-undersaturated and dry QzndashAbndashOr system revisited Experimen-tal results at very low water activities and geological implicationsContributions to Mineralogy and Petrology 141 347ndash57

Hoskin P W O Kinny P D Wyborn D amp Chappell B W 2000Identifying accessory mineral saturation during differentiation ingranitoid magmas an integral approach Journal of Petrology 411365ndash96

Hradetzky H amp Lippolt H J 1993 Generation and distortionof RbndashSr whole-rock isochrons ndash effects of metamorphism andalteration European Journal of Mineralogy 5 1175ndash93

Icenhower J amp London D 1995 An experimental study of elementpartitioning among biotite muscovite and coexisting per-aluminous silicic melt at 200 MPa (H2O) American Mineralogist80 1229ndash51

Irvine T N amp Baragar W R A 1971 A guide to the chemicalclassification of the common volcanic rocks Canadian Journal ofEarth Sciences 8 523ndash48

Jacobsen S B amp Wasserburg G J 1980 SmndashNd evolution ofchondrites Earth and Planetary Science Letters 50 139ndash55

Jahn B M 1990 Origin of granulites geochemical constraints fromArchean granulite facies rocks of the SinondashKorean CratonChina In Vielzeuf D amp Vidal P (eds) Granulites and CrustalEvolution 471ndash92 Dordrecht Kluwer


Jahn B M Wu F amp Chen B 2000 Granitoids of the Central AsianOrogenic Belt and continental growth in the Phanerozoic Trans-actions of the Royal Society of Edinburgh Earth Sciences 91181ndash93

Jakes P 1997 Melting in high-P region ndash case of Bohemian granulitesActa Universitatis Carolinae Geologica 41 113ndash25

Janousek V Fryda J amp Vokurka K 1996 Polyphase developmentof the Moldanubian granulites evidence from the RbndashSr andSmndashNd isotopic study of the Blansky les granulite massif (CzechRepublic) In Treloar P amp OrsquoBrien P J (eds) What DrivesMetamorphism and Metamorphic Reactions Heat ProductionHeat Transfer Deformation and Kinetics 43ndash4 Kingston uponThames Kingston University

Janousek V Rogers G Bowes D R amp Vankova V 1997 Cryptictrace-element variation as an indicator of reverse zoning in agranitic pluton the R ıcany granite Czech Republic Journal of theGeological Society (London) 154 807ndash15

Janousek V Farrow C M amp Erban V 2003a GCDkit new PCsoftware for interpretation of whole-rock geochemical data fromigneous rocks Geochimica et Cosmochimica Acta 67 A186

Janousek V Vrana S amp Finger F 2003b Whole-rock geochemicaland mineralogical constraints on the genesis of the metaigneousVariscan lower crust in Central Europe ndash case study of the Lisovgranulite Massif Southern Bohemia Journal of the CzechGeological Society 48 72ndash3

Kalsbeek F amp Hansen M 1989 Statistical analysis of RbndashSr isotopedata by the lsquobootstraprsquo method Chemical Geology (IsotopeGeoscience Section) 73 289ndash97

Keppler H amp Wyllie P J 1990 Role of fluids in transport andfractionation of uranium and thorium in magmatic processesNature 348 531ndash3

Kodym O Jakes P amp Schovanek P 1978 Granulite und ultra-mafische Gesteine aus der Strukturbohrung Holubov Sbornıkgeologickych ved Geologie 32 7ndash47

Kotkova J Gerdes A Parrish R R amp Novak M 2003 Pressurendashtemperaturendashtime evolution of granulite clasts from LowerCarboniferous conglomerates ndash evidence for rapid exhumation atthe eastern margin of the Variscan Bohemian Massif GeophysicalResearch Abstracts 5 434

Kotkova J amp Harley S L 1999 Formation and evolution ofhigh-pressure leucogranulites experimental constraints andunresolved issues Physics and Chemistry of the Earth Part ASolid Earth and Geodesy 24 299ndash304

Kroner A Wendt I Liew T C Compston W Todt W Fiala JVankova V amp Vanek J 1988 UndashPb zircon and SmndashNd modelages of high-grade Moldanubian metasediments BohemianMassif Czechoslovakia Contributions to Mineralogy andPetrology 99 257ndash66

Kroner A OrsquoBrien P J Nemchin A A amp Pidgeon R T 2000Zircon ages for high pressure granulites from South BohemiaCzech Republic and their connection to Carboniferous hightemperature processes Contributions to Mineralogy and Petrology138 127ndash42

