GeolCarp_Vol58_No5_477

GEOLOGICA CARPATHICA, OCTOBER 2007, 58, 5, 477—486

www.geologicacarpathica.sk

Introduction

The aim of the paper is to study the Telegdi Roth Fault,
one of the most prominent fault structures of western
Hungary. This fault is located in the Bakony Mts
(Transdanubian Range, Figs. 1, 2), in the Alcapa (Alpine-
Carpathian-Pannonian) block of the Intra-Carpathian
area. It was first described by Telegdi Roth (1934) and
later named after him, as a roughly WNW—ESE directed
fault, accomodating major right-lateral offset (Fig. 2).
Mapping has shown that this is a fault which cuts the
Bakony Mts into two parts and which cuts across Triassic
to Oligocene, or even younger Miocene formations (e.g.
Noszky 1957; Knauer & Végh 1967; Korpás 1969;
Császár 1970; Knauer 1977; Gyalog & Császár 1982;
Mészáros 1983; Kókay 1996).

The paper deals with a fault microstructural study in or-

der to reveal the polyphase history of this important fault.
During the work all potential outcrops were visited along
a broader zone of the fault between Ugod and Várpalota
(Fig. 2). Fault-slip and joint data were collected and nu-
merically analysed. A Digital Elevation Model (DEM) of
the sector (Fig. 3), as well as published geological maps
were analysed. Finally we also confronted our data with
the conclusions of relevant earlier publications.

Paleostress investigation and kinematic analysis along the

Telegdi Roth Fault (Bakony Mountains, western Hungary)

ÁGOSTON SASVÁRI

, ADA KISS

and LÁSZLÓ CSONTOS

Eötvös University of Budapest, Department of General Geology, Pázmány Péter sétány 1/c, 1117 Budapest, Hungary;

sasvariagoston@yahoo.com; csontos@ludens.elte.hu

Eötvös University of Budapest, Department of Applied and Environmental Geology, Pázmány Péter sétány 1/c, 1117 Budapest, Hungary;

ada@iris.elte.hu

(Manuscript received January 16, 2006; accepted in revised form March 15, 2007)

Abstract: The Telegdi Roth Fault, a major WNW—ESE fault in the Transdanubian Range, western Hungary is
analysed. Fault striation data suggest that the fault and its neighbourhood experienced polyphase brittle deformation
from the Senonian, mainly during the Tertiary. The first phase is an Albian—Cenomanian NW—SE thrusting, generat-
ing conjugate thrust faults. Then a major sinistral shear due to E—W maximum horizontal stress direction occurred.
This main sinistral shear along the Telegdi Roth Fault appears to have occurred between the Senonian and the Early
Eocene. This second tectonic event was followed by a dextral strike-slip movement along the fault, due to WNW—ESE
maximum horizontal stress. This third movement probably took place from the Middle Eocene to Early Miocene
(Eggenburian). Later (after a possible counterclockwise rotation of the Alcapa Unit in the Ottnangian) the deforma-
tion detected in the vicinity of the Telegdi Roth Fault was connected to a tensional phase which is characterized by
a WSW—ENE minimal stress axis. This movement took place probably in the late Early and early Middle Miocene
(Ottnangian to middle Badenian). Related structures are normal and sinistral faults which cut across the Telegdi Roth
Fault. The last, fifth identified phase is marked by WNW—ESE minimal horizontal and NNE—SSW maximum horizontal
stress directions. The suggested age interval for these deformations is late Middle and Late Miocene (late Badenian to
Pannonian). The topographical expression of the main fault and neotectonic observations suggest a probable Quaternary
reactivation as well.

Key words: Tertiary, Transdanubian Range, kinematic evolution, microstructural analysis, strike-slip fault, Telegdi
Roth Fault.

Structural features of the Telegdi Roth Fault and

its neighbourhood

On a regional scale, the Telegdi Roth Fault represents

an important, approximately hundred km long right-lat-
eral fault with WNW—ESE strike (Fig. 2). There are other
faults, however, which cut and offset the main fault. These
will be listed as different fault trends.

