GEOLOGICA CARPATHICA, 48, 5, BRATISLAVA, OCTOBER 1997
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE
METAMORPHISM AND MIGMATITIZATION IN THE MALÁ FATRA
CRYSTALLINE COMPLEX, THE WESTERN CARPATHIANS
MARIAN JANÁK* and BRANISLAV LUPTÁK
Department of Mineralogy and Petrology, Faculty of Sciences, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic
(Manuscript received October 9, 1996; accepted in revised form June 24, 1997)
Pressure-temperature conditions of metamorphism and migmatitization were investigated in the Malá Fatra
crystalline complex, representing one of the deepest segments of the Variscan basement in the Western Carpathians.
Field observations together with structural data document close relationships between migmatitization and deformation.
The penetrative, syn- to post-metamorphic Variscan deformation with generally top-to-the south-southeast sense of shearing
has been documented. Thermobarometric data obtained by conventional and internally consistent (TWEEQU) methods
indicate the attainment of ca. 700–750
C and 6 kbar in metapelitic migmatites and 700–750
C and 8–10 kbar in garnet-
clinopyroxene amphibolites. Migmatitization took place by partial melting during decompression, producing granitic
leucosome in metapelites and tonalitic-trondhjemitic one in the metabasites. Initial high-pressure stage and a “clock-
wise” P-T path is inferred from a) kyanite-sillimanite transformation in metapelites and b) kelyphitic and symplectitic
textures in garnet-clinopyroxene metabasites, indicating the breakdown of eclogites reequilibrated at upper-amphibolite
to granulite facies conditions. The proposed metamorphic evolution is consistent with considerable crustal thickening
and extension of the West-Carpathian crystalline basement during the Variscan orogeny.
Western Carpathians, Malá Fatra, Variscan orogeny, high-grade metamorphism, thermobarometry,
consists of two partial segments — the Ve ká Lúka Massif in
the west and the Kriváň Massif in the east, separated by a
NNW–SSE trending Alpine fault. The investigated area is the
southeastern part of the Ve ká Lúka Massif (Fig. 1) where
metamorphic rocks are abundant in contrast to the northern part
— the Kriváň Massif, which is mainly composed of granitoids
(Ivanov & Kamenický 1957; Benko 1996; Broska et al. 1997).
Metamorphic rocks in the Ve ká Lúka Massif represent
several lithological types of sedimentary as well as igneous
pre-metamorphic origin, which have been affected by high-
grade metamorphism and migmatitization (Fig. 1).
Metapelites are represented by biotite, garnet and silliman-
ite paragneisses exhibiting migmatitization. Orthogneisses
with characteristic augen texture and mylonitic fabric are
thought to represent former granitoids, and/or acid volcanic
rocks (Kamenický & Macek 1984). Metabasites are repre-
sented by several types of amphibolites: fine- to coarse-
grained amphibolites, massive garnet and garnet-clinopy-
roxene amphibolites, banded and migmatitic amphibolites
to amphibole gneisses. Rare metaultramafic rocks have been
described as amphibole peridotites (Ivanov & Kamenický
1957; Hovorka et al. 1985). Sporadic calc-silicates have also
been reported (Korikovsky et al. 1987).
The granitoids in the Ve ká Lúka Massif correspond to to-
nalites and hybrid tonalites (Kamenický et al. 1987). They are
crosscut by lamprophyric dykes (Ivanov & Kamenický 1957;
Hovorka 1967). The U-Pb zircon age of tonalite from the quar-
ry Dubná Skala is 353 Ma, according to Scherbak et al. (1990).
The structural relations between the metamorphic rocks and
granitoids can be best studied in the profile across Mlynský
The Malá Fatra crystalline complex represents one of the
deepest segments of the pre-Mesozoic basement exposed in
the Central Western Carpathians. One of the most striking
features of this crystalline complex is widespread migmati-
tization, observed in paragneisses as well as amphibolites
(e.g. Hovorka 1969, 1974). The metamorphic conditions in
the Malá Fatra Mts. have been estimated by several authors
(Perchuk et al. 1984; Korikovsky et al. 1987; Krist et al.
1992; Hovorka & Méres 1991; Hovorka et al. 1993), who
suggested the attainment of amphibolite facies. However,
relict assemblages indicating a higher-pressure (eclogite fa-
cies) metamorphism in metabasites have also been reported
(Hovorka et al. 1992).
In this study, we present new thermobarometric data from
both migmatitic metapelites and metabasites which suggest
their generation by partial melting at the upper amphibolite-
granulite facies transition, most probably during decompres-
sion from higher-pressure, eclogite facies conditions. The aim
of this paper is also to emphasize the role of ductile deforma-
tion in melt segregation during the Variscan evolution of the
Malá Fatra crystalline complex.
The Malá Fatra Mts. represent a typical core complex lo-
cated in the furthest northwestern protrusion of the Tatric Unit
in the Central Western Carpathians. The crystalline basement
*Present address: Geological Institute, Slovak Academy of Sciences, Dúbravská 9, 842 26 Bratislava, Slovak Republic
288 JANÁK and LUPTÁK
Schematic geological map of the southern part of the Malá Fatra —Ve ká Lúka Massif.
Potok — Ve ká Lúka 1470 m e.p. (Fig. 2). Structurally up-
wards, the metamorphic rocks show increasing migmatitiza-
tion and leucosome vs. paleosome proportions. Thus, the mig-
matites pass gradually into the hybrid tonalites in the
uppermost levels of the entire sequence.
The metamorphic foliation moderately to steeply dips to
the NW (Figs. 1, 2). Mineral lineation, as defined by elon-
gation of biotite, sillimanite and amphibole, varies between
NW-SE and N-S direction. The metamorphic rocks dip be-
neath granitoids and there is no intrusive penetration of
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 289
metamorphic rocks by granitoids from beneath. Numerous
ductile shear zones indicate high temperature conditions of
deformation; brittle deformation is characteristic of younger
faults crosscutting metamorphic foliation. These can be
temporally connected with Alpine tectonic processes. How-
ever, most of the ductile mesoscopic structures and kine-
matic indicators, e.g. asymmetric feldspar porphyroclasts
indicate that the (sense) direction of major tectonic transport
was top-to-the SSE-SE. This is attributed to Variscan defor-
mation (Lupták 1996).