Kuhn A Glodny J Iden K amp Austrheim H 2000 Retention ofPrecambrian RbSr phlogopite ages through Caledonian eclogitefacies metamorphism Bergen Arc Complex W-Norway Lithos51 305ndash30

Leeman W amp Phelps D 1981 Partitioning of rare earths and othertrace elements between sanidine and coexisting volcanic glassJournal of Geophysical Research B 86 10 193ndash9

Liew T C amp Hofmann A W 1988 Precambrian crustal com-ponents plutonic associations plate environment of theHercynian Fold Belt of Central Europe indications from a Ndand Sr isotopic study Contributions to Mineralogy and Petrology98 129ndash38

Linnemann U Gehmlich M Tichomirowa M Buschmann BNasdala L Jonas P Lutzner H amp Bombach K 2000 Themid-European segment of the Variscides tectonostratigraphicunits terrane boundaries and plate tectonic evolution In FrankeW Haak V Oncken O amp Tanner D (eds) Orogenic ProcessesQuantification and Modelling in the Variscan Belt 131ndash153Geological Society London Special Publication 179 LondonGeological Society

Mahood G A amp Hildreth E W 1983 Large partition coefficientsfor trace elements in high-silica rhyolites Geochimica etCosmochimica Acta 47 11ndash30

Matte P Maluski H Rajlich P amp Franke W 1990 Terraneboundaries in the Bohemian Massif result of large-scale Variscanshearing Tectonophysics 177 151ndash70

Medaris L G Jr Wang H F Mısar Z amp Jelınek E 1990Thermobarometry diffusion modelling and cooling rates ofcrustal peridotites two examples from the Moldanubian Zoneof the Bohemian Massif Lithos 25 189ndash202

Medaris L G Jr Wang H F Jelınek E amp Jakes P 2003 Garnetperidotite in the Moldanubian Zone in the Czech Republic ndasha heat source for Variscan metamorphism Journal of the CzechGeological Society 48 92ndash3

Miller C F McDowell S M amp Mapes R W 2003 Hot and coldgranites Implications of zircon saturation temperatures andpreservation of inheritance Geology 31 529ndash32

Miller C F amp Mittlefehldt D W 1982 Depletion of light rare-earthelements in felsic magmas Geology 10 129ndash33

Miller C F amp Mittlefehldt D W 1984 Extreme fractionation infelsic magma chambers a product of liquid-state diffusion orfractional crystallization Earth and Planetary Science Letters 68151ndash8

Montel J M 1993 A model for monazitemelt equilibrium andapplication to the generation of granitic magmas ChemicalGeology 110 127ndash46

Morgan G B VI amp London D 2003 Trace-element partitioning atconditions far from equilibrium Ba and Cs distributions betweenalkali feldspar and undercooled hydrous granitic liquid at200 MPa Contributions to Mineralogy and Petrology 144 722ndash38

Nance R D amp Murphy J B 1996 Basement isotopic signaturesand Neoproterozoic paleogeography of AvalonianndashCadomianand related terranes in the circum-North Atlantic In Nance RD amp Thompson M D (eds) Avalonian and Related Peri-Gondwanan Terranes of the Circum-North Atlantic 333ndash46 Geo-logical Society of America Special Paper 304 Boulder Coloradoand Lawrence Kansas Geological Society of America and Uni-versity of Kansas Press

OrsquoBrien P J 2000 The fundamental Variscan problem high-temperature metamorphism at different depths and highndashpressuremetamorphism at different temperatures In Franke W HaakV Oncken O amp Tanner D (eds) Orogenic Processes Quantifi-cation and Modelling in the Variscan Belt 369ndash86 GeologicalSociety London Special Publication 179 London GeologicalSociety

OrsquoBrien P J amp Rotzler J 2003 High-pressure granulites formationrecovery of peak conditions and implications for tectonicsJournal of Metamorphic Geology 21 3ndash20

Otamendi J E De la Rosa J D Patino Douce A E amp Castro A2002 Rayleigh fractionation of heavy rare earths and yttriumduring metamorphic garnet growth Geology 30 159ndash62

Owen J V amp Dostal J 1996 Contrasting corona structures in maficgranulite from the Blansky Les complex Bohemian Massif CzechRepublic Canadian Mineralogist 34 959ndash66

Pearce J A Harris N W amp Tindle A G 1984 Trace elementdiscrimination diagrams for the tectonic interpretation of graniticrocks Journal of Petrology 25 956ndash83