Fault trend ‘A’: The Telegdi Roth Fault

A main WNW—ESE system of strike-slip faults is present

throughout the Bakony Mts (Figs. 2 and 3) which was al-
ready observed by Telegdi Roth (1934). The main fault
shows a total of 4.7 km dextral separation (e.g. Noszky
1957; Knauer & Végh 1967; Korpás 1969; Császár 1970;
Knauer 1977; Gyalog & Császár 1982; Mészáros 1983;
Kókay 1996). It seems to curve near its western termina-
tion (Figs. 2 and 3). Two alternative models are brought
up. Either it turns south near Tevelvár—Pápavár—
Hideghegy—Hajszabarna (TPHH on Fig. 2), and limits an
elevated block of Triassic against Eocene and Egerian for-
mations (Korpás 1981), or it turns north and forms a horse-
tail structure east of Ugod. Individual splays also limit the
Egerian basin remnants there. In the former case the

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SASVÁRI, KISS and CSONTOS

curved portions should operate as thrusts, in the latter case
the faults splays should act as normal faults during the
main dextral movement. It is interesting to note that on
the maps of Noszky (1957) and Gyalog & Császár (1982)
the western part of the fault limiting the TPHH block
(Fig. 2) from the east is suggested as normal.

The main fault also gently curves at the eastern end near

Várpalota, where its compressive character was demon-
strated as a repetition of Miocene coal layers (Kókay
1968). The Telegdi Roth Fault can be followed as a sharp
line on the Digital Elevation Model (Fig. 3). In one expo-
sure (site 3 by the Eperkés Hill on Fig. 2) we found loess
directly in tectonic contact with the Albian limestone. The
loess showed several faults, not parallel but oblique to the
Telegdi Roth Fault.

Fault trend ‘B’

There are roughly N—S striking parallel faults east of

Zirc (Figs. 2 and 3) which cut the Telegdi Roth Fault. On
the DEM – see also Knauer & Végh (1967), Knauer
(1977) or Gyalog & Császár (1982) – they show a
clearly visible dextral offset. These faults regularly bor-
der the Egerian fluviatile deposits. The Egerian is a
widespread formation (Korpás 1981), which covered the
whole Transdanubian Range, so the little grabens

Fig. 1. Location of the studied area.

marked by this N—S striking fault were possibly born af-
ter its deposition.

Fault trend ‘C’

In some places, especially south of Zirc town, the

Telegdi Roth Fault may be sinistrally offset by NW—SE
striking faults (Fig. 2). Some other faults with similar orien-
tation are well expressed in topography (Rózsa et al. 1997).

Fault measurements and analysis

Observations

During fault measurement we concentrated on outcrops

along the immediate vicinity of the Telegdi Roth Fault.
Mainly the Mesozoic rocks form outcrops here; the Neo-
gene (Miocene) rocks, very important for dating, were ex-
posed only near Várpalota-Bántapuszta (site 2 on Fig. 2).
Since these Tertiary outcrops were very few, we added an-
other Tertiary site – near Csesznek – which was some-
what more distant.

We made important observations at three outcrops. First

in the Bántapuszta Basin (site 2 on Fig. 2) the Ottnangian—
Karpatian gentle unconformity (Kókay 1991) was cut and

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PALEOSTRESS AND KINEMATIC ANALYSIS ALONG THE TELEGDI ROTH FAULT (W HUNGARY)

dextrally offset by about 200 m. This shear zone is
directly adjacent and roots in the Telegdi Roth Fault.
Quarries in the same rocks yielded some strike-slip fault
planes and many joints parallel to the main fault. Adjacent
abandoned Middle Miocene (Badenian) coal mines also
testified important lateral and thrust displacements, affect-
ing even the Early and the Middle Miocene formations
(Kókay 1968).

On the second location – an elongated area not far

from Somhegypuszta (site 12 on Fig. 2), practically lying
on the Telegdi Roth Fault – a chaotic mixture of rocks
from the Upper Triassic to the Eocene was found. This
mixture was interpreted as a fault megabreccia.

In the third important outcrop, in a quarry of Upper Tri-

assic limestone east of Ugod (site 15 on Fig. 2), both left-
and right-lateral slips (Sasvári 2003) parallel to the main
fault were recorded. Dominance of the left-lateral slip con-
tradicts all previous works and the map view and hence
needs an explanation.

Analysis

In the visited outcrops all detected faults were mea-

sured. Attention was focused on planes with slickenslides,
where the sense of shear and eventual superposition of
striae were also noted. Unfortunately, these surfaces are

Fig. 2. Schematic geological map of the Bakony Mts with the measured outcrops, after Gyalog & Császár (1982). TPHH – Tevelvár—
Pápavár—Hideghegy—Hajszabarna Hills; TRF – Telegdi Roth Fault.