Petrography and mineral chemistry
The chemical compositions of selected minerals were de-
termined using JEOL 733 electron microprobe at Geological
Institute of Dionýz Štúr (Geological Survey of the Slovak Re-
public) in Bratislava. A point beam at operating conditions of
10 nA and 15 kV was used. The data were reduced by the
ZAF correction method. Mineral abbreviations in this paper
are given according to Kretz (1983).
Garnet-sillimanite gneisses and
The migmatitization in metapelitic gneisses is shown by in-
homogeneous texture, with characteristic segregations into
the leucosome, melanosome and/or mesosome (nomenclature
according to Ashworth 1985). Leucosome is coarse grained,
sometimes pegmatoid-like, composed of variable contents of
plagioclase, quartz and K-feldspar, thus corresponding to
granite-granodiorite composition. Mesosome is fine- to medi-
um-grained. The most common mineral assemblages include:
garnet + sillimanite + biotite + quartz + plagioclase + K-feld-
spar + muscovite with ilmenite and minor amount of rutile as
Fe-Ti oxides. Melanosome consists of accumulations and sel-
vadges of biotite.
The texture is mostly stromatitic, with alternating leuco-
cratic and melanocratic layers. The lineation is defined by the
alignment of biotite and/or biotite + sillimanite aggregates, as
well as long dimensions of quartz ribbons. Asymmetric por-
phyroclasts of feldspars and shear bands which deform the foli-
ation indicate a shear component of the deformation. The leu-
cocratic material is often located in the shears, boudin necks
and dilation fractures, indicating that the melt was focused
into a tectonically weakened shear zones and veins forming
an anastomosing network (Fig. 3). With increasing portions
of leucosome, the texture becomes more homogeneous; thus,
the migmatites (diatexites) are passing gradually into the hy-
forms porphyroblasts of varying size, mostly less
than 1–2 mm in diameter, but in some cases they reach up to
10 mm. The majority of garnets are idiomorphic (Fig. 4a), in-
dicating equilibrium with the matrix, whereas some garnets
show resorption in the rims due to rection with the biotite. In-
Geological cross-section of the Ve ká Lúka Massif in the southern part of the Malá Fatra.
290 JANÁK and LUPTÁK
clusions of biotite, plagioclase and quartz are sometimes
present in the garnet cores. Garnet composition (Table 1) cor-
responds to a mixture of almandine (65–75 %) and pyrope
(15–30 %) component with low grossular (3–4 %) and spes-
sartine (2–5 %) contents. The majority of the garnets show no
substantial changes in composition, except for the outermost
part of grains where almandine and the Fe/(Fe+Mg) ratio in-
creases and the pyrope decreases with respect to the core
(Fig. 5). Spessartine contents across the grain are constant, or
increase in the rims.
Homogeneous compositions in the garnet cores are inter-
preted as the result of intragranular diffusion at high tempera-
ture (Yardley 1977; Woodsworth 1977), combined with inter-
granular diffusion (Spear 1991) modifying the garnet rim due
to retrograde exchange reaction between the garnet and bi-
otite (increasing Fe/Fe+Mg in the garnet). Preferential frac-
tionation of Mn into the garnet is thought to be the conse-
quence of the retrograde, garnet-consuming net-transfer
reaction garnet + K-feldspar + H
O = biotite + sillimanite +
quartz. This can be deduced from the biotite-sillimanite inter-
Migmatite textures in the Malá Fatra crystalline complex. a — Melt segregetion into the shear bands in the metapelitic migmatite,
— coarse-grained metapelitic diatexite, c — tonalitic-trondhjemitic veins and segregations in amphibolite, d — thin leucosome, layer-par-
allel oriented and folded in the amphibolite, e — segregation of coarse-grained plagioclase-quartz-amphibole leucosome in amphibolite, f —
“recrystallized” amphibole in tonalitic-trondhjemitic leucosome at the contact with fine-grained amphibolite.
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 291
growths around the resorbed subhedral garnets in the pres-
ence of K-feldspar in the matrix.
occurs both in the form of prismatic crystals and
fibrolite (Fig. 4a,b). Large needles up to 1cm thick and 2–3 cm
long form aggregates and knots (Fig. 4c), which indicate the
presence of former kyanite transformed into sillimanite. How-
ever, only sillimanite has been detected by X-ray diffraction.
Prismatic sillimanite forms individual crystals or is intergrown
with biotite in the matrix. Large sillimanite crystals are concor-
dant with foliation and exhibit folding and bending, being of-
ten wrapped around the garnet and plagioclase porphyroclasts
in the deformed matrix (Fig. 4a,b). Some of the sillimanite nee-
dles are disrupted by minor cracks, indicating the changing
ductile-brittle and compressional-tensional regime during de-
formation. Consequently, the alignment of sillimanite needles
defines a syn- to post-crystalline deformation and transport
during Variscan exhumation.
occur mostly in the matrix where they are mostly
segregated together with quartz, forming the leucosome. Pla-
gioclase inclusions (An
) are only sporadically present in the
Photomicrographs of: a — biotite, sillimanite and garnet porphyroblasts in the mesosome of metapelitic migmatite exhibiting mylo-
nitic SC fabric, width of view is 10 mm; b — prismatic sillimanite wrapped around the garnet in metapelitic migmatite, width of view is
10 mm; c — randomly oriented aggregates of sillimanite probably pseudomorphing kyanite in metapelite; d — photomicrograph of thick sil-
limanite, indicating the transformation of former kyanite to sillimanite in metapelite, width of view 8 mm; e — characteristic breakdown tex-
tures in garnet-clinopyroxene amphibolite with kelyphitic rim of amphibole and plagioclase (Amp II+Pl) around garnet (Grt) and symplec-
tites of clinopyroxene with plagioclase (Cpx+Pl) replaced by amphibole (Amp III). Width of view is 15 mm; f — symplectite of
clinopyroxene+plagioclase invaded by amphibole (dark-grey) indicating the breakdown of omphacite in garnet-clinopyroxene amphibolite.
