www.geologicacarpathica.sk
GEOLOGICA CARPATHICA, DECEMBER 2010, 61, 6, 469—481 doi: 10.2478/v10096-010-0029-9
Introduction
The Tisia Unit in the sense of Csontos et al. (1992), which is
equivalent to the Tisia Megaunit of Szederkényi (1996), rep-
resents a large lithosphere block with a complex internal
structure. It has traditionally been regarded as one of the
most stable parts of the Pannonian Basin basement which
practically escaped Alpine metamorphism. Over the last few
decades several researches (Árkai et al. 1998, 2000; Árkai
2001 and references therein) pointed out that this is not com-
pletely true, showing that large areas of the Pannonian Basin
basement were in fact metamorphosed or overprinted as a re-
sult of the Eoalpine (Cretaceous) metamorphism.
The Tisia Unit is made up of Variscan igneous and meta-
morphic complexes and post-Variscan overstep sequences.
Typical Tisia rocks are widespread and can be found in the
South Transdanubian ranges (Mecsek, Villány Hills), in the
Apuseni Mountains (Bihor, Pădurea Craiuli, Codru-Moma,
Higni ) and in the Slavonian Mountains (Psunj, Papuk,
Krndija), where some of the best outcrops of the South Tisia
igneous and metamorphic rocks occur in Mt Papuk
(e.g. Pamić & Jurković 2002; Pamić et al. 2002). These
rocks, which can provide detailed insight into the geological
history of the Tisia Unit form polymetamorphic complexes
(Pamić & Lanphere 1991). The complexes of the Slavonian
Mts are subdivided on the basis of structural and lithostrati-
graphic studies by Jamičić (1983, 1988). He distinguished
three metamorphic complexes with distinct metamorphic
evolution paths; namely the Psunj metamorphic complex,
Eoalpine (Cretaceous) very low- to low-grade metamorphism
recorded on the illite-muscovite-rich fraction of
metasediments from South Tisia (eastern Mt Papuk, Croatia)
VANJA BIŠEVAC
1
, KADOSA BALOGH
2
, DRAŽEN BALEN
1
and DARKO TIBLJAŠ
1
1
Institute of Mineralogy and Petrology, Department of Geology, Faculty of Science, University of Zagreb, Horvatovac 95, HR-10000 Zagreb,
Croatia; vabisevac@geol.pmf.hr
2
Institute of Nuclear Research, Hungarian Academy of Science, Bem tér 18/c, 4001 Debrecen, Hungary
(Manuscript received February 11, 2010; accepted in revised form October 13, 2010)
Abstract: Eoalpine very low- to low-grade metamorphism related to Cretaceous orogenesis has been investigated in the
Slavonian Mts, Croatia. Samples belonging to the Psunj metamorphic complex (PMC), the Radlovac metamorphic
complex (RMC) and Permian-Triassic and Triassic sedimentary sequences (PTSS) were studied. The Kübler and Árkai
indices of all the analysed samples indicate high-anchizonal to epizonal metamorphism. The degree of Eoalpine meta-
morphism tends to be constant in all samples implying that the different complexes passed through and recorded the
same event. Measurements of illite-white K-mica b
0
-parameter of the RMC samples imply transitional low- to medium-
pressure character of the metamorphism. These data together with K-Ar ages ( ~ 100—80 Ma) measured on illite-white
K-mica rich < 2 m grain-size fractions point to Late Cretaceous very low- to low-grade regional metamorphism pre-
sumably related to the main nappe-forming compressional events in the Pannonian Basin and the Carpathians. The P-T-t
(pressure-temperature-time) evolution of the studied area is in good agreement with similar scenarios in the surround-
ing areas of Tisia, but also in Eastern Alps, Carpathians and Pannonian Basin (ALCAPA).
Key words: Eoalpine metamorphism, South Tisia, Radlovac metamorphic complex, thermobarometry, geochronology,
Kübler index, Árkai index, K-Ar dating.
the Papuk metamorphic complex and the Radlovac meta-
morphic complex.
The present study focuses mostly on the Radlovac meta-
morphic complex (RMC) which consists of very low- to low-
grade metamorphic sequences locally intruded by metabasic
rocks (Pamić & Jamičić 1986). According to Jamičić & Brkić
(1987) and Jamičić (1988) the RMC occupies the highest
structural position of all the Variscan complexes in the area
and is uncomformably overlain by Permian-Triassic and
Triassic sedimentary sequences (PTSS). The RMC represents
the original sedimentary cover over the PMC (Jamičić 1988).
Although some previous studies indicated a certain P-T evolu-
tion of this area (Jamičić 1983, 1988; Slovenec 1986; Pamić
& Lanphere 1991; Jerinić et al. 1994; Judik et al. 2002; Biše-
vac et al. 2009), no research has been carried out so far in or-
der to constrain the spatial, temporal and metamorphic
conditions of a possible Eoalpine metamorphism in this area.
In this paper a more detailed study concerning the degree and
age of metamorphic evolution of this area in the specific geo-
logical timeframe is presented and correlated with similar in-
vestigations carried out in other parts of the Tisia Unit and
surrounding areas.
The main aim of the present paper is to provide new data on
the nature and regional distribution of the Eoalpine metamor-
phism that affected the Variscan and post-Variscan formations
of the southern part of the Tisia Unit in the Slavonian Mts. For
this purpose, rocks belonging to the RMC as well as those rep-
resenting the PTSS and parts of PMC sampled along the
Kutjevo transect (Balen et al. 2006) were studied by the illite
470
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
“crystallinity” (Kübler index), chlorite “crystallinity” (Árkai
index) and vitrinite reflectance methods in order to determine
the temperature conditions, while the b
0
-parameter of K-white
mica was used in order to estimate the pressure conditions of
metamorphism. The K-Ar age dating method was used to de-
termine the age of metamorphism and metamorphic overprint
of the studied rocks.
The new P-T and age data presented in this paper form a
solid base for further research and reconstruction of the tec-
tono-metamorphic history of the wider area and its correlation
with similar metamorphic complexes in Central and Eastern
Europe.
Geological settings
The Slavonian Mts, situated in Slavonia, the north-eastern
region of Croatia (Fig. 1), are characterized by numerous
outcrops of igneous and metamorphic rocks that form the
Tisia Unit. Tisia represents a continental fragment broken off
from the southern rim of the Eurasian plate (i.e. the southern
margin of Variscan Europe) during the Alpine evolution of
Tethys (Géczy 1973). After complex drifting and multiple
rotation events, mostly during Mesozoic and Cenozoic
times, the Tisia reached its present tectonic position (Csontos
1995; Haas & Péró 2004) (Fig. 1). The Tisia Unit is made up
of three nappe systems (Mecsek, Villány-Bihor and Békés-
Codru) comprising the Variscan igneous and metamorphic
basement and post-Variscan overstep sequences (Haas &
Péró 2004; Csontos & Vörös 2004; Schmid et al. 2008). Ac-
cording to the interpretation of Schmid et al. (2008) the
Slavonian Mts represent an integral part of the Villány-Bihor
nappe system. The Variscan igneous and metamorphic com-
plexes of south Tisia, which crop out in the Slavonia region,
constitute a part of the metamorphic belt characterized by
granitoid rocks accompanied by migmatites (Pamić &
Lanphere 1991). These rocks can be well correlated with
similar rocks in the Mecsek Mts (south Hungary) (Buda
Fig. 1. a – Tectonic setting of the Tisia Unit within the Alpine-Carpathian-Dinaric framework with the position of the Slavonian Mts. b – Sketch
map of the Slavonian Mts (Papuk, Psunj, Ravna gore and Krndija) with approximate position of the studied area (marked by the black box).
c – Simplified geological map of the investigated area showing the position of the samples within the complexes as defined by Jamičić (1988).
