INSIGHTS INTO EXTENSIONAL EVENTS IN THE BETIC CORDILLERAS...

Tectonophysics 603 (2013) 179–188
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Tectonophysics
journal homepage: www.elsevier.com/locate/tecto
Insights into extensional events in the Betic Cordilleras, southern Spain:
New fission-track and U–Pb SHRIMP analyses
José Julián Esteban a,⁎, José María Tubía a, Julia Cuevas a, Diane Seward b, Alexander Larionov c,
Sergey Sergeev c, Francisco Navarro-Vilá d
a
Departamento de Geodinámica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, Apartado 644, 48080 Bilbao, Spain
School of Geography, Environment and Earth Sciences, Victoria University, PO Box 600, Wellington, New Zealand
Centre of Isotopic Research, VSEGEI, 199106 St. Petersburg, Russia
d
Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced s/n, 37007 Salamanca, Spain
b
c
a r t i c l e
i n f o
Article history:
Received 21 December 2012
Received in revised form 17 May 2013
Accepted 23 May 2013
Available online 3 June 2013
Keywords:
Fission-track analysis
U–Pb SHRIMP
Extensional tectonics
Malaguide Complex
Los Reales nappe
Betic Cordilleras
a b s t r a c t
A combination of the U–Pb SHRIMP and zircon fission-track analyses has been used to constrain the age and
evolution of the extensional tectonics in the Betic Cordilleras, southern Spain. The studied rocks are dolerite
dykes intruded in the Malaguide Complex and in the underlying Los Reales nappe and their country rocks.
The dykes are grouped in two nearly perpendicular systems, characterized by N–S strikes in the Los Reales
nappe and E–W strikes in the Malaguide Complex. Two periods of extension have been identified. The age
of the older event, ranging from ~ 33 to 25 Ma, is constrained by the intrusion of the dykes (33 Ma) and
the joint cooling of the Los Reales–Malaguide domain from 25 Ma onwards. This event is associated with
the structural emplacement of the Malaguide Complex over the Los Reales nappe, along a brittle–ductile
extensional detachment and is tentatively ascribed to the tectonic collapse of the orogenic belt. A minimum
time span of 10 m.y. is established between the onset of the extensional collapse and the widespread Aquitanian HT-LP metamorphism. In the present geographic frame, the kinematics of this event is characterized
by a change from an E–W extension at lower levels (Los Reales nappe) to a N–S extension in upper levels
(Malaguide Complex). A younger extensional event of Miocene age (~18 Ma) has been deduced based on
the fission-track analysis within the “calizas alabeadas” member of the Malaguide Complex.
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
The Betic Cordilleras in Spain and the Rif in Morocco form the western
termination of the Mediterranean Alpine Orogen. The Betic Cordilleras
represent a good example of a collisional orogen disaggregated by extensional collapse in a continuous convergent setting between the Iberia and
Africa plates. In this regard, it is worth noting that in the Internal Zones of
the Betic Cordilleras, which are composed by the Nevado–Filabride, the
Alpujarride and the Malaguide complexes from bottom to top, the
structures related to crustal thickening are overprinted by late extensional tectonics. The main tectonic contacts such as that between the
Nevado–Filabride and Alpujarride complexes (Álvarez et al., 1989;
García-Dueñas et al., 1986, 1992; Jabaloy et al., 1992) or the Alpujarride
and Malaguide complexes (Aldaya et al., 1991; Lonergan and Platt,
1995; Tubía et al., 1991, 1993) are nowadays interpreted as extensional
detachments. A few of them have been dated by fission-track analysis
(e.g. Johnson et al., 1997), but little is still known about their precise
age of movement, as the Aquitanian–Burdigalian age of most of these
⁎ Corresponding author.
E-mail address: [email protected] (J.J. Esteban).
0040-1951/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.tecto.2013.05.027
detachments, has been established based on the palaeontological ages
from unconformably overlying sedimentary units (e.g. Aguado et al.,
1990; Durand-Delga et al., 1993; Martín-Algarra and Estévez, 1984).
However, these palaeontological ages are clearly inconsistent with the
youngest isotopic data of the Alpujarride Complex (e.g. Esteban et al.,
2004), as these nappes should still be at depths where the temperatures
were higher than ≫300 °C at Aquitanian–Burdigalian times.
This work deals with the Alpujarride–Malaguide boundary (AMB)
located in the western part of the Betic Cordilleras (Fig. 1), where the
Malaguide Complex appears over the highest tectonic unit of the
Alpujarride Complex, the Los Reales nappe (Navarro-Vilá and Tubía,
1983). The AMB, identified as a brittle–ductile extensional detachment (Tubía et al., 1993), postdates the thrust stacking as evidenced
by the duplication of the some of the stratigraphic units throughout
the complexes. The structural and kinematic analysis of the boundary
(Tubía et al., 1993) confirms that the Los Reales nappe and the
Malaguide Complex comprise a single crustal tectonic domain formed
during thinning of previously thickened crust, in direct relationship
with the exhumation of the Ronda peridotites. In this regard, Tubía
et al. (1993) in the Betic Cordilleras and Negro et al. (2006) in the
Rif already suggested that after the emplacement of the complexes
this crustal domain underwent the same Alpine thermal evolution.
180
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
Fig. 1. Geological map of the western part of the Betic Cordilleras (modified from Navarro-Vilá et al., 2007), showing the location of sample sites for fission-track and U–Pb SHRIMP
analysis. Square marks Fig. 2 location.
However, although its structure and kinematics are well known, its
age is still a matter of question.
In order to clarify the age of the extensional episode of the detachment located between the Los Reales nappe and Malaguide Complex,
zircons from two dolerite dykes were dated by U–Pb SHRIMP and
nine samples from different structural levels (schists, phyllites and
greywackes) by zircon fission track (ZFT) analysis. The new ZFT data
are compared with other published data, in order to understand the
extensional collapse of the Betic Cordilleras. In this regard, it should
be noted that ZFT analysis emerges as a useful and suitable tool for resolving the timing of extensional events in this orogen.
2. Geological setting
The Betic Cordilleras, in southern Spain, formed in response to the
convergence of the African and Iberian plates from Late Cretaceous to
Tertiary times. The External Zones of the chain, known as the Prebetic
and Subbetic, mainly comprise deformed sedimentary rocks of Mesozoic
and Tertiary age, deposited on the southern palaeomargin of Iberia. The
Internal Zones, also called Betic Zone, are composed mainly of metamorphic rocks with original Palaeozoic and Triassic ages distributed in the
three tectonic complexes mentioned above. The contacts between these
complexes have been regarded as large-scale thrusts, but nowadays it is
agreed that they have been reactivated as large-scale detachments,
during the extensional process related to the orogenic collapse of the
chain (e.g. García-Dueñas et al., 1986, 1992; Lonergan and Platt, 1995)
and subsequent to the crustal thickening induced by orogenic compression. Although the division into three Complexes for the Internal Zone
of the Betic Cordilleras is generally accepted, recent works have already
pointed out the possibility for a new reorganization (Navarro-Vilá et al.,
2007; Platt, 2007).
