Content uploaded by Víctor Tendero-Salmerón
Author content
All content in this area was uploaded by Víctor Tendero-Salmerón on May 27, 2023
Content may be subject to copyright.
Citation: Chalouan, A.; Gil, A.J.;
Chabli, A.; Bargach, K.; Liemlahi, H.;
El Kadiri, K.; Tendero-Salmerón, V.;
Galindo-Zaldívar, J. cGPS Record of
Active Extension in Moroccan Meseta
and Shortening in Atlasic Chains
under the Eurasia-Nubia
Convergence. Sensors 2023,23, 4846.
https://doi.org/10.3390/s23104846
Academic Editors: Stefano Savazzi,
Mattia Brambilla and Ludovico Biagi
Received: 8 March 2023
Revised: 2 May 2023
Accepted: 10 May 2023
Published: 17 May 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
sensors
Article
cGPS Record of Active Extension in Moroccan Meseta and
Shortening in Atlasic Chains under the
Eurasia-Nubia Convergence
Ahmed Chalouan 1, Antonio J. Gil 2, Ahmed Chabli 3, Kaoutar Bargach 4, Hoda Liemlahi 5, Khalil El Kadiri 6,
Víctor Tendero-Salmerón7and Jesús Galindo-Zaldívar 7,8 ,*
1Faculty of Sciences, Mohammed V University in Rabat, Rabat 10000, Morocco; chalouan@yahoo.com
2
Departamento de Ingeniería Cartográfica, Geodesia y Fotogrametría, Universidad de Jaén, 23071 Jaén, Spain;
ajgil@ujaen.es
3Centre Régional des Métiers de l’Éducation et de la Formation de Rabat, Rabat 10000, Morocco;
ahmedchabli308@gmail.com
4
Geo-Biodiversity and Natural Heritage Laboratory (GEOBIO), Scientific Institute, Mohammed V University in
Rabat, Rabat 10000, Morocco; kbargach50@gmail.com
5École Normale Supéreure, UniversitéAbdelmalek Essaadi, Martil 93150, Morocco; hodaliemlahi@yahoo.fr
6Facultédes Sciences, UniversitéAbdelmalek Essaadi, Tetouan 93000, Morocco; khalilelkadiri@gmail.com
7Departamento de Geodinámica, Universidad de Granada, 18071 Granada, Spain; vtendero@ugr.es
8Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, 18100 Armilla, Spain
*Correspondence: jgalindo@ugr.es; Tel.: +34-958243349
Abstract:
The northwest-southeast convergence of the Eurasian and Nubian (African) plates in the
western Mediterranean region propagates inside the Nubian plate and affects the Moroccan Meseta
and the neighboring Atlasic belt. Five continuous Global Positioning System (cGPS) stations were
installed in this area in 2009 and provide significant new data, despite a certain degree of errors
(between 0.5 and 1.2 mm year
−1
, 95% confidence) due to slow rates. The cGPS network reveals 1 mm
year
−1
North/South shortening accommodated within the High Atlas Mountains, and unexpected
2 mm year
−1
north-northwest/south-southeast extensional-to-transtensional tectonics within the
Meseta and the Middle Atlas, which have been quantified for the first time. Moreover, the Alpine Rif
Cordillera drifts towards the south-southeast against its Prerifian foreland basins and the Meseta.
In this context, the geological extension foreseen in the Moroccan Meseta and Middle Atlas agrees
with a crustal thinning due to the combined effect of the anomalous mantle beneath both the Meseta
and Middle-High Atlasic system, from which Quaternary basalts were sourced, and the roll-back
tectonics in the Rif Cordillera. Overall, the new cGPS data provide reliable support for understanding
the geodynamic mechanism that built the prominent Atlasic Cordillera, and reveal the heterogeneous
present-day behavior of the Eurasia-Nubia collisional boundary.
Keywords:
cGPS measurements; Nubian plate boundary; westernmost Mediterranean; slow active
extensional tectonics; anomalous mantle
1. Introduction
The analysis of tectonic displacements is essential for the reconstruction of the Earth’s
geodynamics, and is particularly relevant for understanding active tectonic processes
linked to internal geological hazards. Faulting, volcanism, and seismicity mainly occur
along tectonic plate boundaries, which are the most sensitive regions that have under-
gone catastrophic geological events. GPS (Global Positioning System) observations in
permanent monuments constitute the most accurate technique for revealing active tectonic
deformations in mountain ranges when compared to classical satellite and surface geodetic
observations [
1
]. Continuous GPS (cGPS) records increase the accuracy achieved by non-
permanent GPS networks and allow for obtaining GPS positions with velocity differences
Sensors 2023,23, 4846. https://doi.org/10.3390/s23104846 https://www.mdpi.com/journal/sensors
Sensors 2023,23, 4846 2 of 14
of submillimetric deformations between stations that are tens of kilometers apart. However,
the described technique is more expensive than others because it requires instrumentation
and permanent technical support, which greatly reduce the number of instruments that
can be installed. A preliminary geological survey is needed to carefully select the key
structural locations that enable cGPS stations to consistently reveal the relative motion of
the interacting tectonic domains. The selected location should also provide good conditions
for the safe preservation of equipment, surveillance to avoid vandalism, and an open
horizon for optimal satellite coverage observations.
The Rif and Atlas cordilleras are the most prominent mountain ranges at the
northwestern-most margin of the Nubian (African) plate (Figure 1). These cordilleras
are separated by the Moroccan Meseta, an uplifted region formed by Variscan basement
rocks [
2
] and hosting Cenozoic-to-Quaternary intramontane, satellite or foredeep basins
(Gharb, Saïss, Guercif, Missour, Moulouya, Tadla, Bahira, Ahouz, Souss and Ouarzazate).
Sensors 2023, 23, x FOR PEER REVIEW 2 of 14
permanent GPS networks and allow for obtaining GPS positions with velocity dierences
of submillimetric deformations between stations that are tens of kilometers apart. How-
ever, the described technique is more expensive than others because it requires instru-
mentation and permanent technical support, which greatly reduce the number of instru-
ments that can be installed. A preliminary geological survey is needed to carefully select
the key structural locations that enable cGPS stations to consistently reveal the relative
motion of the interacting tectonic domains. The selected location should also provide good
conditions for the safe preservation of equipment, surveillance to avoid vandalism, and
an open horizon for optimal satellite coverage observations.
The Rif and Atlas cordilleras are the most prominent mountain ranges at the north-
western-most margin of the Nubian (African) plate (Figure 1). These cordilleras are sepa-
rated by the Moroccan Meseta, an uplifted region formed by Variscan basement rocks [2]
and hosting Cenozoic-to-Quaternary intramontane, satellite or foredeep basins (Gharb,
Saïss, Guercif, Missour, Moulouya, Tadla, Bahira, Ahouz, Souss and Ouarzazate).
Figure 1. Geological location of the study area. (a) Simplied tectonic location of the study area. (b)
Structural map of northern Morocco (modied from [3]) which shows the main geological units and
domains. In this gure and the following ones, names in bold correspond to main topographic
and/or geologic features, while those not in bold correspond to smaller or secondary toponymies
and geologic features. Abbreviations of faults: JF: Jebha Fault; NAF: North Atlasic Fault; NF: Nekor
Fault; NJF: North Jebilet Fault; NMAF: North Mid-Atlasic Fault; SAF: South Atlasic Fault; SNMAF:
South Mid-Atlasic Fault. Abbreviations of towns: A: Agadir; C: Casablanca; E: Essaouira; F: Fes; M:
Marrakech; Me: Meknes; O. Oran; S: Sa; T: Tanger.
Plate tectonic reconstructions since the latest Miocene suggest an average conver-
gence rate of 5 mm year−1 northwest-southeast (NW-SE) to North-South (N-S) between the
Nubian and Eurasian plates in the westernmost Mediterranean [4,5]. Present-day Nubian-
Eurasian convergence is also well-constrained by GPS measurements, particularly in the
Figure 1.
Geological location of the study area. (
a
) Simplified tectonic location of the study area.