1 – garnet-staurolite gneisses with lenses of granitoids, amphibolites and amphibolite schists; 2 – chlorite-sericite schists; 3 – me-
tagreywackes and chloritoid schists; 4 – migmatites; 5 – slates, phyllites, quartzites, metasandstones and metaconglomerates; 6 – phyllitic
metaconglomerates; 7 – quartz metasandstones; 8 – metasandstones; 9 – dolomites and dolomitic limestones; 10 – gabbro; 11 – grani-
toid; 12 – reverse fault (covered or assumed); 13 – normal fault (covered or assumed); 14 – erosive or tectono-erosive boundary; 15 – nor-
mal boundary (established, covered). Remark: 1 and 2 belong to Psunj metamorphic complex; 4 represents part of the Papuk metamorphic
complex; 3 and 5 represents the Radlovac metamorphic complex; 6, 7, 8 and 9 belong to the Permian-Triassic sedimentary sequence.
471
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
1981; Hass & Péró 2004), the Western Carpathians (Hovorka
& Petrík 1992) and in other European Variscan terrains, such
as the Bohemian Massif (Liew et al. 1989).
Jamičić (1983, 1988) distinguished three tectono-metamor-
phic complexes in the Slavonian Mts, characterized by several
phases of deformation and metamorphism (Fig. 1). The Psunj
metamorphic complex (PMC) is assumed to be formed by a
metamorphic event during the Baikalian orogeny showing a
strong retrogressive overprint as a result of the Caledonian
orogeny. According to Pamić et al. (2002) the rocks belonging
to the PMC together with Papuk metamorphic complex, as de-
fined by Jamičić (1988), represent a Barrovian metamorphic
sequence, characterized by zonal distribution of index miner-
als, ranging from greenshists to amphibolite facies conditions.
Greenschist facies metamorphic sequences are composed of
metapelites, chlorite schists and micaschists, while amphibo-
lite facies sequences comprise paragneisses, garnetiferous mi-
caschists, amphibolites, metagabbros and marbles, locally
intruded by discordant granodiorites and plagiogranites (i.e.
I-type granites according to Pamić 1986; Pamić & Lanphere
1991). Although geochronological data point to the main
metamorphic phase closely associated to the Variscan oroge-
ny (Pamić et al. 1988, 1996; Pamić 1998), Balen et al. (2006)
proved the existence of a pre-Variscan metamorphic event.
Recent studies (Biševac et al. 2009) showed that PMC also ex-
perienced post-Triassic very low- to low-grade metamorphic
overprint. The Radlovac metamorphic complex (RMC) con-
sists of very low- to low-grade metamorphic sequences largely
composed of slates, metagreywackes, metaconglomerates and
subordinate phyllites. According to Jamičić (1988) it was
metamorphosed during the late stages of the Variscan oroge-
ny. The lower and middle parts of the RMC are intruded by
metabasic rocks (Pamić & Jamičić 1986). The age of sedimen-
tation, but also the age of metamorphism of the RMC, arouses
the curiosity of many researchers. According to the field rela-
tions the RMC unconformably overlies the prograde meta-
morphic sequences (Jamičić 1983, 1988) and contains a
Westphalian microflora (Brkić et al. 1974) which documents a
Pennsylvanian age of the protolith. Jerinić et al. (1994) state
that the protolith rocks are Silurian, Devonian to (?) Missis-
sippian. K-Ar dating of clinopyroxene monomineralic con-
centrate from ophitic metagabbro, which intruded the complex
(Pamić & Jamičić 1986), gave ages of 416.0 ± 9.0 and
318.6 ± 12.2 Ma (Pamić et al. 1988; Pamić & Lanphere 1991).
K-Ar age determinations on two slates from different com-
plexes yielded K-Ar whole rock ages of 203.9 ± 6.9 Ma (slate
belonging to the RMC) and 100.6 ± 3.5 Ma (slate belonging to
the PMC), which, according to Pamić et al. (1988) apparent-
ly represent partially or completely reset ages, due to the
subsequent heating. The available data are not sufficient to
reach a final conclusion concerning the age of metamorphism
of the RMC. The Papuk metamorphic complex was subject-
ed to metamorphism and migmatitization during the Cale-
donian orogeny (Jamičić 1988). It consists predominantly of
(a) S-type granites which are enveloped in the NE and SW
by (b) migmatites and migmatitic gneisses which grade into
(c) amphibolite facies metamorphic sequences composed of
garnetiferous amphibolites, paragneisses and micaschists
(Pamić 1986; Pamić & Lanphere 1991).
According to Jamičić (1988) the PTSS uncomformably
overly the Paleozoic rocks, and is characterized by several
lithostratigraphic units. The base of the sequence is built up by
coarse clastic rocks represented by phyllitic conglomerates
and sandstones which grades continuously into red to purple
fine-grained sandstones and siltstones. This facies contains
granitoid, gneiss and pegmatite clasts derived from the meta-
morphic complex of the Papuk Mountain. The second group,
represented by fine-grained quartz sandstones, is transitional
towards the Lower Triassic strata. The Lower Triassic se-
quence, as part of the PTSS, is represented by sandstones, cal-
careous sandstones and siltstones. Sedimentation in the area
continued into the Middle Triassic which is represented by do-
lomites, calcareous-dolomitic breccias and subordinate lime-
stones. Recently, Biševac et al. (2009) showed that the PTSS
underwent very low- to low-grade metamorphism. This meta-
morphism affected predominately the clay minerals, thus leav-
ing hardly noticeable marks and reassigning (in the strict sense
of metamorphic classification) the Mesozoic sedimentary rock
complex into very-low grade metasediments. Since the effects
of metamorphism studied here are hardly or not at all visible
without the aid of instrumental techniques, we will avoid de-
claring them as metasediments.
Analytical methods
Isotope geochronological measurements were preceded by
petrographic investigations in order to select the appropriate
samples representing the PMC, RMC and PTSS units for fur-
ther analyses (Fig. 1). A detailed description of the petro-
graphic features of the representative samples, as well as the
procedure of sample preparation and the petrographic tech-
nique used were described in Biševac et al. (2009). To assure
the possibility of an inter-laboratory correlation of the Kübler
index (KI) and Árkai index (ÁI) some details of the X-ray dif-
fraction (XRD) work are given here. For detailed explanation
of the standardization procedure together with measurement
conditions see Biševac et al. (2009).
The whole rock powder XRD analysis of the samples (a
modal composition determination) was performed on a Philips
X’Pert Pro diffractometer equipped with the X’celerator de-
tector using CuK radiation from a tube operating at 40 kV
and 45 mA. The step width was 0.017° 2 with 43 s counting
time per step; the samples were run between 4 and 65° 2 .
Special attention was given to the clay minerals ( < 2 µm
fraction) using the procedure proposed by Starkey et al.
