Finite-element modelling of Tertiary Paleostress fields in the eastern part of the Tajo Basin (central Spain)

Abstract

Three subsequent Tertiary paleostress fields that are deduced from fault-slip data for the eastern part of the Tajo Basin are analyzed by finite-element studies. The modelling results show that maximum horizontal stresses (SHmax) are mainly controlled by the geometry of the model limits and the boundary conditions applied. The models are used to test two hypotheses on the origin of the Altomira Range. A local stress field responsible for its formation (‘Altomira') can be modelled successfully by superposition in time and place of two major paleostress fields (‘Iberian' and ‘Guadarrama'). Stress trajectories have been modelled with respect to a homogeneous cover and heterogeneous basement to investigate the role of rheological contrasts between different basement blocks on the orientation of the stress field. Results of this kind of modelling suggest a mechanical decoupling between the cover and the basement, especially for the ‘Altomira' paleostress field.

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ELSEVIER Tectonophysics 300 (1998) 47–62
Finite-element modelling of Tertiary paleostress fields in the eastern
part of the Tajo Basin (central Spain)
A. Mun˜oz-Martı´n a,Ł,S.Cloetinghb,G.DeVicentea,B.Andewegb
aDepartamento de Geodina´mica, Facultad CC Geolo´gicas, Universidad Complutense, Madrid 28040, Spain
bInstitute of Earth Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands
Received 10 March 1998; accepted 9 May 1998
Abstract
Three subsequent Tertiary paleostress fields that are deduced from fault-slip data for the eastern part of the Tajo Basin
are analyzed by finite-element studies. The modelling results show that maximum horizontal stresses (SHmax) are mainly
controlled by the geometry of the model limits and the boundary conditions applied. The models are used to test two
hypotheses on the origin of the Altomira Range. A local stress field responsible for its formation (‘Altomira’) can be
modelled successfully by superposition in time and place of two major paleostress fields (‘Iberian’ and ‘Guadarrama’).
Stress trajectories have been modelled with respect to a homogeneous cover and heterogeneous basement to investigate the
role of rheological contrasts between different basement blocks on the orientation of the stress field. Results of this kind of
modelling suggest a mechanical decoupling between the cover and the basement, especially for the ‘Altomira’ paleostress
field. 1998 Elsevier Science B.V. All rights reserved.
Keywords: paleostress; finite-element modelling; Tajo Basin; Tertiary
1. Introduction
Comparison between results obtained by finite-
element stress modelling and observed (paleo)stress
data is a mighty tool for the understanding of geody-
namic processes. This is specially true where several
stress fields (in the case of the Iberian Peninsula,
the Tertiary stress fields) controlled by different rhe-
ological and structural factors have been described
(Simo´n-Go´mez, 1986; Guimera´, 1988; Galindo et
al., 1993; De Vicente et al., 1996b). Previous stress
modelling results, obtained on theoretical basis, as
well as on practical cases (Richardson et al., 1979;
ŁCorresponding author. Tel.: C34 91 394 48 34; Fax: C34 91
394 48 45; E-mail: amunoz@eucmos.sim.ucm.es
Wortel and Cloetingh, 1985; Cloetingh and Wor-
tel, 1986; Gru¨nthal and Stromeyer, 1992; Go¨lke and
Coblentz, 1996), show that certain tectonic processes
can be simulated by finite-element modelling. This
technique has been applied in different scale mod-
els for recent stresses and paleostress data (Meijer,
1995; Janssen, 1996) as well as for deformations on
several types of structures (Sassi et al., 1993; Go¨lke
et al., 1994).
The Alpine geological evolution of the interior of
the Iberian microplate during the Tertiary is strongly
influenced by the presence of large inherited geo-
logical structures and by stress transmission from its
active borders (Fig. 1): the Pyrenees at the north and
the Betics at the south (Sanz de Galdeano, 1996).
The tectonic activity at these borders is related to
0040-1951/98/$ – see front matter 1998 Elsevier Science B.V. All rights reserved.
PII: S0040-1951(98)00233-9

48 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
Fig. 1. Geological and geographical location of the study area and finite-element modelling area boundaries. DB DDuero Basin; TB DTajo Basin; Z.F. DZa´ncara Fault;
TMEL DToledo Mountains eastern limit; TFZ DTaranco´n Fault Zone; MBB DMadrid Basin Block; VB DValdeolivas Block; CB DCuenca Block.

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 49
the convergence and lateral displacement between
the Iberian, African and Eurasian plates during the
Tertiary (Dewey et al., 1989; Srivastava et al., 1990).
In the interior of the peninsula, sedimentary basins
development (Duero, Tajo and Ebro basins) was con-
trolled by the tectonic activity of its borders. These
borders are a set of mountain ranges (the Spanish
Central System, Iberian Range, Toledo Mountains,
Altomira Range; Fig. 1) that were structured due
to the transmitted stresses from the Iberian Penin-
sula margins. The geometry and characteristics of
these deformation belts are strongly subdued to the
presence of large crustal faults, which have con-
trolled Mesozoic sedimentation and whichhave been
subjected to inversion tectonics during the Tertiary
(A
´lvaro et al., 1979; Viallard, 1983; Guimera´and
A
´lvaro, 1990). We have studied the eastern part of
the Tajo Basin, an area that comprises two Alpine
deformation belts (the SW border of the Iberian
Range and the Altomira Range) and the Madrid and
Loranca Tertiary basins (Fig. 1).
The most important structural characteristic of the
study area is the presence of a 100-km-long thin-
skinned fold-and-thrust belt with a N–S trend and
a W vergence: the Altomira Range. This fold-and-
thrust belt developed under a regional N–S shorten-
ing parallel to the range direction, which makes its
origin arguable. The origin of the Altomira Range
has been basically interpreted in two ways: (a) after
Guimera´ (1988), the Pyrenees, the Iberian Range and
Catalan Coastal Ranges were structured under the
same N10ºE regional compression, resulting from
the collision of the Iberian and Eurasian plates; in
view of this model, the Altomira Range is an oblique
ramp of the Iberian Range foreland fold-and-thrust
belt of the Pyrenean orogen (Guimera´andA
´lvaro,
1990); (b) as a lateral extrusion of the Mesozoic
cover to the west at the foreland of both the Pyrenees
and Betics, produced by the superposition of both
regional compressions (Mun˜oz-Martı´n et al., 1994).
In both hypotheses, the tectonic stresses that
generated the Altomira Range must have been in-
fluenced by previous structures in the Hercynian
basement and in the cover, as well as by the Meso-
zoic sedimentary architecture itself (Van Wees et al.,
1995).
The aim of this study is to investigate, through
a series of finite-element models, the Tertiary pale-
ostress fields deduced from the Mesozoic and Ceno-
zoic cover at the eastern part of the Tajo Basin
(Mun˜oz-Martı´n and De Vicente, 1996). Special at-
tention has been drawn to the boundary conditions,
which have to reflect the main geological structures
of central Iberia. The results of these stress orien-
tation models can provide valid data to discuss the
origin of different paleostress fields and associated
structures, as well as its relation with the tectonic
activity at the northern and southern margins of the
Iberian Peninsula (Pyrenees and Betics). The possi-
ble presence of reorientations of the stress trajecto-
ries in the basement with regard to the cover, caused
by the presence of basement blocks with differ-
ent rheological characteristics, has also been studied
during the modelling. Mechanical decoupling could
be caused by the presence of a detachment level
(Triassic Keuper facies) between the cover and the
basement.
2. Geological setting and Tertiary paleostress
fields
The eastern part of the Tajo Basin reflects a
complex Tertiary geological evolution, with a large
variety of active structures, whose evolution and
kinematic chronology is recorded by the deformation
history of the deformation belts and the sedimentary
infill of the Tertiary basins (Calvo et al., 1993; De
Vicente et al., 1996a). The most important character-
istics of the two deformation belts in this area (the
Iberian and Altomira ranges) and of the Madrid and
Loranca Tertiary basins is described in order to put
the paleostress data and the developed finite-element
models into a larger framework.
The Iberian Range (Fig. 1) is an intraplate range
with an overall NW–SE trend whose origin and ge-
ometry is related to the presence of NW–SE-trending
basement faults, that controlled sedimentation in the
Iberian Basin during the Mesozoic, and which were
inverted during the Tertiary (A
´lvaro et al., 1979).
At the Iberian Range, the Mesozoic sedimentary
cover has a thickness of several thousands of metres,
and the presence of plastic Lower to Middle Trias-
sic rocks (Keuper facies) allows us to distinguish
between a detachable cover formed by Jurassic,
Cretaceous and Tertiary materials and a basement