(
b
) Structural map of northern Morocco (modified from [
3
]) which shows the main geological units
and domains. In this figure and the following ones, names in bold correspond to main topographic
and/or geologic features, while those not in bold correspond to smaller or secondary toponymies
and geologic features. Abbreviations of faults: JF: Jebha Fault; NAF: North Atlasic Fault; NF: Nekor
Fault; NJF: North Jebilet Fault; NMAF: North Mid-Atlasic Fault; SAF: South Atlasic Fault; SNMAF:
South Mid-Atlasic Fault. Abbreviations of towns: A: Agadir; C: Casablanca; E: Essaouira; F: Fes; M:
Marrakech; Me: Meknes; O. Oran; S: Safi; T: Tanger.
Plate tectonic reconstructions since the latest Miocene suggest an average convergence
rate of 5 mm year
−1
northwest-southeast (NW-SE) to North-South (N-S) between the
Nubian and Eurasian plates in the westernmost Mediterranean [
4
,
5
]. Present-day Nubian-
Sensors 2023,23, 4846 3 of 14
Eurasian convergence is also well-constrained by GPS measurements, particularly in the
Rif and Betics [
6
–
10
]. Although these measurements reveal detailed regional displacement
of the Rif Cordillera with respect to Nubia, they do not provide enough resolution in the
Meseta and Atlas due to the low deformation rates and because the GPS sites were based
on non-permanent observations. To refine the geodetic data and properly understand the
present-day behavior of this region, three new permanent stations were built in Morocco as
part of the Topo-Iberia project (2009–2013, TAZA, BENI, ERRA) and have been integrated
with the available stations of RABT and CEU1 [11].
The aim of this contribution is to present the initial results of continuous GPS (cGPS)
data from the 5 key stations located in the weakly deformed northwestward border of
the Nubian plate. Indeed, these data reveal unexpected simultaneous extensional and
shortening deformations in this convergent plate boundary. Moreover, they provide new
insights into how the prominent Alpine Atlasic cordillera was built, the old Variscan
Mesetian basement was uplifted, and Quaternary basaltic volcanism concurrently came
into being.
2. Geological Setting
2.1. Tectonic Structure
The Rif cordillera, along with the Betic cordillera, forms the Alpine Gibraltar Arc
(Figure 1a), a NW-SE convergent interplate region that borders Eurasia and the Nubian
(African) plates in the westernmost Mediterranean. The plate boundary is well-defined
to the east, where it continues into the Tell and the Kabylies, and to the west, where it
extends into the Atlantic Ocean towards the Azores-Gibraltar fault zone. In contrast, in the
Gibraltar Arc, there is a wide deformation zone, irregularly distributed, that reaches more
than 300 km wide, and the location of the plate boundary is still under discussion [10].
The Gibraltar Arc has been emplaced towards the west between the main plates
since the Cenozoic period [
12
]. The Alboran Sea constitutes the westernmost part of the
Mediterranean Sea and is floored by continental crust. It represents the main Neogene basin
surrounded by the Betics and Rif cordilleras, which are the northern and southern branches
of the tectonic arc, respectively. The westward emplacement of the Rif has favored the
development of the large transcurrent sinistral Jebha (JF) and Nekor (NF) faults (Figure 1).
This westward emplacement of the tectonic arc has developed two curved Neogene-to-
Quaternary foreland basins in the Rif, the Gharb towards the west and the Saïss towards
the south. Their mountain fronts show evidence of recent activity affecting the Quaternary
sedimentary rocks, as seen in Fès (F, Figure 1) [
13
]. There, local non-permanent GPS
networks have quantified the active deformation rates [9].
The Moroccan Meseta has been considered as the foreland of the Alpine Rif Cordillera,
and is therefore relatively attached to the Nubian Plate. It is a piece of the Variscan Belt,
mainly formed by metamorphic and igneous rocks that were deformed during the late
Paleozoic and locally covered by undeformed Mesozoic-Cenozoic sedimentary cover [
14
].
It is named the Meseta because it has relatively uplifted topography with generally low
reliefs. It is formed mainly by the Western and Central Meseta and separated by the Middle
Atlas from the Eastern Meseta.
In contrast to the Rif, the Atlas system has been considered as a series of intraplate
ranges [
3
,
15
,
16
] although these ranges are characterized as the highest relief mountains at
the plate boundary. The Atlas system is formed by inverted elongated Mesozoic basins
filled by sedimentary series similar to those found around the Mediterranean Alpine
cordilleras. These deposits were located on the passive continental margins and areas
of continental crustal thinning around the former Tethys Ocean. The Atlas basins were
surrounded by Variscan low deformed blocks (Eastern and Western Moroccan Meseta)
and the Precambrian-to-Paleozoic Anti-Atlas. The pre-Mesozoic blocks were also cov-
ered by Mesozoic to Cenozoic undeformed deposits that now constitute the “plateaus”.
Since the Neogene, compressive deformation due to the Eurasian-African convergence
has affected these elongated, crustal thinned weak zones where the basins were located.
Sensors 2023,23, 4846 4 of 14
Finally, basin inversion has occurred and the elongated cordilleras have developed along
the former sedimentary basins. The Atlas is composed of two main branches, the High
Atlas of east-northeast/west-southwest (ENE-WSW) orientation and the Middle Atlas of
northeast/southwest (NE-SW) orientation.
The High Atlas (Figure 1b) is located along the transcurrent and reverse faults running
between the Variscan Maghrebian realm (Moroccan Meseta) and the northern margin of
the West African shield, which is represented by the Anti-Atlas, where Precambrian and
Paleozoic rocks outcrop. The High Atlas is divided into western, central, and eastern
sections. The western High Atlas reaches the maximum elevation and is made up of
outcropping deformed pre-Mesozoic rocks, including metamorphic and igneous rocks.
It is bounded by compressive tectonic structures that separate the mountains and the
surrounding basements, and favors the development of the Haouz Basin towards the north
and the Souss Basin towards the south in their foot blocks. In contrast, the Central and
Eastern High Atlas only expose the Mesozoic carbonate sedimentary series. To the south,
reverse faulting forms the boundary of the Ouarzazate Basin, while to the north, the Tadla,
Moulouya, and Missour basins are found.
The Middle Atlas is a NE-SW alpine chain that separates the Variscan-derived eastern
Meseta from the western one. This chain is itself divided by the 200 km long North Mid-
Atlas Fault (NMAF), oriented NE-SW, into the Tabular Middle Atlas (also known as the
“Causse,” to the west) and the folded Middle Atlas (to the east). The latter hosts thick
early-to-mid-Jurassic marl-limestone sequences that are folded into several NE-SW oriented
anticlines and synclines separated by decollement faults in the same direction. The folded
Middle Atlas connects the Central High Atlas and the eastern Rif (see Figure 1b). It was
formed by the Alpine reactivation of the Variscan thrust front that pushed the eastern
Meseta over the western one (see Figure 1). To the south and east, this deformation zone
marks the boundary of the Neogene Mouloya Basin, which is sandwiched between the
High and Middle Atlas, as well as the Missour and Guercif basins that separate the Middle
Atlas from the Eastern Moroccan Meseta.
The geodynamic evolution of the region implies the occurrence of several episodes of
volcanism, with one of the most notable being the eruption of Quaternary basaltic rocks
mainly located in the Middle Atlas [
17
]. These eruptions indicate that there is melting at
the base of the crust of this intraplate mountain belt. Volcanic rocks extend to the Central
Meseta and even the Saïss Basin (Figure 1b).
2.2. Seismological and Active Tectonic Setting
Deformations at plate boundaries are accommodated by active tectonic structures,
which include folds and faults. Active faults may move continuously by creep or sud-
denly, producing earthquakes that are determined by the rheological behavior of fractured
rocks [
18
]. Seismicity constitutes the main evidence of the location of the main active
tectonic structures. Moreover, the earthquake focal mechanism allows for the revelation of
faulting features and the stress regime of each region.