Peccerillo R amp Taylor S R 1976 Geochemistry of Eocenecalcndashalkaline volcanic rocks from the Kastamonu area NorthernTurkey Contributions to Mineralogy and Petrology 58 63ndash81

Pin C Binon M Belin J M Barbarin B amp Clemens J D 1990Origin of microgranular enclaves in granitoids ndash equivocal SrndashNdevidence from Hercynian rocks in the Massif Central (France)Journal of Geophysical Research B 95 17 821ndash8

Pin C amp Marini F 1993 Early Ordovician continental break-upin Variscan Europe NdndashSr and trace element evidence frombimodal igneous associations of the southern Massif CentralFrance Lithos 29 177ndash96

Pin C amp Vielzeuf D 1983 Granulites and related rocks in VariscanMedian Europe a dualistic interpretation Tectonophysics 9347ndash74

Poschl-Otrel K 1995 Untersuchungen an Zirkonen aus Granuliten derniederosterreichischen Waldviertels Unpublished MSc thesisUniversitat Salzburg Austria

Powell R Holland T amp Worley B 1998 Calculating phasediagrams involving solid solutions via non-linear equations withexamples using Thermocalc Journal of Metamorphic Geology 16577ndash88

Powell R amp Downes J 1990 Garnet porphyroblast-bearing leuco-somes in metapelites mechanisms phase diagrams and anexample from Broken Hill Australia In Ashworth J R ampBrown M (eds) High-Temperature Metamorphism and CrustalAnatexis 105ndash23 London Unwin Hyman

Powell R amp Holland T 1999 Relating formulations of the thermo-dynamics of mineral solid solutions activity modeling ofpyroxenes amphiboles and micas American Mineralogist 841ndash14


Prince C I Kosler J Vance D amp Gunther D 2000 Comparison oflaser ablation ICP-MS and isotope dilution REE analyses ndashimplications for SmndashNd garnet geochronology ChemicalGeology 168 255ndash74

Provost A 1990 An improved diagram for isochron data ChemicalGeology (Isotope Geoscience Section) 80 85ndash99

Roberts M P Pin C Clemens J D amp Paquette J L 2000Petrogenesis of mafic to felsic plutonic rock associations thecalcndashalkaline Querigut Complex French Pyrenees Journal ofPetrology 41 809ndash44

Roberts M P amp Finger F 1997 Do UndashPb zircon ages fromgranulites reflect peak metamorphic conditions Geology 25319ndash22

Romer R L amp Rotzler J 2001 PndashTndasht evolution of ultrahigh-temperature granulites from the Saxon Granulite MassifGermany Part II Geochronology Journal of Petrology 422015ndash32

Rotzler J amp Romer R L 2001 PndashTndasht evolution of ultrahigh-temperature granulites from the Saxon Granulite MassifGermany Part I Petrology Journal of Petrology 42 1995ndash2013

Rudnick R L McLennan S M amp Taylor S R 1985 Large ionlithophile elements in rocks from high-pressure granulite faciesterrains Geochimica et Cosmochimica Acta 49 1645ndash55

Rudnick R L amp Presper T 1990 Geochemistry of intermediate-to high-pressure granulites In Vielzeuf D amp Vidal P (eds)Granulites and Crustal Evolution 523ndash50 Dordrecht Kluwer

Rudnick R L amp Taylor S R 1987 The composition and petro-genesis of the lower crust a xenolith study Journal of GeophysicalResearch B 92 13981ndash4006

Rutter E H amp Neumann D H K 1995 Experimental deformationof partially molten Westerly Granite under fluid-absent condi-tions with implications for the extraction of granitic magmasJournal of Geophysical Research B 100 697ndash715

Sawyer E W 1999 Criteria for the recognition of partial meltingPhysics and Chemistry of the Earth Part A Solid Earth andGeodesy 24 269ndash79

Schenk V amp Todt W 1983 UndashPb Datierungen an Zirkon undMonazit der Granulite im Moldanubikum Niederosterreichs(Waldviertel) Fortschritte der Mineralogie 61 190ndash1

Shaw D M 1968 A review of KndashRb fractionation trends bycovariance analysis Geochimica et Cosmochimica Acta 32573ndash601

Siebel W Raschka H Irber W Kreuzer H Lenz K LHohndorf A amp Wendt I 1997 Early Palaeozoic acid magma-tism in the Saxothuringian belt new insights from a geochemicaland isotopic study of orthogneisses and metavolcanic rocks fromthe Fichtelgebirge SE Germany Journal of Petrology 38 203ndash30