(1984). Samples were measured as highly oriented air dried
preparations on glass slides additionally treated with ethylene-
glycol (EG) and heated first at 400 °C and than at 550 °C. The
instrumental settings were the same as for the modal composi-
tion determination.
KI and ÁI were measured after Kübler (1967, 1975, 1990)
and Árkai (1991) respectively. The agreed-on boundary be-
tween the diagenetic zone and the anchizone at present is at
KI = 0.42° 2 CuK , while for the anchizone-epizone bound-
ary it is KI = 0.25° 2 CuK . These boundaries are associated
with temperatures of approximately 200 °C and 300 °C re-
spectively (Kübler 1968; Warr & Rice 1994). The anchizone
472
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
is further divided into a high and low temperature anchizone.
The boundary between these two zones is KI = 0.30° 2
CuK and corresponds to the temperature of approximately
260 °C (Potel et al. 2006). The boundaries of the anchizone
for ÁI were redrawn from Árkai et al. (1995b) being:
ÁI (001) = 0.26—0.37° 2 and ÁI (002) = 0.24—0.30° 2
CuK . Sample preparation was made according to the recom-
mendation of Kisch (1991) and the full width at half maxi-
mum (FWHM) was read manually. KI and ÁI were measured
on air dried and EG treated samples. No shift of the basal
white mica reflection after EG treatment was observed, hence
discussion is based only on the air-dried scan results. The
standardization of the KI and ÁI values of samples measured
in the laboratory to those from Kübler’s laboratory, taken as
reference values, was made using eight Kisch’s standards,
namely rock slabs polished parallel to the foliation (Kisch
1990; 1991). Crystallinity Index Standards (CIS) (Warr &
Rice 1994) were used later for monitoring changes of the mea-
sured FWHM caused by tube ageing.
White K-mica geobarometry worked out for lower green-
schist facies pelitic rocks by Sassi (1972) and extended by
Padan et al. (1982) to the high temperature part of the an-
chizone was applied for qualitative estimation of the metamor-
phic pressure conditions. For these geobarometric estimations
the constraints given by Guidotti & Sassi (1986) for appropri-
ate modal composition were also taken into consideration. The
b
0
-parameter was measured on rock slabs cut perpendicular to
the schistosity and, in order to avoid the influence of the detri-
tal mica, on randomly oriented grain-size < 2 µm fraction us-
ing the same instrumental conditions as for KI and ÁI
determination. The 2 range scanned was 59.0—63.0°, while
quartz present within all analysed samples was used as the in-
ternal standard.
With the aim of correlating Kübler and Árkai indices with
vitrinite reflectance, total organic carbon (TOC) was measured
in order to find out whether the investigated samples were
suitable for this kind of analyses. Samples were chosen on the
basis of their colour, assuming that the darker samples should
contain more organic matter. Sample preparation was done ac-
cording to Bush (1970). Standardization of the instrument
(LECO IR-212) was done using the material of a known car-
bon content (steel ring containing 0.3—1.0 % of carbon). For
optical investigation of vitrinite particles a Leitz-MPV3 mi-
croscope was used. The standardization of the instrument was
done using materials of known reflection index (sapphire, dia-
mond and glass).
K-Ar dating was performed in the ATOMKI Institute of Nu-
clear Research, Hungarian Academy of Sciences. Illite—K-white
mica fraction samples were degassed by high frequency in-
duction heating; the released argon was cleaned by applying
furnaces with Ti sponge and St707 getter materials.
38
Ar was
introduced from a gas pipette. For Ar isotopic ratio measure-
ments a magnetic mass spectrometer of 150 mm radius and
90° deflection was used in the static mode. Before the deter-
mination of K, the samples were digested by a mixture of
HF + HClO
4
and dissolved in highly diluted HCl. The K con-
tent of the samples was measured with a flame emission pho-
tometer using 100 ppm Na buffer and Li internal standard.
The results of an interlaboratory calibration were published by
Odin et al. (1982). During this study interlaboratory standards
of LP-6, HD-B1 and Asia 1/65 as well as atmospheric argon
have been used for calibration. K-Ar ages were calculated us-
ing the constants proposed by the IUGS Subcommission on
Geochronology (Steiger & Jäger 1977). K-Ar ages measured
on < 2 µm (and in certain case whole rock) fractions were used
for dating the metamorphism to avoid and/or reduce the dis-
turbing effects of detrital muscovite following the practice of
Clauer & Kröner (1979), Frank & Stettler (1979), Bonhomme
et al. (1980), Reuter (1987) and Árkai et al. (1995a).
Results
The label, lithology, stratigraphic age and tectonic settings
of the studied samples together with their semiquantitative
modal composition, KI and ÁI values, b
0
-parameter data, total
organic carbon content, vitrinite reflectance value as well as
K-Ar ages obtained on whole rock (WR), > 0.1 mm, < 2 µm
and < 0.5 µm grain-size fractions are listed in Table 1.
Modal composition
As can be expected from the lithology, a semiquantitative
whole rock modal composition of the samples as determined
by the XRD method revealed similarities between the samples
from the different tectonic units (Table 1). The dominant con-
stituents of samples belonging to the RMC are quartz, illite-
muscovite, plagioclase and chlorite. Less abundant minerals
are K-feldspar and paragonite (Table 1). Plagioclase, augite
and actinolite were the main constituents of the metadolerite
from the RMC. The reddish colour of samples from all com-
plexes (Table 1) is due to the presence of hematite in the ma-
trix. Calcite, as a secondary mineral, was detected in slate
from the RMC. Chloritoid and pyrophyllite, in association
with illite-muscovite, quartz and subordinate chlorite is a char-
acteristic of Upper Devonian samples found along the Kutjevo
transect (Table 1). Kaolinite was detected as a trace mineral in
metasandstones belonging to the PTSS in which main constit-
uents are quartz and illite-muscovite.
Additional attention was focused on the clay minerals asso-
ciation. Although a mineral size should not be the only criteri-
on defining a certain mineral group, the term “clay minerals”
in this work refers to the sample < 2 µm fraction. The most
abundant minerals in this fraction, detected by XRD on highly
oriented mounts, were illite-muscovite, chlorite and quartz.
Paragonite, pyrophyllite, plagioclase, hematite and kaolinite
were occasionally observed and related to samples in which
they were also detected in whole rock samples. Special inter-
est was given to illite-muscovite and chlorite in order to deter-
mine possible interstratifications and because these minerals
were used later for KI and ÁI analyses.
Kübler and Árkai indices
There is no significant difference between KI and ÁI values
measured on samples from the different lithostratigraphic
units (Table 1). The values point to high anchizonal to epizon-
al thermal alteration.
473
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
Total organic carbon (TOC) and vitrinite reflectance
The TOC in all analysed samples was absent or very low
(Table 1). Nevertheless, vitrinite particles suitable for vitrinite
reflectance measurements were found in one slate from the
RMC (Table 1). The result (R
random
= 4.59; n = 14, standard de-
viation = 0.217) indicates meta-anthracite coal rank.
b
0
-parameter
The b
0
-values evaluated from whole rock range between
9.000 and 9.036 Å, giving an average value of 9.021 Å, while
those obtained on < 2 µm fraction vary between 8.986 and
9.036 Å, giving an average of 9.004 Å (Table 1).
K-Ar age dating
The K-Ar ages of different fractions are shown in Table 1.
