The aim of this article is to present a compilation of available information on the Évora Massif based on structural mapping, whole-rock geochemistry, recognition of metamorphic mineral assemblages, and geothermobarometry. In our view, trans-current movements responsible for strong orogen-parallel stretching were dominant and had a major role in the geodynamic evolution of this part of Ossa-Morena zone (southwest Iberian Massif). Cadomian and Variscan orogenic events separated by a period of intense rifting were the cause for the composite distribution of zones with contrasting metamorphic paths, the structural complexity, the variety of lithological associations, and the sequence of deformation events and magmatism. The proposed geodynamic reconstruction for this segment of the northern Gondwana continental margin includes three main stages in chronological order: (1) Neoproterozoic accretion and continental magmatic arc developing, dismantling, and reworking, followed by late-“orogenic” magmatism; (2) Lower Paleozoic crustal thinning, block tilting, and mantle upwelling, induced by generalized rifting, leading to the formation of marine basins with carbonate platform sediments and thick accumulations of volcaniclastic and terrigenous sediments, contemporaneous with normal and enriched mid-oceanic ridge basalt–type magmatism; and (3) Upper Paleozoic transpressional orogenesis resulting from obliquity of convergence and the geometry of the involved blocks. The third stage includes the tectonic inversion of Lower Paleozoic basins, crustal thickening, the exhumation of high- to medium-pressure rocks and partial exhumation of high-grade metamorphic lithologies (controlled by local transtension and major detachments), the formation of synorogenic basins filled with volcanic-sedimentary sequences, and finally, the emplacement of late Variscan granodiorites and granites.

Abstract Sensitive high-resolution ion microprobe U–Th–Pb age determinations on detrital and inherited zircon from the Évora Massif (SW Iberian Massif, Portugal) provide direct evidence for the provenance of the Ossa–Morena Ediacaran basins (Série Negra) and a palaeogeographical link with the West African craton. Three samples of the Série Negra paragneisses contain large components of Cryogenian and Ediacaran ( c . 700–540 Ma) detrital zircon, but have a marked lack of zircon of Mesoproterozoic ( c . 1.8–0.9 Ga) age. Older inherited zircons are of Palaeoproterozoic ( c . 2.4–1.8 Ga) and Archaean ( c . 3.5–2.5 Ga) age. The same age pattern is also found in the Arraiolos biotite granite, which was formed by partial melting of the Série Negra and overlying Cambrian rocks. These results are consistent with substantial denudation of a continental region that supplied sediments to the Ediacaran Ossa–Morena basins during the final stages of the Cadomian–Avalonian orogeny (peri-Gondwanan margin with principal zircon-forming events at c . 575 Ma and c . 615 Ma). Combined with the detrital zircon ages reported for rocks of the same age from Portugal, Spain, Germany and Algeria, our data suggest that the sediment supply to the Ediacaran–Early Palaeozoic siliciclastic sequences preserved in all these peri-Gondwanan regions was similar. The lack of Grenvillian-aged ( c . 1.1–0.9 Ga) zircon in the Ossa–Morena and Saxo-Thuringia Ediacaran sediments suggests that the sediment in these peri-Gondwanan basins was derived from the West African craton.

Abstract Exhumation of high-pressure (P) rocks may require a long path and multiple deformation phases. During this journey, late faults and folds can introduce changes to the primary tectonic stacking and lead to misleading conclusions regarding subduction polarity and plate reconstructions. This hypothesis has been tested positively via mapping and structural analysis in the eastern section of the Central Unit (Eastern Ossa–Morena Complex, Iberian Massif), which comprises Devonian high-P rocks subducted during the Variscan Orogeny. Following subduction beneath Gondwana, exhumation was assisted by in-sequence underthrusting of the continental crust, along with thinning of the overlying and formerly accreted crust. Convergence persisted and was accommodated by Gondwana-directed, out-of-sequence thrusts. Subsequent extension favoured erosion and basin inception during the Early Carboniferous, whereas further convergence produced late folding and faulting during Late Carboniferous sinistral transpression. Late faults duplicated the Devonian suture zone several times, producing a series of closely-spaced exposures of a single suture. The manner in which late faults affected the Devonian suture produced an outcome that could be mistaken for a collection of individual suture zones. Late faults may distort the primary relationships between upper and lower plates; however, they provide a geometry-based approach for restoring the primary geometry of suture zones.

Abstract We present a new structural study of a D 2 –M 2 tectono-thermal structure in SW Iberia (Ponte de Sor–Seda gneiss dome) characterized by a spatial distribution of telescoping isograds providing a record of Buchan-type metamorphic conditions. The gneiss dome comprises an infrastructure made up of a lower gneiss unit (LGU) and an intermediate schist unit (ISU), separated by early D 2 ductile extensional shear zones. The LGU and the ISU are composed of Ediacaran–Cambrian rocks that experienced the highest-grade M 2 metamorphic conditions (amphibolite facies). Late Ediacaran–Early Terreneuvian and Late Miaolingian–Early Furongian protolith ages for LGU (496 ± 3 Ma) and ISU (539 ± 2 Ma) orthogneisses are reported. A superstructure made of Cambrian–Devonian rocks (Upper Slate Unit, USU) deformed under M 2 greenschist facies conditions, tectonically overlies the ISU across a D 2 extensional shear zone. Kinematic criteria associated with D 2 –M 2 fabrics indicate top-to-ESE–SE sense of shear. A late-D 2 brittle-ductile high-angle extensional shear zone (Seda shear zone) crosscuts the gneiss dome. D 3 upright folds, thrusts and transpressive shear zones caused the steepening of D 2 structures and the local crenulation of S 2 foliation. The Mississippian D 2 –M 2 event recorded in the Ossa–Morena Zone may be regarded as a regional-scale phenomenon that markedly influenced the crustal architecture of North Gondwana during the assembly of Pangaea.

Abstract Paleozoic calcitic marbles are found in the Estremoz Anticline, Ossa-Morena Zone (Southern Branch of the European Variscides in Portugal). This 40 km NW–SE structure presents outcrop continuity and intense mining activity since the Roman Period. The structure has a Precambrian core and the younger rocks are from the Devonian Period. The marbles occupy an intermediate stratigraphic position in the Cambrian age Volcano Sedimentary Sequence. The Variscan Orogeny had two pulses with different intensities under ductile and brittle tension fields. The Alpine Cycle also caused more fracturing of the marbles. The geological features imprinted in the marbles are beautiful aesthetic patterns highlighted when used as dimension stone. Since the Roman period, pieces of art made with Estremoz Marble were exported abroad and can be found in museums and archaeological sites throughout Europe and North Africa countries. Present day, Estremoz Marble objects can be found all over the world. The very rich marble based heritage is omnipresent in cities, and the countryside is marked by intense mining activity side by side with rural industries; therefore the region has unique characteristics allowing the development of integrated industrial tourism routes, promoting sustainable development of industrial, scientific and technological cultural opportunities. The historical and widespread application of these marbles in national and international monuments, some of them already part of the UNESCO World Heritage Sites, is a condition to propose them as Global Heritage Stone Resource for their international recognition.