The Malaguide Complex, defined in the Montes de Malaga region by
its extensive outcrops (Figs. 1 and 2), consists of a dominant Palaeozoic
series unconformably overlain by Permo-Triassic redbeds and a condensed rock sequence (Azéma, 1961; Mäkel, 1985), of Jurassic dolomites and limestones, Cretaceous marls and Tertiary sediments. The
lowermost part of the Palaeozoic series is composed of fine-grained
bluish-grey schists that have experienced the static growth of garnet
and andalusite postdating the main foliation defined by biotite, chlorite
and quartz (Tubía, 1988; Tubía et al., 1993). The thermal structure of the
Malaguide Complex indicates a temperature variation from ~500 °C at
its base to b 330 °C at the top (Negro et al., 2006), consistent with the
aforementioned garnet–andalusite recrystallization. Such thermal imprint has been ascribed to the widespread LP-HT Alpine metamorphism
of the Betic Cordilleras (Negro et al., 2006; Tubía et al., 1993). In this
regard, K–Ar ages of white micas from the lowest most parts of the
Ghomaride Complex (equivalent to the Malaguide in the Rif, Morocco)
yield fully reset ages of ca. 25 Ma (Chalouan and Michard, 1990). Furthermore, Platt et al. (2003) have reported a still younger, 18.6 ±
1.6 Ma, Ar–Ar age on muscovite from the lowest part of the Malaguide
Complex. Upwards, the schists are gradually replaced by grey phyllites
with sparse beds of strained quartz–pebble conglomerates and dark
Silurian limestones (Agard et al., 1958; Geel, 1973). The phyllites
grade into slates and greywackes that alternate with extremely folded
limestones referred to as the ‘calizas alabeadas’ (de Orueta, 1917) of
Devonian age (Kockel, 1963). Over the ‘calizas alabeadas’, the Lower
Carboniferous greywacke–slate member is located with several beds
of polymictic conglomerates, the Marbella conglomerate, interlayered
with slates and greywackes in the upper levels. The Marbella conglomerate, post-Early Namurian in age (Herbig, 1983), is unconformably covered by a Mesozoic and Cenozoic condensed sequence
up to Chattian–Aquitanian (Jutson, 1980; Mäkel, 1985). The Palaeozoic
basement, metamorphosed to greenschist facies conditions during the
Variscan, and the Permo-Triassic redbeds can be correlated with the
Piar Group and Saladilla Formation, in an eastern section of the Malaguide
Complex (Geel, 1973).
In the Montes de Malaga region, the Benamocarra Unit represents the
Alpujarride Complex to the east (Figs. 1 and 2). The latter lacks fissiontrack data and some members are missed compared to its western tectonic equivalents. Thus we focused our study to the west, where the
Malaguide Complex overlies the Los Reales nappe (Tubía et al., 1993).
The Los Reales nappe is a composite thrust sheet that includes, in ascending order, a portion of subcontinental mantle – the Ronda peridotites – and a crustal sequence of felsic granulites (kinzigites), gneissic
migmatites, and medium-to-low grade schists. The crustal sequence
preserves evidence of a complex polymetamorphic history with preAlpine HP-HT (Sánchez-Rodríguez, 1998) and Alpine LP-HT metamorphic conditions (Argles et al., 1999; Zeck et al., 1992).
The AMB corresponds to a brittle–ductile extensional detachment
developed on ductile andalusite-bearing schists, which locally form
S–C structures. However, breccia and fault gouges, with thickness
ranging between 15 cm and several metres, predominate along this
brittle–ductile detachment. In some cases, the Malaguide Complex
is involved in major rollover anticlines near the AMB (Tubía et al.,
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
181
Fig. 2. Geological map and location of dated samples within the Montes de Malaga region (map modified from Cuevas et al., 2001). Sample of Duggen et al. (2004) is located outside the map.
1993). Kinematic criteria point to downward motions of the hanging
wall rocks, but according to structural and kinematic observations
compiled in the Montes de Malaga region (Fig. 1) the detachments
and high-angle normal fault associated with the AMB can be grouped
in two generations linked to the development of extensional domes: the
first one dipping to the east and with top-to-the-east shearing and a
second cross-cutting set, dipping to the west in the present-day reference frame (Cuevas et al., 2001).
3. Dolerite dyke swarm in the AMB
The Malaguide Complex, Los Reales nappe and the Benamocarra
unit are cut by a dolerite dyke swarm. These dykes are thought to represent the remnants of the earliest magmatic episode related to Alpine
extensional collapse of the Betic Cordilleras (Torres-Roldán et al.,
1986), resulting in the exhumation of deep metamorphic rocks and
the lithospheric mantle during a continuing N–S to NW–SW convergence between the Iberian and African plates (Dewey et al., 1989; Platt
and Vissers, 1989). The swarm is formed by two perpendicular sets of
subvertical dykes. They intruded within the Malaguide Complex with a
mean E–W strike whereas those emplaced in the Los Reales nappe and
Benamocarra unit show a N10 °E strike. The dyke thickness varies
from 10 cm to 4 m and they crosscut the main structure of the country
rocks. The fresh dykes are greyish-green in colour and have ophitic texture, in thin section, defined mainly by plagioclase and pyroxene. Other
minor minerals like chlorite, epidote and pyrrhotite with minute inclusions of magnetite, transformed to hematite in altered samples, are present. In the study area, the dolerite dykes are confined to the lower part of
the Malaguide Complex (from garnet- and andalusite-bearing schists to
the Devonian ‘calizas alabeadas’) and in the crustal sequence of the Los
Reales nappe from migmatites to schists (Tubía, 1988). Similar dolerite
dykes have been described within the Malaguide Complex of the
easternmost part of the Betic Cordilleras, even within the Middle-Upper
Triassic pelites of the Saladilla Formation (Fernández-Fernández et al.,
2007).
The dolerite dykes represent a significant volume of outcrop in the
Montes de Malaga region (Fig. 3a). They maintain nearly vertical dips,
except close to the AMB, showing that at the regional scale no significant
tilting has occurred after dyke emplacement. This field observation contrasts with the inference of a 34° rotation of about a horizontal axis
trending 025°, proposed by Platzman et al. (2000) aiming to explain
the shallow inclination of the high-temperature component of magnetization revealed by palaeomagnetic analyses of the dykes. Nevertheless,
the local nature of such tilting is clear, since otherwise the vertical N–S
striking dykes should dip less than 60°. Indeed, all the palaeomagnetic
samples analysed by Platzman et al. (2000) come from the Malaguide
Complex and are located in the western limb of a late, gentle and upright
antiform with a N-striking axial surface. The andalusite-bearing schists
of the Malaguide Complex crop out in the core of such antiform (Fig. 2).
Towards the lower part of the Malaguide Complex, most dykes are
cut by late normal faults (Fig. 3b) that exhibit a near NS-strike and gentle
dips, less than 30°, to the E or W. The number of normal faults and their
displacement increases notably towards the AMB. Some dykes display
asymmetric folds with flat-lying axial surfaces parallel to the regional
cleavage (Fig. 3c). The folds denote a vertical shortening consistent
with the extensional tectonics. Almond-shaped fragments of dolerite
with asymmetric tails, resembling σ-porphyroclasts, are isolated within
the fault zone (Fig. 3d). Taking into account that cooled dolerite is much
more competent than schist, the dykes had to be still hot enough for
these quasi-plastic structures to develop. These observations have two
implications: (1) the AMB was already activated as an extensional detachment by the time of the dolerite intrusion, and (2) interpreting
the dykes as Andersonian intrusions, an overall N–S extension arises,
in the present-day geographic frame, from the consistent E–W strike
of the dolerite dyke swarm in the Malaguide Complex. This point will
be discussed later because, as we already mentioned, structural indicators from the fault zones point rather to E-directed extension (Tubía et
al., 1993).
In the Los Reales nappe the overall number of dykes is far lower than
in the Malaguide Complex. Not only the orientation of the dykes but
also that of the main foliation in the country rocks differ in these two
tectonic domains. Both dyke systems intruded at high-angle with respect to the penetrative foliation of the country rocks, which changes
from a dominant N–S strike in cleavage of the Malaguide Complex to
an E–W strike in the schistosity of the Los Reales nappe. With increasing
distance to the AMB, the dolerite dykes of the Los Reales nappe become
182
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
Fig. 3. Field structures of the dolerite dyke swarm within the Malaguide Complex showing the strain increasing from the lower phyllite member (a, b) towards the AMB (c, d). (a) General
view of the vertical dyke swarm of dolerite dykes in the A-45 road to Malaga. (b) Fractured dolerite dykes showing downward hanging wall movement. (c) Sheared and folded dyke parallel
to the main foliation of the andalusite-bearing schists. (d) Almond shape block of dolerite where the asymmetry provides a top-to the SE shear sense.
free of structural evidences on extensional deformation. In contrast,
there is a widespread development of extension related structures,
S–C tectonites and shear bands in the metamorphic country rocks
(Tubía et al., 1993), suggesting that the localized deformation leading
to the development of discrete brittle–ductile detachments along the
AMB gives way to a distributed deformation at deeper levels. Interestingly though, the dykes in the Los Reales nappe are nearly perpendicular to
the trend, N110 °E, of the stretching lineation associated with the extensional structures.