The oldest age was obtained from the WR of sample no. 4
(153.1 ± 6.6). The youngest age was obtained on the < 0.5 µm
fraction of sample no. 34 (66.2 ± 2.5 Ma). The results together
with analytical and statistical parameters and errors of the
K-Ar isotopic measurements can be obtained from the corre-
sponding author upon request.
Discussion
Clay mineralogy and P-T evolution
The generally accepted theory is that illite is formed by
transformation of smectite as a result of heating (Hower et al.
1976; Merrimann & Peacor 1999). In spite of the fact that dif-
ferent authors propose different mechanisms of transformation
of smectite to illite (Morton 1985; Dong 2005), all authors
agree that the effect of heating in the presence of a K-contain-
ing fluid will result in progressive loss of smectite layers and a
simultaneous increase of illite layers in interstratified illite-
smectite.
Many researchers tried to assign a particular temperature to
the thermal stability of smectite – interstratified illite-smec-
tite – illite series. According to Weaver (1989), 5—10 % of
smectite layers are present in illite-smectite interstratified
clays at 200—250 °C, while according to Viczián (1994)
around 50 % of smectite layers are present at 90—130 °C and
5—10 % at 160—220 °C. Inoue et al. (2004) gave the most defi-
nite statement: smectite is stable from room temperature up to
150 °C, the R1 type of illite-smectite interstratification in the
range of 150—225 °C, while illite is stable at temperatures
higher than 175 °C.
In order to determine a possible presence of smectite, either
as a discrete mineral phase or interstratified with illite, the
classical XRD analysis as proposed by Starkey et al. (1984),
was performed. After these treatments, no shift of the 10 Å
diffraction maximum of illite-muscovite and the 14 Å diffrac-
tion maximum of chlorite was observed (Fig. 2). The data,
characteristic for all analysed samples, imply that the samples
do not contain smectite. In order to ascertain this statement the
concept of poorly- (PCI) and well-crystallized illite (WCI)
Fig. 2. Representative XRD patterns pertaining to: a – phyllite
no. 13 and b – metasandstone no. 4. Both samples belong to the
RMC. AD – air dried; EG – ethylene-glycol treated mounts.
was used. In general, as the number of coherent diffracting do-
mains becomes smaller, the diffraction peak becomes wider
and shifts to higher d-values. The width of peak at half height
(FWHM) and the position of the peak maximum of the studied
samples were plotted in the appropriate diagram (Lanson et al.
1998) (Fig. 3). The position of the studied samples in the dia-
gram and lack of shift to higher d-values after EG treatment
indicates an absence of interlayering even with very small
amounts of smectite. The data point to thermal alteration high-
er than 220—250 °C, taking into consideration the smectite
thermal stability pointed out by Weaver (1989), Viczián
(1994) and Inoue et al. (2004). For better estimation of the de-
gree of thermal alteration, KI and ÁI were used. Although
these parameters are very good tools for monitoring the
progress of the phyllosilicate reaction and their transformation
with increasing temperature, the exact temperature of thermal
alteration can only be estimated. KI indicates that the samples
Fig. 3. Peak positions and full width at half maximum (FWHM) of
the (001) diffraction maximum of illite-muscovite shown in the dia-
gram of Lanson et al. (1998). N indicates number of diffracting lay-
ers. The shaded areas indicate poorly- (PCI) and well-crystallized
illite (WCI) obtained from sequences of sedimentary rocks reported
by Lanson et al. (1998).
474
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
Table 1:
An
overview
of
rock
type,
stratigraphy,
semiquantitave
mineral
composition
(
–
dominant;
–
abundant;
–
significant;
x
–
poor),
“crystallinity”
values,
b
0
-parameter,
total
organic
car-
bon
(TOC)
content,
vitrinite
reflectance
(R
random
)
and
K-Ar
ages
of
samples
representing
the
Psunj
metamorphic
complex,
the
Radlovac
metamorphic
complex
and
the
Permian-Triass
ic
sedimentary
se-
quences.
*
– ÁI (002) determined after treatment with DMSO;
**
– according to Jamičić & Brkić (1987);
***
– calculated with atomic constants suggested by Steiger & Jäger
(1977). Legend:
PCm
–
Precambrian;
D
3
–
Upper
Devonian;
C
–
Carboniferous;
P
–
Permian;
PT
–
Permo-Triassic;
T
–
Triassic.
The
mineral
abbreviations
are
after
Kretz
(1983):
Qtz
–
quartz;
Ill-Ms
–
illite-musco-
vite;
Pl
–
plagioclase;
Kfs
–
K-feldspar;
Chl
–
chlorite;
Cld
–
chloritoid;
Prl
–
pyrophyllite;
Hem
–
h
ematite;
Kln
–
kaolinite;
Pg
–
paragonite;
Act
–
actinolite;
Aug
–
augite;
Cal
–
calcite.
475
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
Table 1:
Continued
passed through transitional high anchizonal to epizonal ther-
mal alteration (Table 1, Fig. 4). Similar results were obtained
using ÁI (Table 1, Fig. 4). KI and ÁI (002), as well as ÁI
(001) and ÁI (002) show a good correlation (Fig. 5). The esti-
mated degree of thermal alteration is in good agreement with
the previously established presence of paragonite and pyro-
phyllite in some slates from the RMC as reported by Slovenec
(1986). According to Frey (1987) these two minerals are char-
acteristic of the sub-greenschist facies and indicate, as well as
KI and ÁI measured here, that the RMC experienced a very
low- to low-grade metamorphic event. The data indicate that
samples from the PMC as well as the overlying PTSS sampled
along the Kutjevo transect also record a very low- to low-
grade metamorphic event. The degree of metamorphism ap-
pears to be constant in all the analysed samples irrespective to
their stratigraphic age.
It is important to mention that small differences between KI
and ÁI data are closely related to the chlorite content. Lower
chlorite content results in weaker basal reflections and conse-
quently less precise measurement of the FWHM.
The presence of kaolinite in the samples can make ÁI (002)
measurements very difficult and uncertain because of the
overlapping of the (001) diffraction maximum of kaolinite and
the (002) diffraction maximum of chlorite. This problem can
be overcome by the dimethyl-sulfoxide (DMSO) treatment as
shown in the study of Biševac et al. (2009). The appearance of
ordered kaolinite in some samples (Table 1) can be connected
to post-metamorphic hydrothermal alteration as proposed by
Árkai et al. (2000).
Good correlation of KI and ÁI for samples containing para-
gonite or pyrophyllite indicates that they did not have any sig-
nificant influence on the measured KI values due to their low
quantity.
In order to correlate the KI and ÁI with other parameters
which change with the thermal conditions, vitrinite particles
were measured on one slate sample from the RMC. The vitrin-
ite reflectance corresponds to meta-anthracite coal rank. The
value is in good agreement with the KI and ÁI for the same
sample (Table 1).
Epizonal (chlorite zone) and medium- to high-temperature
anchizonal fine-clastic metasedimentary rocks with common
mineral assemblages consisting of quartz, albite, white
K-mica±chlorite and calcite can be taken into consideration
for evaluating pressure conditions using the b
0
-parameter
(Padan et al. 1982; Guidotti & Sassi 1986). The data for
< 2 µm grain-size fraction implies transitional low- to medi-
um-pressure formation conditions for RMC, while whole rock
measurements on same samples indicate medium pressure
conditions. The b
0
-parameter of the < 2 µm fraction can be re-
lated to the metamorphic pressure while the slightly higher
pressure conditions indicated by whole rock measurements
can be explained by the influence of the detrital mica.
