Sedimentary Geology 156 (2003) 71 – 94
www.elsevier.com/locate/sedgeo
Subsidence analysis and tectonic evolution of the external
Carpathian–Moesian Platform region during Neogene times
L. Matenco a,*, G. Bertotti b, S. Cloetingh b, C. Dinu a
a
Faculty of Geology and Geophysics, University of Bucharest, 6 Traian Vuia str. sect. 1, RO-70139 Bucharest-1, Romania
b
Department of Earth Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
Received 20 September 1999; received in revised form 13 July 2000; accepted 19 July 2002
Abstract
The Miocene – Pliocene subsidence of the tectonic platforms in the Romanian Carpathians foreland is analysed using
standard 1D backstripping techniques for individual wells, combined in two regional sections and six contour maps. The
subsidence patterns were integrated together with previous paleostress and kinematic studies, in order to derive the Tertiary
kinematics of the buried faults in the Carpathians lower plate. The study revealed accelerated subsidence during the Early
Miocene in the western part of the Moesian Platform/Getic Depression, in direct relationship with the opening of a WSW – ENE
trending extensional basin. The largest subsidence recorded in the front of the Carpathians took place during the Late Miocene,
due to final E-ward emplacement of the thrust sheets. The Late Miocene subsidence showed anomalous high values between the
Intramoesian and Trotus faults as a result of the orogenic collision with the East-European Platform northward and acceleration
of the subduction process in the SE Carpathians corner. Further Pliocene subsidence continued only in the latter region, the
depocenter being shifted southward near the junction with the South Carpathians foreland.
D 2002 Elsevier Science B.V. All rights reserved.
Keywords: Carpathians; Foredeep basins; Flexure; Romania
1. Introduction
The Romanian Carpathians represent a large-scale
arcuate belt formed as a response to the Triassic to
Tertiary evolution of two continental blocks, the
Median Dacides (Sandulescu, 1984, 1988), or Rhodopian fragment (Burchfiel, 1976) to the west and
south, and the East-European/Scythian/Moesian Platforms to the east and north (Sandulescu, 1984; San-
*
Corresponding author. Fax: +40-1-211-7390.
E-mail address: [email protected] (L. Matenco).
dulescu and Visarion, 1988; Visarion et al., 1988)
(Fig. 1). The Carpathians consist of thick- and thinskinned nappe piles (de)formed by thrusting and
dextral transpression during Middle Cretaceous to
Pliocene times (e.g., Sandulescu, 1984, 1988; Ratschbacher et al., 1993; Csontos, 1995; Linzer et al., 1998;
Zweigel et al., 1998 and references therein). The
nappes are made of crystalline rocks and Paleozoic
to Tertiary sediments, partly deposited in a Triassic to
Early Cretaceous extensional basin. Shorter periods of
orogen-parallel extension (e.g., Schmid et al., 1998;
Rabagia and Matenco, 1999; Matenco and Schmid,
1999) interrupted the overall shortening.
0037-0738/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 3 7 - 0 7 3 8 ( 0 2 ) 0 0 2 8 3 - X
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Fig. 1. Tectonic map of the external part of the Romanian Carpathians and of major boundary faults in the foreland platforms. Faults in the thinskinned belt and adjacent platforms are defined according to surface maps (1:200,000, 1:50,000), seismic exploration studies, and from Matenco
(1997) and Rabagia and Matenco (1999). Major boundary faults in the platforms are defined according to Sandulescu and Visarion (1988) and
Visarion et al. (1988). TF—Trotus Fault, PCF—Peceneaga-Camena Fault, COF—Capidava-Ovidiu Fault, IMF—Intramoesian Fault.
The Carpathians –Pannonian structural assemblage
provides a natural laboratory for the study of highly
complicated polydeformed terranes, resulting from the
interaction between thrusting units (mainly the inter-
nal and median Dacides) and highly arcuate shape of
the foreland. Large-scale rotations (e.g., Patrascu et
al., 1990, 1992, 1994) and extension in the Pannonian
Basin (e.g., Horváth, 1993) coeval with contraction
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
and transcurrent movements at the exterior of the
Carpathians are some of the features associated with
such complex interactions.
The Tertiary evolution of the Romanian Carpathians and adjacent foreland is characterised by temporal
changes in the stress and strain fields. This is not only
shown by recently acquired structural data, but it is
also a consequence of the arcuate shape of the belt.
Models assuming a roughly contemporaneous emplacement of thrust sheets in the various segments of
the Carpathians (e.g., Sandulescu, 1984, 1988) are incompatible with the absence of structures able to accommodate the coeval large orogen-parallel extension
required (e.g., Morley, 1996; Zweigel et al., 1998).
Other models, envisaging the Carpathians as mainly
due to E-ward translation of the Intra-Carpathians units
(Royden, 1988; Ellouz and Roca, 1994), are at odds
with the abovementioned structural data and with the
absence of large-scale transcurrent movements within
the South Carpathians (e.g., Rabagia and Fülop, 1994).
Models taking into account quantitative analysis of the
stress field and associated deformation structures
within the Romanian Carpathians, as well as the
integration with the regional plate-tectonic scenarios,
are still to be developed. As a result, important differences exist between the tectonic models, mainly concerning the timing and especially the directions of
motions through time.
In the foreland, major uncertainties still exist in
establishing the kinematics and (re)activation of
regional faults penetrating the basement (e.g., Intramoesian, Peceneaga-Camena, Trotus, Bistrita faults,
Figs. 1 and 2) during the Tertiary. Whether or not
these faults have influenced the lateral variations in
the thin-skinned thrusting kinematics is still to be
pursued. Important sedimentary basins developed during the Tertiary on the foreland platforms, which are
often referred to as foredeeps. However, the kinematics of subsidence has rarely been documented. To
fill this gap, we analysed a large number of subsurface
data (wells, geological profiles and seismic interpretations) distributed in all the units to the E and S-ward
of the Carpathian thrust front and derived the Tertiary
(mostly Miocene and Pliocene) subsidence curves of
the foreland platforms. This subsidence evolution is
then compared with the Tertiary structural evolution
of the Carpathians units to correlate kinematics and
deformation patterns.
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2. Structure of the autochthonous platforms
The undeformed foreland of the Carpathians is
composed of the amalgamation of three major units
with different geometries and characteristics. They all
represent cratonic continental platforms (senso Twiss
and Moores, 1992) with Precambrian crystalline rocks
and a Paleozoic –Mesozoic sedimentary cover overlain by Tertiary sediments belonging both to the
Carpathians foredeep basin and to the flat-lying platform successions. The separation between the two
types of Tertiary sediments is formed by the flexural
bulge of the Carpathians lower plate (e.g., Dumitrescu
and Sandulescu, 1970) and is thus somehow arbitrary.
