GeolCarp_Vol59_No3_199

GEOLOGICA CARPATHICA, JUNE 2008, 59, 3, 199—209

www.geologicacarpathica.sk

Stripped image of the gravity field of the Carpathian-

Pannonian region based on the combined interpretation

of the CELEBRATION 2000 data

ZUZANA ALASONATI TAŠÁROVÁ

, MIROSLAV BIELIK

2, 3

and HANS-JÜRGEN GÖTZE

Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Geophysik, Otto-Hahn-Platz 1, D-24118 Kiel, Germany;

tasarova@geophysik.uni-kiel.de

Department of Applied and Environmental Geophysics, Faculty of Natural Sciences, Mlynská dolina, Bratislava, Slovak Republic;

bielik@fns.uniba.sk

Geophysical Institute of the Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, Slovak Republic; geofmiro@savba.sk

(Manuscript received August 15, 2007; accepted in revised form December 13, 2007)

Abstract: The Carpathian-Pannonian region is one of the areas of Central Europe with good coverage of geophysical
and geological data. This is due to its complicated evolution that attracted scientific interest already in the past. In
addition, several international seismic experiments were conducted here in the last 10 years. The model to be presented
uses most of these available data to perform a combined gravity—seismic interpretation. The analysis of the gravity
anomalies is performed in order to identify the sources of the anomalies, separate their effects and localize the lithos-
pheric inhomogeneities. The gravity stripped image of the region reveals significant differences in the nature of the
Microplates ALCAPA and Tisza-Dacia from the surrounding regions.

Key words: Carpathian-Pannonian region, Bouguer anomaly, 3-D density modelling, interpretation of the gravity field,
lithospheric structure.

Introduction

The  Carpathian  Mountain  belt,  extending  over  1300 km,  is
surrounded by the Pannonian Basin System, Eastern Alps, Bo-
hemian Massif, Trans-European Suture Zone (TESZ) and the
south-western part of the Precambrian East European Craton
(EEC) (Fennosarmatian Craton). The present structural pattern
of the Carpathians was formed by the Late Jurassic to Tertiary
subduction-collision  orogenic  processes  in  the  Tethyan  mo-
bile belt between the stable European Platform in the NE and
the  Apulia/Adria-related  continental  blocks  (ALCAPA  and
Tisza-Dacia) drifting from the SW (e.g. Kováč 2000).

Recently, several international seismic refraction experi-

ments (POLONAISE’97, CELEBRATION 2000, ALP 2002,
SUDETES 2003), aimed at investigation of the lithospheric
structure in this area, have been performed (e.g. Guterch et
al. 2003a).

The work presented uses most of these data to perform a

combined  gravity  and  seismic  3-D  modelling.  For  this  pur-
pose,  complete  Bouguer  anomaly  newly  compiled  (Bielik  et
al. 2006) was used for the forward modelling by means of the
Interactive  Gravity  and  Magnetic  System  (IGMAS)  (e.g.
Götze 1976; Götze & Lahmeyer 1988). All additional geolog-
ical and geophysical data available were combined into a 3-D
structural  image  of  the  Western  Carpathians  and  Pannonian
Basin. It is impossible, however, to perform 3-D modelling of
the  Carpathian-Pannonian  region  without  including  the  sur-
rounding units. Therefore, this large-scale lithospheric mod-
el  also  comprises  the  TESZ,  EEC,  Bohemian  Massif  and
Eastern  Alps.  It  extends  down  to  a  depth  of  220 km  and  is

developed along 31 parallel cross-sections cutting the above
named units.

Geological setting

The East European Craton (EEC), formed during the Pre-

cambrian, is composed of Proterozoic igneous and metamor-
phic rocks covered by Vendian and Paleozoic strata (Dadlez et
al. 2005). It is divided from the younger Paleozoic platform to
the  SW  by  the  Trans-European  Suture  Zone  (TESZ).  The
TESZ is a broad (up to 200 km) zone, crossing Europe from
the North Sea to the Black Sea. The north-eastern boundary of
the  TESZ  in  Poland  is  the  fault  zone,  called  the  Teisseyere-
Tornquist-Zone  (TTZ)  (Dadlez  et  al.  2005  and  references
therein). In Poland, the TESZ consists of several suspected ter-
ranes accreted to the south-western margin of the EEC during
the  Paleozoic  (e.g.  Winchester  et  al.  2002;  Guterch  &  Grad
2006). These terranes are referred to as Bruno-Silesian (called
also  Upper-Silesia),  Małopolska  and  Łysogóry  blocks.  The
latter two are exposed in SE Poland in the Holy Cross Moun-
tains (HCM) and are separated by the Holy Cross Fault. The
SW  part  of  the  HCM  belongs  to  the  marginal  parts  of  the
Małopolska block (Kielce Unit) and the NE part of the HCM
belongs to the Łysogóry block (Łysogóry Unit) (e.g. Schätz et
al.  2006).  Both  blocks  are  interpreted  as  Baltica  derived  ter-
ranes  (e.g.  Malinowski  et  al.  2005;  Janik  et  al.  2005).  The
Bruno-Silesian  block  seems  to  differ  from  the  Małopolska.
These two units have different stratigraphic development and
are  separated  by  a  500 m  wide  zone,  referred  to  as  the

200

ALASONATI TAŠÁROVÁ, BIELIK and GÖTZE

Kraków-Lubliniec Zone (Buła et al. 1997). Hence the Bruno-
Silesian block is interpreted as a fragment of Gondwana (e.g.
Malinowski et al. 2005). However, some authors (e.g. Schätz
et al. 2006 and references therein) interpreted all three terranes
as exotic terranes of Gondwanan provenance.

The Bohemian Massif, forming the easternmost part of the

Variscan belt, is the largest stable outcrop of pre-Permian
rocks in Western Europe. It consists mainly of metamorphic
rocks, granites, and subordinate fossiliferous Paleozoic rocks
(Hrubcová et al. 2005 and references therein).