Fig. 3. Digital Elevation Model (DEM) in the vicinity of the Telegdi Roth Fault with the major townships.

relatively rare, that is why joints were also measured. In all
more than 300 fault planes were measured, of which 122
carried information – slickenslides – about the direction
of motion.

After application of analytical methods (mainly

Angelier 1984 and the P-T method after Turner 1953) on
the fault measurements, 6 stress fields were defined. As a
first approach, an outcrop-by-outcrop numerical process-
ing of fault-slip data was tried (Angelier 1984), but this
failed because of lack of sufficient data. Grouping the
data by age of the lithology was also meaningless (with
some rare exceptions), because either the rocks giving
well-constrained data were too old (Mesozoic), or data in
a particular age group were too few. Finally we
considered the data collected along the fault as a single
data set and we processed this set by fault-slip analysis.

This data set needed separation, which was done by

three methods. A full automatic separation was applied,
but this gave only rough results. However, the defined 6
stress fields were practically identical to those defined
with the other method. The separation process was also
done in a semi-manual way by either visual analysis, or by
application of the P-T method (Turner 1953). The first
method chooses a fault set which might apparently work
together in a Mohr or Riedel system. The latter method
calculates ideal shortening and extension axes on all indi-

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SASVÁRI, KISS and CSONTOS

vidual fault planes with striae, and plots them on a
stereoplot. The grouping of the ‘Pressure’ and ‘Tension’
axes defines the axes of the stress field, in which the faults
were capable of sliping. These faults were then entered in
the Angelier software (Angelier 1984) and the stress fields
were recalculated, the fit of the faults was checked. The
stress axes given by the automatic separation were slightly
modified by the semi-manual method. This method also
gave 6 stress fields, which are different from each other
within the given misfit angle which is defined by the an-
gular difference between the measured and the calculated,
‘ideal’ motion on the fault plane. The misfit angle serves
to check the fit of a given single fault to the stress field; its
maximum value was defined as 20º.

Fault analysis results

In the following the separated 6 stress fields are de-

scribed (Fig. 4). Stress field ‘1’ is defined by relatively few
faults which are characterized by NW—SE compression
generating flat thrusts (

= 313/4;

= 43/5;

= 181/83;

stress ratio: 0.43). The software could fit a left-lateral fault
and a steep dip-slip reverse fault, too. We speculate, how-
ever, that the single strike-slip fault (dotted on Fig. 4)
could be grouped rather to set ‘3’ (see later), because of
parallelism of faults, while the steep surface could be
grouped to stress field ‘4’. These operations were rejected
by the Angelier (1984) software (within the given rela-
tively tight misfit angle). We still think, however, that
pure compression should be separated from the strike-slip
dominated stress state. Considering all faults allowed by
the software to act in stress field ‘1’ the youngest mea-
sured formation was of Ottnangian age (site 2 on Fig. 2). If
we separate the steep strike-slip and oblique-slip faults
from the thrust faults, the youngest formation carrying
thrust faults is of Albian age (site 3 on Fig. 2). We ac-
cepted the latter solution.

The group of faults ‘2’ (

= 81/16;

= 237/72;

= 349/7;

stress ratio: 0.25; Fig. 4) contains mainly left-lateral slips
parallel and acute to the Telegdi Roth Fault and a single
conjugate right-lateral fault. The strike-slip type stress
field is characterized by a roughly E—W compression and
a N—S tension. Beside the strike-slip faults, two thrusts and
a normal fault can act in this stress field. The youngest
formation carrying these faults is of Senonian age (site 16
on Fig. 2).

The group of faults ‘3’ can be generated by a WNW—

ESE compression and perpendicular horizontal tension
(

= 291/21;

= 132/67;

= 24/8; stress ratio: 0.80;

Fig. 4). The principal axes are subhorizontal and
subvertical. The main faults are N—S striking left-lateral
and (W)SW—(E)NE striking right-lateral faults. Some of
the latter faults are parallel to the Telegdi Roth Fault, so
this stress field should be responsible for the main right-
lateral offset along the fault. The number of measured
right-lateral striae seems to be fewer than the left-laterals.
A great number of strike-slip faults without a defined char-
acter of movement were measured at the Kőkapu exposure
(site 9 on Fig. 2) which has a parallel orientation to the

main trend of the Telegdi Roth Fault. If we suppose that
these striae have a right-lateral character, the amount of
left-lateral striae is exceeded by the right-laterals. The
principal axes of stress field differ slightly from the second
one, but this difference is large enough to create opposite
movements along the main Telegdi Roth Fault. The
youngest measured formation carrying these faults was an
Ottnangian sediment (site 2 on Fig. 2).