Width of view is 2 mm.
292 JANÁK and LUPTÁK
garnet cores. The compositions in the matrix correspond to
oligoclase-andesine (Table 2). K-feldspar is restricted mostly
to the segregated leucosomes. Rarely, it also occurs in the in-
terstices between plagioclase and quartz in the muscovite-
free mesosome, suggesting the overstepping of muscovite +
quartz equilibrium in favour of K-feldspar stability during the
initial stage of melting, e.g. the dehydration-melting reaction
muscovite + plagioclase + quartz = K-feldspar + sillimanite +
forms lath-shaped porphyroblasts, which commonly
define the metamorphic foliation000000. The orientation of
biotites indicates a simple shear regime with top-to-the east
and southeast sense of transport during Variscan syn- to post-
metamorphic deformation. Small biotites form inclusions in
the cores of garnets.
The composition of biotites is shown in the Table 3. The
nearly constant composition of the matrix biotites indicates
that they were equilibrated at the same P-T conditions. Only a
minor part of the biotite has been affected by chloritization
during retrograde processes.
forms large individual porphyroblasts, oriented
in the planes of metamorphic foliation together with biotite,
or across the foliation. In samples where K-feldspar is absent,
muscovite may be considered as a stable phase during peak
metamorphic conditions, i.e. below the stability of K-feld-
spar. On the other hand, in some samples muscovite is
present together with K-feldspar. Such muscovite may be ret-
rograde with respect to peak metamorphic conditions, as indi-
cated by thermobarometry discussed below.
and mafic migmatites
Amphibolites in the Malá Fatra show strong migmatitiza-
tion on a centimetre to decimetre scale (Fig. 3). The texture is
Table 1: Chemical compositions of garnet.
Recalculated on the basis of 12 oxygens
Compositinal profile across garnet in the sample MF 13/93.
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 293
inhomogeneous, exhibiting layering and segregations into
leucosome and more mafic mesosome. Melanosome is repre-
sented by amphibole-rich segregations, sometimes present at
the contact with leucosome.
Leucosome is medium to coarse-grained, composed of pla-
gioclase + quartz, with sporadic large (up to 1–2 cm) horn-
blendes. The leucosome composition thus corresponds to to-
nalite and trondhjemite in contrast to metapelitic migmatites
where K-feldspar is present. Mesosome is medium-grained
and is composed mostly of hornblende + plagioclase +
quartz + biotite. The texture is mostly stromatitic. Tonalitic-
trondhjemitic leucosome forms an anastomosing network of
chaotic veins or it is interlayered with mafic mesosome. The
distribution of leucosome is clearly related to deformation
with quartzo-feldspathic material focused into the shear-
bands, boudin necks and dilational fractures.
Within the mafic migmatites, more homogeneous bodies
and lenses containing garnet and/or clinopyroxene can be ob-
served. Massive garnet-clinopyroxene amphibolites were de-
scribed by Hovorka et al. (1992) who suggested their eclogit-
ic origin. In these rocks, the garnets rimmed by plagioclase
and fine-grained clinopyroxenes, symplectitically intergrown
with plagioclase, are replaced by amphiboles (Fig. 4e).
The mineral compositions of garnet-clinopyroxene am-
phibolites with signs of eclogite breakdown were investigat-
ed in detail:
forms subhedral grains, up to 5–10 mm in diameter,
surrounded and partly resorbed by plagioclase and plagio-
clase-amphibole kelyphitic rims (Fig. 4e). The inclusions in
the garnet cores are quartz, amphibole and rutile/ilmenite.
The garnets correspond to almandine with significant grossu-
lar and pyrope contents (Table 1). Their compositions show
increasing pyrope and decreasing spessartine contents as well
as Fe/(Fe+Mg) ratio in rims relative to cores. Only very close
to the edges, the compositional patterns become reverse, re-
flecting retrograde resorption and diffusion during the garnet
breakdown and kelyphite formation.
forms fine-grained, glomeroblastic and ver-
micular grains, symplectitically intergrown with plagioclase
and amphibole (Fig. 4e,f). This indicates breakdown of an old-
er, primary clinopyroxene (Cpx I-omphacite?) to secondary cli-
nopyroxene (Cpx II) and plagioclase. However, the character-
istic “fingerprint” textures have mostly been recrystallized to
granoblastic aggregates (Joanny et al. 1991). According to
composition, clinopyroxene II is diopside (Table 4) with very
low Al and Na contents.
occurs as several compositional and textural
types (Table 5). Amphibole I forms blue-green, small euhe-
dral crystals enclosed in the garnet cores. Amphibole II can
be recognized in kelyphitic rims around garnets as blue-
green, lath-shaped crystals touching the garnet. Matrix am-
phiboles (Am III), at a distance from the garnet contacts, are
either large, strongly pleochroic, dark-green to brown-green
poikiloblastic grains, or smaller grains that replace or form part
of symplectites with clinopyroxene and plagioclase (Fig. 4).
These amphiboles are rather inhomogeneous (Fig. 8): close to
Table 2: Chemical compositions of feldspars.
next to grt
next to grt
98.83 101.80 101.55 100.51
Recalculated on the basis of 8 oxygens
294 JANÁK and LUPTÁK
Table 3: Chemical compositions of biotite.
next to grt
next to grt
Recalculated on the basis of 22 oxygens
Table 4: Chemical compositions of clinopyroxene.
Recalculated on the basis of 6 oxygens
the garnets they are more aluminous (tschermakite) than in
the matrix. Actinolite (Am IV) is a later phase that grew
along fractures within earlier amphiboles.
compositions depend on their textural position.