50 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
consisting of Paleozoic and lower Triassic materials
(A
´lvaro et al., 1979; Viallard, 1983). This Hercynian
basement crops out at the Iberian Range in spindle
(or almond) shaped massifs, stretched in a NW–SE
direction parallel to the chain, usually limited by
high dip faults with lateral movement (Guimera´and
A
´lvaro, 1990). The tectonic activity of the Iberian
Range presents two main different stages for the
Tertiary. (1) In a first stage (Oligocene) the range
acted as a dextral transpressive zone located at the
foreland of the Pyrenees orogen (Guimera´andA
´l-
varo, 1990; Salas and Casas, 1993). (2) During the
Middle–Late Miocene the eastern part of the range
acted as a dextral transpressive limit of the Central
Spanish System, clearly related to the formation of
the Betics (De Vicente et al., 1996a). This dextral
movement is also expressed at the southern border of
the Almaza´n Basin, by the development of abundant
transpressive structures (Bond, 1996).
The Altomira Range (Fig. 1) is a west-verging
fold-and-thrust belt that only affects the Mesozoic
cover. Geophysical data (Querol, 1989; Perucha et
al., 1995) show that the basement below the Upper
Triassic (Keuper) evaporitic facies is not involved
in the compressive structures that appear at the Al-
tomira Range and Loranca Basin. Inherited basement
structures, however, controlled the location of the
cover deformation, as well as the vergence and the
lateral extension of the thrusts. The presence of frac-
tures in the basement that are oblique to the cover
thrusts, produces a series of transfer zones devel-
oped in the cover that separate zones with different
structural characteristics, and control sedimentation
in the Tertiary basins (Rodrı´guez-Aranda, 1995; Ro-
drı´guez-Aranda et al., 1995). In this general scheme
two different sectors can be distinguished, which are
separated by a NW–SE fracture zone that affects the
basement (the Taranco´n Fault Zone; Capote, 1983).
At its northern half part, the Altomira Range presents
peculiar structural properties, such as a straight trace
in a N–S to N20ºE trend and deformation condensed
in one or two narrow anticlinories. At its northern
surficial termination, the Loranca and Madrid basins
join together due to the cushioning of the compres-
sive structures (Figs. 1 and 2).
From the Taranco´n Fault Zone to the south, the
folds and thrusts rotate in an anticlockwisesense in a
NW–SE direction parallel to the Iberian Range. This
change in orientation of the structures is favored by
transfer zones that developed in the cover on the
top of NE–SW- to E–W-trending basement faults
(Figs. 1 and 2).
The Madrid Basin (Fig. 1) is an intraplate basin
whose infilling is formed by a sequence of Tertiary
continental sediments that is clearly related to dif-
ferent tectonic activity of its borders (the Spanish
Central System, Altomira Range, Iberian Range and
Toledo Mountains; Calvo et al., 1989; De Vicente et
al., 1996a). A series of progressive unconformities
of Late Oligocene and Early Miocene age devel-
oped in relation to the emplacement of the Altomira
Range folds and thrusts. These unconformities allow
to date the onset and stages of activity of Altomira
Range structures. From Middle Miocene on, alluvial
sediments from the Spanish Central System onlap
the compressive structures of the Altomira Range,
showing a low tectonic activity of this range during
this period and thus indicating an upper age limit of
major deformation in the Altomira Range.
The Loranca Basin (Fig. 1) is an intraplate basin
filled up with mainly Oligocene–Lower Miocene
continental sediments, whose deposition was con-
trolled by the folds and thrusts of the Altomira and
Iberian ranges (Dı´az-Molina et al., 1989). The main
basin infill phase occurred during the Late Oligocene
and Late Miocene with a series of alluvial fans
whose apexes are located to the south of Cuenca
and at the Iberian Range (Dı´az-Molina et al., 1989;
Dı´az-Molina and Tortosa, 1996).
2.1. Tertiary paleostress fields
The different paleostress fields for this region that
have been modelled in this study have been recon-
structed by Mun˜oz-Martı´n and De Vicente (1996)
from more than 3000 fault-slip data, measured on
78 sites in Mesozoic, Tertiary and Quaternary rocks
(Fig. 2). The stress inversion method used in or-
der to obtain paleostress tensors is the one devel-
oped by Reches et al. (1992), while the smoothed
SHmax trajectory maps have been constructed follow-
ing Lee and Angelier (1994). According to these
data Mun˜oz-Martı´n and De Vicente (1996) have de-
duced three paleostress fields, that differ with respect
to their ages, their principal stress axes directions
and the different activated structures along the east-