The Western Carpathians belong to the ALCAPA micro-

plate  (e.g.  Kováč  2000),  which  reaches  the  Pieniny  Klippen
Belt (PKB) in the north, and the Tisza-Dacia microplate in the
south. The ALCAPA microplate is thrusted over the Tisza-Da-
cia microplate along the Mid-Hungarian Line, which is a Ter-
tiary  strike-slip  fault  zone  (e.g.  Plašienka  et  al.  1997).  The
Western Carpathians comprise, from north to south: the Outer
Western  Carpathians,  Pieniny  Klippen  Belt  (PKB)  and  the
Central Western Carpathians. The Carpathian Foredeep is lo-
cated  in  front  of  the  Outer  Carpathians  along  the  entire  Car-
pathian orogen (Fig. 1).

The Pannonian Basin System (PBS) was formed as a back-

arc system due to the lithospheric extension and mantle up-
welling behind the Carpathian arc during two stages (e.g. Hor-

váth 1993; Kováč 2000). The driving mechanism for the ex-
tension is thought to be, traditionally, the subduction roll-back
of the European Platform (e.g. Royden et al. 1983; Konečný et
al. 2002; Szabó et al. 2004). The PBS is filled with Tertiary
and Quaternary strata that reach, in some places, more than
6 km (e.g. Kováč 2000; Makarenko et al. 2002).

Review of results of the previous geophysical

investigations

The former geophysical investigations provided informa-

tion  on  the  crustal  thickness,  revealing  the  crust-mantle
boundary (Moho) to be very shallow in the Pannonian Basin.
The Moho deepens towards the Carpathians to the north and
east, as well as towards the Bohemian Massif and the Eastern
Alps in the west (e.g. Horváth 1993; Šefara et al. 1996). Simi-
larly to the Moho, also the lithosphere-asthenosphere bound-
ary (LAB) in the Pannonian Basin region is very shallow. Ac-
cording  to  the  seismological  data,  magnetotelluric  sounding
and geothermal measurements (e.g. Babuška et al. 1987; Praus
et al. 1990; Horváth 1993; Čermák 1994), the lithosphere-as-
thenosphere boundary in the Pannonian Basin is at depths of
60  to  80 km.  More  recent  data  based  on  the  2-D  integrated

Fig. 1. Location map. Acronyms stand for: PBS – Pannonian Basin System, PKB – Pieniny Klippen Belt, OWC – Outer Western
Carpathians, CF – Carpathian Foredeep, BSB – Bruno-Silesian Block, HCM – Holy Cross Mts, TTZ – Teisseyre-Tornquist Zone,
VF – Variscan Front.

201

GRAVITY FIELD OF THE CARPATHIAN-PANNONIAN REGION BASED ON CELEBRATION 2000 DATA

modelling combining the heat flow density distribution, abso-
lute  topographic  elevation,  gravity  data  and  geoid  (Zeyen  et
al.  2002;  Dérerová  et  al.  2006)  show  the  Pannonian  Basin
LAB to be at a depth of 80 km. The S-wave receiver function
method reveals that the LAB in the northern edge of the Pan-
nonian Basin is at a depth of 75 km (Geissler et al. 2007). Pet-
rological analysis of the upper mantle xenoliths also confirms
that  a  significant  mantle  uplift  (50—60 km)  occurred  beneath
the Pannonian Basin (Falus et al. 2000). Additionally, accord-
ing to the global thermal model for the continental lithosphere
of Artemieva (2006), the lithosphere of the Pannonian Basin
region is 50 to 100 km thick.

Maps of heat flow density distribution show a clear differ-

ence between the Pannonian Basin System and the surround-
ing units. While the Bohemian Massif, Carpathian Mountains
and the European Platform are characterized by medium val-
ues of 40 to 70 mW/m

, the heat flow in the PBS reaches 80—

130 mW/m

. Higher heat flow values of 80—100 mW/m

oc-

cur partly also in the Eastern Alps (e.g. Pollack et al. 1993;
Čermák 1994; Lenkey et al. 2002).

The region of Central Europe is also well covered by

gravimetric  and  magnetic  measurements.  The  Bouguer
anomaly  used  in  this  work  was  compiled  based  on  the  na-
tionally  acquired  data  of  Slovakia,  Poland,  Hungary,  the
Czech  Republic  and  Austria  by  Bielik  et  al.  (2006).  The
Bouguer anomalies are characterized by low values of some
—20 to —65 mGal (1 mGal = 1

×10

—5

m/s

) along the Western

Carpathians (Central and Outer) and drop down to less than
—120 mGal  above  the  Eastern  Alps  and  the  Eastern  Car-
pathians.  The  Pannonian  Basin,  Bruno-Silesian  block  and
so-called Małopolska High in southern Poland, have positive
values  of  0—20 mGal  (Fig. 2).  The  Małopolska  High  (e.g.
Grabowska  &  Bojdys  2001  and  references  therein)  has  two
parts,  distinctive  also  in  the  Bouguer  gravity  anomaly.  The
NE  part,  located  on  the  south-western  edge  of  the  EEC  is
called  the  Lublin  High.  The  SW  part  belongs  to  the

Fig. 2. Bouguer anomaly modified after Bielik et al. (2006). Acronyms stand for: PBS – Pannonian Basin System, PKB – Pieniny Klip-
pen Belt, OWC – Outer Western Carpathians, CF – Carpathian Foredeep, BSB – Bruno-Silesian Block, HCM – Holy Cross Mts,
TTZ – Teisseyre-Tornquist Zone, VF – Variscan Front. The Małopolska High, stretching from the HCM to the southern edge of the
EEC, is separated by the TTZ into two parts. The Kolárovo gravity high (KGH) is marked by a circle. The location of the cross-sections of the
3-D model (thin grey lines) and of the CELEBRATION 2000 experiment (thick black lines) are also shown (upper right corner).

202

ALASONATI TAŠÁROVÁ, BIELIK and GÖTZE

Łysogóry and Małopolska blocks and partly overlaps with
the Holy Cross Mts (HCM, Fig. 2).