For simplicity, our further discussion will include
these units in the generic term of ‘‘foreland platforms’’.
According to Sandulescu and Visarion (1988) and
Visarion et al. (1988), the autochthonous platforms in
the foreland of the Romanian Carpathians are composed of two, internally complex, relatively stable
areas, the East-European/Scythian and the Moesian
Platforms, separated by the North Dobrogean orogenic zone (Fig. 2).
The platform domains are overthrusted by the thinskinned units of the Outer Romanian Carpathians. In
the East Carpathians, the most external thrusted units,
i.e. the Tarcau, Marginal Folds and Subcarpathian
units (Fig. 1), come in contact and influenced the
deformation patterns of the platforms. These thinskinned units contain clastic sediments (Fig. 3),
deposited on a thinned continental crust (Sandulescu,
1988) and thrusted during Middle Miocene (Late
Burdigalian – Badenian) and Late Miocene (Sarmatian – Early Meotian) tectonic events (Matenco,
1997; Fig. 3). In the frontal part of the South Carpathians, only the deformed foredeep (Getic Depression)
is in direct contact with the Moesian Platform (Fig. 1).
The Tertiary evolution of the Getic Depression –Moesian Platform is characterised by major changes in
deformation patterns (Fig. 4); details are discussed
below.
2.1. East-European and Scythian Platforms
The East-European and Scythian Platforms are two
crustal blocks delimited towards the south by the
Trotus Fault and towards the W by the Câmpulung-
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Bicaz Fault (Sandulescu and Visarion, 1988) (Fig. 2).
The geological and mechanical characteristics of these
crustal blocks influenced the thin-skinned nappe pile
thrusting patterns and therefore defined the first major
foreland domain (Matenco, 1997).
The deep structure of the East-European/Scythian
Platforms has been documented by geophysical
soundings. Deep reflection profiles show an overall
thickness of 10 km for the sedimentary cover, and
Conrad and Moho discontinuities being located at 20
and 40 km, respectively (Raileanu et al., 1994), while
seismological data show a crustal thickness of 43 km
(Enescu et al., 1988, 1992). West of the Solca Fault, in
the Scythian Platform, a thinning to 35 km has been
documented by magnetotelluric studies (Visarion et
al., 1988). The Solca Fault thus represents the eastern
limit of the Trans-European Suture Zone (former
Tornquist – Teissere lineament) (e.g., Botezatu and
Calota, 1983; Guterch et al., 1986), which in the
Romanian foreland coincides with the Scythian Platform and the North-Dobrogean orogen (Pinna et al.,
1991).
The East-European Platform extends underneath
the frontal part of the Romanian East Carpathians,
north of the Bistrita and west of the Solca faults (Fig.
2). The East-European Platform is internally subdivided by the NNW – SSE trending Siret Fault. The
eastern block has metamorphic basement elements
very similar to those of the Ukrainian Massif, as
documented by few deep wells and typical magnetic
anomalies (Airinei et al., 1966). The western block
(Radauti-Pascani, after Sandulescu and Visarion,
1988), located between the Siret and Solca faults,
narrows towards the south and disappears south of
Piatra Neamt (Fig. 2). While Paleozoic rocks in few
deep wells are similar to those of the eastern block,
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the nature of the basement is unknown (Airinei et al.,
1966).
The thickness of the sedimentary cover of the EastEuropean Platform is comprised between 6 and 12 km
near the main thrust front (Raileanu et al., 1994),
decreasing toward the east. Three major sedimentation
cycles separated by major unconformities are defined
(Ionesi, 1989): Paleozoic (Upper Vendian – Devonian),
Mesozoic – Paleogene (Cretaceous – Middle Eocene)
and Tertiary (Upper Badenian –Lower Pliocene). This
undeformed Tertiary cover has a thickness of 3 – 9 km
near the frontal nappe contact, slightly decreasing
towards the east.
The Scythian Platform is a NW – SE to W – E
oriented continental block, extending between the
Bistrita and Trotus faults (Fig. 2). It is clearly documented south of the East-European Platform in the
Bı̂rlad Depression. Towards the W and NW, the
Scythian Platform is continuous with the basement
block between Solca and Câmpulung-Bicaz faults
(Sandulescu and Visarion, 1988). Here, a similar type
of Scythian basement has been documented by magnetic anomalies and deep wells as in the Bı̂rlad
Depression (Sandulescu and Visarion, 1988). The
internal structure of the Scythian Platform is less well
known than that of the East-European Platform, due to
thicker Tertiary sediments in the Bı̂rlad Depression
and to underthrusting below the East Carpathians
nappe pile. However, three major sedimentation
cycles have been defined (Ionesi, 1989): Upper Paleozoic – Lower Mesozoic (Permian – Lower Triassic),
Mesozoic –Paleogene (Jurassic – Eocene) and Tertiary
(Upper Badenian –Romanian), sediments of the last
period partly belonging to the undeformed foredeep.
Mesozoic and Tertiary deformations occur within
the East-European/Scythian Platforms, and consist of
Fig. 2. (A) Simplified structural map of the autochthonous units in the frontal part of the Romanian Carpathians (compiled after Sandulescu and
Visarion, 1988; Visarion et al., 1988; Dicea, 1995, 1996) and contour map of the pre-Miocene basement of the foreland platforms. The contour
map is made through direct interpolation of the pre-Miocene basement from the present study data. Fault offsets have been neglected. Note the
high depth values of the basement in the Focsani Depression and the apparent dextral offset along the Intramoesian Fault and sinistral offset
along the Trotus Fault. (B) Contour map of the pre-Miocene (basement) crustal thickness obtained by subtracting the depth of pre-Miocene
basement of the foreland platform (A) from the present-day crust thickness map of Romania (Radulescu, 1988). The contour map is made
through direct interpolation of values. Fault offsets are neglected. Note the strong differences in the crust thickness between the East-European/
Scythian platforms + North Dobrogean orogen and the much thinner Moesian platform. CBF—Câmpulung-Bicaz Fault, ScF—Solca Fault,
SiF—Siret Fault, VF—Vaslui Fault, BF—Bistrita Fault, TF—Trotus Fault, PCF—Peceneaga-Camena Fault, COF—Capidava-Ovidiu Fault,
IMF—Intramoesian Fault, JF—Jiu Fault, MF—Motru Fault, CF—Cerna Fault, TkF—northern extension of Timok Fault, CTF—CălimănesßtiTg. Jiu Fault.