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 51
Fig. 2. Upper panel: paleostress data sites and main basement faults deduced from geophysical data. Lower panel: simplified geological
profile of the general structure deduced from structural and geophysical data (Perucha et al., 1995; Mun˜oz-Martı´n, 1997), and
differentiated basement blocks, separated by the Sacedo´n Fault (S.F.).
ern part of Tajo Basin. The most recent stress field,
called ‘Guadarrama’, is compatible with present-day
stress trajectories deduced from earthquake focal
mechanisms for the centre of the Iberian Peninsula
(De Vicente et al., 1996b), and with recent stress data
deduced in Morocco and western Europe (Mu¨ller et
al., 1992; Medina, 1995).
2.2. ‘Iberian’ paleostress field (Oligocene, Fig. 3)
The compressive paleostress field can be char-
acterised by a regional strike-slip stress tensor
in transpressional regime, with ¦1horizontal ori-
ented to N55ºE, vertical ¦2and a stress ratio
RD0:2.RD.¦2¦1/=.¦1¦3/). This paleostress

52 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
Fig. 3. (A) Paleostress and SHmax trajectory maps of ‘Iberian’ paleostress field (Oligocene). (B) Main axis orientations. (C) Rvalue
histograms.
field activatedseveral structures that affect the Meso-
zoic cover and reactivated basement faults in the
Iberian Range (Fig. 3). In the study area active struc-
tures associated with this paleostress field are mainly
NW–SE-trending NE-dipping thrusts and dextral
(NNE–SSW) and sinistral (ENE–WSW) strike-slip
faults (Mun˜oz-Martı´n, 1997). Deformation related to
this paleostress field is restricted to the SW border
of the Iberian Range and to the southern half of the
study area. The northern boundary of this deforma-
tion in the interior of Loranca Basin is marked by
the SW–NE-trending Taranco´n Fault Zone (Figs. 1
and 3). The origin of this paleostress field must be
related to the collision with Eurasia along the north-
ern limit of the Iberian microplate generating the
‘Pyrenees-push’ from the north (Guimera´andA
´l-
varo, 1990). This regional stress field experienced a
counterclockwise rotation of the SHmax south of reac-
tivated NW–SE-trending crustal faults in the Iberian
Range (Simo´n-Go´mez, 1984) that controlled sedi-
mentation at the Iberian Basin during the Mesozoic.
(A
´lvaro et al., 1979; Guimera´andA
´lvaro, 1990).
2.3. ‘Altomira’ paleostress field (Upper
Oligocene–Lower Miocene; Fig. 4)
A stress field in the context of a general transpres-
sional regime, with a N100ºE-trending horizontal ¦1,

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 53
Fig. 4. (A) Paleostress and SHmax trajectory maps of ‘Altomira’ paleostress field (Upper Oligocene–Lower Miocene. (B) Main axis
orientations. (C) Rvalue histograms.
a vertical ¦2and a mean RD0:13, is interpreted
to be responsible for the structuring of the northern
and westernmost sectors of Altomira and Bascun˜ana
Ranges (Fig. 4). Active structures affected by this
stress field are N–S- to N20ºE-trending thrusts and as-
sociated folds, and ENE–WSW dextral and WNW–
ESE sinistral strike-slip faults (Fig. 4). The smoothed
SHmax trajectories are homogeneous and only present
a small clockwise rotation at the SE part of the study
area. The shortening associated with thrusting im-
posed by this stress field, reaches a maximum close
to the north of the Taranco´n Fault Zone (Mun˜oz-
Martı´n and De Vicente, 1998). Microstructural analy-
sis shows that this stress field reactivated the main
structures that developed under the ‘Iberian’ pale-
ostress field in the southern half of the study area. The
‘Altomira’ paleostress field has a Late Oligocene–
Early Miocene age deduced from the age of syn-
tectonic sediments related to Altomira Range thrusts
(Dı´az-Molina and Tortosa, 1996), and from the fact
that compressive structures of the Altomira Range
are sealed by Middle and Upper Miocene sediments
(Calvo et al., 1989; Rodrı´guez-Aranda, 1995). Spatial
distribution of deformation related to this paleostress
field basically coincides with the study area. Fault
data assigned to this stress field have been measured
in Jurassic, Cretaceous and Paleogene rocks of the
Altomira Range and the SW border of the Iberian

54 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
Range, as well as on Lower Miocene sediments of the
Madrid and Loranca basins.
2.4. ‘Guadarrama’ paleostress field (Middle
Miocene–Present)
This paleostress field is responsible for a major
part of the formation of the Spanish Central System
during Middle–Late Miocene (De Vicente, 1988;
Capote et al., 1990), and is compatible with the pre-
sent-day stress field, deduced from earthquake focal
mechanisms (De Vicente et al., 1996b). In the study
area the ‘Guadarrama’ stress field is identified as a
strike-slip regime, with a constant N155ºE-trending
Fig. 5. (A) Paleostress and SHmax trajectory maps of ‘Guadarrama’ paleostress field (Middle Miocene–Present). (B) Main axis
orientations. (C) Rvalue histograms.
horizontal ¦1and an Rvalue around 0.33 (Fig. 5).
Main structures activated by this stress field are
NW–SE dextral and NNE–SSW sinistral strike-slip
faults. Fault data assigned to this stress field have
been measured on Jurassic to Quaternary sediments.
In several sites it has been proved that previous
weakness planes (faults, bedding planes, etc.) have
been reactivated as strike-slip faults by this stress
field (Mun˜oz-Martı´n, 1997). SHmax trajectories are
very homogeneous within the study area, and extend
to the north and to the west, covering the Spanish
Central System (De Vicente et al., 1996b). The origin
of this paleostress field is related to the transmission
of stresses from the southeast due to the ongo-