The station complete Bouguer gravity anomaly is tied to the

IGSN71 datum (e.g. Torge 1989). However, although this da-
tum  has  been  conventional  for  more  than  30  years,  some
works  (e.g.  Grabowska  &  Bojdys  2001;  Malinowski  et  al.
2005; Janik et al. 2005) still use data in the Potsdam Gravity
System, shifted with respect to the IGSN71 by  ~ 14 mGal. For
this reason, their values of the Bouguer gravity anomaly in Po-
land are higher than those shown here in Figs. 2 and 3.

Constraining data and indirect density

determination

The large-scale international Central European Lithospher-

ic Experiment based on Refraction (CELEBRATION 2000)
was conducted in June 2000, as a joint experiment of 28 insti-
tutions in Europe and North America (Guterch et al. 2003b).
The  data  were  collected  along  ~ 17  profiles,  giving  a  total
length of 8,900 km. So far, 7 of these profiles have been pro-
cessed  and  published.  These  are  profiles  CEL01,  CEL02,
CEL03,  CEL04,  CEL05,  CEL09  and  CEL10  (Fig. 2)  (Mali-
nowksi  et  al.  2005;  Janik  et  al.  2005;  Hrubcová  et  al.  2005;
Środa et al. 2006; Grad et al. 2006 and Růžek et al. 2007). The
CELEBRATION data together with the results of the previous
investigations of the region (e.g. Bielik et al. 2004 and refer-
ences therein) and information from 2-D integrated modelling
of Dérerová et al. (2006) were the primary input for the 3-D
modelling performed within this study. All of these data con-
strain  the  geometry  of  the  structures  modelled  (the  depth  to
major  boundaries,  such  as  sediments,  Moho,  lithosphere-as-
thenosphere boundary). In addition, the P-wave seismic veloc-
ities  from  the  CELEBRATION  2000  experiment  were  con-
verted  into  densities  using  the  empirical  relationships  of
Christensen  &  Mooney  (1995)  and  Sobolev  &  Babeyko
(1994).

There are significant differences reaching 0.05—0.13 Mg/m

(1 Mg/m

= 1 g/cm

= 1000 kg/m

) in the calculated density

values  obtained  from  the  two  empirical  relationships  (Ta-
ble 1). Thus, there is a wide range of densities corresponding
to the observed seismic velocities. Additionally, the empirical
velocity-density curves, or linear relationships, provide only a
mean  density  of  a  particular  rock  unit,  which  internally  may
be quite variable. It has been demonstrated by various studies
(e.g. Hacker & Abers 2004) that both velocities and densities
strongly depend on the composition of rocks. Thus, rocks with
similar  velocities  may  have  significantly  different  densities
and vice versa. The determination of densities based only on a
velocity-density  relationship  is  hence  one  of  the  major  prob-
lems  related  to  developing  combined  gravity  and  seismic
models. Therefore, all information related to the composition
of the structures modelled should be considered while gravity
modelling is performed. However, a density model always ap-
proximates the real structures in a simplified way, with larger
units extending sometimes over tens of kilometers (in distance
and  depth).  These units are usually characterized by a single
(constant)  density  value.  For  this  reason,  although  a  signifi-
cant scatter around the mean value is associated with empiri-

Table 1:  Densities  for  particular  depths  derived  from  the  P-wave
seismic  velocities  (vp)  using  the  approach  of  Sobolev  &  Babeyko
(1994) (S&B) and Christensen & Mooney (1995) (C&M). The tem-
peratures for the approach of Sobolev & Babeyko (1994) were cal-
culated  assuming  surface  heat  flow  of  40—50 mW/m

for cold,

60 mW/m

for medium, 70 mW/m

for warm and 80—90 mW/m

for

a hot region. The relationship of Christensen & Mooney (1995) is a
nonlinear relationship derived for all rock types (including the up-
per mantle rocks) and is recommended for crust-mantle sections.

Table 2: Observed P-wave seismic velocities (vp) from the CEL-
profiles and densities employed in the 3-D density model. The den-
sities of an alternative model reproducing the Małopolska High are
marked by an

. The asterisks mark maximum values, which occur

only locally and should not be taken as average values.

203

GRAVITY FIELD OF THE CARPATHIAN-PANNONIAN REGION BASED ON CELEBRATION 2000 DATA

cal velocity-density relationships (Barton 1986 and references
therein), they may be applied to larger-scale lithospheric mod-
els. Moreover, existing seismic models or boreholes also con-
strain the depth to the major boundaries, such as sedimentary
basins and the Moho. The structures modelled are, therefore, a
trade-off between the seismic models (extent of the structures
and their velocities) and gravity anomalies.

The relationship of Sobolev & Babeyko (1994) requires P/T

conditions in order to calculate the in situ densities from the
seismic velocities. This is very convenient for the modelling
of Central Europe because here the various units are character-
ized by extremely different temperature conditions. Therefore,
this relationship was found more appropriate for the determi-
nation of densities from seismic velocities. The temperatures
at various depths are calculated on the basis of the known sur-
face heat flow values (Pollack et al. 1993; Majorowicz et al.
2003) according to the heat conduction equation (e.g. Turcotte
& Schubert 2002). In situ pressure is estimated as a function
of depth, standard density and overpressure factor.

The summary of the observed P-wave velocities (Table 2)

shows significant differences between the units considered in
the model (the Western Carpathians, Pannonian Basin, Bohe-
mian Massif, TESZ, EEC and Eastern Alps).

