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135 ultrama fi cs, and minor granitoids ( Arenas et al., 2007a; Díaz García et al., 1999; Sánchez Martínez et al., 2009 ). These sequences were strongly de- formed and metamorphosed under low- to medium-P greenschist and amphibolite facies conditions during the Variscan orogeny ( Arenas and Sánchez Martínez, 2015 , and references therein). The upper allochthonous units are constituted by metasedimentary rocks, large massifs of granitic orthogneisses and gabbros, some ultra- ma fi c massifs, and minor lenses of ma fi c rocks (e.g., Albert et al., 2012; Andonaegui et al., 2012; Fuenlabrada et al., 2010; Girardeau and Ibarguchi, 1991; Gómez Barreiro et al., 2007 ). These tectonic units show a two-layer structure regarding their metamorphic imprint. The uppermost section recorded intermediate-P metamorphism, whereas the lower section attained high-P and high-T conditions during the ini- tial stages of the Variscan orogeny (ca. 400 Ma; Fernández-Suárez et al., 2007; Gil Ibarguchi et al., 1990; Ordóñez Casado et al., 2001 ). 2.2.2. Lithostratigraphy of the basal and ophiolitic allochthonous units The lower sequence of the basal allochthonous units of NW Iberia includes albite-bearing schists and paragneisses and banded metagreywackes (Bouma cycles), some quartzites, amphibolites, orthogneisses, and minor calc-silicate layers, whereas the uppermost sequence is dominated by mica schists, with minor graphite-bearing schists, metabasites, calc-silicate layers, and metacherts. The maximum age of deposition (as constrained from detrital zircon) of the sedimen- tary protoliths of these series is late Ediacaran (ca. 560 – 550 Ma) and Middle-Late Cambrian (ca. 512 – 480 Ma), respectively ( Díez Fernández et al., 2010, 2013 ). The crystallization age of the igneous rocks intruding the series (orthogneisses and amphibolites) ranges between Middle-Late Cambrian and Ordovician ( Abati et al., 2010; Díez Fernández et al., 2012a; Montero et al., 2009 ). The ophiolitic units can be grouped according to their age and relative structural position. The lower ophiolitic units consist of either a thick sequence of metabasites (greenschists) intercalated with some metasedimentary rocks (mica schists and phyllites) and rare tonalitic orthogneisses (ca. 500 Ma, Vila de Cruces Ophiolite; Arenas et al., 2007b ), or a ca. 4000 m thick sequence of metagabbros and minor ultrama fi c rocks (ca. 495 Ma, Bazar Ophiolite; Sánchez Martínez et al., 2012 ). The upper ophiolitic units are Middle Devonian (ca. 395 Ma) in age and represent amphibolites after gabbroic rocks (Purrido Ophiolite; Sánchez Martínez et al., 2006, 2011 ), or peridotites and deformed gabbros intruded by stocks of pegmatoids, gabbros, and doleritic dykes (Careón Ophiolite; Díaz García et al., 1999; Sánchez Martínez et al., 2007b ), or a sequence of greenschists with few lenses of metagabbroic rocks, and some alternations of phyllites and rare serpentinite pods (Moeche Ophiolite; Arenas et al., 2014b; Sánchez Martínez et al., 2007a ). NossaSra. daBoaFé Santiago do Escoural S.Brissos 70 20 30 10 10 20 25 60 50 40 40 50 40 40 35 40 40 30 20 20 70 40 50 60 50 60 60 70 50 50 65 50 60 70 40 50 50 60 40 30 60 50 70 35 60 20 70 40 20 20 30 20 30 30 60 60 40 20 60 70 60 70 50 70 60 60 50 30 10 40 60 50 30 40 58 40 70 70 70 70 60 50 60 85 80 70 50 60 50 80 70 80 60 80 70 70 80 80 50 A B C D E F EV-1 EV-2 EV-3,5 EV-4,6,7 EV-8 EV-10,17 EV-11 4280 555 560 565 570 575 570 565 560 555 4275 4270 4265 4270 4275 4280 COVER CENOZOICAND QUATERNATY AUTOCHTHON Migmatites, gneisses, and metabasites Thrust Fault (subvertical) Synform (upright) SOUTH PORTUGUESE ZONE Metapelites and metavolcanics VARISCAN GRANITOIDS Tonalites, gabbros, diorites, granodiorites, and porphyroids Orthogneisses VARISCAN SYN-OROGENIC SEDIMENTS CABRELA BASIN Pelites, sandstones, greywackes, conglomerates, limestones, and volcanic rocks ALLOCHTHONOUS COMPLEXES OPHIOLITIC UNITS Greenschists and amphibolites Phyllites, mica schists, calc-silicate rocks, and metasandstones BASAL UNITS LOWER SEQUENCE Fine- to coarse-grained orthogneisses Amphibolites (garnet-bearing) Marbles (with lenses of metabasites and felsic gneisses) Calc-silicate rocks, metabasites, and meta-arcoses Black quartzites (metasandstones and metacherts?) Paragneisses (metagreywackes), schists, and black schists N 0 2 km Extensional detachment Antiform (upright) Main foliation Bedding 25 25 EV-X Rock samples Railway Road BASAL ALLOCHTHONOUS UNITS (Lower Sequence) ESCOURALUNIT MONFURADOUNIT (igneous and sedimentary complex) EV-1,11 EV-2,3,4,5,6,7 EV-8,10,17 (a) (b) (c) (d) ? ? CARVALHALUNIT (igneous and sedimentary complex) OPHIOLITIC UNITS A B C D E F Boa Fé shear zone Cabrela-Carvalhal synform Fig. 3. (a) Geological map, (b) composite cross-section and (c and d) idealized tectonostratigraphic columns of the Cabrela-Carvalhal synform (after Chichorro, 2006 ). The white dashed linesshowthetraceofindividualcross-sections,whicharereferredtoasA – B,C – D,andE – F.Locationofsamplesanalyzedforwhole-rockgeochemistryandSm – Ndisotopesisindicatedin the map and columns. 289 R.D. Fernández et al. / Lithos 268 – 271 (2017) 285 – 301