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Fig. 3. Time correlation table, stratigraphic column and tectonic evolution scheme for the Tarcau, Marginal and Subcarpathian units (modified
after Sandulescu et al., 1981). Correlation between Odin (1994) and the Central and Eastern Paratethys for the Oligocene and Miocene ages after
Rögl (1996) and M. Marunteanu (unpublished data). Note the differences in the Miocene – Pliocene and especially the Miocene – Pliocene
boundary. A, B and C represent the internal, intermediate and external sedimentary facies, respectively, in the displayed units.
two types of faults. NW – SE trending normal faults
account for a progressive deepening of the autochthonous units beneath the flysch nappes (Fig. 2). One
good example is provided by Straja-Gura Humorului
Fault (Fig. 5(a)A). This inherited fault has an offset of
ca. 1 km and forms the external boundary of the
Marginal Folds nappe (Sandulescu, 1984; Sandulescu
and Visarion, 1988; Dicea, 1995). Seismic surveys
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
77
Fig. 4. Foredeep stratigraphic correlation and tectonic evolution scheme of the South Carpathians for the Uppermost Cretaceous – Tertiary with
the structural deformation features and correlation with the tectonic episodes defined by Matenco et al. (1997a), Schmid et al. (1998) and
Rabagia and Matenco (1999) (correlation of Tethys – Parathetys similar to Fig. 3).
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
have also imaged large NE – SW to E – W trending
crosscutting faults (Fig. 2) associated with a progressively deeper basement towards the south. Beneath
the flysch nappes, the top of the sedimentary cover
(i.e., the Badenian anhydrite horizon visible in the
seismic studies) is deepening southward, from an
average of 1500 m in the north to 5000 m in the
region of Bistrita Valley, and further to 8000 – 10,000
m southward (Dicea, 1995).
West of the Câmpulung-Bicaz Fault, magnetotelluric soundings have imaged a clear thickening
of the Paleozoic –Mesozoic sediments in the lower
plate. The deformed Paleozoic basement would then
lie at 9 – 10 km depth (Sandulescu and Visarion,
1988), accounting for the southern extent of the Miechow Depression beneath the thin-skinned thrust belt
(Fig. 2).
2.2. Moesian Platform
The Moesian Platform represents a Precambrian
block incorporated in the Epihercynian European
platforms (Sandulescu, 1984). The Moesian Platform
(Fig. 2) extends S and SW of the Trotus and Peceneaga-Camena faults, and it is composed by two main
domains, the ‘‘Dobrogean’’ and ‘‘Valachian’’ parts
separated by the crustal scale Intramoesian Fault
(Visarion et al., 1988). Along the Peceneaga-Camena
Fault, the Dobrogean block was displaced upward and
dextrally (e.g., Radulescu et al., 1976; Visarion et al.,
1988). Deep refraction seismic profiles in the ‘‘Dobrogean’’ domain show crustal thicknesses around 35 – 40
km (Radulescu, 1988) compatible with the seismological data of f 34 km (Enescu et al., 1992). The
Vrancea (SE bend) area displays anomalous values of
40 –47 km (Radulescu et al., 1976; Cornea et al.,
1981; Enescu et al., 1992; Raileanu et al., 1994). The
Capidava-Ovidiu Fault (Fig. 2) subdivides the Dobrogean zone in two parts, characterised by different
79
basements and pre-Tertiary sedimentary covers, the
Central Dobrogea unit to the north and the South
Dobrogea unit to the south. According to Visarion et
al. (1988), the Central Dobrogea unit is uplifted with
respect to the South Dobrogea along Capidava-Ovidiu
Fault, which seems to display also a right-lateral
displacement (e.g., Radulescu et al., 1976). The
Dobrogean basement generally dips towards the
WNW underneath the Carpathians (e.g., Airinei,
1958), with significant thinning of the basement,
and pre-Tertiary cover below the Focsani Depression
(Fig. 2(B)).
The Intramoesian Fault separates the Dobrogean
and Valachian parts of the Moesian Platform and
represents a deep crustal fracture extending northward
of the Moesian Platform underneath the Getic Nappe
(Figs. 1 and 2(A)) (Sandulescu, 1984; Visarion et al.,
1988). It is site of a large number of shallow to deep
earthquakes (Radulescu et al., 1976; Cornea and
Polonic, 1979). Recent seismic studies (Matenco,
1997) suggest 10 –15 km of right-lateral movement
during the Late Miocene.
South and west of the Intramoesian Fault, the
Moesian Platform is composed of two different segments (Visarion et al., 1988), i.e. the ‘‘Valachian’’ and
‘‘Danubian’’ domains, bounded by the crustal-scale
Călimănesß ti-Tg. Jiu Fault (Fig. 2). This fault represents a NE prolongation of the Timok Fault (Fig. 2)
and separates, at the Paleozoic level, platform-type
sedimentary deposits in the south, from the deformed
and sometimes metamorphosed deposits in the north
(Visarion et al., 1988). In fact, the northern part of the
‘‘Danubian domain’’ represents an Alpine foreland
coupling block, i.e. a lower plate block involved in
thrusting, as commonly observed elsewhere in the
Carpathians (e.g., Ziegler, 1990). This block was
detached from Moesia during Cretaceous contraction
and is presently incorporated in the Danubian thrust
sheets of the South Carpathians nappe pile (Berza and
Fig. 5. (a) Seismically controlled geological profiles in the external thin-skinned units of the Romanian Carpathians. Location of profiles in Fig.
6. Sections have no vertical exaggeration. Note, however, that the sections have different scales. (A) Geological profile in the northernmost part
of the Romanian Carpathians. SGHF = Straja-Gura Humorului Fault (local name of Solca Fault, after Dicea, 1995) separates the East-European
Platform to the east from the Scythian Platform to the west. (B) Geological profile along the Buzau valley (bending area). Note the frontal
triangle zone, the large number of backthrusts and the large subsidence in the frontal Focsani Depression. (C) Geological profile along the
Prahova valley (SW East Carpathians). Note the buried frontal thrust and the large number of Lower Burdigalian salt diapirs. (b) Seismically
controlled geological cross-section in the western part of the Moesian Platform/Getic Depression (after Stefanescu and working group, 1988;
Rabagia and Matenco, 1999). Note the large Early Burdigalian normal fault inverted by a Late Sarmatian flower structure. Location of profile in
Fig. 6.
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Draganescu, 1988). In the ‘‘Valachian domain’’, deep
refraction seismic profiles show crustal thickness
values around 35– 40 km (Radulescu, 1988), while
seismological data show an average value of 34 km
(Enescu et al., 1992). One of the most characteristic
features of the Valachian domain is the presence of
subvertical faults which define subsiding areas (for
instance the Alexandria Depression) and intervening
uplifted regions, where the basement can be observed
close to surface (e.g., Craiova, Bals and Optasi
uplifts). Faults are typically N – S to NNW –SSE and
E –W. A dextral sense of movement is suggested for
the NNW – SSE trending faults by seismically
detected displacements of Miocene markers (Rabagia
and Matenco, 1999).