The plagioclase in kelyphitic rims around garnets is An
while in Pl-Cpx symplectites it is An
(Table 2). The tex-
tures of plagioclase suggest that it is a secondary phase formed
by the breakdown of garnet and clinopyroxene.
The minor minerals are mainly quartz which occurs in gar-
net, in kelyphites, and in the matrix. Rutile and ilmenite are
ubiquitous as inclusions in garnet, matrix amphibole, and ke-
lyphites. Sphene is abundant in the most retrograded domains
and epidote-clinozoisite, biotite, chlorite and calcite have
been recognized as additional retrograde minerals mostly
contained in veinlets along cracks.
Thermobarometric calculations were restricted to microtex-
tural domains where local equilibrium between coexisting
mineral phases have been assumed. Both the “conventional”
and “internally consistent” thermobarometric techniques us-
ing the TWEEQU method (Berman 1991) with the thermody-
namic dataset (Berman 1988) and computer program version
TWQ of January 1992 were applied.
In metapelites, temperatures were calculated using several
calibrations of the garnet-biotite geothermometer, i.e. Ferry &
Spear (1978), Hodges & Spear (1982) Perchuk & Lavrentieva
(1983), Ganguly & Saxena (1984) and Indares & Martignole
(1985). Pressures were evaluated on the basis of the garnet-
plagioclase-sillimanite-quartz geobarometer (GASP) using
the calibrations of Newton & Haselton (1981), Hodges &
Spear (1982), Ganguly & Saxena (1984), Hodges & Crowley
(1985) and Koziol & Newton (1988). In the TWQ calcula-
tions, the mixing models of Berman (1990) for garnet (in-
volving the effect of Mn), of McMullin et al. (1991) for bi-
otite (incorporating corrections for the effect of Al and Ti)
and of Fuhrman & Lindsley (1988) for feldspars were utilized
along with the database.
In metabasites, temperatures were estimated by the garnet-
amphibole (Graham & Powell 1984) and garnet-clinopyrox-
ene (Ellis & Green 1979; Powell 1985) geothermometers.
Pressures were calculated through the application of several
geobarometers determined by suitable mineral assemblage.
In those involving garnet-amphibole -plagioclase-quartz, cal-
ibrations of Kohn & Spear (1989, 1990) with both Fe- and
Mg- end member reactions were used. In garnet-clinopyrox-
ene-plagioclase-quartz assemblages, pressures were calculat-
ed from Mg- end members (GADS) according to Newton &
Perkins (1982), Moecher et al. (1988), and Powell & Holland
(1988). In Powell and Holland’s calibration, both Hodges &
Spear (1982), and Ganguly & Saxena (1984) garnet mixing
models were employed. In garnet-plagioclase-rutile-ilmenite
assemblages, the pressure was estimated by the (GRIPS) ba-
rometer of Bohlen & Liotta (1986). In the TWQ method, ide-
al mixing between tschermakite end-members in amphibole
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 295
Table 5: Chemical compositions of amphibole.
Recalculated on the basis of 13 cations
15 15 15 15
was assumed, as well as that between diopside and heden-
bergite in clinopyroxene.
The metamorphic P-T conditions of metapelites were esti-
mated in two representative samples MF 14/95 and MF 13/93.
Sample MF 14/95 (Fig. 6, Table 6) contains mineral as-
semblage: Grt + Sil + Bt + Pl + Kfs + Qtz. The garnet is ho-
mogenous except for a very narrow retrograde rim which is
in contact with biotite. Therefore, presumed peak conditions
were calculated from the composition of the garnet core,
and those of biotite and plagioclase in the matrix. The tem-
perature and pressure range is 692–850
C and 4.5–9.8 kbar
on the basis of conventional thermobarometry, and 724 + 35
and 6018 + 559 bar according to the TWQ method. Retro-
grade conditions were estimated from the composition in
the garnet rim and those of biotite and plagioclase in contact
with garnet. Temperature and pressure calculations yield
C and 2.9–5 kbar (conventional methods) and 608
C at 3293 + 1456 bar (TWQ method) respectively.
In contrast, sample MF 13/93 (Fig. 7, Table 6) contains mus-
covite but K-feldspar is lacking, hence the mineral assemblage
is Grt + Sil + Bt + Pl + Mu + Qtz. The garnet is affected by
retrograde diffusion and resorption (Fig. 5). The inferred peak
conditions were obtained from the garnet core and from the
composition of plagioclase inclusion in the garnet and biotite
in the matrix. The temperatures and pressures calculated by
conventional thermobarometry reached 615–690
C and 4.4–
7.7 kbar, the TWQ method yields 662 + 2
C and 6133 +
30 bar. Retrograde conditions, estimated from the garnet rim,
the biotite contacting the garnet and plagioclase near the garnet
correspond to 590–635
C and 3.7–6.4 kbar (conventional meth-
ods), as well as 615 + 14
C and 4495 + 175 bar (TWQ method).