We conclude that the analysed samples, regardless to their
stratigraphic age, record the same metamorphic event which is
indisputably younger than Early Triassic, that is, younger than
their protolith ages. Middle Triassic dolomites and dolomitic
limestones (Jamičić & Brkić 1987; Jamičić et al. 1987), repre-
senting the youngest rocks of the Kutjevo transect, were omit-
ted from this research because of the lack and/or very low
476
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
quantity of illite-muscovite which can influence the reliability
of the KI measurements. Upper Jurassic-Lower Cretaceous se-
quences, otherwise present in the Slavonian Mts, cannot be
found in the investigated area.
Chronology of metamorphism
When evaluating and interpreting the K-Ar data in order to
determine the age of the metamorphism, a possible influence
of the detrital material should be taken into consideration
(Hunziker et al. 1986). The effect of the detritus was tested by
dating different mineral grain fractions ( < 0.5 µm and < 2 µm)
including the whole rock. The whole rock age is the oldest one
in all cases (Table 1). The youngest age was measured on
< 0.5 µm fractions. The whole rock age represents the average
age of all K-bearing constituents present in the rock, while the
age of finer fractions, < 0.5 µm and < 2 µm in this case, corre-
sponds to the average age of the different generations of illitic
material present within the dated fractions. Such interpretation
suggests that the oldest K-Ar age constrains the lowest age for
the metamorphic event which reset most of the mineral ages in
the dated rocks. The youngest age, measured on the < 0.5 µm
fraction, sets the oldest limit for the termination of illite for-
mation. The K-Ar whole rock age does not have any signifi-
cant geological meaning, it only implies that minerals older
and younger than the whole rock age exist. A microscopic in-
vestigation revealed that those minerals could be coarse-
grained mica flakes (Fig. 6.1—3). The K-Ar ages of
coarse-grained muscovite ( > 0.1 mm fraction) confirmed this
assumption (Table 1). Concerning the well known closure
temperature concept of the K-Ar system (Purdy & Jäger 1976;
Wagner et al. 1977), the results indicate that the formation of
illite minerals took place at temperatures below the blocking
temperature of muscovite ( ~ 350 °C; Rollinson 1993). If this
was not the case, the coarse-grained muscovite would be fully
reset. Such an interpretation is in good agreement with the es-
timates of the degree of thermal alteration deduced from the
KI and ÁI data.
As recommended by Árkai et al. (1995a, 2000), the < 2 µm
fraction ages were used for determination of the metamorphic
age. The exception was Early Triassic metasandstone (PTSS)
which, according to the microscopic investigation, does not
contain coarse-grained detrital mica (Fig. 6.4). We can assume
that the thermal alteration that affected this lithostratigraphic
unit reset all the K-bearing minerals present in it. The ob-
served difference between K-Ar whole rock age and ages of
the finer fractions (in this case < 0.5 µm and < 2 µm) is the
consequence of prolonged formation of clay minerals. For this
reason, the K-Ar whole rock age of Early Triassic metasand-
stone, assumed to be equivalent to the < 2 µm ages of other
samples which contain coarse-grained mica, was used for dis-
cussion regarding the age of the metamorphism.
If we take into consideration that in all dated samples, rang-
ing from Early Paleozoic to Early Triassic, the K-Ar age data
of clay fractions point to Late Cretaceous, then the age of the
very low- to low-grade metamorphic event can be set as Eoal-
pine (Table 1, Fig. 7). On a regional scale this event is most
likely related to the main nappe-forming compressional events
in the Pannonian Basin area and the Carpathians which result-
Fig. 4. Graphic representation of the degree of thermal alteration ac-
cording to Kübler and Árkai indices as presented in Table 1. KI and
ÁI values are expressed in ° 2 CuK . Boundaries of the anchizone
were taken from Kübler (1968) and Potel et al. (2006) for KI and from
Árkai et al. (1995b) for ÁI. “E” – epizone; “HA” – high anchizone;
“LA” – low anchizone; “A” – anchizone;“D” – diagenetic zone.
477
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
Fig. 5. Correlation of Kübler index and Árkai index as metamorphic indicators: a – ÁI (14 Å) vs. ÁI (7 Å); b – KI (10 Å) vs. ÁI (7 Å).
Fig. 6. Microphotographs showing samples of: 1 – phyllite (RMC, no. 1B); 2 – quartzite (RMC, no. 4); 3 – metasandstone (RMC,
no. 32) in which coarse-grained muscovite flakes are clearly visible; 4 – Metasandstone (PTSS, no. 50) does not contain coarse-grained
mica. The mineral abbreviations are after Kretz (1983): Qtz – quartz; Ms –muscovite.
478
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
ed in the nappe stacking. Similar results have been already re-
ported from other parts of Tisia and ALCAPA (Árkai 2001
and references therein). The Late Cretaceous deformational
event, distinctive for the Tisia and Dacia area, can be distin-
guished from the Early Cretaceous deformational episode re-
corded in the ALCAPA and Dacia (Schmid et al. 2008).
Earlier research (Jamičić 1988) associated the metamor-
phism of the RMC with the folding processes during the last
stages of the Variscan orogeny. According to present knowl-
edge there is no reliable age dating proving Variscan meta-
morphism of the RMC. Moreover most of the RMC samples
of Carboniferous to Permian age have one clearly visible
schistosity. Nevertheless the presence of Variscan metamor-
phism of the RMC with a grade not higher than that of the re-
corded Cretaceous event cannot be ruled out unequivocally.
Reasons for this opinion are the presence of two foliations on
some samples from the RMC and the presence of differently
oriented clasts of very low- to low-grade metamorphic rocks
in the Permian-Triassic metaconglomerates. Nevertheless, our
K-Ar data (Table 1) indicate that rocks belonging to the PMC,
RMC and PTSS were altered during the Cretaceous. No con-
siderable systematic or gradual variation between the K-Ar
age of the < 2 µm fraction and metamorphic indicators of the
analysed samples, regardless of the stratigraphy, was observed
(Fig. 8). This could imply that the analysed tectonic units were
not additionally affected by younger thermal alterations.
Correlation with the surrounding areas of the Tisia Unit and
ALCAPA
Most of the previous researches regarding the metamorphic
evolution, using Kübler and Árkai indices, b
0
-parameter and
K-Ar dating, are related to the Paleozoic and/or Mesozoic se-
quences of the Hungarian part of the Tisia Unit, but also to the
surrounding area belonging to ALCAPA (Árkai 1977, 1983,
1995; Árkai et al. 1981, 1995a, 1998, 2000, 2003; Sadek-
Ghabrial et al. 1996; Faryad & Henjes-Kunst 1997; Janák et
al. 2001; Lupták et al. 2003). Similar very low-grade meta-
morphic studies of the Croatian part of Tisia are rare. We com-
pare our results with those from similar studies in other parts
of the Tisia Unit (Mecsek, Villány-Bihor and Békés-Codru
nappe systems), the Bükkium (Bükk, Uppony and Szendrő)
and parts of the Central Western Carpathians (Veporic and
Gemeric Units) (Table 2).