The sedimentary cover of the Moesian Platform is
thickest in the Vrancea area (up to 18 km; Cornea et
al., 1981) and thins to 8 –10 km elsewhere. Sediments are organised in four major successions (Ionesi, 1989). The Upper Cambrian – Westphalian
succession is up to 6500 m thick and composed of
a lower detritic (shales) group and an upper limestone group. It is unconformably followed by up to
5000-m thick, predominantly clastic (shales– sandstones) Permian – Triassic succession with Permian
evaporitic and tuff levels, followed by thick Middle
Triassic carbonate-evaporites. Younger deposits (up
to 3000 m thick) are made up of a Jurassic detritic
sequence (sandstones and shales) and Upper Jurassic
to Upper Cretaceous mainly limestones, being followed by detritic Tertiary (Paleogene to Pliocene)
sediments. The latter range in thickness between 2
and 7 km near the Carpathians sole thrust and
slightly thinning towards the foreland. Striking thicknesses of 9 km Neogene sediments are observed in
the Focsani Depression.
2.3. North Dobrogea orogen
The North Dobrogea zone, located between the
Scythian and Moesian Platforms, is composed of a
complex polydeformed Hercynian basement and a
Triassic – Cretaceous sedimentary cover, unequally
developed (e.g., Ionesi, 1989 and references therein).
West of the Danube, the basement and Mesozoic
sediments are covered by a thick succession of Tertiary deposits, forming the pre-Dobrogean Depression
(Fig. 2).
Large geometrical and mechanical differences
exist among the foreland units. The pre-Miocene
crustal thickness map (Fig. 2(B)) indicates steep
changes along the Peceneaga-Camena Fault and the
Trotus Fault, separating the East-European/Scythian
Platforms and the North Dobrogean orogen from the
much thinner Moesian platform. As flexural modelling studies (e.g., Matenco et al., 1997b) have
demonstrated similar differences in the mechanical
characteristics across the Trotus Fault (larger EET
values to the north), one has to look for correlative
changes in the thin-skinned thrust belt kinematics.
The previously suggested sinistral offset along the
Peceneaga-Camena Fault (e.g., Girbacea and Frisch,
1998; Linzer et al., 1998) is not supported by
seismic studies, due to the absence of this fault
northward and to the clear truncation along the
Trotus Fault.
3. Subsidence evolution of the Romanian foreland
platforms on the basis of burial history restoration
The subsidence of the Romanian foreland was
reconstructed for all the three major platform units
composing the frontal part of the Carpathians (EastEuropean, Scythian and Moesian) as well as for the
pre-Dobrogean Depression (the buried prolongation
of the North-Dobrogean orogen) (Fig. 2(A), coloured areas). More specifically, data were used from
the area between the east Romanian border and the
frontal thrust of the East Carpathians, and from the
South Romanian border to the northern contact of
the sediments with the allochthonous units of the
South Carpathians. The Miocene sediments of the
eastern part of the Getic Depression are allochthonous and, therefore, were not used for subsidence
analysis.
In most cases, data used for subsidence analysis
come from deep wells (Fig. 6). In areas with few or
no wells, synthetic stratigraphic columns were
derived from well-controlled seismic profiles and
from their geological interpretation. In the western
part of the Getic Depression and the Valachian
Moesian Platform (Fig. 6), we used data from 50
deep wells (Figs. 7 and 8), one seismically controlled
geological profile (Fig. 5(b)) and four regional profiles controlled from wells (profiles A18, A20, A21,
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
81
Fig. 6. Location of data used for basement subsidence reconstructions. Real wells mean that depth of various stratigraphic limits and porosities
have been derived from real well logs. Real depth wells mean that basement subsidence has been calculated (Fig. 7) for the entire stratigraphic
column, for sediments as old as Silurian. Pseudo-wells mean that depth of various stratigraphic limits has been collected from geological
interpretations. Circles are seismically controlled profiles of Matenco (1997); triangles are interpretations of Stefanescu and working group
(1988) and unpublished data of Petrom, R.A. Two-dimension reconstructions 2D A and B represent geological profiles in Fig. 5(b) and A14
(Stefanescu and working group, 1988). S-A to S-D represent locations of geological interpretations in Fig. 5.
A22; Stefanescu and working group, 1988). In the
frontal part of the East Carpathians (Fig. 6), subsidence
analysis took into account 40 deep wells, 16 seismically controlled geological profiles (eastern part of
profiles 1 – 16; Matenco, 1997) placed nearby the
frontal Pericarpathian sole thrust, and five regional
profiles controlled from wells (profiles A9 – 12 and
A14; Stefanescu and working group, 1988). Less detail has been obtained for the SE-most part of the
studied area, near Danube, where only three deep wells
could be used.
3.1. Method
Standard 1D backstripping techniques (Steckler
and Watts, 1978; Watts et al., 1982) were employed
to reconstruct the vertical evolution of the basement
during Miocene and Pliocene times. The compaction
correction was made according to porosity versus
depth relations (e.g., Sclater and Christie, 1980). A
porosity profile has been computed for each major
tectonic unit from well electrical logs (unpublished
data of R.A. Petrom). We have assumed an exponen-
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Fig. 7. Paleozoic – Tertiary basement subsidence based on 10 deep wells in the Getic Depression – Moesian Platform. Location in Fig. 6. (A)
Central Moesian Platform, (B) the NW part of Getic Depression and (C) the eastern part of the Moesian Platform.
tial compaction law for six standard lithological types
(sandstone, siltstone, clay, limestone, salt and anhydrite), and we have averaged the compaction dependencies with the real log porosity.
Paleobathymetries have always been taken as zero,
due to absence of a consistent data set. In any case, the
introduced error is not likely to be large since no
deepwater formations have been described so far in
the studied area. Sea level corrections took into
account tectonic/eustatic base level variation curves
(senso Prosser, 1993) of Rabagia and Matenco (1999)
for the Getic Depression – Valachian Moesian Platform and general Haq curves for the East-European/
Scythian Platform (Haq et al., 1987). The latter values
may introduce a certain degree of error for the
computed subsidence values, but there seem to be a
rough correlation with the more precise data of the
first author.