In metabasites, P-T conditions were estimated from the
garnet-clinopyroxene amphibolite sample MF 16/94 (Fig. 8,
Table 6). The texture shows the breakdown of garnet to pla-
gioclase and amphibole (Amp II), which have replaced the
garnet, and now form the kelyphitic rim. Moreover, the sym-
plectite of Cpx + Pl is thought to be the breakdown product of
former omphacite. Therefore, only inclusions of amphibole
(Am I) enclosed in the garnet may be considered to record the
prograde metamorphism, i.e. 663–692
C (Table 6), assuming
that amphibole was entrapped during the garnet growth in
amphibolite facies conditions. The eclogite stage can be only
inferred from reaction textures, indicating the breakdown of
eclogite assemblage (garnet + Cpx I-omphacite?) to a high-
pressure granulite (Grt + Cpx II + Pl + Amp II) and amphibo-
lite assemblage (Amp III + Pl + Grt), as observed in strongly
retrograded eclogites (e.g. O‘Brien 1993). Therefore, peak-
pressure conditions cannot be estimated, but only those of a
lower-pressure reequilibration. The compositions of garnet
rim and those of kelyphitic plagioclase and amphibole (Amp
II) as well as symplectitic clinopyroxene were used in several
geothermometers and barometers described above. In addi-
296 JANÁK and LUPT
Plots of thermobarometric caculations in metapelite, sample MF 14/9. a — Sketch of analysed points, b — conventional thermobarometry results, Koz — Koziol & Newton (1988),
— Newton & Haselton (1981), H&C — Hodges & Crowley (1985), H&S — Hodges & Spear (1982), F&S — Ferry & Spear (1978), P&L — Perchuk & Lavrentieva (1983), Berm —
Berman (1990), c — WQ intersections of retrograde conditions, d — TWQ intersections of peak conditions. Unlabelled reactions: 1 — Phl+Alm = Ann+Py, 2 — Kfs+Alm+W =
Ann+2Qtz+Si, 3 — Gr+2Kfs+2Py+2W = 3Qtz+2Phl+3An, 4 — 3Si+Kfs+2Gr+Alm+W = Ann+6An, 5 — Kfs+Py+W = Si+2Qtz+Phl.
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 297
Plots of thermobarometric results in metapelite, sample MF 13/93. a — sketch of analysed points, b — conventional thermobarometry results, c — TWQ intersections of retrograde
conditions, d — TWQ intersections of peak conditions. Unlabelled reactions have the same numbers as in the Fig. 6.
298 JANÁK and LUPT
Plots of thermobarometric results in garnet-clinopyroxene metabasite, sample MF 16/94. a — sketch of analysed points, b — conventional thermobarometry results of breakdown
conditions, E&G — Ellis & Green 1983, G&P — Graham & Powell 1984, Pow — Powell 1985, P&H — Powell & Holland 1986, B&L — Bohlen & Liotta 1986, N&P — Newton & Perkins
1982, Moech — Moecher 1988, 1–6 Kohn & Spear 1989, 1990, c — plots of analysed amphiboles in the diagram of Leake (1978) showing Amp I and II by circles, Amp III by squares and
Amp IV by stars, d — TWQ intersections of peak conditions.
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 299
tion, the presence of rutile and ilmenite in kelyphitic domains
was utilized for geobarometry.
The estimated breakdown conditions correspond to 679–
C and 7.4–10.9 kbar according to conventional ther-
mobarometry (Fig. 8, Table 6). The TWQ results yield
C and 9270 bar for Grt + Cpx II + Pl assemblage
whereas that involving Grt + Amp II(tsch) + Pl yield 768
and 9656 bar which is somewhat higher even for reduced
water activity in the fluid (aH
O = 0.7) as shown in Fig. 8.
The rock textures and thermobarometric data support an
anatectic origin of both metapelitic and mafic migmatites
ahigh-grade conditions exceeding 700
C. Taking into con-
sideration that diffusion has homogenized the compositions
of garnet cores, peak temperatures, however, could have
been even higher than obtained by geothermometry (e.g.
Spear 1991; Spear & Florence 1992).
Estimated P-T conditions for metapelites are above the
water saturated granite solidus (Fig. 9), thus supporting the
anatectic origin of metapelitic migmatites. Moreover, as
demonstrated by sample MF 14/94, muscovite-free and K-
feldspar-bearing assemblages exceeded even the conditions
of muscovite dehydration-melting according to Thompson
(1990). Dehydration-melting of biotite (e.g. Le Breton &
Thompson 1988) would require a higher temperature (ca.
C) than indicated by thermometry, however, as
discussed above, the peak temperatures are mostly obscured
due to diffusion and retrogression.
The inferred kyanite-sillimanite transformation may indi-
cate a pressure decrease at increasing temperature during
“clockwise” P-T-t paths from the kyanite to the sillimanite
stability field (Fig. 9). Therefore, the partial melting could
have been facilitated by decompression; the crossing of the
dehydration-melting curve of muscovite with positive dP/dT
during the uplift is effective for increasing the volume of
melt (Clemens & Vielzeuf 1987; Thompson 1990).
In metabasites, partial melting produced tonalitic to
trondhjemitic leucosome, similar to field and experimental ob-
servations (e.g. Percival 1983; Hartel & Pattison 1996; Beard &
Lofgren 1991; Rapp et al. 1991; Rapp & Watson 1995; Rush-
mer 1991; Wyllie & Wolf 1993). The P-T conditions estimated
from the garnet-clinopyroxene amphibolite are above the water-
TWQ (Berman 1991)
6133 (30 bar)
4495 (±175 bar)
6018 (±559 bar)
3293 (±1456 bar)
Sample MF 16
714-724 (Powell 1985)
7.4 (Kohn & Spear 1990)
9.1 (Kohn & Spear 1990)
TWQ (Berman 1991)
9656 (±0.51 bar)
9270 (±0.82 bar)
*Abbreviations: H&S Hodges & Spear (1982), Koz Koziol & Newton (1988), P&L Perchuk & Lavrentieva (1983), Moech
Moecher et al. (1988), N&P Newton & Perkins (1982), G&P Graham & Powell (1984), E&G Ellis & Green (1979), P&H Powell
& Holland (1986), B&L Bohlen & Liotta (1986)
Summary of thermobarometric data.
300 JANÁK and LUPTÁK
Pressure-temperature diagram showing tentative P-T paths
of analysed samples with respect to melting conditions. Shaded el-
Grt — Cpx metabasite (MF 16/94), black square: Kfs —
bearing and Mu — free metapelite (MF 14/94), white square: Mu
— bearing and Kfs — free metapelite (MF 13/93). Melting equi-
libria are from Thompson (1990 and references therein) and Wyl-
lie & Wolf (1993). Alumosilicate stabilities are according to Hold-
saturated solidus of basalt (Fig. 9), hence partial melting as a
major process of migmatitization is possible. The calculated
temperatures are below most experimentally investigated am-
phibole dehydration-melting equilibria in fluid absent condi-
tions (see references above). However, as pointed out by Wyllie
& Wolf (1993), the amphibolite dehydration-melting solidus
and the melting interval for a fully-hydrated amphibolite
(hornblende + plagioclase) producing liquid and garnet-amphib-
olite residues can be largely expanded to much lower tempera-
tures and pressures than the other experimental results.