Slaby J 1983 Modal composition and petrochemistry of granulites ofthe Lisov and Blansky les massifs (South Bohemia) Casopis promineralogii a geologii 28 41ndash60 [in Czech with English summary]

Steiger R H amp Jager E 1977 Subcommission on Geochronologyconvention on the use of decay constants in geo- and cosmo-chronology Earth and Planetary Science Letters 36 359ndash62

Stix J amp Gorton MP 1990 Variations in trace element partitioncoefficients in sanidine in the Cerro Toledo Rhyolite JemezMountains New Mexico effects of composition temperature andvolatiles Geochimica et Cosmochimica Acta 54 2 697ndash708

Strejcek M 1986 Petrology of granulites in the Plesovice quarry nearCesky Krumlov Unpublished MSc thesis Charles UniversityPrague [in Czech]

Svojtka M Kosler J amp Venera Z 2002 Dating granulite-faciesstructures and the exhumation of lower crust in the MoldanubianZone of the Bohemian Massif International Journal of EarthSciences 91 373ndash85

Sylvester P J 1998 Post-collisional strongly peraluminous granitesLithos 45 29ndash44

Taylor S R amp McLennan S M 1985 The Continental Crust ItsComposition and Evolution Oxford Blackwell

Tollmann A 1995 Das Ausmass des variszischer Deckbaues imMoldanubikum Krystalinikum 18 117ndash32

Turniak K Mazur S amp Wysoczanski R 2000 SHRIMP zircongeochronology and geochemistry of the OrlicandashSunieznik gneisses(Variscan belt of Central Europe) and their tectonic implicationsGeodinamica Acta 13 293ndash312

Valbracht P J Vrana S Beetsma J J Fiala J amp Matejka D1994 Sr and Nd isotopic determinations in three Moldanubiangranulite massifs in southern Bohemia Journal of the CzechGeological Society 39 114

van Breemen O Aftalion M Bowes D R Dudek A Mısar ZPovondra P amp Vrana S 1982 Geochronological studies of theBohemian Massif Czechoslovakia and their significance inthe evolution of Central Europe Transactions of the Royal Societyof Edinburgh Earth Sciences 73 (for 1982) 89ndash108

Vellmer C 1992 Stoffbestand und Petrogenese von Granuliten undgranitischen Gesteinen der sudlichen Bohmischen Masse in Nieder-osterreich Unpublished PhD thesis GeorgndashAugustndashUniversitatGottingen

Vigneresse J-L Barbey P amp Cuney M 1996 Rheological transi-tions during partial melting and crystallization with application tofelsic magma segregation and transfer Journal of Petrology 371579ndash600

Vrana S 1989 Perpotassic granulites from southern Bohemia anew rock-type derived from partial melting of crustal rocksunder upper mantle conditions Contributions to Mineralogy andPetrology 103 510ndash22

Vrana S amp Jakes P 1982 Orthopyroxene and two-pyroxene granu-lites from a segment of charnockitic crust in southern BohemiaVestnık Ceskeho geologickeho ustavu 57 129ndash43

Vrana S amp Novak M 2000 Petrology and geochemistry of granuliteclasts in the Visean Lulec conglomerate Kulm in centralMoravia Czech Republic Bulletin of the Czech Geological Survey75 405ndash13

Watson E B amp Harrison M 1983 Zircon saturation revisitedtemperature and composition effects in a variety of crustal magmatypes Earth and Planetary Science Letters 64 295ndash304

Watt G R amp Harley S L 1993 Accessory phase controls on thegeochemistry of crustal melts and restites produced during water-undersaturated partial melting Contributions to Mineralogy andPetrology 114 550ndash66

Wedepohl K H 1995 The composition of the continental crustGeochimica et Cosmochimica Acta 59 1217ndash32

Wen S amp Nekvasil H 1994 SOLVCALC an interactive graphicsprogram package for calculating ternary feldspar solvus andfor two-feldspar thermometry Computers and Geosciences 201025ndash1040

Wendt J I Kroner A Fiala J amp Todt W 1994 UndashPb zircon andSmndashNd dating of Moldanubian HPHT granulites from southBohemia Czech Republic Journal of the Geological Society(London) 151 83ndash90

Whalen J B Currie K L amp Chappell B W 1987 A-type granitesgeochemical characteristics discrimination and petrogenesisContributions to Mineralogy and Petrology 95 407ndash19