Our subsidence analysis concerns Miocene and
younger sediments and considers older rocks as
‘‘basement’’. This is justified by the observation that
the Paleogene of the foreland platforms is largely
characterised by nondeposition or sediment erosion
(with exceptions in the Moesian Platform and Getic
Depression). In order to provide a general image of
the Paleozoic, Mesozoic and Tertiary subsidence evolution of the Moesian platform, subsidence curves
from 10 deep wells were calculated for the entire
stratigraphic column, including sediments as old as
the Silurian (Fig. 7). Mesozoic sea level changes were
taken from the Haq curves, while no sea level changes
have been considered for the Paleozoic.
We have computed only ‘‘basement subsidence’’
curves. Tectonic subsidence curves were not calculated, because they generally imply local isostatic
compensation, which is incompatible with significant
flexural strength of the Carpathian foreland (effective
elastic thickness between 10 and 20 km; Matenco et
al., 1997b).
Quantitative 2D reconstructions have been built
along two profiles derived from depth-converted,
interpreted seismic lines calibrated with wells. Sub-
Fig. 8. Miocene – Pliocene subsidence in the Getic Depression – Moesian Platform. (A) Basement subsidence curves in domains of Early
Burdigalian extension. (B) Basement subsidence curves in the frontal part of the Getic Depression sole thrust where significant Sarmatian
subsidence is observed. (C) Basement subsidence curves in the Late Burdigalian – Sarmatian piggyback basins. (D) Basement subsidence curve
underlying the large Eocene subsidence. Note that the horizontal scale in the latter diagram is different from the previous ones.
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
83
84
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
sidence curves were constructed for synthetic wells
read at constant 1-km interval along these profiles
and assembled together into the 2D reconstructions
(Fig. 10).
From 1D and 2D reconstructions, we have built
basement subsidence maps (Figs. 11 and 12), through
direct interpolation between data, without taking into
account possible intervening fault offsets.
Fig. 9. Miocene – Pliocene subsidence in the frontal part of the East Carpathians. (A) Basement subsidence curves in the East-European Platform
based on real wells. (B) Basement subsidence curves near the East Carpathians sole thrust (Matenco, 1997). (C) Basement subsidence curves on
the flanks of the Focsani Depression based on real wells for the upper part of the stratigraphic column and depth-converted seismic lines for the
lower part.
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
3.2. Results
The record provided by the deep wells penetrating
Mesozoic and older rocks is obviously incomplete but
the curves we have obtained suggest a significant
episode of subsidence during Silurian – Devonian
times (Fig. 7, wells B3 and C1) and during the
Triassic (Fig. 7, wells A1, A3, B3 and C2) in the
Moesian platform. Triassic subsidence is related to
continental rifting along presently ENE –WSW trending normal faults (e.g., Alexandria Depression) (Rabagia, unpublished data). Significant subsidence is
observed also during the Jurassic –Lower Cretaceous
(Fig. 7, wells C1 and C3), probably in connection
with extension in the Outer Dacidian Trough (e.g.,
Sandulescu, 1988).
Miocene to Pliocene subsidence is recorded by all
curves obtained. The most apparent feature is the
Sarmatian subsidence, which is practically ubiquitous
in all curves (Figs. 7– 9). Subsidence is contemporaneous with the large-scale Sarmatian thrusting and
there should be, therefore, a genetic relation between
the two phenomena. It is thus not surprising that
Sarmatian subsidence values decrease from the frontal
thrust towards the foreland.
Relevant information is further derived by the
analysis of subsidence curves in the various domains
of the foreland. In the Getic Depression – Moesian
Platform, one deep well (901 Ticleni, Fig. 8, curve
D) suggests roughly 3000 m of basement subsidence
(at a rate of 230 m/Ma) during the Early –Middle
Eocene. This may be correlated with coeval largescale extension and core-complex formation in the
Danubian units of the neighbouring South Carpathians (Schmid et al., 1998; Matenco and Schmid, 1999).
Generalized subsidence (up to 3000 m in the basin
depocenter, approximately 1100 m/Ma) affected the
area already in the Early Miocene (Fig. 8(A)) in
connection with the Lower Burdigalian extension
which lead to the opening of ENE – WSW trending
basins (Matenco et al., 1997a; Rabagia and Matenco,
1999). Basement subsidence decreased during the
Late Burdigalian (Fig. 8(C)). At this time, the earlier
extensional basin was inverted, and shortening along
small-offset thrusts was propagating in a more external position. In the NW parts of the Getic Depression,
subsidence continued until recent times, although at
low rates.
85
In the foreland units of the East Carpathians,
subsidence is dominated by the Sarmatian tectonic
event. East of the Carpathians frontal thrust, the
Sarmatian basement subsidence has values in order
of 1000 –2000 m (500 –1000 m/Ma) for the EastEuropean Platform (Fig. 9(A) and (B1)), 3500 –4000
m (1750 – 2000 m/Ma) for the Scythian Platform
(Fig. 9(B2)) and high values of 3000 – 6000 m
(1500 – 3000 m/Ma) for the northern part of the
Moesian Platform, around the Focsani Depression
area (Fig. 9(B2), (B3)). Further to the S and SWward, Sarmatian subsidence gradually decreases to
2000– 3000 m (1000 –1500 m/Ma, Fig. 9(B4) and
(B5)). Pliocene – Pleistocene subsidence values of
2000 – 3000 m (200 – 300 m/Ma) are observed in
the Focsani Depression (Fig. 9(B2) and (B3)) and
reach 4 km (400 m/Ma) in the SW corner of the East
Carpathians (Fig. 9(B4) and (B5)) in association with
the Late Pliocene thrusting.
By assembling 1D subsidence curves along a
cross-section, we have obtained a 2D restoration of
the basement subsidence in the western part of the
Getic Depression – Moesian Platform (Fig. 10(A)).
The section nicely shows Lower Burdigalian subsidence in the WNW-part of the profile associated
with the opening of the extensional basin along a
SW– NE trending normal fault. The remaining of
the section was practically stable. Generalized subsidence affected the areas crossed by the profile in
the Badenian and, even more, in the Sarmatian. It is
interesting to note that, with exception of the westernmost part of the profile, the magnitude of
Sarmatian vertical movements was 1500– 2000 m
and fairly constant along the section. After the
Sarmatian, subsidence continued over most of the
profile although at a much lower rates. Similarly to
previous times, little lateral differences are observed.
A similar 2D basement restoration in the northern
part of the Moesian Platform (Fig. 10B) shows a
more regular pattern with subsidence gradually
increasing towards the east, as a result of flexural
loading of the lower plate in the front of the
Carpathians. This overall pattern remained fairly
constant through time suggesting a persistence of
the mechanisms driving subsidence. Although the
largest movements are recorded during the Sarmatian
(3000 m near the Carpathians front), also Pliocene
86
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Fig. 10. Basement subsidence through time along two sections across the South and the East Carpathians. Locations in Fig. 6. (A) Basement
subsidence restoration along the profile in Fig. 5(b). (B) Basement subsidence along the profile A14 of Stefanescu and working group (1988).
subsidence is significant (3500 m near the thrust
front).