As indicated by reaction textures, the Malá Fatra metabasites
most probably followed the “clockwise” P-T-t trajectories
(Fig. 9) from higher-pressure (eclogite facies) conditions. They
were reequilibrated, and most probably also melted, at condi-
tions which are transitional between the amphibolite and high-
pressure granulite facies (e.g. Bucher & Frey 1994). This is in-
dicated by the assemblage Grt + Cpx + Plg + Qtz in the
breakdown domains. The absence of orthopyroxene indicates
that conditions of high-temperature, medium-pressure granu-
lite facies were not reached. Alternatively, orthopyroxene
could have been totally consumed by amphibole due to “rehy-
dration-crystallization” of the trondhjemite melt during the ret-
rograde portion of the P-T-t path (e.g. Stevens & Clemens
1993; Brown 1994).
Taking into consideration the above reconstructed P-T-t paths,
decompressional, dehydration-melting in both- metapelite and
metabasite protoliths could be a viable process of migmatitization
in the Malá Fatra crystalline basement.
The estimated P-T conditions indicate that melting took
place at deep-crustal levels corresponding to 5–10 kbar,
whereas the emplacement of granitoids in the northern part of
the Malá Fatra, estimated from the amphibole barometry
(Benko 1996; Broska et al. 1997) corresponds to 3–3.5 kbar.
The textures observed in the migmatites suggest close rela-
tionships between melt distribution and deformation, hence
the melt could have been extracted from its source and trans-
ported via a network of shear zones and fractures structurally
upwards, forming more voluminous portions of the melt col-
lecting into the pluton (e.g. Hollister & Crawford 1986; Cle-
mens & Mawer 1993; Collins & Sawyer 1996). Field rela-
tions and the geological structure in the profile across the
southern part of the Malá Fatra (Fig. 2) demonstrate that there
is an increasing abundance of melt structurally upwards, i.e.
from migmatitic gneisses and amphibolites to the “hybrid”
granitoids (granodiorites and tonalites).
The Malá Fatra crystalline basement closely resembles the
situation in some other areas in the Central Western Car-
pathians (mainly the Tatra Mts. and Low Tatra Mts.), where
high-grade metamorphism and partial melting of lower-crustal
protoliths has been documented (Janák et al. 1988, 1995, 1996;
Janák 1994; Krist et al. 1992; Hovorka et al. 1993; Petrík et al.
1994). Generally south to southeast-vergent, syn- to post-meta-
morphic penetrative deformation, decompression from high-
pressure (eclogite facies) and recrystallization at medium-pres-
sure and high-temperature conditions accompanied by partial
melting is characteristic for the Variscan tectono-metamorphic
evolution of the Western Carpathian basement, similar to the
situation in the Central European Variscides (e.g. Matte 1986;
Neubauer & Von Raumer 1993).
This paper is part of the MSc thesis of
B.L., supported by Department of Mineralogy and Petrology,
Comenius University Bratislava. We are grateful to Pavol Si-
man (Geological Survey, Bratislava) for the help with the mi-
croprobe analyses. Milan Kohút (Geological Survey, Brat-
islava), Pavel Pitoňák (Geol. Inst. Academy of Science,
Banská Bystrica) and Lívia Ludhová (Comenius University,
Bratislava) are thanked for their help during the field work.
Peter Nábělek (University of Missouri, Columbia) and Ján
Spišiak (Geol. Inst. Academy of Science, Banská Bystrica)
provided very helpful and constructive reviews, which great-
ly improved the manuscript.
Ashworth J. R., 1985: Introduction. In: Ashworth J.R. (Ed.): Mig-
Beard J.S. & Lofgren G.E., 1991: Dehydration melting and water-
saturated melting of basaltic and andesitic greenstones and
amphibolites at 1, 3, and 6.9 kbar. J. Petrology, 32, 365–401.
Benko P., 1996: Geochemical and mineralogical study of granitoid
rocks in the Kriváň massif of the Malá Fatra Mts. M.Sc.thesis,
Department of Mineralogy and Petrology, Comenius Univer-
Berman R.G., 1990: Mixing properties of Ca-Mg-Fe-Mn garnets.
Berman R.G., 1991: Thermobarometry using multi-equilibrium
calculations: a new technique, with petrological applications.
, 29, 833–855.
PRESSURE-TEMPERATURE CONDITIONS OF HIGH-GRADE METAMORPHISM 301
Bohlen S.R. & Liotta J.J., 1986: A barometer for garnet amphibo-
lites and garnet granulites. J. Petrology, 27, 1025–56.
Broska I., Petrík I. & Benko P., 1997: Petrology of the Malá Fatra
granitoid rocks (Western Carpathians, Slovakia). Geol. Car-
48, 1, 27–37.
Brown M., 1994: The generation, segregation, ascent and em-
placement of granite magma: the migmatite-to-crustally-de-
rived granite connection in thickened orogens. Earth Sci.
Bucher K. & Frey M., 1994: Petrogenesis of Metamorphic rocks.
Clemens J.D. & Mawer C.K., 1992: Granite magma transport by
fracture propagation. Tectonophysics, 204, 339–360.
Clemens J.D. & Vielzeuf D., 1987: Constraints on melting and mag-
ma production in the crust. Earth Planet. Sci. Lett., 86, 287–306.
Collins W.J. & Sawyer E.W., 1996: Pervasive granitoid magma trans-
fer through the lower-middle crust during non-coaxial compres-
sional deformation. J. Metamorphic Geol., 14, 565–579.