4. U–Pb SIMS SHRIMP dating of the dolerite dyke swarm
Zircons were extracted from 20 to 30 kg blocks of dolerite dykes.
After routine mineral separation only two (see sampled-sites location
in Fig. 1) of the nine sampled dykes yielded zircons. These two dykes
are located within the migmatites (tb-06-833) and sillimanite-bearing
schists (tb-08-03) of the Los Reales nappe. Selected zircon grains were
mounted in epoxy resin together with the TEMORA 1 (Black et al.,
2003) and 91500 (Wiedenbeck et al., 1995) reference zircons and
analysed on a SHRIMP-II SIMS in the Centre of Isotopic Research (CIR)
at VSEGEI (Saint Petersburg). Cathodoluminescence and electron backscattering images were used to reveal the internal structures of zircons
and as a guide for analytical spot choice. The results were obtained
with a secondary electron multiplier in peak-jumping mode following
the procedure described by Larionov et al. (2004). The U–Pb ion microprobe data are presented in Table 1. The results were processed with the
SQUID 1.13a (Ludwig, 2005a) and Isoplot/Ex 3.22 (Ludwig, 2005b) software, using the decay constants of Steiger and Jäger (1977). The common lead correction was done on the basis of measured 204Pb/206Pb
according to the model of Stacey and Kramers (1975).
Separated zircon grains display rounded, may be eroded edges
that attest to their inherited, possibly detrital origin. Some of them
(Fig. 4) display: a) a very thin and light luminescent external rim or,
b) dark/light luminescent irregular areas that truncate their internal
structures or protrude into their cores. The light luminescent external
rims are thinner than the spot diameter (≈20 μm) and only two
analyses were carried out on sufficiently wide enough rims to yield
reliable 206Pb/238U ages of 980 and 377 Ma. Otherwise, those dark/
light luminescent irregular zircon areas yield 206Pb/238U ages ranging
from 1187 to 28 Ma. Four of the youngest analysed zircons show very
low Th/U (b 0.05) that is consistent with a metamorphic origin and
contrasts with high Th/U values of zircons extracted from basic igneous
rocks (e.g. Wingate, 2001). The zircon ages define a mixing line
intersecting the Concordia at 20.9 ± 8.9 Ma (Fig. 5). Although the
error is large (~43%), the result is consistent with earlier reported
ages for the thermal Alpine metamorphism of the Betic Cordilleras
(e.g. Sánchez-Rodríguez and Gebauer, 2000).
Zircons with igneous appearance (euhedral, oscillatory zoned,
high Th/U ratio) yield 206Pb/238U ages between 1799 and 263.7 Ma,
but this cannot be the intrusion age of the dolerite dyke swarm as
they intrude into Middle-Late Triassic pelites of the Malaguide Complex (Fernández-Fernández et al., 2007). Only two dark luminescent
areas with high Th/U (spots tb-06-833_4.1 and tb-06-833_3.2) provide concordant Palaeogene ages (Fig. 5). The youngest 206Pb/238U
age, 33.1 ± 0.7 (1σ) Ma, is the only one to have geological meaning,
as similar ages have been obtained using 40Ar/39Ar geochronology for
similar dykes (see Figs. 1 and 2 for samples location) by Turner et al.
(1999) in the Malaguide Complex (30.2 ± 0.9 (1σ Ma and by
Duggen et al. (2004) in the Los Reales nappe (33.6 ± 1.4 (1σ Ma).
Regarding the oldest age (39 Ma), although from the statistical
point of view it could be considered as a coherent age for the intrusion, no magmatic events older than 33 m.y. have been detected
within the Malaguide Complex. Therefore, we suggest that the age
of 33.1 ± 0.7 (1σ) Ma could represent the intrusion age of the dolerite dyke swarm whereas the age of 20.9 Ma, would represent the
superimposed thermal Alpine metamorphism. These ages agree
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
183
Table 1
SHRIMP U–Pb–Th isotopic data for analysed zircons recovered from two dolerite dykes of Los Reales nappe. Bold analyses are those used for individual zircon Tera-Wasserburg plots
in Fig. 3, whereas the square represents the best age estimation for dyke intrusion.
206
Spot name
Info
Pbc
(%)
U
(ppm)
Th
(ppm)
232
Th /
238
U
206
(1)
(ppm)
206
Pb*
Age (Ma)
Pb /
238
U
(1)
Age (Ma)
207
Pb /
206
Pb
Dis.
%
(1)
238
U/
±
206
Pb*
(%)
(1)
207
Pb*/
206
±
Pb*
(%)
Dolerite Dyke (Los Reales nappe–Santi Petri area) [36°45'2.00'' N −4°38'27.03'' W]
tb-08-03_11.1
o
1.0
567.9
15.4
0.03
29.7
376.4 ± 3
402.0 ± 120
6.8
16.6
0.8
0.1
5.4
tb-08-03_9.1
er
0.0
190.2
51.0
0.28
9.9
377.6 ± 7.5
340.0 ± 130
−
16.6
2.1
0.1
5.6
tb-08-03_5.2
er
0.5
411.3
34.0
0.09
24.2
426.4 ± 5.9
432.3 ± 81.8
1.4
14.6
1.4
0.1
3.7
tb-08-03_1.1
c
0.0
572.9
136.0
0.25
34.0
430.5 ± 5.3
467.6 ± 29.6
8.2
14.5
1.3
0.1
1.3
tb-08-03_7.1
c
0.8
463.2
62.3
0.14
27.8
436.0 ± 5.9
388.8 ± 88.1
−
14.3
1.4
0.1
3.9
tb-08-03_4.2
c
−
800.9
311.8
0.40
64.5
578.1 ± 12.9
604.4 ± 22.3
4.5
10.7
2.3
0.1
1.0
tb-08-03_4.1
c
0.5
406.7
205.0
0.52
33.4
588.1 ± 7.4
559.9 ± 54.8
−
10.5
1.3
0.1
2.5
6.3
tb-08-03_10.1
o
0.0
10.7
0.3
0.03
1.0
655 ± 19
1637 ± 120
149.9
9.4
3.0
0.1
tb-08-03_8.1
m
0.2
1883.3
88.0
0.05
188.0
708.9 ± 11.2
718.7 ± 20.8
1.4
8.6
1.7
0.1
1.0
tb-08-03_5.1
c
0.4
760.4
60.9
0.08
80.7
750.9 ± 8.9
910.3 ± 25.9
18.5
8.1
1.3
0.1
1.3
tb-08-03_3.1
m
0.4
445.9
84.3
0.20
62.9
980.6 ± 14.8
1060.5 ± 40.3
8.1
6.1
1.6
0.1
2.0
tb-08-03_2.1
er
0.2
941.3
18.8
0.02
136.0
−
5.9
1.6
0.1
1.1
tb-08-03_6.1
c
0.2
276.2
398.0
1.49
40.8
1.6
tb-08-03_6.2
er
0.0
1324.6
74.9
0.06
210.0
tb-08-03_12.1
m
3.7
483.4
60.0
0.13
88.0
1002 ± 14.5
973.8 ± 21.8
1023 ± 13
1006 ± 31.9
−
5.8
1.4
0.1
1094 ± 13.4
1102 ± 11.9
0.8
5.4
1.3
0.1
0.6
1187 ± 20
1932 ± 120
62.7
4.9
1.8
0.1
6.5
6.3
Dolerite Dyke (Los Reales nappe–Sierra Alpujata area) [36°31'44.90'' N –4°45'19.75'' W]
tb-06-833_9.1
o
22.1
932.5
6.3
0.01
3.5
28.4 ± 0.6
2828 ± 102.5
99.2
226.8
2.0
0.2
tb-06-833_9.2
o
24.5
896.6
5.7
0.01
3.4
28.8 ± 0.4
3152 ± 60.6
99.3
223.7
1.5
0.2
3.8
tb-06-833_10.1
o
31.1
946.8
35.4
0.04
3.8
30.2 ± 2.5
3307 ± 268.8
99.3
213.1
8.2
0.3
17.1
22.0
tb-06-833.3.2
o
2.2
1154.0
16.5
5.22
0.0
33.1 ± 0.7
−
−
194.4
2.2
0.0
tb-06-833_10.2
er
35.8
905.0
33.0
0.04
4.4
36.5 ± 2.4
3580 ± 59.9
99.2
176.3
6.7
0.3
3.9
tb-06-833.4.1
o
2.8
270.9
2.6
1.45
0.0
39.0 ± 1.3
174 ± 870
346.4
164.9
3.2
0.1
37.0
tb-06-833_11.1
er
93.0
353.2
102.2
0.30
5.1
106.4 ± 0.5
tb-06-833.5.1
c
0.7
170.9
38.1
6.17
0.2
263.7 ± 4.7
4887 ± 38
261 ± 170
98.5
60.1
0.5
0.8
2.7
−
24.0
1.8
0.1
7.4
−
17.2
1.6
0.1
5.4
33.4
14.7