The distribution of seismicity in Morocco (Figure 2) is heterogeneous. Most of the
seismicity occurs in a main cluster in the eastern Rif Cordillera, where earthquake series
are mainly related to strike-slip faulting in the Al Hoceima area (Figure 2b). This is a very
active deformation area of the plate boundary where basement blind faults develop [
19
].
Moreover, seismicity is also very active towards the western and southern boundaries of the
Rif Cordillera. Quaternary-to-recent deformations are clearly recorded in the southern Rif
front [
9
]. While the geological structures of these regions support the presence of shallow
compressive structures with westward and southward vergences [
9
,
20
], the earthquake
focal mechanisms suggest the main activity of deep strike-slip, with dominant N-S to
NW-SE compression and orthogonal extension (see focal mechanisms between Tanger and
Meknes, Figure 2b).
Sensors 2023,23, 4846 5 of 14
Sensors 2023, 23, x FOR PEER REVIEW 5 of 14
Figure 2. Seismicity and main faults of the study area. (a) Seismicity from 1991 to 2022, obtained
from IGN (www.ign.es (accessed on 1 February 2023)). Abbreviations of faults: JF: Jebha Fault; NAF:
North Atlasic Fault; NF: Nekor Fault; NJF: North Jebilet Fault; NMAF: North Mid-Atlasic Fault; SAF:
South Atlasic Fault; SNMAF: South Mid-Atlasic Fault. Abbreviations of towns: A: Agadir; C: Casa-
blanca; E: Essaouira; F: Fes; M: Marrakech; Me: Meknes; O. Oran; S: Sa; T: Tanger. (b) Main focal
mechanisms for the same period, obtained from IGN (www.ign.es (accessed on 1 February 2023)),
which provide information about the types of fault that caused the seismicity and the stress that
aects the area.
Simultaneously, the southern margin of the Saïss basin, aached to the Middle Atlas
and to the northern margin of the western Meseta, shows geological brile structures that
support a recent extensional regime [9,13,21–25]. The Moroccan Meseta is aected by
moderate, heterogeneously distributed seismicity which is most intense towards the Cen-
tral Meseta (Figure 2a). The Folded Middle Atlas is bounded by the North and South Mid-
dle Atlasic faults, with maximum seismicity concentration close to the North Middle At-
lasic Fault (NMAF, Figure 2) [2]. The earthquake focal mechanisms close to this main fault
show variable features (Northeast of Beni Mellal, Figure 2b), including strike-slip and re-
verse faulting with N-S-to-north-northwest/south-southeast (NNW-SSE) compression,
but also local strike-slip with NW-SE-to-E-W extension. The NMAF has been interpreted
by eld geological observations as a reverse fault with sinistral strike-slip [22]. This area
is also aected by Quaternary basaltic volcanism. In contrast, the South Middle Atlasic
Fault (SMAF, Figure 2) has lower seismicity than the NMAF and is characterized by a
reverse earthquake focal mechanism, clearly evidencing NW-SE compression and the re-
verse character of the fault.
Figure 2.
Seismicity and main faults of the study area. (
a
) Seismicity from 1991 to 2022, obtained
from IGN (www.ign.es (accessed on 1 February 2023)). Abbreviations of faults: JF: Jebha Fault; NAF:
North Atlasic Fault; NF: Nekor Fault; NJF: North Jebilet Fault; NMAF: North Mid-Atlasic Fault;
SAF: South Atlasic Fault; SNMAF: South Mid-Atlasic Fault. Abbreviations of towns: A: Agadir;
C: Casablanca; E: Essaouira; F: Fes; M: Marrakech; Me: Meknes; O. Oran; S: Safi; T: Tanger. (
b
) Main
focal mechanisms for the same period, obtained from IGN (www.ign.es (accessed on 1 February
2023)), which provide information about the types of fault that caused the seismicity and the stress
that affects the area.
Simultaneously, the southern margin of the Saïss basin, attached to the Middle Atlas
and to the northern margin of the western Meseta, shows geological brittle structures
that support a recent extensional regime [
9
,
13
,
21
–
25
]. The Moroccan Meseta is affected
by moderate, heterogeneously distributed seismicity which is most intense towards the
Central Meseta (Figure 2a). The Folded Middle Atlas is bounded by the North and South
Middle Atlasic faults, with maximum seismicity concentration close to the North Middle
Atlasic Fault (NMAF, Figure 2) [
2
]. The earthquake focal mechanisms close to this main
fault show variable features (Northeast of Beni Mellal, Figure 2b), including strike-slip and
reverse faulting with N-S-to-north-northwest/south-southeast (NNW-SSE) compression,
but also local strike-slip with NW-SE-to-E-W extension. The NMAF has been interpreted
by field geological observations as a reverse fault with sinistral strike-slip [
22
]. This area is
also affected by Quaternary basaltic volcanism. In contrast, the South Middle Atlasic Fault
(SMAF, Figure 2) has lower seismicity than the NMAF and is characterized by a reverse
earthquake focal mechanism, clearly evidencing NW-SE compression and the reverse
character of the fault.
Sensors 2023,23, 4846 6 of 14
Active seismicity also occurs, but at a lower intensity, in the High Atlas, bounded
by the South and North High Atlasic faults. It becomes very scarce in the Anti-Atlas
(Figure 2a), which is presumed to be part of the stable Nubian plate. The earthquake
focal mechanisms of the South High Atlasic Fault (SAF) (South of Beni Mellal, Figure 2b)
support the hypothesis that this fault underwent reverse faulting related to the NNW-SSE
compression and probably strike slip deformation.
2.3. Geodynamic Models
The complex geodynamic setting of the westernmost Mediterranean has been the
subject of various tectonic models that attempt to explain the main features of an Alpine
tectonic arc at a large convergent plate boundary. In addition, the presence of the highest
relief far south of the Alpine ranges, where the plate boundary is expected, is another issue
that needs to be addressed by the proposed models.
Two distinct tectonic mechanisms behind the plate convergence have been proposed:
(i) in the Rif, an east-dipping lithospheric plate is subducted beneath the Gibraltar
Arc [26,27]
,
resulting in a roll-back setting [
28
], and (ii) in the Atlas Mountains, the lithosphere is
abnormally thinned and hot [
3
,
29
–
32
] due to an ascending asthenospheric dome [
33
,
34
],
resulting in the thermal uplift of the entire Atlas chain and the emplacement of Quaternary
alkaline volcanism [
35
]. In this context, the presence of anomalous mantle [
3
] explains
the moderate tectonic shortening of the Atlas Mountains despite their unusually high
topography, with the highest peak reaching 4167 m a.s.l., while the Rif only reaches 2456 m
a.s.l. [3,34] in spite of its comparatively strongest tectonic shortening.
3. cGPS Network, Equipment and Data Processing
This study presents the GPS velocity field derived from continuous observations
(cGPS) carried out under the Topo-Iberia framework [
11
]. Three Topo-Iberia sites (TAZA,
BENI, ERRA) and two EUREF sites (CEU1, RABT) in significant locations in northwestern
Nubia were selected to reveal active tectonics. They are listed below, from south to north
(Figures 1–3):
1.
Errachidia (ERRA) is located over the Anti-Atlas basement and represents a refer-
ence for the stable Nubian plate. It is located just close to the active South Atlasic
thrust front, where the central High Atlas overrides the Anti Atlas. This station is lo-
cated on the Mesozoic-Cenozoic plateaus developed on the Precambrian-to-Paleozoic
basement. No recent geological deformation occurs southward of this station.
2.
Béni Mellal (BENI) is located in the Tadla basin, a foredeep Atlasic structure floored
by the southernmost boundary of the western Meseta basement. The station is located
close to the active Northern Atlasic Fault thrust front and also close to the North
Middle Atlas Fault.
3.
Rabat (RABT) is located in the northernmost outcrops of the Western Moroccan
Meseta, in a region of scarce seismicity close to the southern margin of the Gharb
basin, an Alpine Rifian foreland basin.
4.
Taza (TAZA) is a key station located on the easternmost outcrops of the central Meseta,
close to the North Middle Atlas Fault and close to the junction with the collisional front
of the central southern Rif along the boundary with the Middle-Atlasic basement.