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 55
ing convergence between Africa and Eurasia=Iberia
building up the Betics (Galindo et al., 1993; De
Vicente et al., 1996b).
2.5. Structure of the eastern part of the Tajo Basin
Balanced geological cross-sections extending
from the Madrid Basin to the Iberian Range across
the Altomira Range indicate a maximum shortening
of 18% (16 km) in the central part of the study
area, close to the north of the Taranco´n Fault Zone
(Mun˜oz-Martı´n, 1997). Seismic reflection profiles
(Querol, 1989) and gravity data (Perucha et al.,
1995; Mun˜oz-Martı´n, 1997) allow to constrain the
basement structure under the Madrid and Loranca
Tertiary basins and show that basement is not in-
volved in the compressive deformation of the Al-
tomira Range. This finding is in contrast to what
occurs in the Iberian Range. Nevertheless, basement
faults produced a stepped basement geometry that
seems to control the location and lateral extension
of the thrusts in the cover, which are developed
upon the detachment level (Fig. 2). Geophysical data
Fig. 6. Finite-element meshes and boundary conditions for both models: (A) Model Group I — cover paleostresses; (B) Model Group
II — basement paleostresses. MBB DMadrid Basin Block; VB DValdeolivas Block; CB DCuenca Block. Arrows show the surface
force loads applied on the model boundaries in order to generate both regional stress fields: Iberian and Betic compressions. Mechanical
parameters used for the modelling are listed in Table 1.
reveal the presence of a large normal fault in the
basement located under the Altomira Range thrusts
(Sacedo´n Fault, Figs. 1 and 2). Both this fault and
the westward disappearance of plastic Keuper facies
along a N–S edge in the proximity of the Altomira
Range, must have played an important role in the
nucleation of the deformation (Van Wees et al.,
1995). Combination of both factors has probably
determined the straight trace of the northern half of
the Altomira Range.
Geophysical data enable us to define a series
of blocks in the basement under the Mesozoic–
Tertiary cover, with different lithological and struc-
tural characteristics (Querol, 1989; Perucha et al.,
1995; Mun˜oz-Martı´n, 1997). In this way, three main
blocks have been defined in the study area: the
Madrid Basin Block, the Valdeolivas Block and the
Cuenca Block (Figs. 1 and 6). The Madrid Basin
Block consists of granitic and gneissic rocks with
a low fracture density. The Valdeolivas Block is
formed by Paleozoic metamorphic rocks that are
characterised by a higher fracture density. Finally,
the Cuenca Block has a heterogeneous composi-

56 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
tion, and is characterised by a dense fracture net-
work with large vertical offsets. Boundaries between
these blocks are formed by two important fracture
zones in the basement: the Sacedo´n Fault between
the Madrid Basin and Valdeolivas Block, and the
Taranco´n Fault Zone between these two and the
Cuenca Block (Figs. 1 and 6).
3. Finite-element models of paleostress fields
To model the observed paleostress fields and test
the possibility of mechanical decoupling between
cover and basement, the following approach has
been applied.
(1) Model Group I: modelling of the stress trajec-
tories for the Mesozoic cover in which the fault-slip
data have been obtained. A 2D elastic plate with
constant mechanical properties has been assumed for
which we modified (a) the external geometry accord-
ing to different geological boundaries, and (b) the
boundary conditions of the model limits till for all of
the three stress fields mentioned above; the modelled
stress trajectories fit the observations.
(2) Model Group II: modelling of the stress tra-
jectories for the basement. Once we have found
boundary conditions for which the modelled stress
trajectories for the cover are similar to the observed
ones, we applied the same boundary conditions to
a plate with the same external geometry but sub-
divided into three areas with different mechanical
characteristics. The objectives of this model group
are, firstly, to test the effect of assigning differ-
ent mechanical properties to the different basement
blocks on the stress trajectories and, secondly, to in-
vestigate whether this will give rise to indications for
mechanical decoupling between the Mesozoic cover
(mechanically homogeneous) and the basement (less
homogeneous). Differences in the modelled stress-
trajectories between basement and cover might point
to such a decoupling, favored by a detachment level.
These sorts of decouplings have been described in
other thin-skinned fold-and-thrust belts as the Jura
Mountains (Becker, 1989). Unfortunately, there are
no paleostress data from the basement in the study
area, and therefore, the results of the second model
group cannot be proved, unlike the results obtained
for the cover.
3.1. Model geometries
The geometry and boundaries of both model
groups are shown on Figs. 1 and 6. Mesh 1 cor-
responds to the area where paleostress data have
been obtained and is also the area where the mod-
elling results willbe shown. Due to the long distance
between the study area and some of the most im-
portant geological boundaries of the centre of the
peninsula, it has been necessary to build a second
mesh (Mesh 2) surrounding the first one, to make
the mesh limits coincide with the main geological
structures. The model has been built in plane (2D
plane stress elements), assuming an elastic mechan-
ical behavior and considering the stress sources as
pressures (Surface Force Loads). Calculations have
been carried out with the ANSYS (Swanson Anal-
ysis Systems, Inc.) finite-element package and the
used mechanical parameters are shown in Table 1.
The modelling results of the stress trajectories are
shown for Mesh 1. The stress magnitudes are not
shown because the stress inversion methods provide
only relative main axes magnitudes and orientation,
but not their absolute values.
In order to establish the model geometry and its
boundary conditions, kinematics and geometry of the
main geological structures of the centre of the penin-
sula have been taken into account (Figs. 1, 2 and
6). Although different starting geometries have been
tried, the model that fits the paleostress data in the
cover best, corresponds to the model which it bound-
ary coincides with the main geological structures of
Table 1
Mechanical properties of the elements assigned to each mesh
area on the finite-element models
Area Poisson Young modulus,
coefficient, ×E(GPa)
Model I — homogeneous plate (cover)
Mesh 1 0.25 8.00
Mesh 2 0.25 8.00
Model II — basement plates
Madrid Basin Block 0.25 8.00
Valdeolivas Block 0.25 5.00
Cuenca Block 0.25 4.00
Mesh 2a 0.25 8.00
Mesh 2b 0.25 4.00