1.6
0.1
2.7
443 ± 70
−
12.0
1.5
0.1
3.1
540.4 ± 7.7
556 ± 23
2.9
11.4
1.5
0.1
1.1
1.5
566.4 ± 8.8
527 ± 55
−
10.9
1.6
0.1
2.5
161.00
0.1
600.7 ± 9.5
790 ± 15
31.5
10.2
1.7
0.1
0.7
34.70
0.4
633.6 ± 9.4
617 ± 35
−
9.7
1.6
0.1
1.6
61.8
8.14
0.8
697 ± 12
−
8.8
1.8
0.1
6.8
254.4
41.5
38.80
0.2
1051 ± 15
1983 ± 18
88.7
5.6
1.6
0.1
1.0
976.3
157.3
270.00
0.2
1799 ± 23
2059 ± 6.1
14.5
3.1
1.5
0.1
0.4
tb-06-833.3.1
c
0.8
255.2
95.9
12.90
0.4
364.9 ± 5.8
tb-06-833.8.1
c
0.3
337.9
83.6
19.80
0.3
423.5 ± 6.5
565.0 ± 59
tb-06-833.7.1
o
0.4
418.9
53.8
30.10
0.1
516.3 ± 7.7
tb-06-833.2.2
c
0.1
834.0
115.1
62.70
0.1
tb-06-833.1.1
c
0.2
246.5
353.7
19.50
tb-06-833.7.2
c
0.1
1918.3
164.8
tb-06-833.2.1
c
0.1
390.3
159.0
tb-06-833.4.2
c
0.9
82.3
tb-06-833.6.2
o
0.1
tb-06-833.6.1
c
0.0
296 ± 120
595 ± 150
– er: external rim/ir: internal rim/o: overgrowth/c: core/m: mixed analyses.
– Errors are 1-sigma; Pbc and Pb* indicate the common and radiogenic portions. respectively.
– (1)Common Pb corrected using measured 204Pb.
with previous petrological evidence (Torres-Roldán et al., 1986) that
point to thermal Alpine metamorphism after the dyke emplacement.
5. Fission-track analysis
In order to date extensional detachments and delimit the thermal
effect produced by dolerite dykes on country rocks, samples for
fission-track analysis were collected from sillimanite-bearing schists
of the Los Reales nappe up to the ‘calizas alabeadas’ of the Malaguide
Complex (see Fig. 2 for sample locations). From each locality three
samples were collected: one from the inner part of the dolerite
dykes and two at increasing distance away from the contact within
the country rocks, with the aim to test if the intrusion of the dykes
could have reset, and to what extent, the older fission track ages of
the country rocks. Zircon and apatite grains were extracted according
to conventional mineral separation routines at the University of the
Basque Country, but zircons in an amount appropriate for fission-track
analysis were only recovered from nine of the fourteen country rocks.
For comparative studies and for a better understanding on the relationship of the structural position with the ZFT ages, three chlorite–schist
fission-track ages (Esteban et al., 2007) from the western corner of
the Ronda peridotites have been included.
The FT method used follows that previously described by Seward
(1989) using the zeta approach (Hurford and Green, 1983). All samples
were irradiated at the ANSTO facility, Lucas Heights, Australia. All age
measurements were made by J.J. Esteban at the ETH (Zurich), using a
184
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
Fig. 4. Cathodoluminescense images of studied zircons. Ellipses show the spots' location. The attached numbers yield the spot name and the obtained
Zeiss microscope with a magnification of ×1600 (oil) with ζCN1 values
of 102.1 ± 3.0. Ages are reported as central ages (Galbraith, 1981)
and compared with those previously published for the Los Reales
nappe (Esteban et al., 2004) and the Malaguide Complex (Johnson,
1993; Platt et al., 2003).
The twelve samples yield apparent ZFT ages between 18.6 ± 1.8
and 25.8 ± 1.5 Ma (2σ) (Table 2). The ages overlap statistically, and
do not have a positive correlation with their altitudinal position
(Fig. 6a), which could be due to large-scale, late folding throughout
the Alpujarride and Malaguide Complexes. But they do have a correlation with their relative structural positions (Fig. 6b). This correlation is even more evident when other published fission track ages
from the Los Reales nappe are plotted together (Fig. 7). A similar resetting of zircon fission track ages, decreasing from lower to upper levels,
has been described previously in the Malaguide Complex (Platt et al.,
2003) and correlated with a temperature increase linked to the regional
thermal event of Miocene age, 20 to 22 Ma, recognized in the Betic Zone
(e.g. Monié et al., 1994; Priem et al., 1979; Sosson et al., 1998; Zeck et al.,
1992). However, this Miocene regional thermal overprint does not explain the full reset of the zircon fission-track ages from the upper part
of the Malaguide Complex at 24–25 Ma, but will support a delay between the beginning of the extension and the thermal overprint. Therefore, we suggest that: a) Los Reales nappe and Malaguide Complex
cooled down as a single and thinned crustal domain from at least latest
Oligocene times (~25 Ma), b) the structural emplacement was set before the rocks reached the ZFT closure temperature (260 °C; Foster et
al., 1996) and c) no partial annealing of the ZFT data can be attributed
to contact metamorphism induced by the intrusion of the dolerite
dykes as different ZFT ages are obtained from dyke to dyke. Therefore,
we tentatively suggest that the Los Reales–Malaguide Complex was
already tectonically stacked before the Late Oligocene (≈pre-25 Ma).
When the published FT data of Platt et al. (2003) are located within a
detailed geological map of the Malaguide Complex (Fig. 2: samples
MM), an age-structural position disruption is observed from the ‘calizas
alabeadas’ up to the greywacke–slate member (Fig. 6c). Samples located
within the upper structural levels attest to variable partial annealing of
Palaeozoic or older detrital ZFT ages, while those samples located at
the lowermost levels show a continuous cooling from at least latest
Oligocene. Consequently, the Los Reales nappe and the lower part of
the Malaguide Complex cooled down at higher rates than the upper of
part of the Malaguide Complex. The age disruption is located within
the ‘calizas alabeadas’ member (Fig. 7). Platt et al. (2003) presented
a plausible explanation for the distinctly identified thermal histories,
i.e. that the Malaguide Complex was the upper part of an orogenic
pile that was thinned by Miocene detachments. In order to reconcile
the partially reset fission-track data obtained by Platt et al. (2003),
we propose that the Malaguide Complex and the Los Reales nappe
comprise a unique crustal domain, which underwent several extensional
206
Pb/238U age in brackets.
events from Oligocene times onwards as is evidenced by pre-Miocene
(older than 25 Ma) and Miocene (younger than 25 Ma) low-angle
normal faults developed at brittle–ductile and brittle conditions, respectively (Fig. 7).