Discrepancies in the interpretation of the

CELEBRATION 2000 data

The crustal root of more than 50 km in the TESZ area inter-

preted by Guterch et al. (1986) and shown also in the maps of
the  Moho  depth  of  Bielik  (1999  and  references  therein)  was
not  approved  by  the  CELEBRATION  results  (e.g.  Dadlez  et
al.  2005;  Guterch  &  Grad  2006).  Moreover,  there  are  also
some  discrepancies  among  the  CELEBRATION  profiles
themselves, since 3-D seismic interpretation has not yet been
performed and all of the above mentioned CEL-profiles were
processed in 2-D. The most significant differences (exceeding
the errors estimated) occur at the intersection points of the fol-
lowing profiles:

– CEL01 and CEL02: thickness of sediments differ by

2 km, the thickness of the upper crust and its velocity by 3—
4 km and 0.35 km/s, respectively.

– CEL01 and CEL03: velocity at 15 km depth differs by

0.68—0.88 km/s.

– CEL01 and CEL04: the upper-crustal velocity is differ-

ent by 0.15 km/s and the depth to the interface between the
upper and middle crust differs by at least 1 km; the depth to
the Moho varies by 3 km.

– CEL02 and CEL03: the lower-crustal high-velocity body

is located at different depths, causing a velocity-difference of
~ 0.3 km/s at depths of 30—40 km.

– CEL02 and CEL04: the depth to the boundary between

the upper and middle crust and to the Moho differs by 2 km.

– CEL03 and CEL05: the thickness of the sediments varies

by 6 km and the velocities at ~ 10 km depth are different by
0.5 km/s and 0.15 km/s.

– CEL04 and CEL10: the velocities in the upper and lower

crust differ by 0.2 and 0.3 km/s, respectively; the difference to
the depth of the Moho is 4 km.

Due to these discrepancies, we believe a 3-D approach us-

ing these data as constraining information is very useful in or-
der to bring more insights into the structural image of the area.

Density modelling

The 3-D modelling is performed using IGMAS, where the

modelled geological bodies are approximated by polyhedra of
constant density (e.g. Götze 1976). The structures are defined
along  2-D  cross-sections  that  are  connected  via  triangulation
into a 3-D volume. Thus, the geometry of the geological bod-
ies between the cross-sections is interpolated. Therefore, in or-
der  to  obtain  more  reliable  results,  a  greater  number  of  2-D
planes  must  be  included.  The  model  presented  is  developed
along 31 cross-sections, separated by 20 km across the West-
ern Carpathians and Pannonian Basin and 40 km in the Bohe-
mian Massif and Eastern Alps. They are parallel to each other
and are almost identical with the direction of the CEL05 pro-
file. The model consists of 41 bodies, representing the above
mentioned units, thus giving a rather complex structure. Con-
straining data can be visualized in IGMAS interactively along
the  modelled  cross-sections  by  means  of  the  GIS  functions
(e.g. Schmidt & Götze 1999). This is a great advantage during
the modelling of large areas including various datasets.

In general, each of the units consists of four crustal layers:

sediments, upper, middle and lower crust (Fig. 3). The densi-
ties  employed  in  the  3-D  model  are  summarized  in  Table 2.
The densities of the sediments in the Pannonian Basin System
and Western Carpathians are based on the previous investiga-
tions (e.g. Makarenko et al. 2002; Bielik et al. 2005 and refer-
ences  therein).  The  densities  of  the  sediments  in  the  other
units are mainly based on the P-wave velocities of the CEL-
models  and  relationships  of  Gardner  et  al.  (1974)  and  Wang
(2000), determined for sedimentary rocks. The upper mantle is
in general divided into two parts, the lithospheric and astheno-
spheric  mantles.  The  densities  of  the  lithospheric  mantle  un-
derneath  the  ALCAPA  and  Tisza-Dacia  microplates  and  the
European Platform (EP) are not constant. The colder EP upper
mantle  was  assigned  a  density  of  3.36 Mg/m

, which is by

0.03 Mg/m

greater than the density of the ALCAPA’s lithos-

pheric  mantle  (Fig. 3).  This  is  due  to  the  temperature  differ-
ence of some 200—300 °C at depths of 50 and 100 km (e.g Ar-
temieva  2006).  According  to  the  data  of  Kuskov  &  Kronrod
(2006),  the  density  decrease  associated  with  higher  tempera-
tures (for constant pressure and composition) is in the order of
—0.013 Mg/m

for + 100 °C (meaning that —0.03 Mg/m

cor-

responds to ~ 230 °C difference in temperature). The astheno-
sphere, having a different composition than the lithospheric
mantle, has lower Mg# (100

×Mg/(Mg+Fe)) and higher den-

sity than the lithosphere (e.g. Poudjom Djomani et al. 2001
and references therein; Kuskov & Kronrod 2006). The as-
thenosphere was assigned a density of 3.38 Mg/m

. The Pan-

nonian  Basin  is,  additionally,  a  region  where  a  mantle  up-
welling  takes  place.  The  average  density  of  the  upwelling
asthenospheric  mantle  at  depths  of  80  to  180 km  has  a  low
value of 3.3 Mg/m

This value was determined based on the

calculations of Cella & Rapolla (1997), and it also agrees with
previous models (e.g. Lillie et al. 1994; Bielik 1999).

205

GRAVITY FIELD OF THE CARPATHIAN-PANNONIAN REGION BASED ON CELEBRATION 2000 DATA

The employed densities are not relative to one reference

density, but a three-layered reference model with negative
densities is chosen instead. The reference model used for
this area has two crustal layers. The upper crust (at depths
0—15 km) has a density of —2.67 Mg/m

, while the lower crust

(at depths 15—35 km) has a density of —2.9 Mg/m

. These val-

ues are consistent with the velocity model IASP91 of Kennett
& Engdahl (1991) and the global data of Christensen &
Mooney (1995). The upper mantle (at depths of 35—220 km)
has a density of —3.36 Mg/m

, which is consistent with values

for the subcontinental lithospheric mantle given by Poudjom
Djomani et al. (2001).