A close connection between the metamorphic evolution of
the Hungarian and Croatian parts of the Tisia can be estab-
lished according to the data presented in Table 2. All Paleo-
zoic or Mesozoic rocks of the Tisia Unit were affected by an
Fig. 8. Correlation of KI values with the K-Ar ages of < 2 µm frac-
tion. For sample no. 50 (T
1
; metasandstone; PTSS) whole rock age
is shown.
Fig. 7. Graphic representation of the K-Ar ages measured on < 2 µm fraction. Whole rock age of sample no. 50 (T
1
; metasandstone; PTSS)
is shown (see text for detailed explanation). Shaded areas represent the approximate duration of Alpine orogenic phases.
479
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
Eoalpine (Cretaceous) metamorphic event. Where measure-
ments were possible, vitrinite reflectance data correlate well
with the values of “crystallinity” indices. A similar situation
regarding the P-T evolution can be observed by comparing the
Tisia and surrounding area belonging to the ALCAPA (Ta-
ble 2). While the Tisia Unit is characterized only by the Late
Cretaceous very low- to low-grade metamorphism, in the
ALCAPA region, as well as in Dacia, the additional Early
Cretaceous metamorphic event, which did not affect Tisia, can
be distinguished (Schmid et al. 2008).
Conclusions
1. The XRD analysis of clay minerals indicates the presence
of well-crystallized illite (WCI) in all samples. The ordered
crystal structure of illite points to a thermal alteration of at
least 220—250 °C. Chlorite, present in the clay fraction, also
represents a stable mineral phase indicating anchizonal to epi-
zonal thermal alteration.
2. The Kübler index and Árkai index show good correlation
and indicate that samples passed through a high-anchizonal to
epizonal thermal alteration. Variation of KI and ÁI data with
the stratigraphic ages was not observed. All samples recorded
the same metamorphic conditions.
3. The total organic carbon (TOC) content in all samples is
very low. Nevertheless, vitrinite reflectance data, measured in a
single sample, indicates a meta-anthracite coal rank and are in
accordance with both mineral composition and KI and ÁI data.
4. Pressure conditions estimated on the basis of the b
0
-pa-
rameter indicate that a metamorphic alteration of samples
from the RMC proceeded in a transitional low-medium pres-
sure system.
5. K-Ar dating of different grain size fractions of investigat-
ed samples revealed decrease in age with decreasing grain size
of the dated fraction. The whole rock age is the oldest, while
the youngest age is always obtained on the < 0.5 µm fraction.
This effect is closely connected to the amount of detrital mica
in the fraction. Additional K-Ar dating revealed that the oldest
K-bearing phase in analysed samples is detrital muscovite,
giving an age which is older than the whole rock age. This in-
dicates that the formation of illite minerals took place at tem-
peratures that are lower than the closure temperature of
muscovite ( ~ 350 °C). The presence of detrital muscovite im-
plies an easy access to K, which may help the prolonged low-
temperature formation of fine-grained illite.
6. K-Ar ages of < 2 µm fraction indicates Late Cretaceous
metamorphism of the PMC, RMC and PTSS.
7. Correlation of K-Ar ages with other metamorphic indica-
tors (KI and ÁI) relating to stratigraphic age was not observed.
8. K-Ar data imply that all the analysed samples were altered
as a consequence of a very low- to low-grade metamorphic
event presumably related to the main nappe-forming compres-
sional events in the Pannonian Basin and the Carpathians.
9. The investigation of P-T-t evolution in a certain timeframe
presented here is in good agreement with similar researches
conducted in Hungary (Mecsek, Villány-Bihor and Békés
Codru) showing the same Eoalpine metamorphic evolution of
the Hungarian and Croatian parts of the Tisia Megaunit.
Table
2:
Data
from
this
work
(Kübler
and
Árkai
indices,
vitrinite
refle
ctance,
b
0
-parameter
and
K-Ar
dating)
as
compared
with
data
from
other
pa
rts
of
Tisia
(Mecsek,
Villány-Bihor
and
Békés-
Codru)
and
ALCAPA
(Bükkium,
Veporic
and
Gemeric).
480
BIŠEVAC, BALOGH, BALEN and TIBLJAŠ
Acknowledgments: We thank Prof. H.J. Kisch from the
Department of Geology and Mineralogy, Ben-Gurion Univer-
sity of Negev, Beer-Sheva, Israel and Prof. Warr from Geolo-
gisch-Paläontologisches Institut, Ruprecht Karls Universität,
Heidelberg, Germany for providing a set of standards neces-
sary for instrument calibration in this study. We also thank
Goran Šutej for measuring “crystallinity” of same samples as
part of his diploma thesis and Darko Španić from INA – Oil
Company, Corporate Processes, Research and Development
Sector for measuring TOC and vitrinite reflectance. The au-
thors would also like to thank reviewers Prof. P. Árkai and
Prof. W. Frisch for their stimulating comments. This study
was supported by the Ministry of Science, Education and
Sports, project no. 119-1191155-1156 and by the Hungarian
Academy of Science, Project No. OTKA T060965.
References
Árkai P. 1977: Low-grade metamorphism of Paleozoic formations of
the Szendrő Mountains (NE-Hungary). Acta Geol. Acad. Sci.
Hung. 21, 53—80.
Árkai P. 1983: Very low- and low-grade Alpine regional metamor-
phism of the Paleozoic and Mesozoic formations of the Bükki-
um, NE Hungary. Acta Geol. Hung. 26, 83—101.
Árkai P. 1991: Chlorite crystalinity: An empirical aproach and corre-
lation with illite crystalinity, coal rank and mineral facies as ex-
emplified by Palaeozoic and Mesozoic rocks of northeast
Hungary. J. Metamorph. Geology 9, 723—734.
Árkai P. 2001: Alpine regional metamorphism in the main tectonic
units of Hungary: a review. Acta Geol. Hung. 44, 329—344.
Árkai P., Horváth Z.A. & Tóth M. 1981: Transitional very low- and
low-grade regional metamorphism of the Paleozoic formations,
Uppony Mountains, NE-Hungary: mineral assemblages, illite-
crystallinity, -b
o
and vitrinite reflectance data. Acta Geol. Acad.
Sci. Hung. 24, 265—294.
Árkai P., Balogh K. & Dunkl I. 1995a: Timing of low-temperature
metamorphism and cooling of the Paleozoic and Mesozoic for-
mations of the Bükkium, innermost Western Carpathians, Hun-
gary. Geol. Rundsch. 84, 334—344.
Árkai P., Sassi F.P. & Sassi R. 1995b: Simultaneous measurement of
chlorite and illite crystallinity: a more reliable tool for monitor-
ing low- to very low-grade metamorphism in metapelites. A
case study from the Southern Alps (NE Italy). Eur. J. Mineral.
7, 1115—1128.
Árkai P., Bérczi-Makk A. & Hajdu D. 1998: Alpine prograde and ret-
rograde metamorphisms in an overthrusted part of the basement,
Great Plain, Pannonian Basin, Eastern Hungary. Acta Geol.
Hung. 41, 179—210.
Árkai P., Bérczi-Makk A. & Balogh K. 2000: Alpine low-T prograde
metamorphism in the post-Variscan basement of the Great Plain
Tisza Unit (Pannonian Basin, Hungary). Acta Geol. Hung. 43, 43—63.
