3. The Atlantic Domain located approximately to the west of Josephine Bank is
characterized by the Gloria transform fault (Argus et al. 1989), as demonstrated
by the earthquake focal mechanisms analyzed in the region (Buforn et al. 1988;
Custódio et al. 2016). This fault has a slightly curved geometry as corresponds to
the Africa-Eurasia sliding vector in this sector (Neres et al. 2016; Hensen et al.
2019). The Gloria fault connects to the west with the Azores triple divergent
junction between North America, Eurasia, and Africa. The Africa-Eurasia boundary (Terceira Ridge) is directed ESE and interpreted as a transfer-divergent
system (Fig. 5.1a) characterized by a transtensive (oblique divergence) regime
(Madeira and Ribeiro 1990; Madeira et al. 2015).
5.3.1 Western Mediterranean
The Western Mediterranean region features elongated Alpine orogenic belts, to both
the north and south, surrounding marine basins floored by thin continental or
Cenozoic oceanic lithospheres (Fig. 5.3). This region has undergone widespread
plate tectonic movements since the early Oligocene, comprising divergence and
convergence. This area’s complex geodynamic evolution entails plate subduction,
slab fragmentation, slab rollback and delamination (Lonergan and White 1997;
Faccenna et al. 2004; Jolivet et al. 2009; Carminati et al. 2012), escape (Chalouan
et al. 2006) and indentation tectonics (Estrada et al. 2018). These large-scale
lithospheric movements occurred within a context of continuous Africa-Eurasia
convergence (Dewey et al. 1989; Vissers and Meijer 2012) and caused intense
crustal deformation in the surrounding orogens (Jolivet et al. 2009). The Western
Mediterranean Alpine belt is constituted by several arched orogenic belts. In the
westernmost Mediterranean region, the Rif and the Betic Cordillera are connected
through the Gibraltar Arc and they extend to the Gulf of Cadiz, forming a tectonic/
gravitational wedge known as the Allochthonous Unit of the Gulf of Cadiz
(Medialdea et al. 2004). Northward, the Iberian Ranges and the Pyrenees constitute
the main alpine chains, which finally connect with the Alps. The Apennines constitute the eastern boundary and delineate a close orocline in the Calabrian Arc, finally
extending through northern Africa toward the Tell, in continuity with the Rif.
Development of the Western Mediterranean Alpine belt was mainly governed to
progressive southward slab retreat detachment associated with northwestward subduction of the former oceanic lithosphere attached to the African plate, and the
development of back-arc basins in an initial Eocene alpine orogenic phase (Cohen
1980; Rehault et al. 1985; Carminati et al. 1998a, 2012; Gueguen et al. 1998;
Rosenbaum et al. 2002a; Faccenna et al. 2004). After 35 Ma the northwestward
subduction and detachment process of the former oceanic Ligurian Tethys
(Carminati et al. 2012) caused extensional processes on the upper plate and formed
the Western Mediterranean basin since the early Oligocene. These processes separated and rotated (anti-clockwise) Corsica and Sardinia lithospheric blocks, thereby
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J.-T. Vázquez et al.
characterized by the Gloria transform fault (Argus et al. 1989), as demonstrated
by the earthquake focal mechanisms analyzed in the region (Buforn et al. 1988;
Custódio et al. 2016). This fault has a slightly curved geometry as corresponds to
the Africa-Eurasia sliding vector in this sector (Neres et al. 2016; Hensen et al.
2019). The Gloria fault connects to the west with the Azores triple divergent
junction between North America, Eurasia, and Africa. The Africa-Eurasia boundary (Terceira Ridge) is directed ESE and interpreted as a transfer-divergent
system (Fig. 5.1a) characterized by a transtensive (oblique divergence) regime
(Madeira and Ribeiro 1990; Madeira et al. 2015).
5.3.1 Western Mediterranean
The Western Mediterranean region features elongated Alpine orogenic belts, to both
the north and south, surrounding marine basins floored by thin continental or
Cenozoic oceanic lithospheres (Fig. 5.3). This region has undergone widespread
plate tectonic movements since the early Oligocene, comprising divergence and
convergence. This area’s complex geodynamic evolution entails plate subduction,
slab fragmentation, slab rollback and delamination (Lonergan and White 1997;
Faccenna et al. 2004; Jolivet et al. 2009; Carminati et al. 2012), escape (Chalouan
et al. 2006) and indentation tectonics (Estrada et al. 2018). These large-scale
lithospheric movements occurred within a context of continuous Africa-Eurasia
convergence (Dewey et al. 1989; Vissers and Meijer 2012) and caused intense
crustal deformation in the surrounding orogens (Jolivet et al. 2009). The Western
Mediterranean Alpine belt is constituted by several arched orogenic belts. In the
westernmost Mediterranean region, the Rif and the Betic Cordillera are connected
through the Gibraltar Arc and they extend to the Gulf of Cadiz, forming a tectonic/
gravitational wedge known as the Allochthonous Unit of the Gulf of Cadiz
(Medialdea et al. 2004). Northward, the Iberian Ranges and the Pyrenees constitute
the main alpine chains, which finally connect with the Alps. The Apennines constitute the eastern boundary and delineate a close orocline in the Calabrian Arc, finally
extending through northern Africa toward the Tell, in continuity with the Rif.
Development of the Western Mediterranean Alpine belt was mainly governed to
progressive southward slab retreat detachment associated with northwestward subduction of the former oceanic lithosphere attached to the African plate, and the
development of back-arc basins in an initial Eocene alpine orogenic phase (Cohen
1980; Rehault et al. 1985; Carminati et al. 1998a, 2012; Gueguen et al. 1998;
Rosenbaum et al. 2002a; Faccenna et al. 2004). After 35 Ma the northwestward
subduction and detachment process of the former oceanic Ligurian Tethys
(Carminati et al. 2012) caused extensional processes on the upper plate and formed
the Western Mediterranean basin since the early Oligocene. These processes separated and rotated (anti-clockwise) Corsica and Sardinia lithospheric blocks, thereby
118
J.-T. Vázquez et al.