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- Calcretos da região de Elvas : Estudo preliminarPublication . Soares, S.; Dias, Ruben Pereira; Ressurreição, Ricardo; Morais, Igor; Albardeiro, Luís; Gonçalves, Pedro; Solá, A. Rita; Castro-Pina, M.SUMMARY: The construction of a new railway in NE Alentejo crossing the Ossa Morena Zona allowed new detailed studies focused on the geological units and the structure of the area. In the Elvas region, the Miocene is represented by a coarse conglomerate covered by sandy mudstones. The conglomerate is coarser near the Messejana fault, where it is also tilted. Its deposition is probably related to the Alpine reactivation of the fault. The sediments and the basement rocks are strongly affected by Miocene calcretization. A chemical characterization of calcrete along vertical profiles was done with portable x-ray fluorescence equipment. The preliminary results show a decrease in CaO content upwards and an increase in SiO2.
- Cartografia do sinclinal de Buçaco-Penedos de GóisPublication . Sequeira, António J. D.; Medina, JorgeSUMMARY: At a normal fieldwork scale (1/25000) problems arise in the cartographic representation of some of the units defined in the Buçaco-Penedo de Góis syncline, which have thicknesses of 50 meters or less. It was necessary to group them resulting in a lithostratigraphic sequence for most of the cartographic separations already carried out by Delgado (1908), although with the designations created by later authors.
- O sinclinório complexo de Destriz-Caramulo (Tondela): litoestratigrafia e estruturaPublication . Romão, José; Ferreira, Pedro TavaresSUMMARY: The revision of the geological mapping of the Caramulo-Destriz region allowed identifying the succession constituted by the Beiras Group (Neoproterozoic), on which Armorican Quartzite Formation is settled in angular discordance. This last unit succeeds in concordance with the Brejo Fundeiro Formation (Middle Ordovician) which has affinities with the sequence recognized in the Buçaco syncline and is in continuity with the Arganil quartzites. A NW-SE synclinorium with NW vergence and axial plane schistosity, associated with the main variscan phase, was also identified in the region. The outline of its axis presents the configuration of a sigmoid that resulted from a right shear, sub-parallel to the Porto-Tomar-Ferreira do Alentejo Shear Zone.
- Contributo do acompanhamento das grandes obras de engenharia para a cartografia geológica : Caso de estudo do Corredor Internacional SulPublication . Morais, Igor; Albardeiro, Luís; Gonçalves, Pedro; Soares, S.; Solá, A. Rita; Dias, Ruben Pereira; Ressurreição, Ricardo; Castro-Pina, M.; Serra, B.; Pereira, Zélia; Mendes, MárciaSUMMARY: The follow up of new railway works, which will be part of the International South Corridor (Corredor Internacional Sul”, allowing the privileged access to new Ossa-Morena Zone outcrops, contributes to refine detailed geological mapping, as part of LNEG's mission. Along the different sections of the railway line, systematic geological sampling was carried out for petrographic, geochronological and paleontological studies. In addition, photographic record and three-dimensional modeling of the main slopes were performed using a drone. This methodology allows the construction of an information repository that can be consulted long after the works have been concluded and the outcrops become inaccessible. Besides the accuracy improvement of the geological contacts of the Ossa-Morena Zone rocks, the preliminary results confirmed the extent of Miocene debris flow sedimentation (conglomerates) and subsequent calcretization, and has identified new mineral occurrences.
- Programa de cartografia transfronteiriça do LNEG-IGME na Zona Sul Portuguesa nas escalas 1/200 000 e 1/400 000. Um contributo para a estratigrafia do SW IbéricoPublication . Matos, João Xavier; Díez-Montes, Alejandro; Dias, Ruben Pereira; Pereira, Zélia; Machado, Susana; Solá, A. Rita; Carmona, J.J. Huerta; Ressurreição, Ricardo; Albardeiro, Luís; Mendes, Márcia; Morais, Igor; González-Clavijo, Emilio J.; Gonçalves, Pedro; Santos, Sara; de Oliveira, Daniel Pipa Soares; Salgueiro, Rute; Henriques, S.B.A.; Oliveira, José Tomás; Fernandes, Paulo; Inverno, Carlos; Lopez, M. T.SUMMARY: The South Portuguese Zone (SPZ) 1/200 000 and 1/400 000 scale maps and stratigraphic program in SW Iberia is presented by a LNEG-IGME consortium and funded by GEO_FPI/Interreg-POCTEP. The 1/200 000 mapped area corresponds to the border area and is based on previous work (Folha 8 and Sevilla-Puebla de Guzmán maps). The 1/400 000 map covered a larger area, from Lisbon to Seville. The following domains of SPZ were considered: Pulo do Lobo (early Frasnian-late Famennian), Iberian Pyrite Belt (late Famennian-late Visean) and Baixo Alentejo Flysch Group (late Visean-late Moscovian). The maps include the Mesozoic Algarve basin and the Cenozoic Guadalquivir/Algarve basins. Field surveys were done using standard stratigraphic and GIS database methodologies. Palynological studies of Paleozoic metasedimentary rocks and U/Pb zircon geochronology of plutonic and volcanic rocks were essential to refine and update the Paleozoic stratigraphy. The new data allowed new knowledge and the validation of the geological models.