5.
Ceuta (CEU1) is located at the northernmost end of the Alpine Rif chain, i.e., in the
central part of the Nubia-Eurasia interplate area, and contributes to determining the
present-day displacements of the Gibraltar Arc.
The Topo-Iberia cGPS network installation was completed in December 2008, and
all the stations have been fully operational since then. The data analysis was performed
at three different analysis centers: Real Instituto y Observatorio de la Armada (ROA),
the University of Barcelona (UB), and the University of Jaen (UJA). Several approaches
to processing GPS data were carried out using different software [
11
]. In this paper, the
cGPS data covering the 2004–2012 timespan have been used for sites CEU1 and RABT, and
the data covering 2008–2012 for BENI, ERRA, and TAZA. After this period, the record of
Sensors 2023,23, 4846 7 of 14
Topo-Iberia stations became discontinuous due to the end of the project and the irregular
economic and technical support.
The cGPS data processing followed the standard method used by the University of
Jaen [
36
]. Initially, the CGPS data underwent a quality analysis. Subsequently, Bernesse
software [
37
], with options shown in [
11
], was employed to carry out the data process-
ing, which resulted in a daily GPS network solution in a loosely constrained reference
frame. Next, the daily network solutions were transformed into ITRF2005 by minimal con-
straints, estimating translations and scale parameters. Then, the estimation of the crustal
velocity field was computed from the ITRF2005 time series using the software NEVE,
which managed the complete stochastic model [
38
,
39
]. The GPS-derived site velocities
and uncertainties in the ITRF2005 reference frame are shown in Table 1. A more effective
representation of the velocity field estimated is thought to determine the residual velocities
with respect to the stable Eurasian plate and take into account the Euler pole of the Eurasian
plate [40] (Figure 3).
Table 1.
Absolute velocities in East and North components from cGPS position time series in ITRF2005
frame and 1
σ
uncertainties. Residual velocities with respect to Eurasia-fixed reference frame and
Errachidia site (Nubia).
Site ID Latitude
(Deg.)
Longitude
(Deg.)
Height
(m)
Velocity
(mm Year−1)
Uncertainty
(mm Year−1)
Res. Velocity
(mm Year−1)
Eurasia
Res. Velocity
(mm Year−1) Errachidia
(Nubia)
East
North
East North East North East North
BENI 32.3768 −6.3186 587.1 15.8 17.3 ±0.5 ±0.6 −4.6 1.2 0.1 −1.1
CEU1 35.8920 −5.3064 52.4 15.2 17.2 ±0.4 ±0.4 −4.5 1.1 0.2 −1.2
ERRA 31.9388 −4.4561
1104.1
16.1 18.4 ±0.6 ±0.7 −4.7 2.3 0.0 0.0
RABT 33.9981 −6.8543 90.1 15.8 19.1 ±0.5 ±0.6 −4.1 3.1 0.6 0.8
TAZA 34.2295 −3.9964 523.5 16.1 19.0 ±0.9 ±0.9 −4.2 2.9 0.5 0.6
Sensors 2023, 23, x FOR PEER REVIEW 7 of 14
data covering the 2004–2012 timespan have been used for sites CEU1 and RABT, and the
data covering 2008–2012 for BENI, ERRA, and TAZA. After this period, the record of
Topo-Iberia stations became discontinuous due to the end of the project and the irregular
economic and technical support.
The cGPS data processing followed the standard method used by the University of
Jaen [36]. Initially, the CGPS data underwent a quality analysis. Subsequently, Bernesse
software [37], with options shown in [11], was employed to carry out the data processing,
which resulted in a daily GPS network solution in a loosely constrained reference frame.
Next, the daily network solutions were transformed into ITRF2005 by minimal con-
straints, estimating translations and scale parameters. Then, the estimation of the crustal
velocity eld was computed from the ITRF2005 time series using the software NEVE,
which managed the complete stochastic model [38,39]. The GPS-derived site velocities and
uncertainties in the ITRF2005 reference frame are shown in Table 1. A more eective rep-
resentation of the velocity eld estimated is thought to determine the residual velocities
with respect to the stable Eurasian plate and take into account the Euler pole of the Eura-
sian plate [40] (Figure 3).
Figure 3. Close-up view of the study area geological map that includes the residual cGPS velocities
with respect to stable Eurasia with error ellipses of 95% condence. The corresponding values for
this gure and the following gures have been obtained through computerization using the Bernese
software [11] and taking into account the Euler pole of the Eurasian plate [40].
Table 1. Absolute velocities in East and North components from cGPS position time series in
ITRF2005 frame and 1σ uncertainties. Residual velocities with respect to Eurasia-xed reference
frame and Errachidia site (Nubia).
Site ID
Latitude
(deg.)
Longitude
(deg.)
Height
(m)
Velocity
(mm year−1)
Uncertainty
(mm year−1)
Res. Velocity
(mm year−1)
Eurasia
Res. Velocity
(mm year−1) Errachidia
(Nubia)
East
North
East
North
East
North
East
North
BENI
32.3768
−6.3186
587.1
15.8
17.3
±0.5
±0.6
−4.6
1.2
0.1
−1.1
CEU1
35.8920
−5.3064
52.4
15.2
17.2
±0.4
±0.4
−4.5
1.1
0.2
−1.2
ERRA
31.9388
−4.4561
1104.1
16.1
18.4
±0.6
±0.7
−4.7
2.3
0.0
0.0
RABT
33.9981
−6.8543
90.1
15.8
19.1
±0.5
±0.6
−4.1
3.1
0.6
0.8
TAZA
34.2295
−3.9964
523.5
16.1
19.0
±0.9
±0.9
−4.2
2.9
0.5
0.6
Figure 3.
Close-up view of the study area geological map that includes the residual cGPS velocities
with respect to stable Eurasia with error ellipses of 95% confidence. The corresponding values for
this figure and the following figures have been obtained through computerization using the Bernese
software [11] and taking into account the Euler pole of the Eurasian plate [40].
Sensors 2023,23, 4846 8 of 14
4. Velocity Rates from cGPS Stations
The absolute velocities obtained and the related errors are presented in Table 1, with
displacement towards the NE. However, their relative displacements are the significant val-
ues that allow us to determine the tectonic deformation rates of the structures in the region.
The residual velocities with respect to fixed Eurasia of each GPS station are presented
in Table 1and Figure 3. All the stations have a displacement towards the WNW with
respect to stable Eurasia (BENI, 4.8; CEU1, 4.6; ERRA, 5.2; RABT, 5.1; TAZA, 5.1 mm year
−1
)
with rates ranging between 4.6 mm year
−1
for CEU1 and 5.2 mm year
−1
for ERRA, and
they characterize the regional NW-SE plate convergence in the area.
Moreover, in order to establish the relative motion with respect to the most stable
Nubian plate, we have determined the relative motion of all these stations with respect
to the ERRA site (Figure 4). BENI has a southward displacement of 1.1 mm year
−1
,
orthogonal to the elongated Central High Atlas Mountains. RABT and TAZA, located in
the northern and northeastern Meseta, respectively, have roughly similar displacement
patterns towards the northeast of 1 mm year
−1
and 0.8 mm year
−1
. These data highlight a
significant northeast-southwest extension in the central Meseta of close to 2 mm year
−1
.
SSW displacement of CEU1 is 1.1 mm year
−1
, and this determines a shortening with respect
to RABT and TAZA, but this displacement is roughly similar in trend and magnitude to
that of the BENI site.
Sensors 2023, 23, x FOR PEER REVIEW 8 of 14
4. Velocity Rates from cGPS Stations
The absolute velocities obtained and the related errors are presented in Table 1, with
displacement towards the NE. However, their relative displacements are the signicant
values that allow us to determine the tectonic deformation rates of the structures in the
region.
The residual velocities with respect to xed Eurasia of each GPS station are presented
in Table 1 and Figure 3. All the stations have a displacement towards the WNW with re-
spect to stable Eurasia (BENI, 4.8; CEU1, 4.6; ERRA, 5.2; RABT, 5.1; TAZA, 5.1 mm year−1)
with rates ranging between 4.6 mm year−1 for CEU1 and 5.2 mm year−1 for ERRA, and they
characterize the regional NW-SE plate convergence in the area.