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 57
the centre of the Iberian Peninsula (Figs. 1 and 6).
Once the model geometry and the mesh elements are
defined, different boundary conditions were applied
on the limits. This process has been repeated until the
model results fit the observed ‘Iberian’ and ‘Guadar-
rama’ paleostress fields. These two stress fields have
been used to constrain the definitive model geometry
and boundary conditions, due to the fact that both
present a regional character. Therefore, their origin
is less arguable than the ‘Altomira’ stress field. The
paleostress sources have been applied at the Iberian
Range SW border fault (‘Iberian’ push) and at the
SE boundary of Mesh 2 (‘Guadarrama’ push; Figs. 1
and 6). The latter has been applied from outside
of Mesh 1, because its origin is far away from the
study area, at the Betic Ranges. Once both regional
stress fields were modelled successfully, we tried to
model the ‘Altomira’ intermediate stress field, taking
into account two possible origins: a push from the
north-northeast (‘Pyrenean push’ as it is suggested
by Guimera´andA
´lvaro, 1990), and a superposi-
tion of both regional pushes (Mun˜oz-Martı´n et al.,
1994). For the latter case both regional field stress
sources were applied and their relative magnitudes
were modified till the modelled trajectories fit the
observations.
In order to model the basement paleostress trajec-
tories (Model Group II), Mesh 1 was subdivided in
three different areas keeping the mean element size
(Fig. 6B). Mechanical behavior of the three areas
corresponding with the above-described basement
blocks, has been considered elastic and homoge-
neous, values of the Poisson coefficient .¹ / and the
Young modulus .E/have been assigned according
to their geological characteristics (Table 1). Since a
model always is a simplification of reality, the more
general objective of this simple model is checking if
the contrast among materials with different mechan-
ical properties is able to produce significant changes
on the stress trajectories, with respect to a mechani-
cally homogeneous material with the same boundary
conditions.
4. Paleostress field model results
The SHmax trajectory maps obtained by modelling
of the homogeneous elastic plate (Model I, Fig. 7)
are very similar to the ones obtained from fault-slip
data (Figs. 3–5). Model results show very regular
SHmax trajectories, although some minor perturba-
tions and rotations with respect to the observations
can be observed. The two factors that have been rele-
vant in order to fit the model results to the geological
data have been the model boundary geometry, the
variation of the surface force load magnitudes and
the position of the applied loads. On the contrary,
values of mechanicalparameters, as well as absolute
values of applied stresses have influenced the mag-
nitudes of the stress components obtained during the
modelling, but not their orientation. The most impor-
tant results obtained during the achievement of both
model groups are described next.
4.1. Results of Model Group I (paleostress in the
cover)
4.1.1. Modelled ‘Iberian’ stress field (Fig. 7A)
A surface force load has been applied directly on
the Iberian Range SW border fault. In order to fit
the model to the data, a reduction to the north of the
compression magnitude along the eastern boundary
has been necessary (from 10 MPa at the southern
side of the boundary decreasing to 5 MPa at the
northern limit). In the case of a constant 10 MPa
surface load along the eastern boundary, significant
extensional stresses perpendicular to the Spanish
Central System Southern Border Fault appear in the
northern part of the model whereas these have not
been found in the geological record. This decrease of
the compression can be justified by the cushioning of
the Iberian Range compressive structures and by the
absence of paleostress data compatible with this field
to the north of the Taranco´n Fault Zone. The mod-
elled SHmax trajectories present a slight clockwise
rotation towards the W boundary of the study area in
agreement with the observed paleostress directions.
This rotation seems to be related by the presence
of N–S-trending faults at the centre of the Madrid
Basin (Fig. 1; De Vicente et al., 1996a).
4.1.2. Modelled ‘Guadarrama’ stress field (Fig. 7C)
When applying a constant surface load force of
10 MPa directly to the southern border of Mesh 1
the results show inhomogeneous stress trajectories
and extensional stresses associated with the Toledo

58 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
Fig. 7. SHmax trajectory results for Mesh 1 in Model Group I (cover). The ‘Iberian’ compression has been applied directly on the eastern
boundary of the model. ‘Guadarrama’ compression has been applied from the southern limit of Mesh 2. Superposition of ‘Guadarrama’
and ‘Iberian’ compressions result in the ‘Altomira’ stress field. See text for explanation and compare with SHmax trajectories maps
obtained from fault-slip data (Figs. 3–5).
Mountains’ eastern border (Fig. 1). Since both have
not been observed, the surface load force has been
shifted to the edge of Mesh 2, 50 km southward, to
fit the model resultsto the data. This stress source lo-
cated at the southeast of the study area is compatible
with a Betic origin. Allowing motion parallel to the
Iberian Range SW border fault is justified because
this area behaves basically as a dextral strike-slip
zone during the Neogene (De Vicente et al., 1996b;
Bond, 1996). The presence of an anticlockwise rota-
tion of the modelled SHmax trajectories with regard to
the microstructural data at the southwest of the study
area could have been balanced by a N–S compres-
sion deduced at the Toledo Mountains (Martı´n and
De Vicente, 1995). This fact has not been checked
on the models due to the absence of paleostress data
between the Toledo Mountains and the study area.
4.1.3. Modelled ‘Altomira’ stress field (Fig. 7B)
In order to test both hypotheses on the origin of
the Altomira Range described in the introduction,
two different approaches have been undertaken with
the aim to predict SHmax trajectories similar to the
observed ‘Altomira’ paleostress field.
(a) Locating the surface load forces at the Iberian
Range SW border fault, we tried to arrive at the
observed E–W paleostress field. We were not able to
model the observed stress field, even if we changed
the geometry and the boundary conditions of the
model in a way that improved the fit slightly but is
not very realistic from a geological point of view.
(b) Superposing of the two regional compressions
that yielded the best results for the ‘Iberian’ and
‘Guadarrama’ regional fields, keeping their relative
magnitudes intact. The result of this first approach
showed a good fit for the southern half of the model,
but it did not coincide with the geological data in
the northern part of the study area. To obtain a
better fit between model results and observations,
we changed the magnitudes of the applied surface
load forces. The best fit was obtained by reducing
the ‘Iberian’ compression at the northern part of
the model (with a magnitude gradient along the
Iberian Range from 10 MPa at the south to 1 MPa
at the northern Mesh 2 boundary) and a constant
Betic compression of the same magnitude as used
to model the ‘Guadarrama’ paleostress field. These
conditions imply that the Betic push was constant
and came from the southeast, while the intensity
of the ‘Iberian’ stress field was starting to diminish
during the formation of the Altomira Range (Late
Oligocene–Early Miocene).

