http://hdl.handle.net/10174/14287 2026-04-06T23:01:50Z 2026-04-06T23:01:50Z Terrinha, Pedro Neres, Marta Noiva, João Brito, Pedro Rosa, Marcos Batista, Luis Ribeiro, Carlos http://hdl.handle.net/10174/41486 2026-02-26T11:18:22Z 2023-03-31T23:00:00Z

Title: New Late Cretaceous and Central Atlantic Magmatic Province magmatic sources off West Iberia revealed by from high-resolution magnetic surveys on the continental shelf Authors: Terrinha, Pedro; Neres, Marta; Noiva, João; Brito, Pedro; Rosa, Marcos; Batista, Luis; Ribeiro, Carlos Abstract: This work investigates the existence and tectonic control of magmatic bodies in the continental shelf of the SW Iberia margin. Magnetic data were densely acquired for a total area of ~4400 km2 and carefully processed. Our new maps reveal a complex magnetic anomaly field, where distinct zones are defined based on the anomaly distribution. A wide number and variety of magmatic bodies are interpreted, from >10 km-scale deeply intruded plutons to small plug-like and dike-like intrusions. Interpretation of magnetic results together with bathymetry and seismic reflection data allows discussing the geometry, extension, and age of the magmatic sources and inferring the faults of fault systems related to their intrusion. The Cabo Raso complex is a densely intruded zone related to the Late Cretaceous alkaline event. The Sines complex comprises the known offshore prolongation of the on-land Sines magmatic rocks but also the newly mapped Côvo and Milfontes anomalies. Côvo is the largest magmatic intrusion recognized in West Iberia. Milfontes intrudes the non-rifted Paleozoic crust and is the first known evidence of a plutonic source of the Central Atlantic Magmatic Province (CAMP) in Iberia. The geographical distribution and geometry of the magmatic bodies are mostly controlled by the crustal tectonic fabric inherited from the Paleozoic Variscan orogeny, which was re-worked during the Mesozoic rifting and the Cenozoic Alpine collision. The magmatic bodies modify the rheological structure of the crust and may affect the strain localization during the Alpine collision and recent tectonics. This work allowed for mapping not only unknown plutons of Mesozoic age but also to define the eastern limit of the West Iberia Late Cretaceous Alkaline Province (WILCAP), which together with the Madeira-Tore Rise north of the Africa-Eurasia plate boundary cover an area equivalent to a Large Igneous Province (LIP).

2023-03-31T23:00:00Z Simões, Maria Roque, Cristina Ribeiro, Carlos Noiva, João Terrinha, Pedro http://hdl.handle.net/10174/41420 2026-02-23T16:23:01Z 2024-04-30T23:00:00Z

Title: Post-rift tectono-sedimentary evolution of the deep West Iberian Margin. Authors: Simões, Maria; Roque, Cristina; Ribeiro, Carlos; Noiva, João; Terrinha, Pedro Abstract: The West Iberian Margin (WIM) is the conjugate margin of the Grand Banks of Canada and the rifting processes that originated both margins have been widely studied over the last decades. Therefore, WIM is well known as a classical example of a non-volcanic rifted margin with two main rifting phases related to the North Atlantic opening. Despite the studies carried out so far, the knowledge about the sedimentary and tectonic evolution of this margin during the post-rift stage is scarce. The main focus of this work is to characterize post-rift tectono-sedimentary sequence of the deep West Iberian Margin. The study area is bounded to the north by the Galicia Bank, to the south by the Narazé Canyon, to the west by the Iberian Abyssal Plain, and by the Iberian coast to the east, covering about 120 000 km2. The dataset includes five multichannel seismic reflection profiles acquired in the scope of the Portuguese Project of Extension of the Continental Shelf by EMEPC (Task Group for the Extension of the Continental Shelf) and the EMODnet (European Marine Observation and Data Network) bathymetry in the study area. The seismic survey was carried out onboard R/V Akademik Shatskiy using a source of 5720 cu in bolt gun array, cable length of 7950 m and shot interval of 50.00 m. Four of the multichannel seismic lines are oriented W-E, and one N-S, three of them with about 200 km length and two approximately 100 km length located, at about 5300 m water depth. Lithostratigraphic information from the Ocean Drilling Program (ODP) drills was used for the characterization of seismic units and the chronological constraint. The multibeam bathymetry used is from an EMODNet digital terrain model (DTM) with tiles of approximately 115m * 115m (1/16 * 1/16 arc minutes) of grid resolution, resulting from the combination of bathymetric survey datasets, DTMs, satellite derived bathymetry (SDB) data, and GEBCO 2020 (General Bathymetric Chart of the Oceans 2020) data to fill in the gaps (www.emodnet-bathymetry.eu). The seismic lines and the bathymetric data were loaded into Landmark software for sismostratigraphic interpretation. The geomorphological analysis was made using ArcMap and Geocap software, in order to identify and characterize the main seafloor reliefs. . The sismostratigraphic interpretation allowed the identification of a pos-rift sequence formed by six seismic units of different ages calibrated with ODP drilling sites. The oldest seismic unit is of Late Cretaceous age and the youngest of Quaternary age. The sedimentary sequence is cut by several normal faults and few reverse faults; sealed fluid scape structures are also present. The joint analysis of the seismic reflection profiles and multibeam bathymetric analysis allowed to recognize that the main sedimentary processes and their interaction responsible for the build-up of the post-rift sedimentary sequence are: i) depositional related to bottom-current circulation, which deposited contourite difts and sediment waves; ii) gravitational responsible for mass transport deposits (MTD) and turbidites; iii) erosive that incised moats and channels; and iv) tectonic processes responsible for structural highs that controlled locally the sedimentary processes. The present-day complexity of the seabed morphology reflects the interaction between the main tectonic episodes like Mesozoic rifting, Cenozoic compression and uplift, and the sedimentary processes.