4. Tectonic model
The subsidence analysis carried out can be correlated with the increasingly detailed kinematic picture
which is emerging from a large amount of structural
and tectonic data (e.g., Ratschbacher et al., 1993;
Csontos, 1995; Linzer, 1996; Matenco, 1997;
Matenco et al., 1997a; Bojar et al., 1998; Zweigel,
1998; Zweigel et al., 1998; Sanders, 1998; Schmid et
al., 1998; Ciulavu, 1999). According to these results,
the evolution of the external Carpathians and the
adjacent foreland areas is subdivided in four stages.
For these stages, we have produced subsidence maps
indicating the position of the ‘‘basement’’ in the
various moments (Figs. 11 and 12). Tectonic stages
for various parts of the Romanian Carpathians may be
pinpointed also in Figs. 3 and 4.
4.1. Paleogene – Early Miocene
The Paleogene– Early Miocene timespan is mainly
a period of nondeposition and/or erosion in large parts
of the Carpathian foreland. The most significant
exception was the Getic Depression and the westernmost Moesian Platform corner where Paleogene –
Lower Miocene sediments are thick and widespread
(Figs. 4 and 11).
Large-scale N to E-ward movement and rotation of
the Inner Carpathian units (median Dacides; Sandulescu, 1984) around the Moesian Platform during the
Paleogene – Early Miocene (Fig. 11) caused differential deformations along the bent East Carpathians –South Carpathians fragment.
During the Late Eocene– Early Oligocene, largescale, orogen-parallel extension took place in the
South Carpathians (Fig. 4), leading to rapid exhumation of the Danubian basement in the footwall of the
Getic detachment, reactivating mainly the Late Cretaceous Getic sole thrust (Schmid et al., 1998; Matenco
and Schmid, 1999). South of the window, the detachment was dipping underneath the Late Cretaceous
foredeep, where normal faults with comparable orientation were also activated.
During the Middle – Late Oligocene, the NE to Eward clockwise rotation of the Inner Carpathians
around Moesia (e.g., Patrascu et al., 1990, 1992,
1994) led to dextral activation of the curved Cerna
(Berza and Draganescu, 1988) and Timok faults
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
87
Fig. 11. Structural map with deformation structures active during Paleogene – Early Miocene along the western part of the South Carpathians –
Getic Depression – Moesian platform and contour map of the calculated basement subsidence at the end of the Burdigalian (16 Ma). CF = Cerna
Fault.
system and to opening of small-scale elongate transtensional (e.g., Petrosani) basins (see also Ratschbacher et al., 1993; Csontos, 1995; Schmid et al.,
1998 and references therein). This rotation is responsible for reorienting the originally WSW –ENE trending Getic detachment north of the Danubian window
into its present NNW –SSE position.
During the Early Miocene, extension migrated
from the Danubian units towards the foreland and
continued mostly within the South Carpathians foredeep (Fig. 4). In the Getic Depression – Moesian
Platform area, the NE-ward movement of the Inner
Carpathians led to the opening of dextral transtensional corridors (Fig. 11). As commonly observed in
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Fig. 12. Subsidence maps for the Carpathians foreland. (A) Contour map of the calculated basement subsidence at the end of Badenian and map
of deformation structures active during the Middle Miocene along the external part of the Romanian Carpathians. (B) Contour map of the
calculated basement subsidence at the end of Sarmatian and deformation structures active during the Late Miocene – Early Pliocene (Sarmatian –
Meotian) along the external part of the Romanian Carpathians. (C) Contour map of the calculated basement subsidence at the end of Pontian
structural map with deformation structures active during the Middle – Upper Pliocene along the external part of the Romanian Carpathians.
Absolute age correlations are made after the local Paratethys scale (see Figs. 3 and 4).
recent case studies (e.g., Ben-Avraham and Zoback,
1992), the main normal faults formed parallel to the
ENE-ward direction of dextral movement. Thick
sedimentary successions were deposited in these
corridors, presently buried below later Miocene –
Pliocene deposits in the west, and well exposed in
the east of the Getic Depression. The width and
depth of these areas were maximal in their central
parts and decreased both to the W and towards the E
(Fig. 11).
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
4.2. Middle Miocene (Late Burdigalian/Carpathian –
Badenian)
Early Middle to Middle Miocene tectonics are
characterised by NE to E-ward translation of the
Carpathian – Pannonian system (Royden, 1988), associated with its extensional collapse and the subduction
and roll-back of the lower plate (Horváth, 1993;
Horváth and Cloetingh, 1996; Royden, 1988).
During the Middle Miocene, the Outer Romanian
Carpathians are dominated by a general ENE –WSW
to E – W contraction, its effects being recognised both
in the East and in the South Carpathians (Fig. 12A).
In the central and southern part of the East Carpathians, ENE – WSW to E – W directed thrusting took
place in the Tarcau and Marginal Folds nappes (Fig.
3). Deformation began during the Late Burdigalian
and probably persisted through the Badenian. Significant lateral differences in the style of deformation
have been postulated in the East Carpathian wedge
and associated with lateral changes of the thickness of
the thrust sheets and/or with lateral variations of
friction coefficients along the major detachment levels
(Matenco, 1997). The northern segments of the East
Carpathians (roughly north of 47jN parallel) tend to
have large internal deformations (closely spaced
thrusts and folds, short thrust sheets, and duplexes)
as well as low offset of the nappe pile over the
foreland platforms. In contrast, the southern segments
of the belt tend to form wide wedges, with long thrust
sheets and widely spaced thrusts with low internal
shortening (ramping associated with backthrusts), and
high offset over the foreland.
Subsidence in the foreland platforms in front of the
Carpathians was limited and fairly homogenous at the
large scale (Fig. 12A). Subsidence values are in the
order of 200 – 300 m in most places. In the East
Carpathians, these low values are the result of the
large distance between the locations where the basement subsidence values were computed and the Carpathians thrust front where deformations was taking
place at the Middle Miocene level. The area of
possible basement subsidence associated with the
Middle Miocene thrusts loading should be presently
located underneath the more than 30-km thick external East Carpathians units. Their emplacement over
the foreland platforms was acquired later on, during
the Late Miocene episode (Matenco, 1997).
89
At the transition between the East-European and
the Moesian platforms, sectors with different thrusting geometries are kinematically linked by tear
faulting reactivating preexisting E –W trending platform faults. As a result, larger subsidence values
are observed in the intermediate Scythian Platform
(Fig. 12(A)).