6. Discussion
The AMB and its eastern equivalents are widely recognized as extensional detachments, according to structural and metamorphic
criteria. The shear zones located along this boundary present structures developed in brittle–ductile conditions (Lonergan and Platt,
1995; Tubía and Navarro-Vilá, 1984; Tubía et al., 1993), which confirm that the Malaguide Complex was tectonically stacked over the
Los Reales nappe before the rocks were cooled down to the zircon closure temperature, >260 °C (Foster et al., 1996) or even as high as
360 °C depending on the cooling rate (e.g. Bernet, 2009). Moreover,
the different ZFT ages obtained in the vicinity of the dykes and their
positive correlation with their structural position also suggest that
the country rock zircons were not affected by annealing during the
dolerite dyke swarm intrusion. The lack of such ZFT annealing could
be due to the fact that: a) the dyke intrusion took place when the
country rocks were at temperatures above the zircon fission-track
Fig. 5. Tera-Wasserburg diagram for Cenozoic zircon ages.
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
185
Table 2
Zircon fission-track data from the Los Reales nappe (LR) and Malaguide Complex (MC). Data from tb-733, tb-734 and tb-735 have been taken from Esteban et al. (2007). Sample
locations are shown in Figs. 1 and 2.
Sample
Geographic location
Lithology
Altitude
(m)
Grains
Counted
ρd (Nd)
(106/cm2)
ρs (Ns)
(106/cm2)
ρi (Ni)
(106/cm2)
U
(ppm)
PX2 (%)
Var (%)
Central Age
(1σ)
DK-1.2
DK-1.3
DK-2.3
DK-3.3
DK-5.2
DK-5.3
DK-6.1
DK-7.1
DK-7.4
Tb-733
Tb-734
Tb-735
36°35′15.81″ N 4°42′25.45″ W
36°35′15.81″ N 4°42′25.45″ W
36°47′3.65″ N 4°25′54.92″ W
36°47′54.37″ N 4°26′32.21″ W
36°48′26.48″ N 4°26′19.65″ W
36°48′26.48″ N 4°2619.65″ W
36°48′40.90″ N 4°22′9.49″ W
36°48′45.24″ N 4°22′4.71″ W
36°48′45.24″ N 4°22′4.71″ W
36°27′35.86″ N 5°13′33.88″ W
36°27′32.80″ N 5°13′36.21″ W
36°27′31.56″ N 5°13′36.18″ W
Schist (LR)
Schist (LR)
Schist (MC)
Phyllite (MC)
Schist (MC)
Schist (MC)
Greywacke (MC)
Greywacke (MC)
Greywacke (MC)
Chloritite (LR)
Chloritite (LR)
Chloritite (LR)
171
171
118
285
196
196
928
930
930
439
426
425
8
13
9
22
19
19
7
24
13
16
24
17
3.799
3.759
3.678
3.637
3.597
3.516
3.435
3.354
3.989
2.948
2.827
2.786
22.105 (252)
20.000 (396)
28.436 (261)
38.631 (1205)
47.556 (1142)
37.569 (1113)
33.541 (275)
38.397 (1034)
35.075 (2899)
50.243 (2899)
99.942 (2156)
79.011 (3516)
20.526 (234)
19.394 (384)
24.600 (225)
27.763 (866)
37.686 (905)
31.324 (928)
24.149 (198)
27.554 (742)
22.140 (380)
40.659 (2346)
76.625 (1684)
55.798 (2483)
171
179
213
246
340
284
265
285
225
440
854
655
99
86
57
93
95
25
79
3
69
82
15
38
0
0
0
0
0
0
0
0
0
0
0
0
20.9
19.8
21.7
25.8
23.1
21.6
24.3
24.1
24.1
18.6
18.8
20.1
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
(2042)
±
±
±
±
±
±
±
±
±
±
±
±
2.0
1.6
2.1
1.5
1.3
1.3
2.2
1.8
1.8
0.9
1.0
0.9
Zircon fission-track data: ρd: density of tracks in the glass dosimeter, Nd: number of tracks counted in the glass dosimeter, ρs: spontaneous tracks density, Ns: number of
spontaneous tracks counted, ρi: induced track density, Ni: number of induced tracks counted, U: uranium content in the sample, PX2: probability of obtaining X2-values for ν
degreees of freedom, where ν is the numbers of crystal-1, Var: variation. Ages were calculated using dosimeter glasses CN-1 (zircon). Analyser (Esteban) ζ values were ζCN-1:
102.1 ± 3.0.
annealing window (>260 °C) and both, dykes and country rocks,
were later cooled together or b) if the intrusion took place after the
country rocks have passed the zircon fission-track annealing window
(b260 °C), the heat issued from the dykes was not enough to cause
partial annealing of the ZTF. The second option can be discarded because the calculated intrusion age, 33 Ma, of the dolerite dykes is
older than ZFT cooling ages. Besides, the dykes are cut by the AMB
and therefore, they predate this detachment.
The extensional collapse of the Betic Cordilleras, explained by processes as different as convective removal of the lithosphere (Platt and
Vissers, 1989; Turner et al., 1999), lithospheric delamination (Docherty
and Banda, 1995; García-Dueñas et al., 1992), back-arc extension
(Jolivet et al., 2008; Lonergan and White, 1997) or slab roll-back
(Duggen et al., 2004), is generally proposed to be Late Oligocene to
Early Miocene in age (33–19 Ma) based on poorly constrained Ar/Ar
data of the oldest Alpine magmatic activity recognized in the Internal
Zones of Betic Cordilleras (Duggen et al., 2004; Torres-Roldán et al.,
1986; Turner et al., 1999). Thermal models (Comas et al., 1999; Platt
and Whitehouse, 1999; Platt et al., 1998, 2003) suggest that the extension should have started during the late Oligocene, 27 Ma (Platt and
Whitehouse, 1999) or 25 Ma ago (Platt et al., 2003). However, no direct
observations of extensional tectonics at that time have been proposed
until the present work. In this regard, we suggest that the extensional
collapse of the Betic Cordilleras probably started before the intrusion
of the dolerite dyke at 33 Ma and the severe thinning of the crust was
mainly accomplished between 33 and 25 Ma. The available geochronological data of the Alpujarride Complex reveal that most of the cooling
ages are clustered around 22–20 Ma representing the HT peak. Consequently, a minimum time span of 10 m.y. between the starting of the
extensional collapse and the related HT-LP metamorphism can be
established. This fact suggests that between 33 and 25 Ma the exhumation of the Alpujarride–Malaguide was mainly accomplished by ductile–
brittle thinning. The thinning was coeval with the upwelling of the
asthenosphere, which will bring up the isotherms leading to the
Miocene thermal peak and the resetting of the geochronometers
(from U–Pb to FT) from the lowest part of the Los Reales nappe up to
the lower part of the Malaguide Complex.
The age-structural position disruption (Fig. 6c), characterized by
Palaeozoic and Mesozoic ZFT ages in the hanging wall and Cenozoic ZFT
ages in the footwall of the Malaguide Complex, were already interpreted
by Platt et al. (2003, 2005) as evidence for extensional Miocene tectonics
in the Montes de Malaga region. This explanation agrees with our observations, as the intra-Malaguide Complex extensional detachment must
be younger than 25 Ma (Fig. 7). Similar extensional timing around 19
to 17 Ma has been also identified for the Cerro Tajo fault, a tilted
extensional fault in the western Los Reales nappe (Esteban et al., 2004).
As the AMB detachment and the Cerro Tajo fault yield a similar extensional timing, we tentatively suggest that both shear zones could be ascribed to the same event.