2024-04-30T23:00:00Z Jacinto, D Mateus, D Maresca, F Correia, MJ Mega Lopes, P Alves, C Silva, T Castro, JJ Cost, JL Cruz, T http://hdl.handle.net/10174/40134 2026-01-05T21:33:45Z 2025-01-01T00:00:00Z

Title: Socio-economic and ecological drivers and challenges: the sea urchin fishery of the central Portuguese coast Authors: Jacinto, D; Mateus, D; Maresca, F; Correia, MJ; Mega Lopes, P; Alves, C; Silva, T; Castro, JJ; Cost, JL; Cruz, T Abstract: Sea urchin harvesting on the central coast of continental Portugal is a traditional activity well rooted in the littoral community. The rock-boring sea urchin, Paracentrotus lividus, is mostly harvested for its gonads by professional and recreational fishers. Recent and renewed interest in this marine resource has led to a first assessment of the local sea urchin population’s current status and the characterization of its fishery. This baseline knowledge is fundamental to promote informed decision-making for the conservation and sustainable management of this important marine resource. Field observations and enquiries to local fishers were carried out between 2019 and 2021 along this coast to describe spatial and temporal variation patterns of key bioecological aspects related to the sea urchin population (e.g. distribution and size structure, gonadal index, recruitment) and to gather socio-economic data related with its fishery (e.g. effort, yield and impact, fishers knowledge and opinion on the state of the resource, current management and legislation). Sea urchins are locally abundant and its density varied across habitats, highest in tide pools and lowest in subtidal habitats, where a higher proportion of larger individuals (>5 cm) were found. The gonadosomatic index peaked from autumn to spring, declining in summer. Recruitment occurred from February to August, peaking in summer. Harvesting mainly occurred in winter and early spring, but involved less than 2% of the active fishers observed in the study area. Results suggest that the local sea urchin population and fishery are not currently threatened. The most important problems associated with this activity and its management are: the rapid increase in demand for this resource; the high uncertainty regarding the actual fishing effort; the lack of awareness and compliance with harvesting regulations (especially in recreational fishing); insufficient surveillance and official fishery data which hardly reflect the harvesting pressure.

2025-01-01T00:00:00Z Vieira, Soraia Maurer, Anne-France Dias, Cristina Barrocas Adão, Helena Sroczynska, Kasia http://hdl.handle.net/10174/39744 2025-12-10T10:41:46Z 2025-07-05T23:00:00Z

Title: Food web attributes to assess estuarine benthic ecosystem Authors: Vieira, Soraia; Maurer, Anne-France; Dias, Cristina Barrocas; Adão, Helena; Sroczynska, Kasia Abstract: Marine ecosystems need rapid and high-performance tools to assess biodiversity and ecosystem functioning. Descriptor 4 - food webs (MSFD) is the most functionally oriented, but challenging to implement due to limited knowledge of benthic interactions. This study investigates how spatially and temporally regulated abiotic factors shape benthic food webs by analyzing natural isotope ratios (δ13C and δ15N) and constructing 12 food web topologies at three sites (Navigator, Gambia, Tróia) in the Sado estuary over two years. Isotopic metrics, integrated with univariate and multivariate analyses, identified food web indicators sensitive to environmental variations. Spatial variability was concomitant to organic matter quality, with simpler food webs in high organic load sites (Navigator, Gambia) and complex structures in the protected site (Tróia). Temporal variability was less evident but detectable. These findings highlight the effectiveness of isotopic metrics in assessing food web complexity and contribute to MSFD D4 implementation in estuarine ecosystems.

2025-07-05T23:00:00Z