Moreover, in order to establish the relative motion with respect to the most stable
Nubian plate, we have determined the relative motion of all these stations with respect to
the ERRA site (Figure 4). BENI has a southward displacement of 1.1 mm year−1, orthogonal
to the elongated Central High Atlas Mountains. RABT and TAZA, located in the northern
and northeastern Meseta, respectively, have roughly similar displacement paerns to-
wards the northeast of 1 mm year−1 and 0.8 mm year−1. These data highlight a signicant
northeast-southwest extension in the central Meseta of close to 2 mm year−1. SSW displace-
ment of CEU1 is 1.1 mm year−1, and this determines a shortening with respect to RABT
and TAZA, but this displacement is roughly similar in trend and magnitude to that of the
BENI site.
Figure 4. Geological map including residual cGPS velocities respect to the Errachidia station, which
can be considered as a representation of Nubia, with error ellipses of 95% condence.
Finally, in order to beer present the deformation of the Meseta, the BENI station has
been considered as the reference (Figure 5) and both RABT and TAZA show notable dis-
placement towards the NNE, while CEU1 is aected by a very low relative displacement
towards the SSE.
Figure 4.
Geological map including residual cGPS velocities respect to the Errachidia station, which
can be considered as a representation of Nubia, with error ellipses of 95% confidence. The trace of
Figure 6 is represented as a red line on the map.
Finally, in order to better present the deformation of the Meseta, the BENI station
has been considered as the reference (Figure 5) and both RABT and TAZA show notable
displacement towards the NNE, while CEU1 is affected by a very low relative displacement
towards the SSE.
Sensors 2023,23, 4846 9 of 14
Sensors 2023, 23, x FOR PEER REVIEW 9 of 14
Figure 5. Geological map including residual cGPS velocities respect to the Beni Mellal station, which
represents the southernmost sector of Central Moroccan Meseta, with error ellipses of 95% con-
dence. The trace of Figure 6 is represented as a red line on the map.
Figure 6. Tectonic sketch along a N-S prole along the transect between the Rif Cordillera and the
Anti-Atlas. It illustrates the geodynamic hypothesis for the extension of the Western and Central
Moroccan Meseta. The projections of the cGPS stations are depicted. Cross and point, strike-slip
faulting.
5. Discussion
5.1. Analysis of the cGPS Tectonic Displacements
The new data obtained from key sites by cGPS open new perspectives for our under-
standing of the simultaneous development of both the alpine Rif and the intraplate Atlasic
cordilleras. The Nubian-plate northern boundary in the westernmost Mediterranean seg-
ment underwent continental collision with distributed active deformation and seismicity
[10]. Although error ellipses are not small, a displacement paern can be aempted for
the rst time in this region.
The general paern of the selected sites when Eurasia is xed (Table 1 and Figure 3)
agrees with the expected northwestward displacement of Nubia in respect to Eurasia at
rates close to 5 mm year−1 [4–9]. However, these results reveal a heterogeneous behavior.
Figure 5.
Geological map including residual cGPS velocities respect to the Beni Mellal station, which
represents the southernmost sector of Central Moroccan Meseta, with error ellipses of 95% confidence.
The trace of Figure 6is represented as a red line on the map.
Sensors 2023, 23, x FOR PEER REVIEW 9 of 14
Figure 5. Geological map including residual cGPS velocities respect to the Beni Mellal station, which
represents the southernmost sector of Central Moroccan Meseta, with error ellipses of 95% con-
dence. The trace of Figure 6 is represented as a red line on the map.
Figure 6. Tectonic sketch along a N-S prole along the transect between the Rif Cordillera and the
Anti-Atlas. It illustrates the geodynamic hypothesis for the extension of the Western and Central
Moroccan Meseta. The projections of the cGPS stations are depicted. Cross and point, strike-slip
faulting.
5. Discussion
5.1. Analysis of the cGPS Tectonic Displacements
The new data obtained from key sites by cGPS open new perspectives for our under-
standing of the simultaneous development of both the alpine Rif and the intraplate Atlasic
cordilleras. The Nubian-plate northern boundary in the westernmost Mediterranean seg-
ment underwent continental collision with distributed active deformation and seismicity
[10]. Although error ellipses are not small, a displacement paern can be aempted for
the rst time in this region.
The general paern of the selected sites when Eurasia is xed (Table 1 and Figure 3)
agrees with the expected northwestward displacement of Nubia in respect to Eurasia at
rates close to 5 mm year−1 [4–9]. However, these results reveal a heterogeneous behavior.
Figure 6.
Tectonic sketch along a N-S profile along the transect between the Rif Cordillera and the Anti-
Atlas. It illustrates the geodynamic hypothesis for the extension of the Western and Central Moroccan
Meseta. The projections of the cGPS stations are depicted. Cross and point, strike-slip faulting.
5. Discussion
5.1. Analysis of the cGPS Tectonic Displacements
The new data obtained from key sites by cGPS open new perspectives for our un-
derstanding of the simultaneous development of both the alpine Rif and the intraplate
Atlasic cordilleras. The Nubian-plate northern boundary in the westernmost Mediterranean
segment underwent continental collision with distributed active deformation and seismic-
ity [
10
]. Although error ellipses are not small, a displacement pattern can be attempted for
the first time in this region.
The general pattern of the selected sites when Eurasia is fixed (Table 1and Figure 3)
agrees with the expected northwestward displacement of Nubia in respect to Eurasia at
rates close to 5 mm year−1[4–9]. However, these results reveal a heterogeneous behavior.
Sensors 2023,23, 4846 10 of 14
In order to unveil this issue, the displacement vectors are considered in respect to
stable Nubia (Errachidia, Figure 4). The southward displacement of Beni Mellal, at about
1 mm yr
−1
rate, which is orthogonal to the High Atlas and its bounding faults (the South
High Atlas and North High Atlas fault), gives evidence that a significant part of the
deformation related to the plate boundary is occurring in the High Atlas. This convergence
trend is also in agreement with the reverse earthquake focal mechanism that occurs in
the South High Atlas Fault (Figure 2b). This shortening, together with the underlying
anomalous mantle [
3
,
33
,
34
], drives this cordillera to uplift highly in respect to its relative
low shortening. In [
34
], the authors showed, through deep seismic survey and recent Atlasic
volcanism, that the Atlasic anomalous topography was conducted during Quaternary times
by an ascending hot asthenospheric dome, topped at 25 km depth beneath the High-
Moulouya plateau. Microtectonic structures affecting continental deposits surrounding the
Atlasic mountains were reactivated during the Quaternary [
41
–
44
] under an NNE/SSW-
to-N/S-directed compressional stress regime. These results agree with the convergence
obtained by cGPS that now allows for quantifying its related deformation rate.
The comparison of the displacements of Beni Mellal, Rabat, and Taza allows us to
constrain the deformation of the presumed stable central Moroccan Meseta. The similar
behavior of the deformation rates of Rabat and Taza (Table 1, Figures 3–5) invites different
interpretations. The easy one is that these locations might belong to the same tectonically
stable block located in the northern part of the central Meseta. Nonetheless, their close
tectonic setting indicates that Rabat undergoes the extensional effect of the transitional
margin between the Meseta and the Gharb basin, whereas Taza is undergoing two combined
effects: the southward displacement of the frontal part of the Rif and the extension induced
by the eastern end of the Gharb basin (Figures 1,2,4and 5). The displacements resulting
from both processes may coincidentally fall in the same rate value. In any case, the relative
northeastward displacement of these stations with respect to stable Nubia (Figure 4) and
with respect to the southern central Meseta (Figure 5) raises a new line of thinking to
understand the present-day behavior of the Meseta.