- Contribuição para a melhoria da cartografia geológica da Bacia Carbonífera do BuçacoPublication . Ferreira, Paulo; Romão, JoséSUMMARY: The geological cartography review of the area where the Buçaco Carboniferous Basin (BCB) is located showed that its limits are either strongly tectonized or in angular discordance over Neoproterozoic and Paleozoic lithology’s. Mesocenozoic sediments mapped also settle limits with the BCB units. At the eastern limit of the basin, a normal fault generated in an extensional regime was identified, active during the deposition of lithostratigraphic units dated from the Gzhelian, while at the opposite limit, a tangential compressive tectonic was identified (ENE-WSW direction), with material transport to ENE, posterior to the predecessor event. The described tectonic episodes are associated with the final stages of the Variscan Orogeny.
- Geodiversidade no troço médio do rio Guadiana, argumentos para um futuro Geoparque no território de Mértola, Serpa, Moura e BarrancosPublication . Matos, João Xavier; Dias, Ruben Pereira; Pereira, Zélia; Ressurreição, Ricardo; Soares, S.; Mendes, Márcia; Albardeiro, Luís; Gonçalves, Pedro; Santos, Sara; Piçarra, José ManuelSUMMARY: The region of Mértola, Serpa, Moura and Barrancos, located in the middle section of the Guadiana River presents a distribution of geosites of great scientific value, constituting the argument to a future Geopark. The studied territory includes the Ossa-Morena (OMZ) and South Portuguese (SPZ) geological sequences, the tectonic boundary between these two variscan domains, the geomorphology conditioned by Alpine tectonics, the Guadiana, Ardila and Chança rivers incision and differential erosion of quartzites, dolomites and marbles. Significant geological heritage is also present in the SPZ Iberian Pyrite Belt VMS and OMZ copper deposits. The Guadiana territory presents a typical landscape and exceptional geosites in a natural habitat (e.g. Pulo do Lobo waterfalls). In total, 50 geosites were considered in 6 regions: Barrancos-Ardila, Ficalho, Serpa-Pias-Moura, Alcaria, Guadiana and São Domingos. The future project of Geopark will be planned by the four municipalities considering geoconservation plans and regional sustainable policy.
- Património Geológico Cadomiano da região de AbrantesPublication . Henriques, S.B.A.; Alves, Paulo; Machado, SusanaSUMMARY: A well preserved Cadomian basement crops out at the contact between the Ossa Morena Zone and the Central Iberia Zone near Abrantes area. The magmatic and metamorphic activity recorded in this area indicates the existence of a long‐lived continental arc (ca. 692–540Ma) with coeval felsic and mafic magmatism and a final collisional event (ca. 540 Ma). This sequence of events, as well as several tectonic and metamorphic features and well‐preserved outcrops of diverse lithologies provides unique conditions for observing and characterize the Cadomian basement. The Geological Heritage from this area has high scientific and didactic relevance, which permit to interpret the past of the Earth.
- A unificação dos inventários de geossítios como estratégia para a geoconservação em PortugalPublication . Aires, R.; Machado, Susana; Pereira, P.; Matos, João Xavier; Brilha, José BernardoSUMMARY: The unification of the two main geosites inventories developed in Portugal (University of Minho and LNEG) is important for the Portuguese geological community, for land use planning and nature conservation procedures. This task aims to reinforce the need of continuing the efforts for a geoconservation strategy in Portugal, stressing the need of the protection of the Portuguese geoheritage and its recognition within the official nature conservation institutions. In this work, the methodological setup of the inventories’ fusion is presented, with emphasis on the definition of information fields and the management of web databases.
- U-Pb detrital zircon ages during tectonic inversion: provenance analysis of siliciclastic sequences of the Ossa-Morena ZonePublication . Chichorro, Martim; Santos, Telmo M. Bento Dos; Solá, A. Rita; Lopes, C.; Cachapuz, P.SUMÁRIO: Análise de proveniência de sucessões detríticas da Zona de Ossa-Morena é reinterpretada a fim de demarcar os estádios de inversão tectónica do Ciclo Varisco. Zircões detríticos de unidades de Rift do Câmbrico médio-superior (Fm de Ossa, Fm de Fatuquedo) mostram não ter existido variações significativas das áreas fonte quando comparadas com os sedimentos ediacarianos, que refletem erosão/reciclagem da crosta Pan-Africana e do Arco Cadomiano, espelhando a herança típica do Norte do Gondwana. O padrão da Fm da Colorada grava o início da subducção, pois mostra que o soco da ZOM já está em inversão, embora ainda com exumação limitada dos depocentros em Rift do Câmbrico. Por sua vez, as curvas da Fm de Terena já são consistentes com exumação ativa e erosão/reciclagem subaérea das sequências vulcano-sedimentares sin-Rift, refletindo as primeiras fases colisionais variscas.