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- The Lourinhã FormationPublication . Mateus, O.; Dinis, J.; Cunha, P. P.; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e GeotecnologiasThis work, as a fieldtrip guide, aims to provide a glimpse into the palaeoenvironments, palaeontology, and diagenesis of one of the most productive areas for Late Jurassic dinosaurs and other vertebrates in Europe, namely, the sites of the Lourinhã Formation, which is coeval with the Morrison Formation of the midwest USA. The Late Jurassic rifting phase of the Lusitanian Basin created several sub-basins separated by major crustal faults. In the western and central areas of the basin, the Caldas da Rainha structure separates three sub-basins with different subsidence and infill characteristics (Consolação to the west, Bombarral–Alcobaça to the northeast, and Turcifal to the southeast). The Upper Jurassic–lowermost Cretaceous succession exposed in the coastal cliffs located between Nazaré and Santa Cruz belongs to the Consolação Sub-basin, whereas the coastal outcrops between Santa Cruz and Ericeira show units of the Turcifal Sub-basin. To place the stops into a coherent context, selected units of the fieldtrip area are detailed. The stratigraphy of the Upper Jurassic of the Lusitanian Basin is quite complex, and no fully accepted overall proposal exists. Thus, a review of lithostratigraphy, sedimentology, age and environmental interpretations is presented. Interpretations of palaeoclimate, palaeogeography, and taphonomy contribute to establishing an overview of the landscape where dinosaurs lived and to understanding the conditions for their fossilization and preservation. This trip, which takes place from north to south, focuses on the vertebrate content, sedimentology, and stratigraphy of the deposits. The first stop at Consolação examines the upper Kimmeridgian shallow-marine to deltaic Alcobaça Formation, which underlies the Lourinhã Formation. Further south, the Paimogo fort cape gives a scenic view of the Lourinhã Formation: to the north, the Praia da Amoreira and Porto Novo members (lower coastal plain alluvium, including distal fan and meandering fluvial systems; upper Kimmeridgian), and, to the south, the Praia Azul Member (lower coastal plain alluvium with three brackish–marine faunally distinct transgressive carbonate levels; uppermost Kimmeridgian to lowermost Tithonian). In Paimogo, we visit sites where dinosaur eggs and a sauropod skeleton have been found. The stop at the Museum of Lourinhã allows a visit to one of the most important collections of Late Jurassic vertebrates in Europe. The last fieldtrip stop at Porto da Calada examines the top of the Assenta Member of the Lourinhã Formation (meandering fluvial system with intercalations of shallow-marine lagoonal carbonates; upper Tithonian to lowermost Berriasian) and the Porto da Calada Formation (meandering fluvial system with thin levels of estuarine and intertidal flats carbonates; Berriasian) and thus includes the Jurassic–Cretaceous boundary.
- Stratigraphy and sequence correlations in the Lower Cretaceous around LisbonPublication . Rey, J.; Caetano, P. S.; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; DCT - Departamento de Ciências da TerraThe cliffs along the Atlantic coast near Lisbon—between Cascais and Guincho Beach, near Ericeira, and north of Cape Espichel—exhibit perfectly preserved Lower Cretaceous formations, with a large variety of sedimentary deposits (siliciclastics and carbonates) and recorded environments (from open distal platform to fluvial systems and palaeosols). These exposures allow the stratal, sedimentological, palaeontological, mineralogical, and geochemical patterns of depositional sequences during the Valanginian–Albian to be analyzed. The series representing the deepest marine environments are found in the vicinity of Cascais, with deposits in more proximal positions being observed both northwards (the Ericeira area) and southwards (Cape Espichel). The cyclic variations in sea level at the second-order scale record the tectonic events linked to the initial episodes of the northward propagation of the opening of the Atlantic. The sea-level changes observed at the third-order scale are registered by transgressive and highstand systems tracts. Lowstand systems tracts are very scarce in these shallow environments.