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 59
The ‘Altomira’ stress field modelling results in-
dicate an elongated band, increasing to the south
in width and adjacent to the eastern boundary of
Mesh 1, where the main horizontal stress magnitudes
are very similar (SHmax DSHmin;Fig.7B).This
area could correspond to the eastern boundary of
the ‘Altomira’ stress field spatial distribution. The
SHmax orientation seems to have rotated anticlock-
wise from this boundary to the northeast, getting a
NE–SW orientation (compatible with the ‘Iberian–
Pyrenean’ compression). This is suggested by mi-
crostructural studies at the northeast of the study
area (Garcı´a-Cuevas et al., 1996). Both the observed
and the modelled paleostress field present very con-
stant N100E-trending SHmax trajectories, except for
the area south of the Taranco´n Fault Zone, where
the SHmax trajectories have a few degrees clockwise
rotation. This fact suggests that from the study area
boundary to the south, the ‘Altomira’ stress field has
changed to a NW–SE compression related to the
Betic chain. Microstructural studies located to the
south of the study area (Vegas and Rinco´n, 1996),
have not detected the presence of an E–W compres-
sion, while NW–SE and NE–SW compressions do
appear along the Tertiary. It is, however, very likely
that for different times the superposition of these two
Fig. 8. SHmax trajectory results for Mesh 1 in Model Group II (basement). Boundary conditions are the same as the ones used for Model
Group I (Fig. 7. See text for explanation and compare with SHmax trajectory maps obtained from fault-slip data (Figs. 3–5). SF D
Sacedo´n Fault; TFZ DTaranco´n Fault Zone.
major stress fields has led to similar local stress fields
in other areas of the centre of the Iberian Peninsula.
4.2. Results of Model Group II (paleostress in the
basement)
4.2.1. Modelled ‘Iberian’ stress field (Fig. 8A)
The most important effect caused by mechanical
inhomogeneities in the basement is a clockwise ro-
tation in the north of the study area, which does not
appear in the results for an elastic homogeneous plate
(Fig. 8). This rotation is produced by the presence
of the Sacedo´n Fault, that is the boundary between
a homogeneous and strong basement (Madrid Basin
Block) and a weaker one under the Loranca Basin
(Valdeolivas Block). On the southern part of Mesh
1, there are some minor clockwise SHmax trajectory
rotations along the Taranco´n Fault Zone.
4.2.2. Modelled ‘Guadarrama’ stress field (Fig. 8C)
These results present the smallest deviation with
regard to the observed paleostress field, in other
words, to the results for the cover. This is due to
the fact that the Taranco´n Fault Zone is oriented per-
pendicular to the general SHmax trend. The Sacedo´n
Fault is oriented oblique to the general SHmax trajec-

60 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
tories, but is too far away from the stress origin and
too close to the model’s northern limit to originate
significant rotations of the stress trajectories.
4.2.3. Modelled ‘Altomira’ stress field (Fig. 8B)
This is the model that presents the largest de-
viation from the elastic homogeneous plate model
adapted for the cover. N100ºE-trending SHmax trajec-
tories, located from Sacedo´n Fault Zone to the west,
rotate anticlockwise to a NE–SW orientation in the
north part of Mesh 1. On the other hand, the bound-
ary between the Cuenca Block and the Valdeolivas
and Madrid Basin blocks defined on Mesh 1, pro-
duced a clockwise rotation along the Taranco´n Fault
Zone. These combined effects generate a less regular
modelled SHmax trajectory map than the one gener-
ated for an elastic and homogeneous plate. In any
case, a N100ºE-trending SHmax trajectory zone ap-
pears in the main part of the area where the Altomira
Range is developed in the cover.
5. Discussion and conclusions
The construction of simple finite-element models
to study the orientation of stress fields as an effect
of changing boundary conditions, has allowed us to
reproduce the observed Tertiary compressive pale-
ostress fields, deduced from fault-slip data from the
cover of the eastern Tajo Basin. The results of the
finite-element stress models confirm the idea that the
geometry of the structures and of the model bound-
aries play a definitive role on the intraplate stress
orientation, as it is suggested in several previous
papers (Cloetingh and Wortel, 1986; Bada et al.,
1998). In this way, the modelled SHmax orientation
of all three paleostress fields is strongly influenced
by the most important crustal faults in the central
peninsula (i.e. Central Spanish System southern bor-
der and Iberian Range SW border faults). Moreover,
the relative magnitudes of the boundary compressive
loads significantly affect the modelling results (i.e. to
simulate the compressions transmitted to the interior
of the plate by the Pyrenean and Betic collisions).
From a geodynamic point of view, the fact that is
has been necessary to diminish the relative intensity
of ‘Iberian’ compression with regard to ‘Guadar-
rama’ compression in order to generate the ‘Al-
tomira’ paleostress field, implies a tectonic chronol-
ogy in which the Altomira Range was active after the
Iberian Range. This confirms previous similar results
based on microstructural analysis (Mun˜oz-Martı´n
and De Vicente, 1996) and on the architecture of
the basin infill (Calvo et al., 1989; Dı´az-Molina and
Tortosa, 1996). It has not been possible to obtain
E–W-oriented stress trajectories through the appli-
cation of stresses solely from the Iberian Range,
not even by less realistic geometries and boundary
conditions. These results contradict the hypothesis
about the origin of the Altomira Range postulated by
Guimera´andA
´lvaro (1990), for which the Altomira
Range would be an oblique ramp of the transpressive
structures of the Iberian Range, which constitutes
the foreland of the Pyrenean orogen. The modelling
results presented in this paper support the hypothesis
that the ‘Altomira’ paleostress field is a local stress
field, generated by spatial and temporal superposi-
tion of both major paleostress fields originated at
the Pyrenees and Betics (Mun˜oz-Martı´n et al., 1994).
These regional stress fields were transmitted from the
northern and southern borders towards the interior of
the Iberian microplate, generating a fold-and-thrust
belt oblique to both regional compressions during
the Oligocene–Early Miocene. This extrusion of the
cover to the west formed the Altomira Range and
has been controlled by inherited Hercynian struc-
tures in the basement, as well as by the presence
of a significant stratigraphic detachment level (Up-
per Triassic Keuper facies). Parallelism between the
Sacedo´n Fault, that controlled Triassic sedimenta-
tion, and the approximate location of the western
border of the Upper Triassic plastic facies, suggests
that these are related to each other and have played
an important role in the nucleation of compressive
structures at the Altomira Range (Van Wees et al.,
1995; Mun˜oz-Martı´n, 1997).
Regarding the results of the basement stress mod-
els, some significant stress reorientations with re-
spect to the sedimentary cover modelling results
have been obtained. These are explained in terms of
variations of the elastic parameters assigned to the
basement blocks. The stress reorientations are most
important for the ‘Altomira’ paleostress field model,
because of the location and orientation of the bound-
aries between the blocks with respect to the general
SHmax trend. In general, the effect of mechanical

