of the Malaga dykes from a peridotitic (mantle) source through the subduction of
oceanic lithosphere (Torres-Roldan et al. 1986; Duggen et al. 2004).
Stage 2 It includes cordierite-bearing volcanic dacite at the Mar Menor, a granitic
volcanic clast from ODP Site 977 (Fig. 5.6), and intrusive igneous leucogranites
from southern Spain of early Miocene ages (Zeck et al. 1989). These rocks point to a
large-scale thermal event occurring in the Alboran region between 23 and 18.5 Ma.
There was a partial melting of continental crustal and these rocks formed through
crustal anatexis (Munksgaard 1984; Zeck et al. 1989) associated with nappe movement (Platt et al. 2003) during the collision of the Alboran block with the South
Iberian and North-African continental margins.
Stage 3 A low-K tholeiitic through high-K calc-alkaline series of volcanic rocks
erupted in the Alboran Sea region during the Middle to Late Miocene. Main volcanic
complexes onshore include Cabo de Gata, Ras Tarf and Trois Fourches; they
correspond to strike-slip fault-bounded blocks on the Alboran Sea margins (Coppier
et al. 1989; Aït Brahim and Chotin 1990; Martínez-Díaz and Hernández-Enrile
2004). It also includes most of the volcanic buildings located in the basin: banks
of Chella, Djibouti and E and W Cabliers, ridges of Adra, Alborán and Yusuf, and Al
Mansour seamount between them (Fig. 5.6). This stage corresponded to the greatest
volcanic activity in the basin, especially in the central and eastern sectors, and meant
a substantial modification of the seafloor. Age data for Alboran Sea volcanic rocks
range from 12.1 Æ 0.2 to 6.1 Æ 0.3 Ma (Al Mansour Seamount, Alboran, and Yusuf
Ridges, ODP 161 Site 977) (Hoernle et al. 1999; Duggen et al. 2008). The volcanism
is explained by subduction of oceanic lithosphere in the westward roll back model
(Hoernle et al. 1999; Zeck 1996; Duggen et al. 2003; Gill et al. 2004) and the release
of hydrous fluids and sediment melts from subducted lithosphere into the mantle
wedge beneath the Alboran Basin (Duggen et al. 2004).
Stage 4 The magmatic stage 3 ceased with the occurrence of Late Miocene to Early
Pliocene shoshonitic and lamproitic magmatism in Spain and Morocco (Hoernle
et al. 1999; Duggen et al. 2003; Gill et al. 2004) that shifted to an intraplate-type, and
finally Early Pliocene to Quaternary alkali basalt erupted in southeastern Spain and
northern Morocco (Hoernle et al. 1999; Duggen et al. 2003; El Azzouzi et al. 2014).
This stage has been explained in the context of a transition from subduction-related
to intraplate-type volcanism by lithospheric tearing in the borders of the subducting
slab that provides a possible mechanism to explain the shoshonitic volcanism by
local melting of the lithospheric mantle (Gill et al. 2004). An associated positive
thermal relief is also proposed that overlaps with the Messinian Salinity Crisis
(Duggen et al. 2003).
5 A Geological History for the Alboran Sea Region
125
oceanic lithosphere (Torres-Roldan et al. 1986; Duggen et al. 2004).
Stage 2 It includes cordierite-bearing volcanic dacite at the Mar Menor, a granitic
volcanic clast from ODP Site 977 (Fig. 5.6), and intrusive igneous leucogranites
from southern Spain of early Miocene ages (Zeck et al. 1989). These rocks point to a
large-scale thermal event occurring in the Alboran region between 23 and 18.5 Ma.
There was a partial melting of continental crustal and these rocks formed through
crustal anatexis (Munksgaard 1984; Zeck et al. 1989) associated with nappe movement (Platt et al. 2003) during the collision of the Alboran block with the South
Iberian and North-African continental margins.
Stage 3 A low-K tholeiitic through high-K calc-alkaline series of volcanic rocks
erupted in the Alboran Sea region during the Middle to Late Miocene. Main volcanic
complexes onshore include Cabo de Gata, Ras Tarf and Trois Fourches; they
correspond to strike-slip fault-bounded blocks on the Alboran Sea margins (Coppier
et al. 1989; Aït Brahim and Chotin 1990; Martínez-Díaz and Hernández-Enrile
2004). It also includes most of the volcanic buildings located in the basin: banks
of Chella, Djibouti and E and W Cabliers, ridges of Adra, Alborán and Yusuf, and Al
Mansour seamount between them (Fig. 5.6). This stage corresponded to the greatest
volcanic activity in the basin, especially in the central and eastern sectors, and meant
a substantial modification of the seafloor. Age data for Alboran Sea volcanic rocks
range from 12.1 Æ 0.2 to 6.1 Æ 0.3 Ma (Al Mansour Seamount, Alboran, and Yusuf
Ridges, ODP 161 Site 977) (Hoernle et al. 1999; Duggen et al. 2008). The volcanism
is explained by subduction of oceanic lithosphere in the westward roll back model
(Hoernle et al. 1999; Zeck 1996; Duggen et al. 2003; Gill et al. 2004) and the release
of hydrous fluids and sediment melts from subducted lithosphere into the mantle
wedge beneath the Alboran Basin (Duggen et al. 2004).
Stage 4 The magmatic stage 3 ceased with the occurrence of Late Miocene to Early
Pliocene shoshonitic and lamproitic magmatism in Spain and Morocco (Hoernle
et al. 1999; Duggen et al. 2003; Gill et al. 2004) that shifted to an intraplate-type, and
finally Early Pliocene to Quaternary alkali basalt erupted in southeastern Spain and
northern Morocco (Hoernle et al. 1999; Duggen et al. 2003; El Azzouzi et al. 2014).
This stage has been explained in the context of a transition from subduction-related
to intraplate-type volcanism by lithospheric tearing in the borders of the subducting
slab that provides a possible mechanism to explain the shoshonitic volcanism by
local melting of the lithospheric mantle (Gill et al. 2004). An associated positive
thermal relief is also proposed that overlaps with the Messinian Salinity Crisis
(Duggen et al. 2003).
5 A Geological History for the Alboran Sea Region
125