- SS Cadomian/Pan-African consolidation of the Iberian Massif assessed by its detrital and inherited zircon populationsPublication . Chichorro, Martim; Solá, Ana Rita; Bento Dos Santos, Telmo M.; Amaral, João Lains; Crispim, Lourenço; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; DCT - Departamento de Ciências da Terra; UNIV BARCELONAThis work assessed the age distribution of Cadomian/Pan-African orogenic events (550-590 and 605-790Ma, respectively) in several zones of Iberian Massif by means of detrital and inherited zircon analysis compilation. Detrital zircon age spectra show that throughout the late Neoproterozoic-to-Early Ordovician era (~120Ma sedimentary record), the main systematic peak occurs at ~610Ma, followed by peaks at typical Cadomian ages (~590-550Ma). Inherited zircons incorporated in Cambrian-to-Lower Ordovician igneous rocks show typical Cadomian ages (~590-550Ma) but, once again, a remarkably consistent Pan-African ~610Ma peak occurs. In accordance with compiled zircon data and taking into account the evidence of North African peri-cratonic inliers, Ediacaran (~610Ma) zircons incorporated in Paleozoic magmas provide indirect evidence of Pan-African magmatism, suggesting that these magmas and synorogenic sediments are likely to constitute the cryptic stratigraphic infrastructure of most of the Iberian Massif. The main source of ~610Ma inherited zircons may be the lateral chrono-equivalents of the Saghro and Bou Salda-M`Gouna Groups (Anti-Atlas, Morocco) and/or coeval igneous rocks from West African Craton or Trans-Sahara Belt, emplaced at a stratigraphic level below the late-Ediacaran sediments of the Ossa Morena Zone and the Central Iberian Zone. Assuming that the Iberian crust is a fragment of the Pan-African orogen, a relative paleoposition situated between the West African Craton and the Trans-Saharan Belt during the Late Neoproterozoic is proposed. The closed-system behaviour of Stenian-Tonian detrital zircon ages in the Trans-Sahara Belt suggests that this mega-cordillera acted as a barrier, in paleogeographic terms, to separating the Sahara Metacraton from Iberia. In Iberia, the opening of the system to Stenian-Tonian detrital zircon during the Ordovician indicates that, at that time, the Trans-Saharan Belt had already become a vast peneplain, which favoured a large drainage system with a long-distance transport mechanism that fed the passive continental margins.
- Stegosaur tracks from the Upper Jurassic of PortugalPublication . Guillaume, Alexandre Renaud Daniel; Costa, Francisco; Mateus, Octávio; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; Faculdade de Ciências e Tecnologia, Universidade Nova de LisboaThe record of Late Jurassic stegosaur tracks from the Lourinhã Formation (Kimmeridgian-Tithonian) is here revised. Thirty-eight dinosaur tracks, preserved as natural infill casts, are here reported, and thirty-two of them are attributed to the ichnogenus Deltapodus. Four of those present impressions of skin, with polygonal scales and random pattern. Deltapodus is the most common ichnogenus in the track record of the Lourinhã Formation. The sizes and shape suggest one single dacentrurine trackmaker, which could be Miragaia longicollum, also common in the same horizons.
- Datação87sr/86sr da formação de alcácer do sal (Miocénico superior, portugal continental)Publication . Ressurreição, Ricardo; Legoinha, Paulo; Dias, Rúben Pereira; Santos, José Francisco; Ribeiro, Sara Monteiro; Patinha, Carla; Miranda, R.; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; LNEG - Laboratório Nacional de Energia e GeologiaThe Lower Tagus Basin was subjected to several marine transgressions along the Neogene, related to positive eustatic oscillations and also controlled by the regional tectonic activity. In the Alcácer do Sal-Sines region, previous studies identified an episode of marine sedimentation interpreted as having occurred during the late Serravalian to early Tortonian interval, based on biostratigraphic data. This episode is represented in the Alcácer do Sal Formation. The study of the SMS-12-01B borehole, drilled for mineral prospection purposes, located about 10 km NNE of Melides, allowed the identification of a 3 m thick layer of sediments containing marine fossils.87Sr/86Sr determinations of oyster shells point to deposition about 11.5 Ma ago, validating previous proposals for the age of the formation. These data correspond to the first numerical ages obtained for the Alcácer do Sal Formation, allowing a solid correlation with other known marine units in the Lower Tagus and Algarve basins related to the same transgression episode.