A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62 61
boundaries is most significant if they make a small
angle with respect to the general stress field. In any
case, an area with N100ºE-trending SHmax appears
on the larger part of the study area. Model Group II
results suggest that a decoupling between sedimen-
tary cover and basement could have occurred, if the
geological boundary conditions were similar to the
ones used in the model. This decoupling would de-
velop on the detachment level formed by the Triassic
Keuper facies. Nevertheless, this decoupling seems
to be less important than the one detectedat the Jura
Mountains (Becker, 1989). This fact may be related
to the higher stress magnitudes and=or lower spatial
constraints imposed by geological structures at the
Jura Mountains.
Acknowledgements
The authors would like to thank to Dr. Reches and
Dr. Lee for providing us with the stress inversion and
the Lissage programs, as well as to M. Go¨lke, M.E.
Janssen and G. Bada for the comments and help
during the realisation of the finite-element models
at the Vrije Universiteit (Amsterdam). The authors
appreciate the referees’ critical reading and improve-
ment of the manuscript. This paper is a part of the
PhD. Thesis of the first author and has been funded
by the DGICYT (Spain) project number PB94-0242
and by GOA (Netherlands). Contribution 970175
of the Netherlands Research School of Sedimentary
Geology.
References
A
´lvaro, M., Capote, R., Vegas, R., 1979. Un modelo de evolucio´n
geotecto´nica para la Cadena Celtibe´rica . Acta Geol. Hisp.
Libro Hom. Prof. Sole´ Sabaris 14, 174–177.
Bada, G., Cloetingh, S., Gerner, P., Horva´th, F., 1998. Sources
of recent tectonic stress in the Pannonian region derived from
finite element modelling. Geophys. J. Int. 134 (1), 87–101.
Becker, A., 1989. Detached neotectonic stress field in the north-
ern Jura Mountain, Switzerland. Geol. Rundsch. 78 (2), 459–
475.
Bond, J., 1996. Tectono-sedimentary evolution of the Almaza´n
Basin, NE Spain. In: Friend, P., Dabrio, C. (Eds.), Tertiary
Basins of Spain. Cambridge Univ. Press, Cambridge, pp. 203–
213.
Calvo, J.P., Alonso, A.M., Garcı´a del Cura, M.A., Sanz, E.,
Hoyos, M., Ordon˜ez, S., Pozo, M., 1989. Sistemas lacustres
miocenos de la Cuenca de Madrid. Guı´a de Campo. V Reunio´n
Grupo Espan˜ol del Terciario, 16 CP-219, 79 pp.
Calvo, J.P., Daams, R., Morales, J., Lo´pez Martı´nez, N., Agustı´,
J., Anado´n, P., Armenteros, I., Cabrera, L., Civis, J., Cor-
rochano, A., Dı´az Molina, M., Elizaga, E., Hoios, M., Martı´n,
E., Martı´nez, J., Moissenet, E., Mun˜oz, A., Perez Garcı´a, A.,
Pe´rez Gonza´lez, A., Portero, J.M., Robles, F., Santisteban,
C., Torres, T., Van der Meulen, A.J., Vera, J.A., Mein, P.,
1993. Up-to-date Spanish continental Neogene synthesis and
paleoclimatic interpretation. Rev. Soc. Geol. Esp. 6, 29–40.
Capote, R., 1983. La tecto´nica de la Cordillera Ibe´rica. Libro
Jubilar J.M. Rı´os II, 109–120.
Capote, R., De Vicente, G.,Gonza´lez-Casado, J.M., 1990. Evolu-
cio´n de las deformaciones alpinas en el Sistema Central Es-
pan˜ol. Geogaceta 7, 20–22.
Cloetingh, S., Wortel, M.J.R., 1986. Stress in the Indo-Australian
plate. Tectonophysics 132, 49–67.
De Vicente, G., 1988. Ana´lisis Poblacional de Fallas. El sector
de enlace Sistema Central–Cordillera Ibe´rica. Tesis Doctoral,
Universidad Complutense de Madrid, 317 pp.
De Vicente, G., Gonza´lez-Casado, J.M., Mun˜oz-Martı´n, A.,
Giner, J., Rodrı´guez, M.A., 1996a. Structure and Tertiary evo-
lution of the Madrid Basin. In: Friend, P., Dabrio, C. (Eds.),
Tertiary Basins of Spain. Cambridge Univ. Press, Cambridge,
pp. 255–259.
De Vicente, G., Giner, J.L., Mun˜oz Martı´n, A., Gonza´lez Casado,
J.M., Lindo, R., 1996b. Determination of the present day stress
tensors and the neotectonic interval in the Spanish Central
System and the Madrid Basin, Central Spain. Tectonophysics
266 (1234), 405–442.
Dewey, J.F., Helman, M.L., Turco, E., Hutton, D.H.W., Knott,
S.D., 1989. Kinematics of the western Mediterranean. In:
Coward, M.P., Dietrich, D., Park, R.G. (Eds.), Alpine Tecton-
ics. Geol. Soc. London Spec. Publ. 45, 265–283.
Dı´az-Molina, M., Bustillo, M.A., Arribas, J., 1989. The To´rtola
and Villalba de la Sierra fluvial fans: Late Oligocene–Early
Miocene, Loranca Basin, Central Spain. 4th Int. Conf. Fluvial
Sedimentology, Fieldtrip Excursion Guidebook, 74 pp.
Dı´az-Molina, M., Tortosa, A., 1996. Fluvial fans of the Lo-
ranca Basin, Late Oligocene–Early Miocene, central Spain.
In: Friend, P., Dabrio, C. (Eds.), Tertiary Basins of Spain.
Cambridge Univ. Press, Cambridge, pp. 292–299.
Garcı´a-Cuevas, C., Gonza´lez-Casado, J.M., De Vicente, G.,
1996. Determinacio´n de los tensores de deformacio´nyes-
fuerzo mediante el estudio comparado de poblaciones de fallas
y del maclado meca´nico de la calcita. Geogaceta 20 (4), 770–
773.
Galindo, J., Gonza´lez, F., Jabaloy, A., 1993. Stress and
palaeostress in the Betic–Rif cordilleras (Miocene to the
present). Tectonophysics 227, 105–126.
Go¨lke, M., Cloetingh, S., Fuchs, K., 1994. Finite-element mod-
elling of pull-apart basin formation. Tectonophysics 240, 45–
57.
Go¨lke, M., Coblentz, D., 1996. Origins of the European regional
stress field. Tectonophysics 266, 11–24.
Gru¨nthal, G., Stromeyer, D., 1992. The recent stress field in