Árkai P., Faryad S.W., Vidal O. & Balogh K. 2003: Very low-grade
metamorphism of sedimentary rocks of the Meliata unit, West-
ern Carpathians, Slovakia: implications and phyllosilicate char-
acteristics. Int. J. Earth Sci. 92, 68—85.
Balen D., Horváth P., Tomljenović B., Finger F., Humer B., Pamić J.
& Árkai P. 2006: A record of pre-Variscian Barrovian regional
metamorphism in the eastern part of Slavonian Mountains (NE
Croatia). Miner. Petrology 87, 143—162.
Biševac V., Balen D., Tibljaš D. & Španić D. 2009: Preliminary re-
sults on degree of thermal alteration recorded in the eastern part
of Mt. Papuk, Slavonia, Croatia. Geol. Croatica 62, 1, 63—71.
Bonhomme M., Saliot P. & Pinault Y. 1980: Interpretation of potassi-
um-argon isotopic data related to metamorphic events in South-
western Alps. Schweiz. Mineral. Petrogr. Mitt. 60, 81—98.
Brkić M., Jamičić D. & Pantić N. 1974: Carboniferous deposits in
Mount Papuk (northeastern Croatia). Geol. Vjesnik 27, 53—58 (in
Croatian).
Buda Gy. 1981: Genesis of the Hungarian granitoid rocks. Acta Geol.
Acad. Sci. Hung. 4, 309—318.
Bush P.R. 1970: A rapid method for determination of carbonate car-
bon and organic carbon. Chem. Geol. 6, 59—62.
Clauer N. & Kröner A. 1979: Strontium and argon isotopic homogeniza-
tion of pelitic sediments during low-grade regional metamorphism:
the Pan-African Upper Damara Sequence of Northern Namibia
(South-West Africa). Earth Planet. Sci. Lett. 43, 117—131.
Csontos L. 1995: Tertiary tectonic evolution of the Intra-Carpathian
area: a review. Acta Vulcanol. 7, 1—13.
Csontos L. & Vörös A. 2004: Mesozoic plate tectonics reconstruction
of the Carpathian region. Palaeogeogr. Palaeoclimatol. Palaeo-
ecol. 210, 1—56.
Csontos L., Nagymarosy A., Horvath F. & Kovac M. 1992: Tertiary
evolution of the Intra-Carpathian area: a model. Tectonophysics
208, 221—241.
Dong H. 2005: Interstratified illite-smectite: A review of contribu-
tions of TEM data to crystal chemical relations and reaction
mechanisms. Clay Sci. 12, 1, 6—12.
Faryad S.W. & Henjes-Kunst F. 1997: K-Ar and Ar-Ar age con-
straints of the Meliata blueschist facies rocks, the Western Car-
pathians (Slovakia). Tectonophysics 280, 141—156.
Frank W. & Stettler A. 1979: K-Ar and Ar-Ar systematics of white
K-mica from an Alpine metamorphic profile in the Swiss Alps.
Schweiz. Mineral. Petrogr. Mitt. 59, 375—394.
Frey M. 1987: Very low-grade metamorphism of clastic sedimentary
rocks. In: Frey M. (Ed.): Low temperature metamorphism.
Blackie, New York, 9—59.
Géczy B. 1973: The origin of the Jurassic faunal provinces and the
Mediterranean plate tectonics. Ann. Univ. Sci. Budapest, Eötvös
Nom. Sect. Geol. 16, 99—114.
Guidotti C. & Sassi F. 1986: Classification and correlation of meta-
morphic facies series by means of muscovite b
0
data from low-
grade metapelites. Neu. Jb. Mineral. Abh. 157, 363—380.
Haas J. & Péró C. 2004: Mesozoic evolution of the Tisza Mega-unit.
Int. J. Earth Sci. (Geol. Rundsch.) 93, 297—313.
Hovorka D. & Petrík I. 1992: Variscan granitic bodies of the Western
Carpathians – the backbone of the mountain chain. In: Vozár J.
(Ed.): The Paleozoic geodynamic domains of the Western Car-
pathians, Eastern Alps and Dinarides. Spec. Vol. IGCP Project
276, Bratislava, 57—66.
Hower J., Eslinger E., Hower M.E. & Perry E.A. 1976: Mechanism
of burial metamorphism of argillaceous sediment: 1. Mineralog-
ical and chemical evidence. Bull. Geol. Soc. Amer. 87, 725—737.
Hunziker J.C., Frey M., Clauer N., Dallmeyer R.D., Friedrichsen H.,
Fleming W., Hochstrasser K., Rogwiller P. & Schwander H.
1986: The evolution of illite to muscovite: Mineralogical and
isotopic data from the Glarus Alps, Switzerland. Contr. Mineral.
Petrology 92, 157—180.
Inoue A., Meunier A. & Beaufort D. 2004: Illite-smectite mixed-lay-
er minerals in felsic voclaniclastic rocks from drill cores,
Kakkonda, Japan. Clays and Clay Miner. 52, 66—84.
Jamičić D. 1983: Structural fabric of the metamorphosed rocks of
Mt. Krndija and the eastern part of Mt. Papuk. Geol. Vjesnik
36, 51—72 (in Croatian).
Jamičić D. 1988: Structural fabric of the Slavonian Mts. (northern
Papuk, Psunj, Krndija). PhD. Thesis, Univ. Zagreb, 1—152 (in
Croatian).
Jamičić D. & Brkić M. 1987: Basic geological map of Yugoslavia
in scale 1 : 100,000, sheet Orahovica L 33—96. Sav. Geol. Inst.,
Beograd.
481
EOALPINE VERY LOW- TO LOW-GRADE METAMORPHISM OF METASEDIMENTS FROM TISIA (CROATIA)
Jamičić D., Brkić M., Crnko J. & Vragović M. 1987: Basic geologi-
cal map of Yugoslavia – Explanatory notes for sheet Orahovica
L 33—96. Fed. Geol. Inst. Beograd, 1—72 (in Croatian).
Janák M., Plašienka D., Frey M., Cosca M., Schmidt S.T., Lupták B.
& Méres S. 2001: Cretaceous evolution of a metamorphic core
complex, the Veporic unit, Western Carpathians (Slovakia): P-T
conditions and in situ
40
Ar/
39
Ar UV laser probe dating of
metapelites. J. Metamorph. Geology 19, 197—216.
Jerinić G., Pamić J., Sremec J. & Španić D. 1994: First palinological
and organic-petrographic dana on very low and low-grade meta-
morphic rocks in Slavonian Mt. (north Croatia). Geol. Croatica
47, 149—155.
Judik K., Tibljaš D., Balen D., Tomljenović B., Horváth P., Pamić J. &
Árkai P. 2002: New data on the low-temperature metamorphism
of Mt Medvednica and the Slavonian Mts (Croatia). In: Michalík
J., Šimon L. & Vozár J. (Eds.): Proceedings of XVIIth Congress
of CBGA. Geol. Carpathica, 53, CD edition, Bratislava.
Kisch H.J. 1990: Calibration of the anchizone: a critical comparison
of illite “crystallinity” scales used for definition. J. Metamorph.
Geology, 31—46.
Kisch H.J. 1991: Illite “crystalinity”: recommendations on sample
preparation, X-ray diffraction settings, and interlaboratory sam-
ples. J. Metamorph. Geology, 665—670.
Kretz R. 1983: Symbols for rock-forming minerals. Amer. Mineralo-
gist 68, 277—279.