The ZFT ages obtained in this work are quite different from those
of Johnson (1993) for a lower grade metamorphic equivalent of the
AMB, in the Sierra de Las Estancias, located in the eastern part of
the Betic Cordilleras. Johnson (1993) interpreted his FT data as indicators of an extensional motion along the boundary in late Oligoceneearlier Miocene time. For Lonergan and Platt (1995), in the same eastern region, the concordant apatite and ZFT ages led them to suggest
that the displacement on the Sierra de Las Estancias detachment took
place in early Miocene time (~18 Ma), as it does with the intraMalaguide detachment. In our opinion, a late reactivation of the Sierra
de Las Estancias boundary could explain the span of 6 m.y. between
the AMB from the west to the eastern regions. Therefore, according to
the concordance of the post-25 Ma age with the frequently observed
age of 18 Ma for the extensional tectonics within the Los Reales nappe
and for the reactivation of the Sierra de Las Estancias boundary, we propose that the Malaguide Complex has recorded at least two stages of
crustal thinning: the first between 33 and 25 Ma, related to the emplacement of the Malaguide Complex over the Los Reales nappe, and
the second of Miocene age (~18 Ma) associated with the development
of intra-Malaguide Complex faults.
We suggest here that the age of 33 Ma (see above), might point to
dyke intrusion during a pre-Miocene extensional event. This interpretation agrees with structural evidence suggesting that the dykes were
affected by the extensional deformation, while they were still hot
enough to be folded (Fig. 3c). Based on isotope and trace geochemistry,
Turner et al. (1999) consider that the Malaguide dykes come from
decompression melting within the asthenosphere following removal
of lithospheric mantle. Although the timing of the asthenospheric upwelling has not been addressed in detail, some works propose Early
Miocene ages for this geodynamic process (Argles et al., 1999; Platt et
al., 2003) or Oligocene-Miocene (Esteban, 2005; Tubía et al., 2004).
These works are based mainly on geochronological studies trying to
date the emplacement of the Ronda peridotites, which occurred around
22 Ma (Esteban et al., 2011; Priem et al., 1979; Sánchez-Rodríguez and
Gebauer, 2000; Zindler et al., 1983).
Two nearly perpendicular directions of extension arise if the dyke systems from the Los Reales and the Malaguide Complex are interpreted as
Andersonian intrusions. In the present location of the Betic Cordilleras, a
N–S extension is deduced from the dominant eastward strike of the
dykes emplaced in the Malaguide Complex. In contrast, the N10 °E
dykes from the underlying Los Reales nappe are consistent with an
186
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
(Tubía et al., 1993) and that an E-directed extension is commonly observed in the low-angle normal faults of the region (Cuevas et al.,
2001). Palaeomagnetic studies on these dolerite dykes have obtained
clockwise rotations in excess of 110° (Calvo et al., 2001; Platzman et
al., 2000). Similar rotations have been found in dykes from the
Malaguide Complex and the Los Reales nappe (Calvo et al., 2001),
which suggests that the nearly perpendicular orientations of these
two dyke systems is a primary, intrusion-related structural feature.
The older extensional deformation has been related to the upwelling
of the asthenosphere subsequent to lithospheric delamination (Tubía
et al., 2004). This interpretation, which is consistent with the mantellic
origin of the magma (Turner et al., 1999), allows to explain the presence
of dykes in the Malaguide Complex and in the metamorphic cover of
Los Reales nappe and its lack in the underlying Alpujarride nappes,
since the overthrusting of the Los Reales nappe over the underlying
Alpujarride nappes postdate the upwelling of the asthenosphere
(Tubía et al., 2004). From the regional point of view, the Betic–Rifian
belt is subjected to a protracted NNW–SSE convergence between the
African and Iberian plates from Cretaceous times (Dewey et al., 1989).
Such a tectonic setting would favour a short-lived asthenosphere upwelling and the final consecution of transpressional conditions (Tubía
et al., 2004). In this context, the second extensional event described
here could express gravity-driven tectonics in the toe of the extruding
lithospheric wedge.
7. Conclusions
- U–Pb SHRIMP data suggest that the intrusion of dolerite swarm
dykes, connected with mantle partial melts produced during the
upwelling of the asthenosphere in response to lithospheric delamination, could be of Oligocene age (33.1 Ma).
- The structural emplacement of Malaguide Complex over the Los
Reales nappe along an extensional detachment is constrained to
the 33–25 Ma span.
- A minimum time span of 10 m.y. can be established between the
onset of the extensional collapse and widespread Aquitanian HT-LP
metamorphism.
- The Malaguide Complex and Los Reales nappe were cooled as an
already juxtaposed and thinned tectonic domain at least from Oligocene (~25 Ma) to Miocene (~18 Ma) time.
- The presence of a disruption in the ZFT age-structural relationship
within the rocks of the Malaguide Complex suggests the existence
of a second post-25 Ma extensional tectonic event. The age of the
second extensional tectonic event can be estimated at around
18 Ma, based on the widely distribution of this age in the Los Reales
nappe and in the Sierra de Las Estancias detachment, in the eastern
Betic Cordilleras.
Acknowledgements
We thank the carefully and constructive reviews of Drs. Argles and
Negro and the editorial work of Dr. Liu that have contributed to improve
the manuscript. The financial support was obtained from the Ministerio
de Ciencia e Innovación (CGL2010-14869 and CGL2011-23755) of Spain
and from the Basque Government (IT364-10).
Fig. 6. Zircon fission-track ages plotted against (a) altitude and (b) relative structural
position of the Los Reales nappe and Malaguide Complex. (c) Zircon fission-track
ages and their relative structural position for the analysed samples (dots) and for those
of the upper members of the Malaguide Complex (squares) obtained by Platt et al. (2003).
Appendix A. Supplementary data
ESE–WNW extension. It is interesting to note that in the study region
the stretching lineation associated with the extensional deformation
in the metamorphic cover of the Los Reales nappe trends to N110 °E
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tecto.2013.05.027.
These data include Google maps of the most important areas described
in this article.
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
187
Fig. 7. Synthetic illustration of the Los Reales nappe and Malaguide Complex with the relative structural position and zircon fission-track ages. Ages in white were the obtained in
this work, whereas those in light-grey were those obtained by Esteban et al. (2004) in the Los Reales nappe and by Platt et al. (2003) in the Malaguide Complex. The figure summarizes the
extensional evolution proposed in this work.
References
Agard, J., Destombes, J., Milliard, Y., Morin, P., 1958. Sur l'existence de Llandovery
supérieur dans le massif paléozoique interne du Rif au N de Tetouan (Maroc
septentrional). Comptes Rendus de l'Académie des Sciences, Paris 246,
2778–2780.
Aguado, R., Gea, G.A., Ruiz-Ortiz, P.A., 1990. Nuevos datos sobre la edad de las
formaciones miocenas transgresivas sobre las Zonas Internas Béticas: la Formación
de San Pedro de Alcántara (Provincia de Málaga). Revista de la Sociedad Geológica
de España 3, 79–85.
Aldaya, F., Álvarez, F., Galindo-Zaldivar, J., González-Lodeiro, F., Jabaloy, A., Navarro-Vilá, F.,
1991. The Malaguide–Alpujarride contact (Betic Cordilleras, Spain): a brittle extensional detachment. (série II) Comptes Rendus de l'Académie des Sciences, Paris 313,
1447–1453.
Álvarez, F., Aldaya, F., Navarro-Vilá, F., 1989. Miocene extensional deformations in the
region of Águilas-Mazarrón (Eastern Betic Cordilleras). Estudios Geológicos 45,
369–374.
Argles, T.W., Platt, J.P., Waters, D.J., 1999. Attenuation and excision of a crustal section
during extensional exhumation: the Carratraca Massif, Betic Cordillera, Southern
Spain. Journal of the Geological Society of London 156, 149–162.
Azéma, J., 1961. Étude géologique des abords de Málaga (Espagne). Estudios Geológicos
17, 131–160.
Bernet, M., 2009. A field-based estimate of the zircon fission-track closure temperature.
Chemical Geology 259, 181–189.
Black, L.P., Kamo, S.L., Allen, C.M., Aleinikoff, J.N., Davis, D.W., Korsch, R.J., Foudoulis, C.,
2003. Temora 1: a new zircon standard for Phanerozoic U–Pb geochronology.
Chemical Geology 200, 155–170.
