Subsidence Analysis & Tectonic Evolution of the External Carpathian-Moesian Platform Region During Neogene Times - Sed Geo, 2003

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

aFaculty of Geology and Geophysics, University of Bucharest, 6 Traian Vuia str. sect. 1, RO-70139 Bucharest-1, RomaniabDepartment 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 Rho-

dopian fragment (Burchfiel, 1976) to the west and

south, and the East-European/Scythian/Moesian Plat-

forms to the east and north (Sandulescu, 1984; San-

dulescu and Visarion, 1988; Visarion et al., 1988)

(Fig. 1). The Carpathians consist of thick- and thin-

skinned nappe piles (de)formed by thrusting and

dextral transpression during Middle Cretaceous to

Pliocene times (e.g., Sandulescu, 1984, 1988; Ratsch-

bacher 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: S0037 -0738 (02 )00283 -X

* Corresponding author. Fax: +40-1-211-7390.

E-mail address: [email protected] (L. Matenco).

www.elsevier.com/locate/sedgeo

Sedimentary Geology 156 (2003) 71–94

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., Horvath, 1993) coeval with contraction

Fig. 1. Tectonic map of the external part of the Romanian Carpathians and of major boundary faults in the foreland platforms. Faults in the thin-

skinned 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.

L. Matenco et al. / Sedimentary Geology 156 (2003) 71–9472

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 Carpathi-

ans 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 em-

placement of thrust sheets in the various segments of

the Carpathians (e.g., Sandulescu, 1984, 1988) are in-

compatible with the absence of structures able to ac-

commodate 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 Fulop, 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 differ-

ences exist between the tectonic models, mainly con-

cerning 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., Intra-

moesian, 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 dur-

ing the Tertiary on the foreland platforms, which are

often referred to as foredeeps. However, the kine-

matics of subsidence has rarely been documented. To

fill this gap, we analysed a large number of subsurface

data (wells, geological profiles and seismic interpre-

tations) 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.

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 over-

lain by Tertiary sediments belonging both to the

Carpathians foredeep basin and to the flat-lying plat-

form 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 plat-

forms’’.

According to Sandulescu and Visarion (1988) and

Visarion et al. (1988), the autochthonous platforms in

the foreland of the Romanian Carpathians are com-

posed of two, internally complex, relatively stable

areas, the East-European/Scythian and the Moesian

Platforms, separated by the North Dobrogean oro-

genic zone (Fig. 2).

The platform domains are overthrusted by the thin-

skinned 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 thin-

skinned 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 (Sarma-

tian –Early Meotian) tectonic events (Matenco,

1997; Fig. 3). In the frontal part of the South Carpa-

thians, only the deformed foredeep (Getic Depression)

is in direct contact with the Moesian Platform (Fig. 1).

The Tertiary evolution of the Getic Depression–Moe-

sian 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 Campulung-

L. Matenco et al. / Sedimentary Geology 156 (2003) 71–94 73


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 Plat-

form 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 subdi-

vided 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,

the nature of the basement is unknown (Airinei et al.,

1966).

The thickness of the sedimentary cover of the East-

European 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 docu-

mented south of the East-European Platform in the

Bırlad Depression. Towards the W and NW, the

Scythian Platform is continuous with the basement

block between Solca and Campulung-Bicaz faults

(Sandulescu and Visarion, 1988). Here, a similar type

of Scythian basement has been documented by mag-

netic anomalies and deep wells as in the Bırlad

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 Bırlad Depression

and to underthrusting below the East Carpathians

nappe pile. However, three major sedimentation

cycles have been defined (Ionesi, 1989): Upper Pale-

ozoic–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—Campulung-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—Calimanes�ti-Tg. Jiu Fault.


two types of faults. NW–SE trending normal faults

account for a progressive deepening of the autoch-

thonous 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

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

Rogl (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.


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).



have also imaged large NE–SW to E–W trending

crosscutting faults (Fig. 2) associated with a progres-

sively 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 Campulung-Bicaz Fault, magneto-

telluric 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 Mie-

chow 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 Pece-

neaga-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 ‘‘Dobro-

gean’’ domain show crustal thicknesses around 35–40

km (Radulescu, 1988) compatible with the seismo-

logical 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 Dobro-

gean zone in two parts, characterised by different

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 seg-

ments (Visarion et al., 1988), i.e. the ‘‘Valachian’’ and

‘‘Danubian’’ domains, bounded by the crustal-scale

Calimanes� ti-Tg. Jiu Fault (Fig. 2). This fault repre-

sents 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.


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. Sedi-

ments are organised in four major successions (Ion-

esi, 1989). The Upper Cambrian –Westphalian

succession is up to 6500 m thick and composed of

a lower detritic (shales) group and an upper lime-

stone group. It is unconformably followed by up to

5000-m thick, predominantly clastic (shales–sand-

stones) 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 fol-

lowed 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 thick-

nesses 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 Ter-

tiary 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 model-

ling 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 (East-

European, Scythian and Moesian) as well as for the

pre-Dobrogean Depression (the buried prolongation

of the North-Dobrogean orogen) (Fig. 2(A), col-

oured 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 allochtho-

nous 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 pro-

files controlled from wells (profiles A18, A20, A21,


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 seismi-

cally 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 de-

tail 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-

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.


tial compaction law for six standard lithological types

(sandstone, siltstone, clay, limestone, salt and anhy-

drite), and we have averaged the compaction depend-

encies 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 Plat-

form 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 evo-

lution 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 calcu-

lated, 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.