62 A. Mun˜oz-Martı´n et al. /Tectonophysics 300 (1998) 47–62
Central Europe: trajectories and finite element modelling. J.
Geophys. Res. 97 (B8), 11805–11820.
Guimera´, J., 1988. Estudi estructural de l’enllac¸ entre la serral-
ada iberica i la serralada costanera catalana. Tesis Doctoral,
Universitat de Barcelona, 600 pp.
Guimera´, J., A
´lvaro, M., 1990. Structure et evolution de la
compression alpine dans la Chaine Iberique et la Chaine
Cotiere-Catalane (Espagne). Bull. Soc. Ge´ol. Fr. 2, 339–348.
Janssen, M., 1996. Intraplate deformation in Africa as a conse-
quence of plate boundary changes. Thesis, Vrije Universiteit
Amsterdam, 161 pp.
Lee, J.-C., Angelier, J., 1994. Paleostress trajectory maps based
on the results of local determinations: the ‘Lissage’ program.
Comput. Geosci. 20 (2), 161–191.
Martı´n, S., De Vicente, G., 1995. Paleoesfuerzos alpinos en
el borde suroccidental de la Cuenca de Madrid (Montes de
Toledo). Geogaceta 18, 11–14.
Medina, F., 1995. Present-day stress in northern Morocco from
focal mechanism analysis. J. Struct. Geol. 17 (7), 1035–1046.
Meijer, P., 1995. Dynamics of active continental margins: the
Andes and the Aegean region. PhD Thesis, University of
Utrecht, 218 pp.
Mu¨ller, B., Zoback, M.L., Fuchs, K., Mastin, L., Gregersen, S.,
Pavoni, N., Stephansson, O., Ljunggren, C., 1992. Regional
patterns of tectonic stress in Europe. J. Geophys. Res. 97,
11783–11803.
Mun˜oz-Martı´n, A., De Vicente, G., Gonza´lez-Casado, J.M.,
1994. Ana´lisis tensorial de la deformacio´n superpuesta en
el lı´mite oriental de la Cuenca de Madrid. Cuad. Lab. Ge´ol.
Laxe 19, 203–214.
Mun˜oz-Martı´n, A., De Vicente, G., 1996. Campos de paleoes-
fuerzos terciarios en el borde oriental de la cuenca del Tajo
(Espan˜a Central). Geogaceta 20 (4), 913–916.
Mun˜oz-Martı´n, A., De Vicente, G., 1998. Cuantificacio´n del
acortamiento alpino y estructura en profundidad del extremo
sur-occidental de la Cordillera Ibe´rica (Sierras de Altomira y
Bascun˜ana). Rev. Soc. Geol. Esp. 11 (3/4), 39–58.
Mun˜oz-Martı´n, A., 1997. Evolucio´n geodina´mica del borde ori-
ental de la cuenca del Tajo desde el Oligoceno hasta la actu-
alidad. Tesis Doctoral, Universidad Complutense de Madrid,
500 pp.
Perucha, M.A., Mun˜oz Martı´n,A.,Tejero,R.,Bergamı´n, J.F.,
1995. Estudio de una transversal entre la Cuenca de Madrid y
la Cordillera Ibe´rica a partir de datos estructurales, sı´smicos y
gravime´tricos. Geogaceta 18, 15–18.
Querol, R., 1989. Geologı´a del subsuelo de la Cuenca del Tajo.
E.T.S.I. Minas de Madrid (Dpto. de Ing. Geol.), 465 pp.
Reches, Z., Baer, G., Hatzor, Y., 1992. Constraints on the
strength of the upper crust from stress inversion of fault
slip data. J. Geophys. Res. 97 (B9), 12481–12493.
Richardson, R.M., Solomon, S.C., Sleep, N.H., 1979. Tectonic
stress in the plates. Rev. Geophys. 17, 981–1019.
Rodrı´guez-Aranda, J.P., 1995. Sedimentologı´a de los sistemas de
llanura lutı´tica-lago salino del Mioceno en la zona oriental de
la Cuenca de Madrid (Taranco´n-Aun˜o´n). Tesis Doctoral, Univ.
Complutense Madrid, 474 pp.
Rodrı´guez-Aranda, J.P., Mun˜oz-Martı´n,A.,Giner,J.L.,Can˜av-
eras, J.C., 1995. Estructuras tecto´nicas en el basamento de la
cuenca de Madrid y su reflejo en la cobertera sedimentaria
neo´gena. Geogaceta 18, 19–22.
Salas, R., Casas, A., 1993. Mesozoic extensional tectonics,
stratigraphy and crustal evolution during the Alpine cycle
of the eastern Iberian Basin. Tectonophysics 228, 33–56.
Sanz de Galdeano, C.M., 1996. Tertiary framework of the Iberian
Peninsula. In: Friend, P., Dabrio, C. (Eds.), Tertiary Basins of
Spain. Cambridge Univ. Press, Cambridge, pp. 9–13.
Sassi, W., Colletta, B., Bale´, P., Paquereau, T., 1993. Modelling
of structural complexity in sedimentary basins: the role of
pre-existing faults in thrust tectonics. Tectonophysics 226, 97–
112.
Simo´n-Go´mez, J.L., 1984. Compresio´n y distensio´n alpinas en
la Cadena Ibe´rica Oriental. Tesis Doctoral, Univ. de Zaragoza.
Publ. Instituto de Estudios Turolenses, Teruel, 269 pp.
Simo´n-Go´mez, J.L., 1986. Analysis of a gradual change in
stress regime (example of the eastern Iberian Chain, Spain).
Tectonophysics 124, 37–53.
Srivastava, S.P., Roest, W.R., Kovacs, L.C., Oakey, J., Le´vesque,
S., Verhoef, J., Macnab, R., 1990. Motion of Iberia since
the Late Jurassic: results from detailed aeromagnetic measure-
ments in the Newfoundland Basin. Tectonophysics 184, 229–
260.
Van Wees, J.D., Cloetingh, S., De Vicente, G., 1995. The role of
pre-existing weak-zones in basin evolution: constraints from
2D finite element and 3D flexure models. In: Buchanan, P.G.,
Nieuwland, D.A. (Eds.), Modern Developments in Structural
Interpretation, Validation and Modelling. Geol. Soc. London
Spec. Publ. 99, 297–320.
Vegas, R., Rinco´n, P., 1996. Campos de esfuerzos, deformacio´n
alpina y volcanismo neo´geno asociado en el antepaı´s be´tico de
la provincia de Ciudad Real (Espan˜a central). Geogaceta 19,
31–35.
Viallard, P., 1983. Le de´collement de la couverture dans la
Chaıˆne ibe´rique me´ridionale: effect de raccourcissements dif-
fe´rentiels entre substratum et couverture. Bull. Soc. Ge´ol. Fr.
(7) Paris 25 (3), 379–383.
Wortel, M.J.R., Cloetingh, S., 1985. Accretion and lateral vari-
ations in tectonic structure along the Peru–Chile trench.
Tectonophysics 112, 443–462.