Calvo, M., Cuevas, J., Tubía, J.M., 2001. Preliminary palaeomagnetic results on
Oligocene-early Miocene mafic dykes from southern Spain. Tectonophysics 332,
333–345.
Chalouan, A., Michard, A., 1990. The Ghomarides Nappes, Rif Coastal Range, Morocco: a
Variscan chip in the Alpine Belt. Tectonics 9, 1565–1583.
Comas, M.C., Platt, J.P., Soto, J.I., Watts, A.B., 1999. The origin and tectonic history of the
Alboran basin: insights from leg 161 results. Proceeding of the Ocean Drilling Program,
Scientific Results 161, 555–580.
Cuevas, J., Navarro-Vilá, F., Tubía, J.M., 2001. Evolución estructural poliorogénica del
Complejo Maláguide (Cordilleras Béticas). Boletín Geológico y Minero 112, 47–58.
de Orueta, D., 1917. Estudio geológico y petrográfico de la Serranía de Ronda. Memorias
del Instituto Geológico y Minero de España 28, 571.
Dewey, J.F., Helman, M.L., Turco, E., Hutton, D.W.H., Knott, S.D., 1989. Kinematics of the
western Mediterranean. In: Coward, M.P., Dietrich, D., Park, R.G. (Eds.), Alpine Tectonics:
Geological Society, London, Special Publications, 45, pp. 265–283.
Docherty, C., Banda, E., 1995. Evidence for eastward migration of the Alboran Sea based
on regional subsidence analysis: a case for basin formation by delamination of the
subcrustal lithosphere? Tectonics 14, 804–818.
Duggen, S., Hoernle, K., van den Bogaard, P., Harris, C., 2004. Magmatic evolution of the
Alboran region: the role of subduction in forming the western Mediterranean and
causing the Messinian Salinity Crisis. Earth and Planetary Science Letters 218,
91–108.
Durand-Delga, M., Feinberg, H., Magné, J., Olivier, P., Anglada, R., 1993. Les formations
oligo-miocènes discordantes sur les Malaguides et les Alpujarrides et leurs implications dans l'évolution géodynamique des Cordillères Bétiques (Espagne) et de
la Méditerranée d' Alboran. Comptes Rendus de l'Académie des Sciences, Paris
317, 679–687.
188
J.J. Esteban et al. / Tectonophysics 603 (2013) 179–188
Esteban, J.J., 2005. Evolución estructural de los macizos ultramáficos de Carratraca (Málaga):
influencia de la serpentinización. Servicio de Publicaciones de la Diputación de Málaga
376.
Esteban, J.J., Sánchez-Rodríguez, L., Seward, D., Cuevas, J., Tubía, J.M., 2004. Late thermal
history of the Ronda area, southern Spain. Tectonophysics 398, 81–92.
Esteban, J.J., Cuevas, J., Tubía, J.M., Liati, A., Seward, D., Gebauer, D., 2007. Timing and
origin of zircon-bearing chlorite schists in the Ronda peridotites (Betic Cordilleras,
Southern Spain). Lithos 99, 121–135.
Esteban, J.J., Cuevas, J., Tubía, J.M., Sergeev, S., Larionov, A., 2011. A revised Aquitanian
age for the emplacement of the Ronda peridotites (Betic Cordilleras, southern
Spain). Geological Magazine 48, 183–187.
Fernández-Fernández, E.M., Jabaloy-Sánchez, A., Nieto, F., González-Lodeiro, F., 2007.
Structure of the Maláguide Complex near Vélez Rubio (Eastern Betic Cordillera,
SE Spain). Tectonics 26 (TC4008).
Foster, D., Kohn, B., Gleadow, A.J.W., 1996. Sphene and zircon fission track closure temperatures revisited: empirical calibration from 40Ar/39Ar diffusion studies of Kfeldspar and biotite. 8th International Workshop on Fission-Track Dating. University of Ghent, Belgium, p. 37.
Galbraith, R.F., 1981. On statistical models for fission track counts. Mathematical Geology
13, 471–478.
García-Dueñas, V., Martínez-Martínez, J.M., Navarro-Vilá, F., 1986. La zona de falla de
Torres Cartas, conjunto de fallas normales de bajo ángulo entre Nevado-Filábrides,
Alpujárrides (Sierra Alhamilla, Béticas Orientales). Geogaceta 1, 17–19.
García-Dueñas, V., Balanyá, J.C., Martínez-Martínez, J.M., 1992. Miocene extensional
detachments in the outcropping basement of the northern Alboran Basin (Betics)
and their tectonic implications. Geo-Marine Letters 12, 88–95.
Geel, T., 1973. The geology of the Betic of Málaga, the Subbetic, and the zone between
these two units in the Vélez-Rubio area (southern Spain). (Ph.D. Thesis) GUA papers
on Geology, 5. University of Amsterdam (179 pp.).
Herbig, H.G., 1983. El Carbonífero de las Cordilleras Béticas. In: Marínez Díaz, C. (Ed.),
Carbonífero y Pérmico de España. Ministerio de Industría y Energía, Madrid, pp. 343–355.
Hurford, A.J., Green, P.F., 1983. The zeta age calibration of fission track dating calibration.
Isotope Geoscience 1, 285–317.
Jabaloy, A., Galindo-Zaldivar, J., González-Lodeiro, F., 1992. The Mecina extensional system:
its relation with the Post-Aquitanian Piggy-Back Basins and the Paleostresses Evolution (Betic Cordilleras, Spain). Geo-Marine Letters 12, 96–103.
Johnson, C., 1993. Contrasted thermal histories of different nappe complexes in SE
Spain: evidence for complex crustal extension. In: Séranne, M., Malavielle, J.
(Eds.), Late Orogenic Extension in Mountain Belts: Doc. BGRM Fr., 209, p. 103.
Johnson, C., Harbury, N., Hurford, A.J., 1997. The role of extension in the Miocene denudation
of the Nevado–Filábride Complex, Betic Cordillera (SE Spain). Tectonics 16, 189–204.
Jolivet, L., Augier, R., Faccenna, C., Negro, F., Rimmele, G., Agard, P., Robin, C., Rossetti, F.,
Crespo-Blac, A., 2008. Subduction, convergence and the mode of backarc extension
in the Mediterranean region. Bulletin de la Société Géologique de France 179,
525–550.
Jutson, D.J., 1980. Oligo-Miocene benthonic foraminifera from Barranco Blanco, province
of Almeria, SE Spain. Revista de la Sociedad Española de Micropaleontología 12,
365–381.
Kockel, F., 1963. Der Geologie des Gebietes zwischen dem Rio Guadalhorce und dem
Plateau von Ronda (Südspanien). Geologie Jahrb 81, 413–480.
Larionov, A.N., Andreichev, V.A., Gee, D.G., 2004. The Vendian alkaline igneous suite of
northern Timan: ion microprobe U–Pb zircon ages of gabbros and syenite. In: Gee,
D.G., Pease, V.L. (Eds.), The Neoproterozoic Timanide Orogen of Eastern Baltica. : ,
30. Geological Society, London, pp. 69–74 (Memoirs).
Lonergan, L., Platt, J.P., 1995. The Malaguide–Alpujarride boundary: a major extensional
contact in the Internal Zone of the eastern Betic Cordillera, SE Spain. Journal of Structural Geology 17, 1655–1671.
Lonergan, L., White, N., 1997. Origin of the Betic–Rif mountain belt. Tectonics 16, 504–522.
Ludwig, K.R., 2005a. SQUID 1.13a a user's manual. A Geochronological Toolkit for
Microsoft Excel. : Berkeley Geochronology Center Special Publication 22.
Ludwig, K.R., 2005b. User's manual for ISOPLOT/Ex 3.22. A Geochronological Toolkit for
Microsoft Excel. Berkeley Geochronology Center Special Publication, p. 71.