Kübler B. 1967: Anchimétamorphisme et schistosite. Bull. Centre
Rech. Pau-SNPA 1, 269—278.
Kübler B. 1968: Evaluation quantitative du métamorphisme par la
cristallinité de I’illite. Bull. Centre Rech. Pau-SNPA 2, 385—397.
Kübler B. 1975: Diagenese – Anchimétamorphisme et Métamor-
phism. Inst. Nat. Recherche Scientifique-Pétrole, Quebec.
Kübler B. 1990: “Cristallinité” de l’illite et mixed-layers: br
e
ve révi-
sion. Schweiz. Mineral. Petrogr. Mitt. 70, 89—93.
Lanson B., Velde B. & Meunirer A. 1998: Late-stage diagenesis of il-
litic clay minerals as seen by decomposition of X-ray diffraction
patterns: Contrasted behaviours of sedimentary basins with dif-
ferent burial histories. Clays and Clay Miner. 46, 69—78.
Liew T.C., Finger F. & Höck V. 1989: The Moldanubian granitoid
plutons in Austria: chemical and isotopic studies bearing on
their environmental setting. Chem. Geol. 76, 41—55.
Lupták B., Janák M., Plašienka D. & Schmidt S.Th. 2003: Alpine
low-grade metamorphism of the Permian-Triassic sedimentary
rocks from the Veporic Superunit Western Carpathians: phillo-
silicate composition and “crystallinity” data. Geol. Carpathica
54, 367—375.
Merrimann R.J. & Peacor D.R. 1999: Very low-grade metapelites:
mineralogy, microfabrics and measuring reaction progress. In:
Frey M. & Robinson D. (Eds.): Low grade metamorphism.
Blackwell Science Ltd, London, 10—60.
Morton J.P. 1985: Rb-Sr evidence for punctuated illite-smectite di-
agenesis in the Oligocene Frio Formation, Texas, Gulf Coast.
Geol. Soc. Amer. Bull. 96, 114—122.
Odin G.S., Adams C.J., Armstrong L.R. & Bagdasaryan G.P. 1982:
Interlaboratory standards for dating purposes, in Numerical Dat-
ing in Stratigraphy. In: Odin G.S. (Ed.): Numerical dating in
stratigraphy. John Wiley & Sons, New York, 123—158.
Padan A., Kisch H.J. & Shagam R. 1982: Use of the lattice parameter
b
o
of dioctahedral illite/muscovite for the characterization of P/T
gradients of incipient metamorphism. Contr. Mineral. Petrology
79, 85—95.
Pamić J. 1986: Magmatic and metamorphic complexes of the adjoin-
ing area of the northernmost Dinarides and Pannonian Mass.
Acta Geol. Hung. 29, 203—220.
Pamić J. 1998: Crystalline basement of the South Pannonian Basin
based on surface and subsurface data. Nafta 49, 371—390.
Pamić J. & Jamičić D. 1986: Metabasic intrusive rocks from the
Paleozoic Radlovac complex of Mt. Papuk in Slavonija (north-
ern Croatia). Rad JAZU, Zagreb 424, 97—125.
Pamić J. & Jurković I. 2002: Paleozoic tectonostratigraphic units of
the northwest and central Dinarides and the adjoining South
Tisia. Int. J. Earth Sci. 91, 538—554.
Pamić J. & Lanphere M. 1991: Hercynian granites and metamorphic
rocks of the Mts. Papuk, Psunj, Krndija and surrounding base-
ment of the Pannonian Basin, North Croatia. Monograph.
Geologija, Ljubljana 34, 81—235 (in Croatian).
Pamić J., Lanphere M. & McKee E. 1988: Radiometric ages of meta-
morphic and associated igneous rocks of the Slavonian Moun-
tains in the southern part of Pannonian Basin, Yugoslavia. Acta
Geol. 18, 13—39.
Pamić J., Lanphere M. & Belak M. 1996: Hercynian I-type and S-type
granitoids from the Slavonian Mountains (southern Pannonian,
north Croatia). Neu. Jb. Mineral. Abh. 171, 155—186.
Pamić J., Balen D. & Tibljaš D. 2002: Petrology and geochemistry of
orthoamphibolites from the Variscan metamorphic sequences of
the South Tisia in Croatia – an overview with geodynamic im-
plications. Int. J. Earth Sci. 91, 787—798.
Potel S., Ferreiro Mählmann R., Stern W.B., Mullis J. & Frey M.
2006: Very low-grade metamorphic evolution of pelitic rocks
under high pressure/low temperature conditions, NW Caledonia
(SW Pacific). J. Petrology 47, 991—1015.
Purdy J. & Jäger E. 1976: K-Ar ages on rock-forming minerals from
the central Alps. Mem. Inst. Geol. Mineral. Univ., Padova, 30, 31.
Rollinson H. 1993: Using geochemical dana: evaluation, presenta-
tion and interpretation. Longman Singapore Publishers, Sin-
gapore, 1—352.
Sadek-Ghabrial D., Árkai P. & Nagy G. 1996: Alpine polyphase meta-
morphism of the ophiolitic Szarvaskő complex, Bükk Mountains,
Hungary. Acta Miner. Petrology 37, 99—128.
Sassi F.P. 1972: The petrological and geological significance of the b
values of potassic white micas in low-grade metamorphic rocks.
An implication to the Eastern Alps. Tschermaks. Mineral.
Petrogr. Mitt. 18, 105—113.
Schmid S.M., Bernoulli D., Fügenschuh B., Matenco L., Schefer S.,
Schuster R., Tischler M. & Ustaszewski K. 2008: The Alpine-
Carpathian-Dinaridic orogenic system: correlation and evolution
of tectonic units. Swiss J. Sci. 101, 139—183.
Slovenec D. 1986: Registration of pyrophyllite, paragonite, margarite
and glauconite in the rocks of the Slavonian Mts. Geol. Vjesnik
39, 61—74 (in Croatian).
Starkey H.C., Blackmon P.D. & Hauff P.L. 1984: The routine miner-
alogical analysis of clay-bearing samples. U.S. Geol. Surv. Bull.
32, 1563.
Steiger R.H. & Jäger E. 1977: Subcommition on geochronology:
Convention on the use of decay constants in geo-and cosmochro-
nology. Earth Planet. Sci. 36, 359—362.
Szederkényi T. 1996: Metamorphic formations and their correlation
in the Hungarian part of theTisia megaunit (Tisia megaunit ter-
rane). Acta Mineral. Petrogr. Szeged 37, 143—160.
Viczián I. 1994: Smectite-illite transformation depending on the tem-
perature. (A szmektit-illit átalakulás függése a hőmérséklettől.)
Földt. Közl. 124, 3, 367—379 (in Hungarian, with English abstract).
Wagner G.A., Reimer G.M. & Jager E. 1977: Cooling ages derived
by apatite fission-track, mica Rb-Sr and K-Ar dating: The uplift
and cooling history of the Central Alps. Mem. Inst. Geoch.
Mineral. Univ., Padova 30, 1—27.
Warr L.N. & Rice H. 1994: Interlaboratory standardization and cal-
ibration of clay mineral crystallinity and crystallite size data.
J. Metamorph. Geology 12, 141—152.
Weaver C.E. 1989: Clay, muds, and shale. Developments in sedimen-
tology. Elsevier, Amsterdam-Oxford-New York 44, 1—819.
è