First, the relative displacement of the northern Meseta (Rabat and Taza) with respect
to Beni Mellal provides evidence for very active extensional tectonics in this area of about
2 mm year
−1
in the NNE-SSW direction (Figures 5and 6). These results agree with the
presence of subtle extensional tectonic deformations envisaged by field geological studies
in this region including normal faults [
45
–
48
] and flexures [
42
]. Moreover, the existence of
basaltic volcanism, in addition to the geophysical evidence of the underlying anomalous
mantle [3], agrees with the present-day active extension simultaneous to the relief uplift.
The northeastward relative displacement of Rabat and Taza, parallel to the North
Middle Atlas Fault (Figures 4and 5), also raises questions about the present-day kine-
matics of this major structure. The fault has traditionally been considered to result
from sinistral transpressional thrust during Quaternary times based on geological field
evidence [9,22,23,46,47,49]
. However, the available focal mechanisms along this major
structure (Figure 2b) are variable and do not provide a clear answer to this issue. More
detailed geodetic research on this area is needed in the future to resolve this apparent
inconsistency between field geological and geodetic results.
Further north, in the Rif Cordillera, the relative convergence of Ceuta in respect to Taza
and Rabat (Table 1and Figures 4and 5) confirms the shortening related to the build-up of
the Alpine Rif Cordillera. Previous GPS research [
6
–
10
] has already shown evidence of this.
The N-S to NNW-SSE trend of convergence with respect to Nubia is in agreement with the
similar trend of compression evidenced by the earthquake focal mechanisms of Figure 2b.
These results raise questions about the present-day low active westward displacement of
the frontal part of the Gibraltar Arc in respect to Nubia, which is substituted by a more
intense NNW-SSE convergence in the Rif Cordillera. The southward emplacement of
the Rif Cordillera with respect to Nubia determines the highest activity of the southern
front of the Cordillera along the northern Saïss basin border, in agreement with geological
observations [9,20], rather than in the western border.
Sensors 2023,23, 4846 11 of 14
5.2. Strain Partitioning in the Northern Nubian Plate Boundary: Towards an Integrated
Tectonic Model
The significant results evidenced for the first time by the cGPS stations
(Figures 2and 3) constitute a useful reference to constrain the geodynamical models
of this region. While a progressive accommodation of the Eurasian-Nubian at a 5 mm yr
−1
rate, NW-SE convergence was expected in this region, the presence of an unexpected fast
extension of 2 mm year
−1
in the Meseta needs to be considered. Moreover, the roughly
southwards displacement of Ceuta (Rif Cordillera) was proved to be roughly similar to
the displacement of Beni Mellal (southern Meseta), and the extension of the Meseta was
also roughly similar to the convergence of the Rif (between Ceuta and Taza/Rabat). In
this setting, a geodynamic model may be proposed for the region based on two coevally
intervening processes (Figure 6): (i) the presence of an anomalous mantle below both the
High Atlas and Meseta [
33
,
34
], and (ii) the roll-back tectonics in the Betic-Rif Cordillera [
28
]
that determine, in the Rif, a relative northeastward displacement of the Variscan basement
in respect to the Alpine cover. The combination of these two processes simultaneously
results in: (i) extensional crustal bands inside the Gharb basin, the northwestern Meseta,
and the Middle Atlas, (ii) the thermal uplift of the High-Atlas, (iii) the basaltic Quaternary
volcanism in the Middle Atlas and the neighboring Meseta, and (iv) the shortening of both
the High Atlas and the Rif. In this regional setting, the anomalous mantle beneath the
Middle and High Atlas remains the driving mechanism behind the development of its
higher reliefs compared to those lower in the more shortened Rif.
These data show the heterogeneous behavior of the studied interplate area and open
the discussion on whether its active, true, southernmost boundary might be located in the
contact between the High Atlas and the Anti-Atlas, instead of being along the classically
admitted Rifian thrust front.
6. Conclusions
The new continuous GPS (cGPS) data provide reliable support for the first time to
understand the geodynamic mechanism that formed the prominent Atlas Cordillera and
reveals the heterogeneous present-day behavior of the Eurasia-Nubia collisional boundary.
The results from the cGPS stations located in key tectonic sites inside the northwest-
ern boundary zone of the Nubian plate provide new data on the present-day extensional
and compressive deformation of this region. They contribute to revealing the origin of
the uplift of the Meseta and Atlas Mountains. The new cGPS data confirm the NW SE
Eurasian-Nubian convergence at an overall rate of 5 mm year
−1
, as well as the already
well-established convergence in the Alpine Rif Cordillera. However, the present-day south-
ward displacement of the northern Rif in respect to Nubia suggests that active tectonic
compressive structures are mainly developed in the southern Rif front while the westward
front that delineates the arched shape of the Cordillera becomes of scarce activity. Moreover,
these data clearly reveal, for the first time, an NNE-SSW extension of close to 2 mm year
−1
in the Meseta and possibly in the Middle Atlas. Simultaneously, the relative uplift and the
presence of Quaternary basaltic volcanism support the presence of an underlying anoma-
lous mantle, also evidenced by geophysical data. Extensional tectonics may also be favored
by the roll-back tectonics occurring in the Rif Cordillera (Figure 6). Southward, convergence
of the High Atlas is established for the first time at a rate of 1 mm year
−1
with an N-S
trend, a moderate shortening rate that, together with the underlying anomalous mantle, is
responsible for the highest reliefs of the above-mentioned southern plate boundary.
These cGPS data reveal the heterogeneous behavior of the Nubia interplate area
and highlight the need to consider the Atlas Mountains as the most prominent Alpine
cordillera in this region, where they underline, at the same time, the sharp boundary with
stable Nubia.
Sensors 2023,23, 4846 12 of 14
Author Contributions:
Conceptualization, A.C.(Ahmed Chalouan), A.J.G. and J.G.-Z.; Data cu-
ration, A.J.G.; Formal analysis, A.C. (Ahmed Chalouan) and A.J.G.; Funding acquisition, A.J.G.;
Investigation, A.C. (Ahmed Chalouan), A.J.G., A.C. (Ahmed Chabli), K.B., H.L., K.E.K., V.T.-S. and
J.G.-Z.; Methodology, A.J.G. and J.G.-Z.; Supervision, A.C. (Ahmed Chalouan), A.J.G., K.B. and
J.G.-Z.; Visualization, A.C. (Ahmed Chalouan), H.L., K.E.K., V.T.-S. and J.G.-Z.; Writing—original
draft, A.C. (Ahmed Chalouan), A.J.G., A.C. (Ahmed Chabli), K.B., H.L., K.E.K., V.T.-S. and J.G.-Z.;
Writing—review
& editing, A.C. (Ahmed Chalouan), A.J.G., A.C. (Ahmed Chabli), K.B., H.L., K.E.K.
and V.T.-S. All authors have read and agreed to the published version of the manuscript.
Funding:
Junta de Andalucia; European Regional Development Fund; grant numbers: AGORA
P18-RT-3275. Programa Operativo FEDER-Andalucia 2014–2020 Project ref. 1263446; University of
Jaén; CEACTEMA; grant number: POAIUJA 23/24. Junta de Andalucía (Andalusian Board); grant
numbers: RNM-148, RNM-282, RNM-370. V.T.S. was supported by the FPU PhD grant (16/04038).
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement: The data are included in Table 1of this paper.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Allmendinger, R.W.; Loveless, J.P.; Pritchard, M.E.; Meade, B. From decades to epochs: Spanning the gap between geodesy and
structural geology of active mountain belts. J. Struct. Geol. 2009,31, 1409–1422. [CrossRef]
2.
Laville, E.; Piqué, A. La distension crustale atlantique et atlasique au Maroc au début du Mésozoïque: Le rejeu des structures
hercyniennes. Bull. Soc. Geol. Fr. 1991,162, 1161–1171.
3.
Anahnah, F.; Galindo-Zaldívar, J.; Chalouan, A.; Pedrera, A.; Ruano, P.; Pous, J.; Heise, W.; Ruiz-Constán, A.; Benmakhlouf,
M.; López-Garrido, A.C.; et al. Deep resistivity cross section of the intraplate Atlas Mountains (NW Africa): New evidence of
anomalous mantle and related Quaternary volcanism. Tectonics 2011,30, TC5014. [CrossRef]
4.