The fault group ‘4’ can be related to a roughly WSW—ENE

tensional stress field (

= 335/70;

= 165/20;

= 74/3;

stress ratio: 0.73; Fig. 4). The minimal stress axis is
subhorizontal. Some NNE—SSW trending left-lateral and
NW—SE trending right-lateral strike-slip faults also occur
in the group. The youngest formation carrying these faults
was of Senonian age (site 16 on Fig. 2).

The group of faults ‘5’ was generated by a NNE—SSW

compression and a WNW—ESE extension (

= 18/3;

= 281/66;

= 110/24; stress ratio: 0.72; Fig. 4). The

Fig. 4. Stereograms of tectonic phases (1—6) with fault planes,
slickenslides and calculated stress fields on Schmidt net, lower
hemisphere.

– star;

– diamond;

– triangle.

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PALEOSTRESS AND KINEMATIC ANALYSIS ALONG THE TELEGDI ROTH FAULT (W HUNGARY)

fault set is dominated by conjugate strike-slip faults. Some
rather steep reverse faults also occur in the stress field. The
principal stress axes

and

are gently tilted from the

ideal horizontal—vertical. The youngest formation carry-
ing these faults was an Eocene limestone in the northern
part of Bakonybél (site 13 on Fig. 2).

The last fault group ‘6’ is also composed of few faults

(Fig. 4). It is characterized by NW—SE subhorizontal ex-
tension. This stress field is highly similar to stress field ‘5’,
but the Angelier (1984) software does not allow the faults
to fit in the strike-slip type stress field. With the exception
of a couple of faults, this stress field contains steep faults
with steep striae, which are most probably rejuvenated sur-
faces. That is why we do not consider the fault group ‘6’ to
be well-constrained.

All the stress fields described above had principal

stresses very close to horizontal and vertical, so a visual
analysis and grouping of joints could be made. Most of
the joints were very steep and parallel to adjoining fault
planes.

Relative dating of the fault sets

Superposition of striae was detected in three cases. In

the case of a fault belonging to stress field ‘3’ its striation
is superposed by the slip working in stress field ‘4’, there-
fore the latter is younger (Fig. 5A).

In another case, superposing striae were assigned by the

software to the same ‘5’ stress field. We attempted to as-
sign the strike-slip motion to the stress field ‘4’, but be-
cause of the narrow interval of the allowed misfit angle,
this was unsuccessful. However, visual analysis could sug-
gest that the strike-slip motion could better fit in stress
field ‘4’, therefore we do not accept the calculation of the
software. According to visual analysis, stress field ‘5’ is
younger than ’4’ (Fig. 5B).

After the numerical analysis one of the superposed striae

was found in the rejected fault group (trash). The super-
posing fault can, however, be assigned to the stress field
‘4’ (not allowed by the software, but following the logic of
fault mechanics). After that operation we can state that
stress field ‘5’ is younger than ‘4’ (Fig. 5C).

An exposure more distant from the main Telegdi Roth

Fault may help in relative dating. Slickenslides were mea-
sured in an outcrop near Noszlop (South Bakony Mts, not
indicated on Fig. 2). The Egerian age of the deformed rock
is the most relevant for dating of phase ‘3’ (Fig. 6, taken
from Kiss & Fodor 2003). Very nice conjugate sets of
strike-slip faults parallel and antithetic to the Telegdi
Roth Fault were observed in Egerian fluviatile beds. This
means that phase ‘3’ is synchronous or younger than
Egerian.

DEM analysis

A detail of the DEM (Fig. 7) shows the main fault trend

‘A’ of the Telegdi Roth Fault, which could function suc-
cessively under stress fields ‘2’ and ‘3’ (compare to

Fig. 5. Relative dating of the stress field generations; the slickenslides
on main fault plane marked with bold. Same legend as for Fig. 4.