Last but not least, it is important to mention differences be-

tween the 2-D and 3-D modelling. A geological structure can
be  treated  as  two-dimensional,  if  its  length  is  much  greater
with respect to its width (e.g. Blakely 1996). This might be of-
ten the case in reality (e.g. rift and fractures zones etc.). How-
ever, due to the arcuate shape of the Carpathians, this condi-
tion in the Western Carpathians is usually not fulfilled. There
is a possibility in IGMAS to compute 2-D gravity effect of the
structures modelled along a particular cross-section. The dif-
ferences between the calculated 2-D and 3-D effects are sig-
nificant. If only the 2-D gravity modelling was performed for
the profile CEL01, with the Moho depth fixed according to the
seismic  model,  the  density  of  the  intra-crustal  structures
would be overestimated in the area of the microplate ALCA-
PA  and  the  TESZ  crust    underlying  the  Outer  Carpathians
(Fig. 3a).  In  contrary,  the  crustal  densities  along  the  CEL05
profile would be underestimated for the microplate ALCAPA
and overestimated for the EEC (Fig. 3b). 3-D gravity model-
ling thus provides more realistic results for regions character-
ized  by  complicated  and  non-linear  geological  structures.
Therefore, it is more adequate than a 2-D modelling for inter-
pretations of the gravity anomalies of such regions.

Results and interpretation

The microplate ALCAPA is separated from the platform by

the Pieniny Klippen Belt (PKB), extending through the whole
crust.  The  ALCAPA  (Pannonian  Basin  System  and  Western
Carpathians) has a constant density lower crust, but the two-
layered  upper  crust  and  sediments  have  different  densities
(Table 2).  North  of  the  PKB,  the  Outer  Carpathians  and  the
Carpathian Foredeep are underlain by the crust of the TESZ.
According to the seismic interpretations, the TESZ and EEC
have similar structure of the middle and lower crust, but sig-
nificantly  different  upper  crust  (low-velocity  TESZ  upper
crust) (e.g. Dadlez et al. 2005; Guterch & Grad 2006). This is
also  included  in  the  3-D  density  model  presented  (Fig. 3).
However, the middle and lower crust of the TESZ in the den-
sity  model  have  higher  densities  than  the  EEC  middle  and
lower crust (Table 2). These higher-density crustal layers are
required to reproduce the Małopolska High, as it was also sug-
gested  by  Grabowska  &  Bojdys  (2001).  Alternatively,  if  the
middle  crust  of  the  TESZ  is  modelled  with  a  density  almost
identical  to  the  EEC  middle  crust,  the  density  of  the  TESZ
lower crust must be increased (Table 2, values indicated by

Additionally, a high-velocity body was interpreted in the tran-

sition area between the TESZ and EEC in the middle crust un-
derneath  the  Lublin  High  (EEC)  along  the  CEL01,  CEL02,
CEL03  profiles  (Malinowski  et  al.  2005;  Janik  et  al.  2005;
Środa et al. 2006). The velocities along the CEL05 (Grad et al.
2006) are also elevated in this region. Similarly, a high-densi-
ty body in the middle crust is required in the density model in
order to reproduce the gravity anomaly. It is a 3-D structure,
stretching  from  the  CEL05  profile  in  the  south  to  ~ 60 km
north of the CEL01 profile. Its high velocity of 7 to 7.15 km/s
and density of 3.12 Mg/m

indicates mafic composition, simi-

lar to olivine gabbro or garnet granulite (Sobolev & Babeyko
1994;  Christensen  &  Mooney  1995).  Grabowska  et  al.  (sub-
mitted)  assume  this  intrusion  to  be  due  to  the  metamorphic
processes,  resulting  in  the  increase  of  the  density  and  varia-
tions  of  magnetic  properties  of  rocks  forming  the  crystalline
crust of this unit.

Fig. 4a,b shows the depth to the bottom of the sediments

and to the Moho obtained from the 3-D modelling with the
available  constraining  data.  The  thickness  of  the  sediments
(Fig. 4a)  is  modelled  according  to  the  data  compiled  by
Makarenko  et  al.  (2002)  and  Bielik  et  al.  (2005).  However,
slightly  different  densities  are  employed  for  the  sediments
and  upper  crust  in  the  3-D  model  presented  and,  therefore,
the results of 3-D modelling differ from the above mentioned
results. The Moho along the CEL-profiles is consistent with
the seismic data. The minimum crustal thickness of  ~ 22 km
is located along the CEL05 profile (Grad et al. 2006) and its
vicinity, which corresponds to the centre of the Pannonian Ba-
sin (Fig. 4b). This observation is also consistent with the xe-
nolith data (Szabó et al. 2004). The xenoliths from the central
part of the basin are significantly deformed because the active
rifting  and  lithosphere  thinning  mostly  took  place  here.  In
contrary, the xenoliths from the margins of the basin are only
slightly deformed or undeformed. The Danube Basin is char-
acterized  by  a  crustal  thickness  of  28—30 km,  increasing  to
35 km toward the west. The Central Western Carpathians have
28—35 km thick crust, while the crust beneath the Outer West-
ern  Carpathians  and  the  Carpathian  Foredeep  is  35  to  43 km
thick. The maximum crustal thickness of  ~ 50 km is modelled
beneath  the  TESZ  along  the  CEL05  profile  (e.g.  Guterch  &
Grad 2006) and Eastern Alps (e.g. Behm et al. 2007).

The gravity stripping is performed in order to analyse the

different components of the gravity signal. The gravity effect
of the sediments (Fig. 4c) was calculated in IGMAS using the
density differences of the sediments with respect to the density
of the upper crust employed in the model for each unit (Ta-
ble 2). The gravity effect of the Moho was calculated using the
Parker algorithm (Parker 1972), with a constant density differ-
ence of 0.3 Mg/m

at the Moho for the whole region (Fig. 4d).

