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3. GEOLOGICAL FRAMEWORK
Fig. 26.
Detailed geological map of the southern part of the Somozas Mélange (Cabo Ortegal Complex), between the
Somozas and Moeche villages.
Unit (
c.
410-385 Ma), in a similar mafic granu-
lite of the Bacariza Formation (
c.
410-385 Ma)
and in a leucosome related to the post high-P
partial melting affecting the same formation (
c.
397-391 Ma) (Fernández-Suárez
et al.
, 2007). An
additional U-Pb zircon age of
c.
391 Ma has been
obtained in a non-retrogressed eclogite body in-
cluded in the Banded Gneisses Formation (LA-
ICP-MS; Albert
et al.
, 2013). Therefore, the real
age of the subduction must be contemporary or
somewhat younger than the oldest metamor-
phic ages obtained for rocks recording this event
(
c.
410-400 Ma). The age of exhumation of the
subduction complex was bracketed by means of
40
Ar/
39
Ar dating of retrogressive hornblende am-
phiboles associated to S
2
to the range 389-381 Ma
(Peucat
et al.
, 1990).
The reported ages indicate that the HP-HT
event and subsequent exhumation, are coeval
to the collisional event described for the overly-
ing IP Upper Units. It can be concluded that the
whole Early to Middle Devonian tectonometa-
morphic record of the Upper Units accounts for
a single collisional event, previous to Variscan
deformation
sensu lato
. Taking into account the
provenance deduced for the Upper Units, the
margin of Gondwana was one of the continents
involved in that eo-Variscan collision.
Somozas Mélange
The lowest part of the Cabo Ortegal Complex
is formed by a thick mélange unit, only repre-
sented in this position within the realm of the
allochthonous complexes of NW Iberia. The So-
mozas Mélange crops out in the eastern sector
of the Cabo Ortegal Complex (Fig. 3) and was
first described by Arenas
et al.
(1986), and then