Fig. 6. Stereogram for the slickenslides observed near Noszlop,
measured in the Egerian fluviatile beds indicated the phase ‘3’.
After Kiss & Fodor (2003).

stereoplots of the same figure). As previously stated, the
little grabens bounded by the fault group ‘B’ can be
formed in stress field ‘4’ (or probably in phase ‘5’), later
than the main right-lateral offset during phase ‘3’. The
DEM also suggests the left-lateral offset of the main fault
between Zirc and Akli (Fig. 2) by faults of the trend ‘C’.
These faults can be observed north of Veszprém.

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SASVÁRI, KISS and CSONTOS

Conclusions on the dating of stress fields

Pure NW—SE compression was recorded in Aptian sedi-

ments (stress field ‘1’, see Fig. 4). This phase was prob-
ably taking place either in the Albian, or in the
Cenomanian (see also Tari 1995; Kiss 1999; Albert
2000; Budai et al. 2005; Fig. 8). The main thrust move-
ments and related folding in the Transdanubian Range
must have taken place before the Senonian, because
these sediments are unconformably overlying older for-
mations and their position is subhorizontal (e.g. Haas et
al. 1984; Tari 1994).

Phase ‘2’ was only recorded in the Senonian forma-

tions, so it may be younger than these sediments, prob-
ably Paleogene. This is also suggested by the lack of
similar slip traces in Eocene or younger formations. This
strike-slip type stress field created left-lateral offsets
along the Telegdi Roth Fault (Sasvári 2003). The pro-
posed age of this striae-generation is from Late Creta-
ceous to Early Eocene (Bada 1999; Bíró 2003; Fig. 8).

A similar, clearly strike-slip type stress field (‘3’) with

observed traces in Eocene and Ottnangian sediments was
responsible for the right-lateral motion of the Telegdi
Roth Fault. This stress field was active from the Middle
Eocene to the Early Miocene (Eggenburgian—Ottnangian;
Bada 1994, 1999; Fodor et al. 1994; Bada et al. 1996;

Fodor et al. 1999; Kiss 1999; Bíró 2003; Márton &
Fodor 2003; Budai et al. 2005; Fig. 8).

Kun Jáger et al. (1994) studied the Iharkút conglomer-

ate, a peculiar coarse clastic formation of Late Eocene to
Early Oligocene age (Korpás 1981; Kun Jáger et al.
1994). They stated that the clasts were derived from local
material, the sedimentary transport directions were to-
wards the south and the conglomerate occurred only
south of the Telegdi Roth Fault, even at places where the
Eocene is preserved north of the fault. All this suggests
that the Telegdi Roth Fault was already active in the Late
Eocene—Early Oligocene and created paleotopographic
changes during its activity. We propose that this activity
could be the right-lateral motion. This conclusion was
also supported by Magyari (pers. com.) and by Sztanó
(pers. com.).

This phase might gradually change to the extensional

phase ‘4’, probably during the late Early and the early
Middle Miocene (Ottnangian to Badenian age, Fodor et
al. 1994; Bada 1999; Kiss 1999; Kiss et al. 2001; Bíró
2003; Márton & Fodor 2003; Budai et al. 2005; Fig. 8).
The chronological order of these phases was established
on superimposed fault-slips (Fig. 5A). In the absence of
younger sediments the activity of these phases is only in-
ferred from the general trend of stress field evolution of the
Pannonian Basin (Csontos et al. 1991; Fodor et al. 1999).

Fig. 7. Blow-up of the Digital Elevation Model and the major faults in the area of the Telegdi Roth Fault. Insert A – stereoplots of
phases ‘2’, ‘3’, ‘4’; Insert B – structural sketch of Mészáros (1983).

483

PALEOSTRESS AND KINEMATIC ANALYSIS ALONG THE TELEGDI ROTH FAULT (W HUNGARY)

Probably, the last stage of the tectonic evolution is

phase ‘5’, which is a combined strike-slip and extensional
event. A Middle to Late Miocene time (late Badenian to
Pannonian) is proposed for the activity of this stress field
(Palotás 1991; Bada et al. 1996; Bada 1999; Kiss et al.
2001; Fig. 8). The thrust of older formations onto the
Badenian coal (e.g. Kókay 1996) might be also caused by
this stress field. After unpublished observations of Kókay

(pers. com.) the Quaternary—recent activity can
also be supposed. Phase ‘5’ would agree with
observations on the recent stress field (e.g.
Gerner 1994; Gerner et al. 1999; Windhoffer et
al. 2001; 2005).