The sediment stripped map (Fig. 5a) in the area of the Cen-

tral Western Carpathians shows the negative effect of the thick
low-density  upper  and  middle  crust  (according  to  the  3-D
model  the  thickness  reaches  ~ 25 km).  In  contrast,  the  Pan-
nonian Basin is generally characterized by a positive anomaly
of ~ 20 mGal. In the eastern part of the PBS, the gravity high
reaches even 40 to 50 mGal, reflecting the extremely shallow
Moho  in  this  region  (Fig. 4b).  A  complete  stripped  map
(Fig. 5b),  however,  clearly  shows  similarities  between  the
PBS and Western Carpathians. When the effect of the Moho

207

GRAVITY FIELD OF THE CARPATHIAN-PANNONIAN REGION BASED ON CELEBRATION 2000 DATA

Fig. 5. Sediment stripped map (a) and the complete stripped map (b), also referred to as a residual “lithospheric” anomaly. The thick lines
mark the units shown also in Figs. 1 and 2.

crustal intrusions, reaching some 10 km in depth (e.g. Ádám
& Bielik 1998), also compensate for the negative effect of the
sediments. Similarly, Kolárovo gravity high is reproduced by
a dense lower crust (Bielik et al. 1986), reaching depths of
9 km and a width of some 10 to 20 km that is included along 2
cross-sections in the 3-D model.

Conclusions and outlook

A 3-D forward modelling was performed for the Western

Carpathians,  Pannonian  Basin  System  and  the  surrounding
units.  The  model  uses  mainly  data  collected  recently  during
the CELEBRATION 2000 experiment. It brings them into one
structural image in order to study the lithospheric structure of
this region. By means of the combined 3-D modelling, prelim-
inary estimates of the density distribution of the crust and up-
per mantle, as well as the depths of the sedimentary basins and
the Moho were derived. These data allowed the performance
of gravity stripping, which is in the area of the Pannonian Ba-
sin crucial for the analysis of the gravity field. In this region,
two pronounced features, namely the deep sedimentary basins
and shallow Moho, with opposite gravity effects hinder the in-
terpretation  of  the  gravity  field  by  means  of  filtering  (e.g.  in
the wavenumber domain), estimating isostatic regional and re-
sidual fields or performing the gravity anomaly inversion. The
results of the gravity stripping revealed the lithosphere of the
ALCAPA and Tisza-Dacia microplates to be very similar and
much less dense than the surrounding lithosphere.

The upper mantle of the Pannonian Basin, where an as-

thenospheric upwelling takes place, significantly differs from
the surrounding regions. The upper mantle characterized by an
asthenospheric upwelling is, with respect to the “normal” up-
per mantle, anomalous in terms of lithospheric thickness, tem-
perature and density distribution. As it has been proved in the
course of the 3-D modelling, the influence of the different up-
per mantle densities of the units modelled on the crustal struc-
tures is pronounced. Thus, the upper mantle density must be
determined as precisely as possible, considering all available
information. Therefore, in order to determine the upper mantle
densities, the combined geophysical—petrological approach of
Afonso  (2006)  will  be  applied.  The  mantle  densities  better
constrained  should  improve  the  estimations  of  the  densities
and  composition  of  the  crust  and  enhance  the  localization  of
the lithospheric inhomogeneities.

Acknowledgments: This work is financed by the Deutsche
Forschungsgemeinschaft (project TA553/1—1). We are thank-
ful to S. Schmidt (Kiel University) for in-house software and
technical assistance. M. Bielik is grateful to the Slovak Scien-
tic Grant Agency (Grants No. 1/3066/06 and 2/6019/06) and
APVT Grant No. APVT-51-002804 for support.

References

Afonso J.C. 2006: Thermal, density, seismological, and rheological

structure of the lithospheric-sublithospheric mantle from com-

208

ALASONATI TAŠÁROVÁ, BIELIK and GÖTZE

bined petrological-geophysical modelling: Insights on lithos-
pheric stability and the initiation of subduction. Ph.D. Thesis,
Carleton Univ., Ottawa.

Artemieva I.M. 2006: Global 1°

×1° thermal model TC1 for the con-

tinental lithosphere: implications for lithosphere secular evolu-
tion. Tectonophysics 416, 245—277,
doi:10.1016/j.tecto.2005.11.022.

Ádám A. & Bielik M. 1998: The crustal and upper-mantle geophysi-

cal signature of narrow continental rifts in the Pannonian basin.
Geophys. J. Int. 134, 157—171,

doi:10.1046/j.1365-246x.1998.00544.x.
Babuška V., Plomerová J. & Šílený J. 1987: Structural model of the

subcrustal  lithosphere  in  central  Europe.  In:  Fuchs  K.  &  Froi-
devaux  C.  (Eds.):  Composition,  structure  and  evolution  of  the
lithosphere-asthenosphere  system.  Geodyn.  Ser.,  AGU,  Wash-
ington D.C. 16, 239—251.

Barton P.J. 1986: The relationship between seismic velocity and den-

sity in the continental crust – a useful constrain? Geophys. J.R.
Astr. Soc. 87, 195—208.

Behm M., Brückl E. & Chwatal Tybo H. 2007: Application of stack-

ing and inversion techniques to 3D wide-angle reflection and re-
fraction seismic data of the Eastern Alps. Geophys. J. Int. (2007),
doi: 10.1111/j.1365-246X.2007.03393.x.

Bielik M. 1999: Geophysical features of the Slovak Western Car-

pathians: a review. Geol. Quart. 43, 3, 251—262.

Bielik M., Fusán O., Plančár J., Biela A. & Túnyi I. 1986: New infor-

mation on subsurface structure of Danube Basin. Geol. Práce,
Spr. 84, 119—134 (in Slovak English summary).

Bielik M., Šefara J., Kováč M., Bezák V. & Plašienka D. 2004: The

Western Carpathians – interaction of Hercynian and Alpine
processes. Tectonophysics 393, 63—86.

Bielik M., Makarenko I., Starostenko V., Legostaeva O., Dérerová J.,

Šefara J. & Pašteka R. 2005: New 3D gravity modeling in the
Carpathian-Pannonian basin region. Contrib. Geophys. Geodesy
35, 1, 65—78.

Bielik M., Kloska K., Meurers B., Švancara J., Wybraniec S. & CEL-

EBRATION 2000 Potential Field Working Group 2006: Gravity
anomaly map of the CELEBRATION 2000 region. Geol. Car-
pathica 57, 3, 145—156.