De Mets, C.; Gordon, R.; Argus, D.; Stein, S. Effect of recent revisions to thegeomagnetic reversal time scale on estimates of current
plate motions. Geophys. Res. Lett. 1994,21, 2191–2194. [CrossRef]
5.
Nocquet, J.M. Present-day kinematics of the Mediterranean: A comprehensive overview of GPS results. Tectonophysics
2012
,579,
220–242. [CrossRef]
6.
Fadil, A.; Vernant, P.; Mcclusky, S.; Reilinger, R.; Gomez, F.; Ben Sari, D.; Mourabit, T.; Feigl, K.L.; Barazangi, M. Active tectonics
of the western Mediterranean: Geodetic evidence for rollback of a delaminated subcontinental lithospheric slab beneath the Rif
Mountains, Morocco. Geology 2006,34, 529–532. [CrossRef]
7.
Vernant, P.; Fadil, A.; Mourabit, T.; Ouazar, D.; Koulali, A.; Davila, J.M.; Gárate, J.; McClusky, S.; Reilinger, R. Geodetic constraints
on active tectonics of the Western Mediterranean: Implications for the kinematics and dynamics of the Nubia-Eurasia plate
boundary zone. J. Geodyn. 2010,49, 123–129. [CrossRef]
8.
Koulali, A.; Ouazara, D.; Tahayt, A.W.; King, R.; Vernant, P.; Reilinger, R.E.; McClusky, S.; Mourabit, T.; Davila, J.M.; Amraoui, N.
New GPS constraints on active deformation along the Africa–Iberia plate boundary. Earth Planet. Sci. Lett.
2011
,308, 211–217.
[CrossRef]
9.
Chalouan, A.; Gil, A.J.; Galindo-Zaldívar, J.; Ahmamou, M.F.; Ruano, P.; de Lacy, M.C.; Ruiz-Armenteros, A.M.; Benmakhlouf, M.;
Riguzzi, F. Active faulting in the frontal Rif Cordillera (Fes region, Morocco): Constraints from GPS data. J. Geodyn.
2014
,77,
110–122. [CrossRef]
10. Palano, M.; González, P.J.; Fernández, J. The Diffuse Plate boundary of Nubia and Iberia in the Western Mediterranean: Crustal
deformation evidence for viscous coupling and fragmented lithosphere. Earth Planet. Sci. Lett. 2015,430, 439–447. [CrossRef]
11.
Gárate, J.; Martin-Davila, J.; Khazaradze, G.; Echeverria, A.; Asensio, E.; Gil, A.J.; de Lacy, M.C.; Armenteros, J.A.; Ruiz, A.M.;
Gallastegui, J.; et al. Topo-Iberia project: CGPS crustal velocity field in the Iberian Peninsula and Morocco. GPS Solut.
2014
,19,
287–295. [CrossRef]
12.
González-Castillo, L.; Galindo-Zaldívar, J.; de Lacy, M.C.; Borque, M.J.; Martínez-Moreno, F.J.; García-Armenteros, J.A.; Gil, A.J.
Active rollback in the Gibraltar Arc: Evidences from CGPS data in the western Betic Cordillera. Tectonophysics
2015
,663, 310–321.
[CrossRef]
13. Bargach, K.; Ruano, P.; Chabli, A.; Galindo-Zaldívar, J.; Chalouan, A.; Jabaloy, A.; Akil, M.; Ahmamou, M.; San De Galdiano, C.;
Benmakhlouf, M. Recent tectonic deformations and stresses in the frontal part of the Rif Cordillera and the Saïss Basin (Fes and
Rabat regions, Morocco). Pure Appl. Geophys. 2004,161, 521–540. [CrossRef]
14.
Michard, A.; Frizon de Lamotte, D.; Saddiqi, O.; Chalouan, A. An outline of the geology of Morocco. In Continental Evolution: The
Geology of Morocco: Structure, Stratigraphy, and Tectonics of the Africa-Atlantic-Mediterranean Triple Junction; Michard, A., Saddiqi, O.,
Chalouan, A., Frizon de Lamotte, D., Eds.; Springer: Berlin/Heidelberg, Germany, 2008; pp. 1–31.
Sensors 2023,23, 4846 13 of 14
15.
Ramdani, F. Geodynamic implications of intermediate-depth earthquakes and volcanism in the intraplate Atlas mountains
(Morocco). Phys. Earth Planet. Inter. 1998,108, 245–260. [CrossRef]
16.
Mora, A.; Parra, M.; Strecker, M.R.; Kammer, A.; Dimaté, C.; Rodríguez, F. Cenozoic contractional reactivation of Mesozoic
extensional structures in the Eastern Cordillera of Colombia. Tectonics 2006,25. [CrossRef]
17.
El Azzouzi, M.H.; Maury, R.C.; Bellon, H.; Youbi, N.; Cotten, J.; Kharbouch, F. Petrology and K-Ar chronology of the Neogene-
quaternary Middle Atlas basaltic province, Morocco. Bull. Soc. Geol. Fr. 2010,181, 243–257. [CrossRef]
18. Harris, R.A. Large earthquakes and creeping faults. Rev. Geophys. 2017,55, 169–198. [CrossRef]
19.
Galindo-Zaldívar, J.; Chalouan, A.; Azzouz, O.; Sanz de Galdeano, C.; Anahnah, F.; Ameza, L.; Ruano, P.; Pedrera, A.; Ruiz-
Constán, A.; Marín-Lechado, C.; et al. Are the seismological and geological observations of the Al Hoceima (Morocco, Rif) 2004
earthquake (M = 6.3) contradictory? Tectonophysics 2009,475, 59–67. [CrossRef]
20.
Roldán, F.J.; Galindo-Zaldívar, J.; Ruano, P.; Chalouan, A.; Pedrera, A.; Ahmamou, M.; Ruiz-Constán, A.; Sanz de Galdeano, C.;
Benmakhlouf, M.; López-Garrido, A.C.; et al. Basin evolution associated to curved thrusts: The Prerif Ridges in the Volubilis area
(Rif Cordillera, Morocco). J. Geodyn. 2014,77, 56–69. [CrossRef]
21.
Ahmamou, M.; Chalouan, A. Distension synsédimentaire plio-quaternaire et rotation anti-horaire des contraintes au Quaternaire
ancien sur la bordure nord du bassin du Saïss (Maroc). Bull. De L’institut Sci. 1988,12, 19–26.
22.
Chalouan, A.; Galindo-Zaldivar, J.; Akil, M.; Marin, C.; Chabli, A.; Ruano, P.; Bargach, K.; Sanz de Galdeano, C.; Benmakhlouf, M.;
Ahmamou, M.; et al. Tectonic wedge escape in the southwestern front of the Rif Cordillera (Morocco). In Tectonics of the Western
Mediterranean and North Africa; Moratti, G., Chalouan, A., Eds.; Geological Society Publishing House: Bath, UK, 2006; pp. 101–118.
23.
Hinaje, S. Tectonique Cassante et Paléochamps de Contraintes Dans le Moyen Atlas et le Haut Atlas Central (Midelt-Errachidia)
Depuis le Trias Jusqu’àl’Actuel. Ph.D. Thesis, UniversitéMohammed V, Rabat, Morocco, 2004.
24.
Chabli, A. Études Sedimentologique et Neotectonique des Formations Plio-Quaternaire Littorales Entre Rabat et Casablanca.
Ph.D. Thesis, Universitéde Mohammed V, Rabat, Morocco, 2009.
25.
Chabli, A.; Chalouan, A.; Akil, M.; Galindo-Zaldívar, J.; Ruano, P.; Sanz De Galdeano, C.; López-Garrido, A.C.;
Marin-Lechado, C.;
Pedrera, A. Plio-Quaternary paleostresses in the Atlantic passive margin of the Moroccan Meseta: Influence of the Central Rif
escape tectonics related to Eurasian-African plate convergence. J. Geodyn. 2014,77, 123–134. [CrossRef]
26.