Comparison with the earlier results

In this chapter our data and interpretations are

compared to earlier works by Mészáros (1983),
Fodor et al. (1999), Kiss et al. (2001) and Márton
& Fodor (2003). The map of Mészáros (1983)
(Fig. 7B) was based on long field mapping and
mining experience. However, many of the faults
on his map are seen neither on earlier, nor later
maps (Noszky 1957; Knauer & Végh 1967;
Korpás 1969; Császár 1970; Knauer 1977;
Gyalog & Császár 1982), nor on the Digital El-
evation Model (Fig. 7A). On the contrary, some
faults which are qualified as right-lateral on his
map, appear to be left-lateral or normal after the
map and DEM analysis. This is the case with the
WNW—ESE trending fault south of Zirc, which is
left-lateral or normal, instead of the right-lateral
offset proposed by Mészáros. Additionally, the
main Telegdi Roth Fault seems to diverge on his
map southeast of Olaszfalu (Fig. 7B). This diver-
gence is not really seen on any geological maps.
Of the roughly N—S striking parallel faults east of
Olaszfalu (Fig. 7A) only one is shown by
Mészáros (1983) with sinistral movement
(Fig. 7B), differing from its clearly visible dex-
tral nature on the map and the DEM. According
to Mészáros (1983) this fault generation is cross-
cut by the Telegdi Roth Fault, which contradicts
the analysis of the fault slip data as well as that
of the DEM and other geological maps (Gyalog
& Császár 1982). The E—W striking dextral fault
east of Akli (Fig. 7A) which is clearly visible on
the DEM and detectable on the geological map,
does not appear in Mészáros’s (1983) work
(Fig. 7B).

Following Mészáros (1983), Tari (1991) sug-

gested that the Transdanubian Range is cut up
by a series of WNW—ESE to NNW—SSE striking
right-lateral faults. In his model the WNW—ESE
striking first generation is followed by NW—SE,
then NNW—SSE strike-slip faults (see Fig. 7B).
Some older NW—SE faults were supposed to be
as old as middle Cretaceous (Mészáros 1983),

Fig. 8. Proposed stress field and structural evolution of the palinspastic Teleg-
di Roth Fault and its neighbourhood, with rotations taken from Márton &
Fodor (2003). ‘N’ shows present-day north direction. Thick lines indicate the
active faults.

but the bulk of the subsequent right-lateral shears were
supposed to be Middle Miocene (Sarmatian). We do not
think that the bulk of deformation was so late – in con-
trast, according to the proposed fault chronology (Fig. 4),
we suggest that the main movements were earlier, probably
in the Middle Eocene to Early Miocene (Eggenburgian);
we propose that the older faults could have been reactivated
in the Middle Miocene (Sarmatian), or later.

484

SASVÁRI, KISS and CSONTOS

Fodor et al. (1999) show a mainly compressional stress

state with (W)NW—(E)SE shortening directions from the
Early Eocene to the Early Miocene (Ottnangian) valid for
the Bakony Mts. The presented stress properties are in
good agreement with the observed stress field ‘3’. For the
late Early and early Middle Miocene (Karpatian—
Badenian) Fodor et al. (1999) present a stress field similar
to the former one, but characterized by strike-slip faulting.
This is in good agreement with our stress field ‘4’. Follow-
ing that, an extensional phase with NW—SE minimal hori-
zontal stress axis for the Transdanubian Range is
presented by Fodor et al. (1999). Conjugate normal
microfaults with NE—SW strike belong to this phase in the
late Badenian to the Pannonian (from the late Middle Mi-
ocene to the Late Miocene) interval. This could corre-
spond to our phase ‘5’. The latest Miocene to Quaternary
stress field can be characterized by WNW—ESE minimal
horizontal stress axis in the Bakony Mts (Fodor et al.
1999). The main microstructures are NNW—SSE striking
normal faults and strike-slip faults. We could not demon-
strate this deformational stage, but normal faults of the
stress field ‘5’ can be reactivated at that time.