- The distribution of dental features in non-avian theropod dinosaurs: Taxonomic potential, degree of homoplasy, and major evolutionary trendsPublication . Hendrickx, Christophe; Mateus, Octávio; Araújo, Ricardo; Choiniere, Jonah; DCT - Departamento de Ciências da Terra; https://doi.org/10.26879/820Isolated theropod teeth are some of the most common fossils in the dinosaur fossil record and are continually reported in the literature. Recently developed quantitative methods have improved our ability to test the affinities of isolated teeth in a repeatable framework. But in most studies, teeth are diagnosed on qualitative characters. This can be problematic because the distribution of theropod dental characters is still poorly documented, and often restricted to one lineage. To help in the identification of isolated theropod teeth, and to more rigorously evaluate their taxonomic and phylogenetic potential, we evaluated dental features in two ways. We first analyzed the distribution of 34 qualitative dental characters in a broad sample of taxa. Functional properties for each dental feature were included to assess how functional similarity generates homoplasy. We then compiled a quantitative data matrix of 145 dental characters for 97 saurischian taxa. The latter was used to assess the degree of homoplasy of qualitative dental characters, address longstanding questions on the taxonomic and biostratigraphic value of theropod teeth, and explore the major evolutionary trends in the theropod dentition. In smaller phylogenetic datasets for Theropoda, dental characters exhibit higher levels of homoplasy than non-dental characters, yet they still provide useful grouping information and optimize as local synapomorphies of smaller clades. In broader phylogenetic datasets, the degree of homoplasy displayed by dental and non-dental characters is not significantly different. Dental features on crown ornamentations, enamel texture and tooth microstructure have significantly less homoplasy than other dental features and can be used to identify many theropod taxa to ‘family’ or ’sub-family’ level, and some taxa to genus or species. These features should, therefore, be a priority for investigations seeking to classify isolated teeth. Our observations improve the taxonomic utility of theropod teeth and in some cases can help make isolated teeth useful as biostratigraphic markers. This proposed list of dental features in theropods should, therefore, facilitate future studies on the systematic paleontology of isolated teeth.
- The Foraminifera.eu Project: A paleoinformatics bridge between science and communityPublication . Hesemann, M.; Ottway, Brian; Legoinha, Paulo; CICEGE - Centro de Investigação em Ciência e Engenharia Geológica; DCT - Departamento de Ciências da Terra; LNEG - Laboratório Nacional de Energia e GeologiaForaminifera.eu is a non-commercial international project to foster the interest in foraminifera. A freely accessible image database with an online multi-criteria search facility based on high quality SEM and optical images and drawings has been developed. The website has become a popular resource with more than 5000 monthly unique visitors viewing more than 50000 pages. About 120 scientists and amateurs are contributing samples, images, drawings, ideas and working on projects, publications, exhibitions, talks and collection. Foraminifera from the Oporto Seamount, from the Luz Formation and from the Mem Moniz spongolithic limestone are the first Portuguese contributions to this project.
- Solos MolesPublication . Silva, Paula F. da; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; DCT - Departamento de Ciências da Terra; Engenho e MédiaA Torre de Pisa é o famoso campanário italiano que está inclinado por ter sido construído na Piazza del Miracoli sobre solos moles. Estes solos são um tipo de terrenos geotécnicos que levantam problemas à atividade humana, nomeadamente em fundações de edifícios e de aterros, devido à baixa resistência ao corte, à compressibilidade (baixo grau de ligação entre as partículas) elevada, que conduz a grandes deformações quando solicitados por cargas adicionais, e ainda à permeabilidade reduzida (< 10-8 m/s). Estas caraterísticas mecânicas e hidráulicas refletem-se na prática por assentamentos importantes à superfície, às vezes métricos, que se processam lentamente, durante um intervalo de tempo elevado ...