ENE-ward movement of the inner South Carpathians upper plate induced small-scale contraction
(NNW – SSE striking thrusts) in the Getic Depression
(Fig. 4). The thrusts’ offset increased to the west,
probably associated with the already present bend of
the western South Carpathians. Subsidence in the
westernmost corner of the Moesian Platform took
place mainly in small piggyback basins, in the hinterland of most thrust lineaments.
4.3. Late Miocene (Sarmatian) – Early Pliocene
(Meotian)
The most important Tertiary tectonic event of the
Carpathians and neighbouring platform areas took
place during Late Miocene (Sarmatian) (Fig. 12B).
Large-scale differential contraction and uplift in the
Outer East Carpathians and transcurrent deformations
in the external South Carpathians – Getic Depression
occurred during thermal cooling and postrift sedimentation in the Pannonian Basin (Horváth, 1993; Horváth and Cloetingh, 1996).
4.3.1. Late Miocene (12 –11 Ma)
In the Outer Romanian Carpathians, Late Miocene
tectonics were characterised by large-scale eastward
motion of the inner East and South Carpathians,
causing differential contraction and uplift in the East
Carpathians and right-lateral shearing along a roughly
E– W trending corridor between South Carpathians
and Moesian Platform (Fig. 12B).
Once more, the contraction pattern was influenced
by the structure of the underthrusted platforms. The
most advanced East Carpathians nappes reached the
East-European block in the northern sectors. The
introduction into the subduction system of this EastEuropean block with up to 50-km thick crust and very
thick lithosphere strongly modified the boundary
conditions, thus resulting in major changes in the
thrust geometry. The most important consequence
was the onset of substantial uplift in the rear part of
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L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
the orogenic wedge (Sanders, 1998; Huismans, 1999).
Fission track analysis (Sanders, 1998) shows that
exhumation became important in the internal East
Carpathians at 11– 13 Ma (Late Miocene). The overall
Late Burdigalian –Sarmatian tectonic phase is mainly
responsible for the present-day double vergent geometry of the East Carpathians and to the up to the 4-km
accelerated exhumation of the rocks (e.g., Sanders,
1998) probably associated with the activation of
regional backthrusts in the internal part of the orogen
and along the NE margin of the Transylvania Basin.
In addition, the reduced thickness of the East-European successions involved in shortening provoked a
narrowing of the wedge and a transition to closerspaced thrusts and shorter thrust sheets. The slowdown or cessation of frontal thrusting has been considered as representative for a progressive migration
of deformation towards the S (e.g., Csontos, 1995;
Meulenkamp et al., 1996). This is not necessarily the
case since forward thrusting was replaced by out-ofsequence thrusts in the more internal nappes, or
backthrusts in the rear part of the orogen in the
moment when the nappes reached the East-European
Platform. The strong buoyancy of this platform and its
vertical stability are clearly demonstrated by our
subsidence analysis (Fig. 9(A) and (B1)).
None of such changes took place in the southern
segments of the chain where the thinner and substantially weaker Moesian plate (e.g., Lankreijer et al.,
1997) was still involved in subduction. Large-scale
tear faults developed in the lower plate between the
two platform (East-European/Moesian) areas (i.e.,
Trotus –Bistrita faults). This lead to the initiation of
large-scale subsidence during the Sarmatian times in
the Scythian Platform, but most importantly, in the
Moesian Platform, where strong Sarmatian subsidence
is recorded in the foreland of the thrust front, and
further to the E in the Focsani Depression (Fig. 12B).
Further to the south, the eastward motion of the
Inner Carpathians was accommodated by large-scale
E –W dextral shearing within the South Carpathians,
in the South Carpathians foredeep and Moesian Platform. However, the 130– 150 km Miocene shortening
of the East Carpathians (Roure et al., 1993; Ellouz and
Roca, 1994; Ellouz et al., 1994) cannot be entirely
taken up by the right-lateral movements within the
South Carpathians and Getic Depression, where total
displacements are in order of tens of kilometers. Part
of this dextral displacement could alternatively be
taken up by the South Transylvania and associated
faults, which deformed the Late Miocene –Pliocene
series in the internal Bı̂rsei Depression (see also
Ciulavu, 1999).
4.3.2. Latest Miocene– Early Pliocene (11 –9 Ma)
In the late stages of the E-ward motion episode
(Late Sarmatian – Meotian corresponding to latest
Miocene – Early Pliocene), strike-slip deformations
took place in front of the East Carpathians, as often
observed in purely contractional to oblique thrust belts
(e.g., Ratschbacher et al., 1992). This episode was
mainly dextral transpressional in the southern areas
and sinistral in the northern part of the East Carpathians, accommodating the SE lateral migration of the
plate boundary activity. This strike-slip episode is
plotted together with the previous Late Miocene
episode in the same Fig. 12B.
Two different domains can be distinguished in the
Romanian Carpathians (Fig. 12(B)).
(A) In the Getic Depression and in the SW termination of the East Carpathians, transpressional structures formed in a strike-slip stress field with roughly
N – S compression. Dextral faults often reactivated
older faults. Associated NNE – SSW sinistral faults
are common in the foredeep and external parts of South
Carpathians. Large E – W striking thrusts occurred in
the frontal part of the Getic foredeep, and were associated with strong basement subsidence in the frontal
part of the Pericarpathian line.
(B) In the central East Carpathians, a strike-slip
stress field with NNE – SSW compression direction
induced sinistral displacement along E – W to NE –
SW trending faults such as Trotus and related (e.g.,
Bistrita) structures. Transcurrent faulting was, however, widespread both in the upper and lower plates.
In the bend zone (Fig. 12B), the two dominant
fault systems, dextral NW – SE trending in the South
Carpathians and sinistral ENE – WSW directed in the
central East Carpathians, interacted, resulting in SEward movement of the area bounded by the Intramoesian and Trotus/Bistrita faults. Despite the large
number of strike-slip faults observed, the total displacement of this domain during the latest Miocene–
Early Pliocene did not exceed few tens of kilometers
in the external part of the Romanian Carpathians
belt.
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
Subsidence continued during this timespan (Fig.
12(B)), especially in the Carpathians bend zone (e.g.,
Figs. 9(B2), (B3), (C) and 10B) where up to 2000 m
of basement subsidence were recorded during the Late
Sarmatian –Meotian times. North of the Trotus Fault,
the East-European Platform becomes vertically stable,
no subsidence being recorded during the latest Miocene through Pliocene (Fig. 9(A) and (B1)). In the
frontal part of the South Carpathians, subsidence
continued in the Moesian Platform, especially in
vicinity of the frontal sole thrust. About 1000 – 1500
m of basement subsidence were recorded during this
timespan, clearly smaller than the previous Sarmatian
period (Fig. 8B).