Kiss et al. (2001) dealt with striae sets in the northern

part of the Bakony Mts. Their work was concentrated on
the area around Csesznek, where a complex strike-slip cor-
ridor is visible. This corridor, parallel to the Telegdi Roth
Fault, is also dextral and affects Eocene to Egerian beds.
The first stress field described by Kiss et al. (2001) is a
compressional one with NW—SE shortening and perpen-
dicular extension directions. Their proposed middle Creta-
ceous age is in agreement with our observations and
dating. The authors also present two other stages of the
structural evolution in the studied area: the second stage
acting from the Early to the Middle Miocene (Ottnangian
to Sarmatian) is characterized by a NNW—SSE shortening
direction (Kiss et al. 2001). The third tectonic phase of
Late Miocene (Pannonian) age is a pure (W)NW—(E)SE
tension (Kiss et al. 2001). It is to be noted that their sec-
ond deformation is very similar to our phase ‘4’, and the
third to our phase ‘5’; but our stress fields show tensional
and strike-slip properties, respectively.

Márton & Fodor (2003) compared the structural results

to the paleomagnectic rotations of the Transdanubian
Range showing 4 (or even 5) stages of the structural evo-
lution. The first described stress field characterized by
NW—SE compression and perpendicular tension could
have acted from the Middle or Late Eocene to the earliest
Miocene (Ottnangian) which is in good agreement with
our stress field ‘3’. The second tensional and third strike-
slip stress field can be characterized by NE—SW tension
and NNW—SSE compression (Márton & Fodor 2003)
which acted from the late Early to early Middle and the
late Middle Miocene, respectively. Our stress field ‘4’
could be a combination of these.

Márton & Fodor (2003) also proposed two exten-

sional faulting events marked by approximately E—W and
ESE—WNW tension for the Late Miocene—Quaternary
period, respectively. Our stress field ‘5’ could be equivalent
to a combination of these. The main idea of Márton &

Fodor (2003) was to link this stress-field evolution and
their observed apparent rotation of the principal stress
field directions to the measured paleomagnetic rotations.
In their model ‘A’ they propose a first 30º counterclock-
wise rotation in the Early Miocene (Ottnangian) followed
by a second 15º counterclockwise rotation in the Middle
Miocene (Badenian). Finally a last 25º counterclockwise
rotation is proposed in the Pliocene. Model ‘B’ of
Márton & Fodor (2003) differs from the first one by
suggesting that the time of first rotation was the Late
Eocene instead of Early Miocene. If these rotations are
reconstructed, the principal stress directions remain
constant (N—S compression) for most of the Tertiary and
the external stress field changes direction only in the Late
Miocene (Márton & Fodor 2003, their Fig. 10).

We have also observed a change in the apparent princi-

pal stress directions from phases ‘2’ to ‘5’. This observa-
tion can also be explained by the rotation models briefly
discussed above (Fig. 8). The angular difference between
our stress fields ‘2’ and ‘3’ equals about 30º, which is
identical to the first rotation of Márton & Fodor (2003).
We proposed that ‘2’ acted prior to Late Eocene and ‘3’
acted in the Late Eocene—Ottnangian. Therefore the rota-
tional model ‘B’ would perfectly explain the difference
between these stress fields. Similarly, there is about 30º
difference between our stress fields ‘3’ and ‘4’, which
might be explained by the rotational model ‘A’. Naturally
both cannot be applied, but according to our data we can-
not discriminate between rotational models of Márton &
Fodor (2003). Finally, the angular difference between our
stress fields ‘4’ and ‘5’ equal about 15º, which is identical
to the second rotation of Márton & Fodor (2003). It seems
that the last, Pliocene rotation does not appear in our data
set. However, because of the robust paleomagnetic data
presented in the cited work, we applied this last rotation to
our data set (Fig. 8).

Regional framework

The northern part of the Pannonian Basin, named

Alcapa, suffered extrusion from the Alpine sector (e.g.
Balla 1984; Kázmér & Kovács 1985; Balla & Dudko
1989; Ratschbacher et al. 1991; Fodor et al. 1999; Sperner
et al. 2002). Extrusion can be separated into a phase of
major right-lateral shear along the Periadriatic fault (and
its continuation, the Balaton fault) in the Late Eocene to
the Oligocene—earliest Miocene (Eggenburgian); followed
by a 90—60º counterclockwise rotation, extension in W—E
and compression in N—S directions in the Early Miocene
(Kázmér & Kovács 1985; Balla & Dudko 1989; Csontos
1995; Márton & Fodor 1995; Fodor et al. 1994; Fodor et
al. 1999; Csontos & Vörös 2004). During this later phase
the right-lateral shear component along the southern pe-
riphery of Alcapa still prevailed. Rotation placed Alcapa
into the Carpathian embayment, where it was possibly
pulled eastwards by the subducting European slab
(Horváth & Royden 1988; Csontos 1995). This centripetal
pull created a complex back-arc type basin. The initiation