Ellis D.J. & Green D.H., 1979: An experimental study of the effect
of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria.
Contr. Mineral. Petrology
, 71, 13–22.
Fuhrman M. & Lindsley D., 1988: Ternary - feldspar modelling and
thermometry. Amer. Mineralogist, 73, 201–215.
Ganguly J. & Saxena S.K., 1984: Mixing properties of aluminosil-
icate garnets: constraints from natural and experimental data
and applications to geothermo-barometry. Amer. Mineralo-
, 69, 88–97.
Graham C.M. & Powell R., 1984: A garnet-hornblende geother-
mometer and application to the Pelona schists, southern Cali-
fornia. J. Metamorphic Geol., 2, 13–22.
Hartel T.H.D & Pattison D.R.M., 1996: Genesis of the Kapuskas-
ing (Ontario) migmatitic mafic granulites by dehydration
melting of amphibolite: the importance of quartz to reaction
progress. J. Metamorphic Geol., 14, 591–611.
Hodges K.V. & Spear F.S., 1982: Geothermometry, geobarometry
and the Al
triplepoint at Mt. Moosilauke, New Hamp-
shire. Amer. Mineralogist, 67, 1118–1134.
Hodges K.V. & Crowley, 1985: Error estimation for empirical geother-
mometry for pelitic system. Amer. Mineralogist, 70, 702–709.
Holdaway M.J., 1971: Stability of andalusite and the aluminium
silicate phase diagram. Amer. J. Sci., 271, 97–245.
Hollister L.S., 1966: Garnet zoning: an interpretation based on the
Rayleigh fractionation model. Science, 154, 1647–1651.
Hollister L.S. & Crawford M.L., 1986: Melt-enhanced deforma-
tion: a major tectonic process. Geology, 14, 558–561.
Hovorka D., 1967: Porphyrites and lamprophyres of the tatrove-
poric crystalline. Sbor. Geol. Vied, Západ. Karpaty, 8, 51–78.
Hovorka D., 1969: Metasomatic alterations of amphibolites in the
Malá Fatra. Geol. Práce, Spr., 49, 5–61.
Hovorka D., 1974: Amphibolites of migmatite areas, West Car-
pathian Mts. Chemie der Erde, 33, 3, 221–242.
Hovorka D., Ivan P., Kratochvíl M., Reichwalder P., Rojkovič I.,
Spišiak J. & Turanová L., 1985: Ultramafic rocks of the West-
ern Carpathians. GÚDŠ, Bratislava, 1–258.
Hovorka D. & Méres Š., 1991: Pre-upper carboniferous gneisses
of the Strážovské Vrchy upland and the Malá Fatra Mts. Acta
geol. geogr. Univ. Comen., Geol
., 46, 103–70.
Hovorka D., Méres Š. & Caňo F., 1992: Petrology of the garnet-
clinopyroxene metabasites from the Malá Fatra Mts. Miner.
, 24, 45–52.
Hovorka D., Méres Š. & Ivan P., 1994: Pre-Alpine Western Car-
pathians basement complexes: lithology and geodynamic set-
ting. Mitt. Österr. Geol. Gesell., 86, 33–44.
Indares A. & Martignole J., 1985: Biotite-garnet geothermometry
in granulite facies: influence of Ti and Al in biotite. Amer.
, 70, 272–278.
Ivanov M. & Kamenický L., 1957: Contributions to geology and
petrology of the Malá Fatra crystalline. Geol. Práce, Zoš., 45,
Janák M., 1994: Variscan uplift of the crystalline basement, Tatra
Mts., Central Western Carpathians: Evidence from
laser probe dating of biotite and P-T-t paths. Geol. Carpathi-
, 45, 293–300.
Janák M., Kahan S. & Jančula D., 1988: Metamorphism of pelitic
rocks and metamorphism in SW part of Western Tatra Mts.
crystalline complexes. Geol. Carpathica, 39, 455–488.
Janák M., Pitoňák P., Spišiak J., Petrík I. & O’Brien P.J., 1995:
Trondhjemitic-tonalitic melts in the Western Carpathian base-
ment: implications for partial melting of amphibolite and dif-
ferentiation of the lower crust. Terra Abstr., Suppl. 1, 7.
Janák M., O’Brien P.J., Hurai V. & Reutel Ch., 1996: Metamorphic
evolution and fluid composition of garnet-clinopyroxene am-
phibolites from the Tatra Mountains, Western Carpathians.
Joanny V., van Roermund H. & Lardeaux J.M., 1991: The clinopy-
roxene/plagioclase symplectite in retrograde eclogites: a po-
tential geothermobarometer. Geol. Rdsch., 80, 303–320.
Kamenický L. & Macek J., 1984: Ein profil durch die lithostratig-
raphischen schichtenfolgen des kristallinikum des gebirges
Malá Fatra. Geol. Zbor. Geol. Carpath., 35, 157–160.
Kamenický L., Macek J. & Krištín J., 1987: Contribution to pe-
trography and geochemistry of granitoids in the Malá Fatra.
Kohn M.J. & Spear F.S., 1989: Empirical calibration of geobarom-
eters for the assemblage garnet + hornblende + plagioclase +
quartz. Amer. Mineralogist, 74, 77–84.
Kohn M.J. & Spear F.S., 1990: Two new geobarometers for garnet
amphibolites, with applications to Southeastern Vermont.
Korikovsky S.P, Kamenický L, Macek J. & Boronikhin V.A.,
1987: P-T conditions of metamorphism of the crystalline
schists in the Malá Fatra (in the profile of the Mlynský Potok
area). Geol. Zbor. Geol. Carpath., 38, 409–427.
Koziol A.M. & Newton R.C., 1988: Redetermination of the anorthite
breakdown reaction and improvement of the plagioclase-garnet-
-quartz geobarometer. Amer. Mineralogist, 73, 216–233.