Blankely R.J. 1996: Potential theory in gravity and magnetic applica-

tions. Cambridge University Press, 1—441.

Buła Z., Jachowicz M. & Zaba J. 1997: Principal characteristics of

the Upper Silesian Block and Małopolska Block border zone
(southern Poland). Geol. Mag. 5, 669—677.

Cella F. & Rapolla A. 1997: Density changes in upwelling mantle.

Ph. Earth and Plan. Interior 103, 63—84.

Christensen N.I. & Mooney W.D. 1995: Seismic velocity structure

and composition of the continental crust: A global view. J. Geo-
phys. Res. 100(B7), 9761—9788.

Čermák V. 1994: Results of heat flow studies in Czechoslovakia. In:

Bucha V. & Blížkovský M. (Eds.): Crustal structure of the Bo-
hemian Massif and the West Carpathians. Springer, New York,
85—118, edited by Horváth F., Cloetingh S. & Bada G. Eur.
Geophys. Soc., Strasbourg, France 165—194.

Dadlez R., Grad M. & Guterch A. 2005: Crustal structure below the

Polish Basin: Is it composed of proximal terranes derived from
Baltica? Tectonophysics 411, 111—128.

Dérerová J., Zeyen H., Bielik M. & Salman K. 2006: Application of

integrated geophysical modeling for determination of the conti-
nental lithospheric thermal structure in the Eastern Carpathians.
Tectonics 25,
TC3009, doi:10.1029/2005TC001883.

Falus G., Szabó C. & Vaselli O. 2000: Mantle upwelling within the

Pannonian Basin: evidence from xenolith lithology and mineral
chemistry. Terra Nova 12, 6, 295—302.

Gardner G.H.F., Gardner L.W. & Gregory A.R. 1974: Formation ve-

locity and density – the diagnostic basics for stratigraphic
traps. Geophysics 29, 6, 770—778.

Geissler W.H., Sodoudi F. & Kind R. 2007: The thickness of the Eu-

ropean Lithosphere as seen by S receiverfunctions. Geophys.
Res. Abstr. 9, 07345.

Götze H.-J. 1976: Ein numerisches Verfahren zur Berechnung der

gravimetrischen und magnetischen Feldgrößen für dreidimen-
sionale Modellkörper. Dissertation, Technical University
Clausthal, Germany.

Götze H.-J. & Lahmeyer B. 1988: Application of three-dimensional

interactive modeling in gravity and magnetics. Geophysics 53, 8,
1096—1108.

Grabowska T. & Bojdys G. 2001: The border of the East-European

Craton in south-eastern. Terra Nova 13, 2, 92—98.

Grabowska T., Bojdys G., Bielik M. & Csicsay K. submitted: Densi-

ty and magnetic models of the lithosphere along CELEBRA-
TION 2000 PROFILE CEL01. Submitted to Tectonophysics.

Grad M., Guterch A., Keller G.R., Janik T., Hegedus E., Vozár J.,

Ślączka A., Tiira T. & Yliniemi J. 2006: Lithospheric structure
beneath trans-Carpathian transect from Precambrian platform to
Pannonian basin: CELEBRATION 2000 seismic profile CEL05.
J. Geophys. Res. 111(B03301).

Guterch A. & Grad M. 2006: Lithospheric structure of the TESZ in

Poland based on modern seismic experiments. Geol. Quart. 50,
1, 23—32.

Guterch A., Grad M., Materzok R. & Perchuć E. 1986: Deep struc-

ture of the Earth’s crust in the contact zone of the Paleozoic and
Precambrian platforms in Poland (Tornquist—Teisseyre Zone).
Tectonophysics 128, 251—279.

Guterch A., Grad M., Špičák A., Brückl E., Hegedüs E., Keller G.R.,

Thybo H. & CELEBRATION 2000, ALP 2002 & SUDETES
2003 working groups 2003a: Special contributions: An overview
of recent seismic refraction experiments in central Europe. Stud.
Geophys. Geod. 47, 3, 651—657.

Guterch A., Grad M., Keller G.R., Posgay K., Vozár J., Špičák A.,

Brückl E., Hajnal Z., Thybo H., Selvi O. & CELEBRATION
2000 Experiment Team 2003b: CELEBRATION 2000 seismic
experiment. Stud. Geophys. Geod. 47, 3, 659—669.

Hacker B.R. & Abers G.A. 2004: Subduction Factory 3. An Excel

worksheet and macro for calculating the densities, seismic wave
speeds, and H2O contents of minerals and rocks at pressure and
temperature. Geochem., Geophys., Geosystems – an Electronic
J. Earth Sci. 5, 1,
Q01005, doi:10.1029/2003GC000614.

Horváth F. 1993: Towards a kinematic model for the formation of the

Pannonian basin. Tectonophysics 226, 333—357.

Hrubcová P., Środa P., Špičák A., Guterch A., Grad M., Keller G.R.,

Brückl E. & Thybo H. 2005: Crustal and uppermost mantle
structure of the Bohemian Massif based on CELEBRATION
2000 data. J. Geophys. Res. 110(B11305).

Janik T., Grad M., Guterch A., Dadlez R., Yliniemi J., Tiira T.,

Keller G.E., Gaczyński G.R. & CELEBRATION 2000 Working
Group 2005: Lithospheric structure of the Trans-European Su-
ture Zone along the TTZ-CEL03 seismic transect (from NW to
SE Poland). Tectonophysics 411, 129—156.

Kennett B.L.N. & Engdahl E.R. 1991: Traveltimes for global earth-

quake location and phase identification. Geophys. J. Int. 105,
429—465.

Konečný V., Kováč M., Lexa J. & Šefara J. 2002: Neogene evolution

of the Carpatho-Pannonian region: an interplay of subduction
and back-arc diapiric uprise in the mantle. EGS Stephan Mueller
Spec. Publ. Ser. 1, 165—194.