- Tectónica da Cadeia da ArrábidaPublication . Kullberg, Maria Carla; Kullberg, José Carlos Ribeiro; Terrinha, Pedro; DCT - Departamento de Ciências da TerraA tectonic map of the Arrábida fold and thrust belt (30 km x 6 km) based on aerial-photo interpretation and field work is presented together with geological cross-sections constrained by seismic and gravimetric data, one restored section and kinematic models for the evolution of the Sesimbra salt-wall and the Palmela gravitational slide. Two rifting episodes of Lias-Dogger, and Malm ages, were recognized in the Arrábida rotated fault-block that were accommodated by two normal fault systems striking approximately N-S and E-W. Two episodes of tectonic inversion occurred during Miocene times (Burdigalian and Late Tortonian) during which the N-S faults were reactivated as lateral ramps and the E-W faults as thrusts that formed on a backward propagation sequence. The structure and style of deformation of the Arrábida belt were controlled by the inherited Mesozoic structure and the non-stretched basement that bounds the Arrábida block to the south and east. Although most of the inversion structure appears to be thin-skinned gravimetric modelling (SILVA, 1992) indicates some involvement of the basement in the Viso duplex. The existence of only one detachment, the Hettangian evaporite complex, whose depth to is estimated between 3.5 km and 2.2 km, as constrained by gravimetric and geometric models, is the reason for the simple and elegant geometry of the Arrábida fold and thrust belt. Shortening across the belt was estimated in e = 35% (RAMSAY, 1967) using a 10 km section drawn between Quinta do Anjo (loose line) and Albarquel (pin point) in the eastern sector of the Arrábida belt, across the Serra de São Luís and Viso structures.Apositive strain gradient from north to south and west to east is observed at cartographic scale and was corroborated by independent strain analysis ( P. RIBEIRO, et al., 1996; A. RIBEIRO, et al., 1996)
- Interpretação tectónica de um conjunto de lineamentos WNW-ESE observados em imagens Landsat da Margem Oeste IbericaPublication . Kullberg, Maria Carla; Kullberg, José Carlos Ribeiro; DCT - Departamento de Ciências da TerraThe existence of satellite images ofthe West Iberian Margin allowed comparative study of images as a tool applied to structural geology. Interpretation of LANDSAT images of the Lusitanian Basin domain showed the existence of a not previously described WNW-ESE trending set of lineaments. These lineaments are persistent and only observable on small scale images (e.g. approx. 11200000 and 11500 000) with various radiometric characteristics. They are approximately 20 km long, trend l200±15° and cross cut any other families of lineaments. The fact that these lineaments are perpendicular to the Quaternary thrusts of the Lower Tagus Valley and also because they show no off-set across them, suggests that they resulted from intersection oflarge tensile fractures on the earth's surface. It is proposed in this work that these lineaments formed on a crustal flexure of tens ofkm long, associated with the Quaternary WNW-ESE oriented maximum compressive stress on the West Iberian Margin. The maximum compressive stress rotated anticlockwise from a NW -SE orientation to approximately WNW-ESE, from Late Miocene to Quaternary times (RIBEIRO et aI., 1996). Field inspection of the lineaments revealed zones of normal faulting and cataclasis, which are coincident with the lineaments and affect sediments of upper Miocene up to Quaternary age. These deformation structures show localized extension perpendicular to the lineaments, i.e. perpendicular to the maximum compressive direction, after recent stress data along the West Portuguese Margin (CABRAL & RIBEIRO, 1989; RIBEIRO et at., 1996).Also, on a first approach, the geographical distribution of these lineaments correlates well with earthquake epicenters and areas of largest Quaternary Vertical Movements within the inverted Lusitanian Basin (CABRAL, 1995).