4.4. Pliocene– Pleistocene
Very little deformation, limited to E –W to NE –
SW trending thrusts, took place during the Pliocene–
Pleistocene (Fig. 12(C)), nearly exclusively found in
the southern corner of the East Carpathians (see also
Hippolyte and Sandulescu, 1996; Hippolyte et al.,
1999). Thrusts are often out-of-sequence and sometimes reactivated latest Miocene transpressional
structures. Thrusting was coeval with strong subsidence in the area south of the Focsani Depression
and east of the Intramoesian Fault (e.g., compare
basement position in Fig. 12(C) with the present one
in Fig. 2(A)). Here, up to 4 km of Pliocene subsidence is observed, higher than the 2– 3 km recorded during Sarmatian times (e.g., Fig. 9(B4) and
(B5)).
Note that the major subsidence for the Focsani
Depression –Vrancea area was acquired already during the Late Miocene to Early Pliocene (e.g., compare
Focsani subsidence at the end of Sarmatian in Fig.
12(B) to total Tertiary values in Fig. 2(A)) and not
Pliocene– Pleistocene as previously suggested (e.g.,
Sperner, 1996; Sperner et al., 1999; Wenzel and
Mocanu, 1999). During the Pliocene, the subsidence
depocenter had ‘‘shifted’’ southward, towards the SWmost corner of the East Carpathians foreland.
5. Conclusions
The Tertiary evolution of the Romanian Outer
Carpathians and their foreland can be summarised in
91
two major periods, from the Paleogene to the Sarmatian and from the Sarmatian to present.
The first stage, Paleogene to Sarmatian, is basically
characterised by the right-lateral displacement of the
Inner Carpathians with respect to the Moesian foreland. In the Inner Carpathians/Pannonian basin, this
resulted in overall dextral transpression accompanied
by large-scale rotations along an E –W directed corridor and, beginning from the Middle Miocene, transtensional deformation characterised by rifting and
subsequent cooling phase in the Pannonian basin.
The deformation pattern in the Outer Carpathians
was different. The area in front of the South Carpathians and of the southern termination of the East
Carpathians underwent Paleogene – Early Miocene
orogen-parallel extension to transtension, followed
by Middle to Late Miocene right-lateral transpression
to contraction. In contrast, the regions adjacent to the
East Carpathians were affected by pure to oblique
contraction throughout the entire timespan from the
Lower Miocene to the Sarmatian.
The subsidence pattern recorded in the Carpathians
foreland during Paleogene to Sarmatian is characterised by significant vertical motions. The opening of
the Early Miocene transtensional basin in the Getic
Depression/western Moesian Platform led to the accumulation of up to 5 km of Lower Burdigalian sediments, while other platform areas were characterised
by nondeposition and/or erosion. Smaller subsidence
values are recorded in the same area in connection
with Middle Miocene thrusting. Starting with the
Sarmatian, the entire Romanian foreland platform area
starts to subside, the major depocenter of the foreland
basin being located in the Focsani Depression (e.g., a
rate of 1500– 3000 m/Ma in and around the Focsani
Depression for the Late Miocene). In contrast with
previously proposed scenarios (e.g., Meulenkamp et
al., 1996), our data do not support the notion of
Middle – Late Miocene systematic depocenters migration along the East Carpathians foreland.
This picture changed substantially when, in the
Late Sarmatian (latest Miocene), the East Carpathians
thrust belt reached the East-European Platform. This
not only imposed a change in the style of thrusting in
the East Carpathians but also caused some significant
changes in the mechanical properties of the system.
Indeed, from this moment, the entire Carpathian
system and its foreland started behaving as a single
92
L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94
block with similar stress field being documented from
both the Intra- and Outer Carpathian units. The stress
field was strike-slip with NE –SW to N –S directed
compression until the Early Pliocene and then compressional with NNW –SSE oriented r1 afterwards.
Subsidence associated with Late Miocene thrusting
and dextral transpression increased in the area
between the Intramoesian and the Trotus/Bistrita
faults due to larger SE-ward displacements. During
the Middle Pliocene to Pleistocene, the subsidence in
the Focsani Depression is significantly decreased
(e.g., a rate of 200– 300 m/Ma for the whole Pliocene – Pleistocene). The depocenter of the basin is
located southward, at the East Carpathians SW edge.
This suggests a causal relationship between the largescale subsidence and that of the deep ‘‘Pliocene’’
Focsani Depression during the Sarmatian. Younger
subsidence and basin fill would then be a prolongation
of the earlier mechanism. In this context, the previously suggested relationship (e.g., Sperner, 1996;
Girbacea and Frisch, 1998; Linzer et al., 1998; Zweigel et al., 1998; Wenzel and Mocanu, 1999 and
references therein) between a possible advanced slab
retreat (senso Royden, 1993) and slab break-off (senso
Wortel et al., 1993) in SE East Carpathians corner at
the Pliocene– Pleistocene level, and the subsidence of
the Focsani Depression plus Vrancea deep earthquakes is questionable. Such a foreland slab position
is debatable also due to the absence of any clear
influence of the Focsani Depression on the basement
crustal map (Fig. 2B). Good seismic and tomographic
images of the deep configuration will soon be available (e.g., Wenzel et al., 1998) and will provide
further constraints.
The southern part of the East Carpathians and its
foreland have Tertiary structural characteristics more
similar to those of the South Carpathians foreland
(Getic Depression) than to the central and northern
segments of East Carpathians. The classical separation
between the East and South Carpathians in the external areas along the Intramoesian Fault is, in this
respect, somewhat arbitrary.
The reconstruction of the Tertiary evolution of the
Romanian Carpathians foreland presented in this
paper has demonstrated the existence of comparable
kinematic episodes simultaneously occurring in the
frontal part of both East and South Carpathians.
Similar patterns appear to exist at the scale of the
Carpathians belt as a whole. Subsidence analysis has
demonstrated the (re)activation of major platform
faults during the Miocene– Pliocene tectonic episodes,
providing constraints for the quantitative assessment
of the lateral variations in the emplacement mechanism of various tectonic units.
Acknowledgements
The research carried out in this paper was possible
due to Peri-Tethys Programme funding. L.M. acknowledges this project for partially funding his PhD
thesis. M. Wagreich, F. Roure, F. Horváth and G.
Bada are thanked for their reviews which helped us to
improve the paper. This is publication no. 20020904
of the Netherlands Research School of Sedimentary
Geology.
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