Kováč M. 2000: Geodynamical, paleographical and structural devel-

opment of the Carpathian-Pannonian region in Miocene. New
view on Slovak Neogene basins. Veda, Bratislava, 5—202 (in
Slovak).

209

GRAVITY FIELD OF THE CARPATHIAN-PANNONIAN REGION BASED ON CELEBRATION 2000 DATA

Kuskov O.L. & Kronrod V.A. 2006: Determining the temperature of

the Earth’s continental upper mantle from geochemical and seis-
mic data. Geochem. Int. 44, 3,

doi:10.1134/S00167029060300250
Lenkey L., Dövényi P., Horváth F. & Cloetingh S.A.P.L. 2002: Geo-

thermics of the Pannonian basin and its bearing on the neotec-
tonics. EGU Stephan Mueller Spec. Publ. Ser. 3, 29—40.

Lillie R., Bielik M., Babuška V. & Plomerová J. 1994: Gravity mod-

elling of the lithosphere in the Eastern Alpine-Western Car-
pathian-Pannonian Basin Region. Tectonophysics 231, 4,
215—235.

Majorowicz J.A., Čermak V., Šafanda J., Krzywiec P., Wróblewska

M., Guterch A. & Grad M. 2003: Heat flow models across the
Trans-European Suture Zone in the area of the POLONAISE 97
seismic experiment. Physics Chem. Earth 28, 375—391.

Makarenko I., Legostaeva O., Bielik M., Starostenko V., Dérerová J.

& Šefara J. 2002: 3D gravity effects of the sedimentary com-
plexes in the Carpathian-Pannonian region. Geol. Carpathica,
Spec. Issue 53.

Malinowski M., Zelazniewicz A., Grad M., Guterch A. & Janik T.

2005: Seismic and geological structure of the crust in the transi-
tion from Baltica to Palaeozoic Europe in SE Poland – CELE-
BRATION 2000 experiment, profile CEL02. Tectonophysics
401, 1—2, 55—77.

Parker R.L. 1972: The rapid calculation of potential anomalies. Geo-

phys. J.R. Astr. Soc. 3, 447—455.

Plašienka D., Grecula P., Putiš M., Kováč M. & Hovorka D. 1997:

Evolution and structure of the Western Carpathians: an over-
view. Miner. Slovaca, Monograph, Bratislava, 1—24.

Pollack H.N., Hurter S.J. & Johnson J.R. 1993: Heat flow from the

Earth’s interior: Analysis of the global data set. Rev. Geophys.
31, 267—280.

Poudjom Djomani Y.H., O’Reilly S.Y., Griffin W.L. & Morgan P.

2001: The density structure of subcontinental lithosphere
through time. Earth Planet. Sci. Lett. 184, 605—621.

Praus O., Pěčová J., Petr V., Babuška V. & Plomerová J. 1990: Mag-

netotelluric and seismo-logical determination of lithosphere-as-
thenosphere transition in central Europe. Phys. Earth Planet.
Inter. 60, 212—228.

Royden L., Horváth F., Nagymarosy A. & Stegena L. 1983: Evolu-

tion of the Pannonian Basin System 2, subsidence and thermal
history. Tectonics 2, 91—137.

Růžek B., Hrubcová P., Novotný M., Špičák A. & Karousová O.

2007: Inversion of travel times obtained during active seismic re-
fraction experiments CELEBRATION 2000, ALP 2002 and SU-
DETES 2003. Studia Geophysica et Geodaetica 51, 1, 141—164.

Schätz M., Zwing A., Tait J., Belka Z., Soffel H.C. & Bachtadse V.

2006: Paleomagnetism of Ordovician carbonate rocks from
Małopolska Massif, Holy Cross Mountains, SE Poland – Mag-
netostratigraphic and geotectonic implications. Earth Planet.
Sci. Lett. 244, 349—360.

Schmidt S. & Götze H.-J. 1999: Integration of data constraints and

potential field modelling – an example from southern Lower
Saxony, Germany. Physics and Chemistry of the Earth (A) 24, 3,
191—196.

Sobolev S.V. & Babeyko A.Y. 1994: Modeling of mineralogical

composition, density and elastic wave velocities in anhydrous
magmatic rocks. Surveys in Geophysics 15, 5, 515—544.

Szabó C., Falus G., Kovács I. & Bali E. 2004: Composition and evo-

lution of lithosphere beneath the Carpathian-Pannonian Region:
a review. Tectonophysics 393, 119—137.

Šefara J., Bielik M., Konečný P., Bezák V. & Hurai V. 1996: The lat-

est stage of development of the Western Carpathian lithosphere
and its interaction with asthenosphere. Geol. Carpathica 47,
339—347.

Środa P., Czuba W., Grad M., Guterch A., Tokarski A.K., Janik T.,

Rauch M., Keller G.R., Hegedüs E., Vozár J. & Celebration
2000 Working Group 2006: Crustal and upper mantle structure
of the Western Carpathians from CELEBRATION 2000 profiles
CEL01 and CEL04: seismic models and geological implications.
Geophys. J. Int. 167, 737—760.

Torge W. 1989: Gravimetry. Walter de Gruyter and Co., Berlin,

1—465.

Turcotte D.L. & Schubert G. 2002: Geodynamics: application of con-

tinuum physics to geological problems. John Wiley, Hoboken,
N.J., 1—450.

Wang Z. 2000: Velocity-density relationships in sedimentary rocks.

Geophysics reprint series, Soc. Explor. Geophys. 19, 19, 258—268.

Winchester J.A. & The PACE TMR Network Team 2002: Palaeo-

zoic amalgamation of Central Europe: new results from recent
geological and geophysical investigations. Tectonophysics 360,
5—21.

Zeyen H., Dérerová J. & Bielik M. 2002: Determination of the conti-

nental lithosphere thermal structure in the Western Carpathians:
Integrated modelling of surface heat flow, gravity anomalies and
topography. Phys. Earth Planet. Inter. 134, 89—104.