Gutscher, M.A.; Malod, J.; Rehault, J.P.; Contrucci, I.; Klingelhöfer, F.; Spakman, W.; Sismar Scientific Team. Active subduction
beneath the Gibraltar Arc. In Proceedings of the EGS General Assembly Conference Abstracts, Vienna, Austria, 23–27 May 2002.
27.
Gutscher, M.A.; Dominguez, S.; Westbrook, G.K.; Le Roy, P.; Rosas, F.; Duarte, J.C.; Terrinha, P.; Miranda, J.M.; Graindorge, D.;
Gailler, A.; et al. The Gibraltar subduction: A decade of new geophysical data. Tectonophysics 2012,574, 72–91. [CrossRef]
28.
Pedrera, A.; Ruiz-Constan, A.; Galindo-Zaldívar, J.; Chalouan, A.; Sanz de Galdeano, C.; Marín-Lechado, C.; Ruano, P.;
Benmakhlouf, M.; Akil, M.; López-Garrido, A.C.; et al. Is there an active subduction beneath the Gibraltar orogenic arc?
Constraints from Pliocene to present-day stress field. J. Geodyn. 2011,52, 83–96. [CrossRef]
29.
Wigger, P.; Asch, G.; Giese, P.; Heinsohn, W.D.; Alami, S.O.E.; Ramdani, F. Crustal structure along a traverse across the Middle
and High Atlas mountains derived from seismic refraction studies. Geol. Rundsch. 1992,81, 237–248. [CrossRef]
30.
Giese, P.; Jacobshagen, V. Inversion tectonics of intracontinental ranges: High and Middle Atlas, Morocco. Geol. Rundsch.
1992
,81,
249–259. [CrossRef]
31.
Jacobshagen, V.; Görler, K.; Giese, P. Geodynamic evolution of the Atlas System (Morocco) in post-Palaeozoic times. In The
Atlas System of Morocco: Studies on Its Geodynamic Evolution; Jacobshagen, V.H., Ed.; Lecture Notes in Earth Sciences; Springer:
Berlin/Heidelberg, Germany, 1988; Volume 15, pp. 481–499.
32.
Missenard, Y.; Zeyen, H.; Frizon de Lamotte, D.; Leturmy, P.; Petit, C.; Sébrier, M.; Saddiqi, O. Crustal versus asthenospheric
origin of relief of the Atlas Mountains of Morocco. J. Geophys. Res. Solid Earth 2006,111, B03401. [CrossRef]
33.
Fullea, J.; Fernández, M.; Afonso, J.C.; Vergés, J.; Zeyen, H. The structure and evolution of the lithosphere–asthenosphere
boundary beneath the Atlantic–Mediterranean Transition Region. Lithos 2010,120, 74–95. [CrossRef]
34.
Miller, M.; Becker, T.W. Reactivated lithospheric-scale discontinuities localize dynamic uplift of the Moroccan Atlas Mountains.
Geology 2014,42, 35–38. [CrossRef]
35.
Benamrane, M.; Jadid, M.; Dahmani, H.; Talbi, F. L’histoire éruptive du volcan monogénique quaternaire de Timahdite (Moyen
Atlas, Maroc). Quaternaire. Rev. De L’association Française Pour L’étude Du Quat. 2020,31, 309–326. [CrossRef]
36.
Gil, A.J.; Lacy, M.C.; Ruiz, A.M.; Armenteros, J.A.; Adán, R.; Avilés, M.; Riguzzi, F.; Devoti, R.; TopoIberia GPS Group. Topo-Iberia
GPS Network: Preliminary Results at UJA Analysis Centre. The Portuguese–Spanish Assembly of Geodesy and Geophysics, San
Sebastian. In Proceedings of the EGU General Assembly 2010, Vienna, Austria, 7–12 April 2013.
37.
Dach, R.; Hugentobler, U.; Fridez, P.; Meindl, M. User Manual of the Bernese GPS Software, version 5.0; Astronomical Institute,
University of Bern: Bern, Switzerland, 2007; 612p.
38.
Devoti, R.; Riguzzi, F.; Cuffaro, M.; Doglioni, C. New GPS constraints on the kinematics of the Apennines subduction. Earth
Planet. Sci. Lett. 2008,273, 163–174. [CrossRef]
39.
RR2 Devoti, R.; Esposito, A.; Pietrantonio, G.; Pisani, A.R.; Riguzzi, F. Evidence of large scale deformation patterns from GPS data
in the Italian subduction boundary. Earth Planet. Sci. Lett. 2011,311, 230–241. [CrossRef]
40.
Altamimi, Z.; Collilieux, X.; Legrand, J.; Garayt, B.; Boucher, C. ITRF2005: A new release of the International Terrestrial Reference
Frame based on time series of station positions and Earth Orientation Parameters. J. Geophys. Res. Solid Earth
2007
, 112. [CrossRef]
Sensors 2023,23, 4846 14 of 14
41.
Fraissinet, C.; Zouine, M.E.; Morel, J.L.; Poisson, A.; Andrieux, J.; Faure-Muret, A. Structural evolution of the southern and
northern central High Atlas in Paleogene and Mio-Pliocene times. In The Atlas System of Morocco; Springer: Berlin/Heidelberg,
Germany, 1988; pp. 273–291.
42.
Zouine, E.M. Géodynamique récente du Haut Atlas. Evolution de sa Bordure Septentrionale et du Moyen Atlas Sud-Occidental
au Cours du Cénozoïque. Ph.D. Thesis, UniversitéMohammed V, Rabat, Morocco, 1993.
43.
Morel, J.L.; Zouine, E.M.; Andrieux, J.; Faure-Muret, A. Déformations néogènes et quaternaires de la bordure nord haut atlasique
(Maroc): Rôle du socle et consequences structurales Neogene and Quaternary deformation of the northern High Atlas border
[Morocco]: Role of the basement and structural consequences. J. Afr. Earth Sci. 2000,30, 119–131. [CrossRef]
44.
Ellero, A.; Ottria, G.; Malusà, M.G.; Ouanaimi, H. Structural Geological Analysis of the High Atlas (Morocco): Evidences of a
Transpressional fold-thrust belt. In Tectonics-Recent Advances; Sharkov, E., Ed.; InTech: Rijeka, Croatia, 2012; pp. 230–258.
45.
Laouina, A.E. Observations géomorphologiques dans la région du Moyen Sebou, en amont de Fès. Rev. Géographique Du Maroc
1973,23–24, 3–31.
46.
Martin, J. Le Moyen Atlas central. Etude géomorphologiques. In Notes et Mémoires Service Géologique; Maroc 258bis: Tanger,
Morocco, 1981; p. 447.
47.
Charrière, A. Héritage Hercynien et Evolution Géodynamique Alpine D’une Chaîne Intracontinentale: Le Moyen Atlas au SE de
Fès (Maroc). Ph.D. Thesis, UniversitéPaul Sabatier, Toulouse III (Sciences), Toulouse, France, 1990.
48.
El Fertati, M.; Hinaje, S.; Amrani, S.; Gharmane, Y.; Yaagoub, D. Le Bassin de Skoura-Tazouta (Moyen Atlas, Maroc): Un Exemple
de Paléo-Barrage D’âge NéogèneQuaternaire d’origine Tectonique et àRemplissage Fluvio-Lacustre et Travertineux. Eur. Sci. J.
2019,15, 339–361.
49.
Frizon de Lamotte, D.; Zizi, M.; Missenard, Y.; Hafid, M.; El Azzouzi, M.; Maury, R.C.; Charrière, A.; Taki, Z.; Benammi, M.;
Michard, A. The Atlas System. In Continental Evolution: The Geology of Morocco; Lecture Notes in Earth, Sciences; Michard, A.,
Saddiqi, O., Chalouan, A., Lamotte, D.F., Eds.; Springer: Berlin/Heidelberg, Germany, 2008; Volume 116, pp. 133–202.
Disclaimer/Publisher’s Note:
The statements, opinions and data contained in all publications are solely those of the individual
author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to
people or property resulting from any ideas, methods, instructions or products referred to in the content.