Krist E., Korikovsky S.P., Putiš M., Janák M. & Faryad S.W.,
1992: Geology and petrology of metamorphic rocks of the
Western Carpathian crystalline complexes. Comenius Univer-
, Bratislava, 1–324.
Kretz R., 1983: Symbols for rock-forming minerals. Amer. Miner-
, 68, 277–279.
Leake B.E., 1978: Nomenclature of amphiboles. Amer. Mineralo-
, 63, 1023–1052.
Le Breton N. & Thompson A.B., 1988: Fluid-absent (dehydration)
melting of biotite in metapelites in the early stages of crustal
anatexis. Contr. Mineral. Petrology, 99, 226–237.
Lupták B., 1996: Petrological and petrotectonic study of metamor-
phic rocks in the Malá Fatra (Ve ká Lúka Massif). M.Sc. thesis.
Department of Mineralogy and Petrology, Comenius universi-
McMullin D.W.A., Berman R.G. & Greenwood H.J., 1991: Cali-
bration of the SGAM thermobarometer for pelitic rocks using
data from phase equilibrium experiments and natural assem-
blages. Canad. Mineralogist, 29, 889–908.
Moecher D.P., Anovitz L.M. & Essene E.J., 1988: Calculation of
clinopyroxene-garnet-plagioclase-quartz geobarometers and
application to high grade metamorphic rocks. Contr. Mineral.
, 100, 92–106.
Neubauer F. & von Raumer J.F., 1993: The Alpine basement - linkage
302 JANÁK and LUPTÁK
between variscides and East-Mediterranean mountain belts. In:
J. F. von Raumer & F. Neubauer (Eds.): Pre-Mesozoic geology in
the Alps. Springer-Verlag,
Matte P., 1986: Tectonics and plate tectonics model for the
Variscan belt of Europe. Tectonophysics, 126, 329–374.
Newton R.C. & Haselton H.T., 1981: Thermodynamics of the gar-
-quartz geobarometer. In: Newton
R.C. Navrotsky A. & Wood B.J. (Eds.): Thermodynamics of
Minerals and Melts. Advances in Physical Geochemistry, Vol.
, New York, 129–145.
Newton R.C. & Perkins D., 1982: Thermodynamic callibration of
geobarometers based on the assemblages garnet-plagioclase-
orthopyroxene (clinopyroxene)-quartz. Amer. Mineralogist,
O’Brien P.J., 1993: Partially retrograded eclogites of the Münchberg
Massif, Germany: records of a multistage Variscan uplift history
in the Bohemian Massif. J. Metamorphic Geol., 11, 241–260.
Percival J.A., 1983: High-grade metamorphism in the Chapleau-
Foleyet area, Ontario. Amer. Mineralogist, 68, 667–686.
Perchuk L.L. & Lavrentieva I.V., 1983: Experimental investiga-
tions of the exchange equilibria in the systems cordierite-gar-
net-biotite. In: Saxena S.K. (Ed.): Kinetics and equilibrium in
Mineral Reactions. Advances in Physical Geochemistry,
New York, 199–240.
Perchuk L.L., Lavrentieva I.V., Aranovich L.J. & Petrík I., 1984:
Comparative characteristics of thermodynamic regimes of
metamorphic rocks from Caucasus ridge and Western Car-
pathians. Geol. Zbor. Geol. Carpath., 37, 3, 33–363.
Petrík I., Broska I. & Uher P., 1994: Evolution of the Western Car-
pathians granite magmatism: Age, source rock, geotectonic
setting and relation to the Variscan structure. Geol. Carpathi-
, 42, 5, 283–291.
Powell R. & Holland T.H.B., 1988: An internally consistent ther-
modynamic dataset with uncertainties and correlations: 3.
Applications to geobarometry, worked examples and a com-
puter program. J. Metamorphic Geol., 6, 173–204.
Powell R., 1985: Regression diagnostics and robust regression in
geothermometer/geobarometer calibration: the garnet-cli-
nopyroxene geothermometer revisited. J. Metamorphic Geol.,
Rapp R.P., Watson E.B & Miller C.F., 1991: Partial melting of am-
phibolite/eclogite and the origin of Archean trondhjemites
and tonalites. Precambrian Research, 51, 1–25.
Rapp R.P. & Watson E.B., 1995: Dehydration melting of metaba-
salt at 8–32 kbar: Implications for continental growth and
crust-mantle recycling. J. Petrology, 36, 891–931.
Rushmer T., 1991: Partial melting of two amphibolites: contrasting
experimental results under fluid-absent conditions. Contr.
, 107, 41–59.
Scherbak N.P., Cambel B., Bartnitsky E.N. & Stepanyuk L.M., 1990:
U-Pb age of granitoids rock from the quarry Dubná Skala-Malá
Fatra Mts. Geol. Zbor. Geol. Carpath., 41, 4, 407–414.
Spear F.S., 1991: On the interpretation of peak metamorphic tem-
peratures in light of garnet diffusion during cooling. J. Meta-
Spear F.S. & Florence F.P., 1991: Thermobarometry in granulites: pit-
falls and new approaches. Precambrian Research, 55, 209–241.
Stevens G. & Clemens J.D., 1993: Fluid-absent melting and the
roles of fluids in the lithosphere: a slanted summary? Chem.
., 108, 1–17.
Thompson A.B., 1990: Heat, fluids, and melting in the granulite
facies. In: D.Vielzeuf & Ph.Vidal (Eds.): Granulites and
Crustal Evolution NATO. ASI Series, Vol. 311, Kluwer
Woodsworth G.J., 1977: Homogenisation of zoned garnet from
pelitic schists. Canad. Mineralogist, 15, 230–242.
Wyllie P.J. & Wolf M.B., 1993: Amphibolite dehydration-melting:
sorting out the solidus. In: H.M. Prichard, T. Alabaster, N.B.W.
Harris & C.R. Neary (Eds.): Magmatic processes and plate tec-
tonics. Geological Society Special Publication
, 76, 405–416.
Yardley B.W.D., 1977: An empirical study of dffusion in garnet.