Mäkel, G.H., 1985. The geology of the Malaguide Complex and its bearing on the
geodynamic evolution of the Betic–Rif Orogen (Southern Spain and Northern Morocco).
, 22. University of Utrech, GUA papers on Geology 263 (Ph.D. Thesis).
Martín-Algarra, A., Estévez, A., 1984. La Brèche de la Nava: depot continental de la structuration pendant le Miocène inférieur des zones internes de l'Ouest des Cordillères
Bétiques. Comptes Rendus de l'Académie des sciences, Paris 120, 177–185.
Monié, P., Torres-Roldán, R.L., García-Casco, A., 1994. Cooling and exhumation of the
Western Betic Cordilleras, 40Ar/39Ar thermochronological constraints on a collapsed
terrane. Tectonophysics 238, 353–379.
Navarro-Vilá, F., Tubía, J.M., 1983. Essai d'une nouvelle différenciation des Nappes
Alpujarrides dans le secteur occidental des Cordillères Bétiques (Andalousie, Espagne).
(série II) Comptes Rendus de l'Académie des Sciences, Paris 296, 111–114.
Navarro-Vilá, F., Cuevas, J., Esteban, J.J., Tubía, J.M., 2007. Reorganización de las Zonas
Internas del tercio occidental de las Cordilleras Béticas: criterios e implicaciones
tectónicas. Revista de la Sociedad Geológica de España 20, 201–210.
Negro, F., Beyssac, O., Goffé, G., Saddiqi, O., Bouybaouène, M.L., 2006. Thermal structure
of the Alboran Domain in the Rif (northern Morocco) and the Western Betics
(southern Spain). Constraints from Raman spectroscopy of carbonaceous material.
Journal of Metamorphic Geology 24, 309–327.
Platt, J.P., 2007. From orogenic hinterlands to Mediterranean-style back-arc
basins: a comparative analysis. Journal of the Geological Society of London 164,
297–311.
Platt, J.P., Vissers, R.L.M., 1989. Extensional collapse of thickened continental lithosphere. A
working hypothesis for the Alboran Sea and Gibraltar Arc. Geology 17, 540–543.
Platt, J.P., Whitehouse, M.J., 1999. Early Miocene high-temperature metamorphism and
rapid exhumation in the Betic Cordillera (Spain): evidence from U–Pb zircon ages.
Earth and Planetary Science Letters 171, 591–605.
Platt, J.P., Soto, J.I., Whitehouse, M.J., Hurford, A.J., Kelley, S.P., 1998. Thermal evolution,
rate of exhumation, and tectonic significance of metamorphic rocks on the floor of
the Alboran extensional basin, western Mediterranean. Tectonics 17, 671–689.
Platt, J.P., Argles, T.W., Carter, A., Kelley, S.P., Whitehouse, M.J., Lonergan, L., 2003.
Exhumation of the Ronda peridotite and its crustal envelope: constraints from
thermal modelling of a P–T-time array. Journal of the Geological Society of London
160, 655–676.
Platt, J.P., Kelly, S.P., Carter, A., Orozco, M., 2005. Timing of tectonic events in the
Alpujarride Complex, Betic Cordillera, southern Spain. Journal of the Geological Society
of London 162, 451–462.
Platzman, E., Platt, J.P., Kelly, S.P., Allerton, S., 2000. Large clockwise rotation in an extensional allochthon, Alboran Domain (southern Spain). Journal of the Geological
Society of London 157, 1187–1197.
Priem, H.N.A., Boelrijk, N.A.I.M., Hebeda, E.H., Oen, I.S., Verdurmen, E.A.Th., Verschure, R.H.,
1979. Isotopic dating of the emplacement of the ultramafic masses in the Serrania de
Ronda, Southern Spain. Contributions to Mineralogy and Petrology 70, 103–109.
Sánchez-Rodríguez, L., 1998. Pre-Alpine and Alpine evolution of the Ronda Ultramafic
Complex and its country rocks (Betic chain, southern Spain): U–Pb SHRIMP zircon
and fission-track dating. ETH, Zurich 152 (Ph.D. Thesis).
Sánchez-Rodríguez, L., Gebauer, D., 2000. Mesozoic formation of pyroxenites and
gabbros in the Ronda area (southern Spain), followed by Early Miocene subduction
metamorphism and emplacement into the middle crust: U–Pb sensitive highresolution ion microprobe dating of zircon. Tectonophysics 316, 19–44.
Seward, D., 1989. Cenozoic basin histories determined by fission track dating of basement granites, south Island, New Zealand. Chemical Geology 19, 501–531.
Sosson, M., Morillon, A.C., Bourgois, J., Feraud, G., Poupeau, G., Saint-Marc, P., 1998. Late
exhumation stages of the Alpujarride Complex (western Betic Cordilleras, Spain):
new thermochronological and structural data on Los Reales and Ojen nappes.
Tectonophysics 285, 253–273.
Stacey, S., Kramers, J.D., 1975. Approximation of terrestrial lead isotope evolution by a
two-stage model. Earth and Planetary Science Letters 26, 207–221.
Steiger, R.H., Jäger, E., 1977. Subcommission on geochronology: convention on the use of
decay constants in geo- and cosmochronology. Earth and Planetary Science Letters
36, 359–362.
Torres-Roldán, R.L., Poli, G., Peccerillo, A., 1986. An Early Miocene arc-tholeiitic magmatic dike event from the Alboran Sea-Evidence for precollisional subduction
and back-arc crustal extension in the westernmost Mediterranean. Geologische
Rundschau 75, 219–234.
Tubía, J.M., 1988. Estructura de los Alpujárrides occidentales: Cinemática y condiciones
de emplazamiento de las peridotitas de Ronda. Publicaciones Especiales del Boletín
Geológico y Minero, Madrid 124.
Tubía, J.M., Navarro-Vilá, F., 1984. Criterios para la diferenciación entre los esquistos de
grado medio del Complejo Maláguide y del Manto de Los Reales al W de Málaga. La
posición del contacto de corrimiento, in: El borde mediterráneo español: evolución
del Orógeno Bético y geodinámica de las depresiones neógenas, Granada, pp. 33–34.
Tubía, J.M., Navarro-Vilá, F., Cuevas, J., 1991. La evolución tectonometamórfica del
Manto de Los Reales y el Maláguide, al oeste de Málaga. Geogaceta 10, 141–143.
Tubía, J.M., Navarro-Vilá, F., Cuevas, J., 1993. The Malaguide–Los Reales nappe: an example of crustal thinning related to the emplacement of the Ronda peridotites
(Betic Cordillera). Physics of the Earth and Planetary Interiors 78, 343–354.
Tubía, J.M., Cuevas, J., Esteban, J.J., 2004. Tectonic evidence in the Ronda peridotites,
Spain, for mantle diapirism related to delamination. Geology 32, 941–944.
Turner, S.P., Platt, J.P., George, R.M.N., Kelley, S.P., Pearson, D.G., Novell, G.M., 1999.
Magmatism associated with orogenic collapse of the Betic–Alboran Domain, SE
Spain. Journal of Petrology 40, 1011–1036.
Wiedenbeck, M., Allé, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., Von Quadt, A.,
Roddick, J.C., Spiegel, W., 1995. Three natural zircon standards for U–Th–Pb, Lu–
Hf, trace element and REE analyses. Geostandards Newsletter 19, 1–23.
Wingate, M.T.D., 2001. SHRIMP baddeleyite and zircon ages for an Umkondo dolerite
sill, Nyanga Mountains, Eastern Zimbabwe. South African Journal of Geology 104,
13–22.
Zeck, H.P., Monié, P., Villa, I., Hansen, B.T., 1992. Very high rates of cooling and uplift in
the Alpine belt of the Betic Cordilleras, southern Spain. Geology 20, 79–82.
Zindler, A., Staudigel, H., Hart, S.R., Endres, R., Goldstein, S., 1983. Nd and Sr isotopic
study of a mafic layer from Ronda ultramafic complex. Nature 304, 226–230.