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.



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.


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 trend-

ing normal faults (e.g., Alexandria Depression) (Raba-

gia, 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 contempora-

neous 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 large-

scale extension and core-complex formation in the

Danubian units of the neighbouring South Carpathi-

ans (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 exter-

nal position. In the NW parts of the Getic Depression,

subsidence continued until recent times, although at

low rates.

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 East-

European 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 SW-

ward, 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 sub-

sidence 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 sub-

sidence 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 west-

ernmost 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 ob-

served.

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


subsidence is significant (3500 m near the thrust

front).

4. Tectonic model

The subsidence analysis carried out can be corre-

lated 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 western-

most 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; Sandu-

lescu, 1984) around the Moesian Platform during the

Paleogene–Early Miocene (Fig. 11) caused differ-

ential deformations along the bent East Carpathi-

ans–South Carpathians fragment.

During the Late Eocene–Early Oligocene, large-

scale, orogen-parallel extension took place in the

South Carpathians (Fig. 4), leading to rapid exhuma-

tion of the Danubian basement in the footwall of the

Getic detachment, reactivating mainly the Late Creta-

ceous Getic sole thrust (Schmid et al., 1998; Matenco

and Schmid, 1999). South of the window, the detach-

ment was dipping underneath the Late Cretaceous

foredeep, where normal faults with comparable ori-

entation were also activated.

During the Middle–Late Oligocene, the NE to E-

ward 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

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).


system and to opening of small-scale elongate trans-

tensional (e.g., Petrosani) basins (see also Ratsch-

bacher et al., 1993; Csontos, 1995; Schmid et al.,

1998 and references therein). This rotation is respon-

sible for reorienting the originally WSW–ENE trend-

ing 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 fore-

deep (Fig. 4). In the Getic Depression–Moesian

Platform area, the NE-ward movement of the Inner

Carpathians led to the opening of dextral transten-

sional corridors (Fig. 11). As commonly observed in

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.


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).

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).


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), asso-

ciated with its extensional collapse and the subduction

and roll-back of the lower plate (Horvath, 1993;

Horvath 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 Carpa-

thians, 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. Signifi-

cant 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 base-

ment subsidence values were computed and the Car-

pathians 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 exter-

nal East Carpathians units. Their emplacement over

the foreland platforms was acquired later on, during

the Late Miocene episode (Matenco, 1997).

At the transition between the East-European and

the Moesian platforms, sectors with different thrust-

ing geometries are kinematically linked by tear

faulting reactivating preexisting E–W trending plat-

form faults. As a result, larger subsidence values

are observed in the intermediate Scythian Platform

(Fig. 12(A)).

ENE-ward movement of the inner South Carpathi-

ans 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 hinter-

land 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 sedimen-

tation in the Pannonian Basin (Horvath, 1993; Hor-

vath 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 East-

European 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


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 geom-

etry 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-Euro-

pean successions involved in shortening provoked a

narrowing of the wedge and a transition to closer-

spaced thrusts and shorter thrust sheets. The slow-

down or cessation of frontal thrusting has been con-

sidered 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-of-

sequence 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 substan-

tially 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 Plat-

form. 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 Bırsei 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 Carpa-

thians, 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 termi-

nation of the East Carpathians, transpressional struc-

tures 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 asso-

ciated 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, how-

ever, 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 SE-

ward movement of the area bounded by the Intra-

moesian and Trotus/Bistrita faults. Despite the large

number of strike-slip faults observed, the total dis-

placement 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.


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 Mio-

cene 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 some-

times reactivated latest Miocene transpressional

structures. Thrusting was coeval with strong subsi-

dence 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 sub-

sidence is observed, higher than the 2–3 km re-

corded during Sarmatian times (e.g., Fig. 9(B4) and

(B5)).

Note that the major subsidence for the Focsani

Depression–Vrancea area was acquired already dur-

ing 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 SW-

most corner of the East Carpathians foreland.

5. Conclusions

The Tertiary evolution of the Romanian Outer

Carpathians and their foreland can be summarised in

two major periods, from the Paleogene to the Sarma-

tian 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 fore-

land. In the Inner Carpathians/Pannonian basin, this

resulted in overall dextral transpression accompanied

by large-scale rotations along an E–W directed corri-

dor and, beginning from the Middle Miocene, trans-

tensional 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 Carpa-

thians 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 character-

ised by significant vertical motions. The opening of

the Early Miocene transtensional basin in the Getic

Depression/western Moesian Platform led to the accu-

mulation of up to 5 km of Lower Burdigalian sedi-

ments, 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 migra-

tion 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


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 com-

pressional 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 Plio-

cene–Pleistocene). The depocenter of the basin is

located southward, at the East Carpathians SW edge.

This suggests a causal relationship between the large-

scale 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 previ-

ously suggested relationship (e.g., Sperner, 1996;

Girbacea and Frisch, 1998; Linzer et al., 1998; Zwei-

gel 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 earth-

quakes 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 avail-

able (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 exter-

nal 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 mecha-

nism of various tectonic units.

Acknowledgements

The research carried out in this paper was possible

due to Peri-Tethys Programme funding. L.M. ac-

knowledges this project for partially funding his PhD

thesis. M. Wagreich, F. Roure, F. Horvath 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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