485

PALEOSTRESS AND KINEMATIC ANALYSIS ALONG THE TELEGDI ROTH FAULT (W HUNGARY)

(rifting) of the individual little basins happened in the late
Early Miocene and their merging into a big back-arc basin
took place in the Middle Miocene (Fodor et al. 1999).
During the Late Miocene the gentle but very effective
thermal subsidence (Horváth & Royden 1988) was inter-
rupted by smaller transtensional and transpressional, even-
tually rotation events (Csontos 1995; Horváth 1995;
Fodor et al. 1999).

Conclusions

The brittle fault data measured around the Telegdi Roth

Fault, a major, map-scale fault in the Transdanubian
Range enabled us to differentiate 5 tectonic events, all
characterized by different fault sets and related stress
fields presented with their retro-rotated stress directions.

The first, compressional tectonic event (stress field ‘1’

on Figs. 4 and 8) NE—SW pure compression generating flat
thrusts. This tectonic phase fits well into the Aptian—
Albian tectonic evolution of the Alcapa block (Tari 1995).
The second tectonic phase (stress field ‘2’ on Figs. 4 and 8)
with NW—SE compression and perpendicular extension
direction was responsible for the sinistral shear along the
Telegdi Roth Fault; the supposed age of this tectonic
phase is Late Cretaceous—Early Eocene. The main dextral
movement of the fault is generated by the third tectonic
event (stress field ‘3’ on Figs. 4 and 8) characterized by N—S
compression and E—W extension direction. This tectonic
phase could have been active from the Middle Eocene to
the Early Miocene (Ottnangian). Divergence of the stress
axes in the Albian—Early Miocene (Ottnangian) period
should be considered normal because of the major age
gap. However, the 30º angular difference between stress
fields ‘2’ and ‘3’ could be induced by a 30º CCW rotation
of Alcapa in the Late Eocene, postulated by Márton &
Fodor (2003, their model ‘B’). If the general behaviour of
Alcapa is taken into account (Balla 1984; Márton & Fodor
1995; Csontos & Vörös 2004) it is more probable that a
major rotation occurred in the Early Miocene (Model ‘A’
of Márton & Fodor 2003). Therefore we rather suggest that
a 30º change of the external stress field took place in the
early Paleogene and this change controlled the left and
right lateral slips along the Telegdi Roth Fault.

The next differentiated stress field of our study is ‘4’,

characterized by ENE—WSW extension (stress field ‘4’ on
Figs. 4 and 8). This tectonic phase created the roughly N—S
striking parallel faults east of Zirc (Figs. 2 and 3) which
cut the Telegdi Roth Fault. The apparent 30º angular dif-
ference between the phases ‘3’ and ‘4’ can be perfectly ex-
plained by the 30º counterclockwise rotation (model ‘A’)
of the Transdanubian Range proposed by Márton & Fodor
(2003) for the Early Miocene (Ottnangian). Since this is
the age when most major rotations took place in the Intra-
Carpathian area (op. cit.) we think this model is valid for
our area as well. The late Middle Miocene—Late Miocene
period is marked by a strike-slip stress field with NNE—SSW
compression directions (stress field ‘5’ on Figs. 4 and 8).
Between the early Middle and the late Middle Miocene

(Badenian) – in good accordance with the model of
Márton & Fodor (2003) – we can also suppose a 15º
counterclockwise rotation.

The character of the stress field changed from pure ten-

sional to transtensional (Figs. 4, 8). The overthrusts ob-
served in the Badenian coal may be generated by an even
younger, Quaternary stress regime. The Pliocene 25º coun-
terclockwise rotation of the stress directions presented by
Márton & Fodor (2003) cannot be observed in our study
area because of lack of data.

Acknowledgments: The authors are thankful for the very
useful and helpful comments of L. Fodor (Budapest), F.
Marko (Bratislava), Gy. Maros (Budapest), M. Vrabec
(Ljubljana) and D. Plašienka (Bratislava). The work was
supported by OTKA Grant No. T-043760.

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