White R W Powell R amp Holland T 2001 Calculation of partialmelting equilibria in the system Na2OndashCaOndashK2OndashFeOndashMgOndashAl2O3ndashSiO2ndashH2O (NCKFMASH) Journal of MetamorphicGeology 19 139ndash53

White R W amp Powell R 2002 Melt loss and the preservation ofgranulite facies mineral assemblages Journal of MetamorphicGeology 20 621ndash32

Wiegand B 1997 Isotopengeologische und geochemische Unter-suchungen zur pravariszischen magmatischen und sedimentarenEntwicklung im saxothuringisch-moldanubischen Ubergangs-bereich (Grenzgebiet BRDCR) Geotektonische Forschungen 88Stuttgart E Schweizerbartrsquosche Verlagsbuchhandlung

Winchester J A 2002 Palaeozoic amalgamation of Central Europenew results from recent geological and geophysical investigationsTectonophysics 360 5ndash21

York D 1969 Least-squares fitting of a straight line with correlatederrors Earth and Planetary Science Letters 5 320ndash4

Zhang R Y Zhai S M Fei Y W amp Liou J G 2003 Titaniumsolubility in coexisting garnet and clinopyroxene at very highpressure the significance of exsolved rutile in garnet Earth andPlanetary Science Letters 216 591ndash601


VOJTECH JANOUSEK FRITZ FINGER and MALCOLM P ROBERTS Institut furMineralogie Universitat Salzburg Hellbrunnerstraszlige 34 A-5020 Salzburg Austriae-mail vojtechjanouseksbgacat

MALCOLM P ROBERTS The Council for Geoscience PO Box 5347 Walmer Port Elizabeth6065 South Africa (Present address)

JIR Iu FRYuDA Czech Geological Survey Klarov 3131 118 21 Prague 1 Czech Republic

CHRISTIAN PIN Departement de Geologie CNRS Universite Blaise Pascal 5 rue KesslerF-63038 Clermont-Ferrand France

DAVID DOLEJS Department of Earth and Planetary Sciences McGill University 3450 rueUniversity Montreal Quebec Canada H3A 2A7

MS received 10 November 2003 Accepted for publication 4 May 2004


subdivided into a structurally lower mainly metasedimentaryamphibolite-facies Drosendorf Assemblage and an overlyinghigher-grade allochtonous Gfohl Assemblage (eg Matteet al 1990 Fiala et al 1995 Franke 2000)

The lower part of the Drosendorf Assemblage consists ofthe Monotonous Unit (Ostrong Unit) made up mainlyof cordieritendashbiotitendashsillimanite paragneisses which are partlymigmatitic and contain intercalations of orthogneisses andminor amphibolites The upper part termed the Varied (orVariegated) Unit consists of paragneisses orthogneissesamphibolites carbonate rocks calc-silicate gneisses quartzitesand graphite schists

The lower parts of the Gfohl Assemblage include mainlyanatectic orthogneisses (Gfohl gneiss) The higher are domi-nated by granulites associated with minor bodies of garnet

and spinel peridotites pyroxenites dunites and eclogites(Fuchs amp Matura 1976 Fiala et al 1995)

12 Granulite bodiesSeveral granulite massifs occur in the Waldviertel region ofLower Austria These are interpreted as the isolated klippenof an original regionally extensive nappe (Tollmann 1995)From SW to NE these are the Yspertal PochlarnndashWieselburgDunkelsteiner Wald St Leonhard and Blumau massifs (Fuchsamp Matura 1976 Fig 1) In the southern Czech Republic thegranulite bodies tend to be roughly oval-shaped and dome-like The largest is the Blansky les Massif (244 km) followedby Kristrsquoanov Prachatice Lisov Krasejovka and othernumerous small occurrences (Fig 1) In southwest Moravia

Figure 1 Geological sketch of the Moldanubian Zone in southern Bohemia south-western Moravia and LowerAustria (simplified from the Czech Geological Survey map 1500 000) The numbers of felsic granulite samplesfrom larger massifs (totalnew determinations) are shown
























































































3 Discussion























































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3 Discussion























































4 Conclusions













5 Acknowledgements
















7 References






































































































































































































4 Conclusions













5 Acknowledgements
















7 References






























































































































































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Vojte ÿch Janous ÿek, Fritz Finger, Malcolm Roberts, Jir ÿõ« Fry … · 2017-06-30 ·...

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