http://hdl.handle.net/10174/14284 Mon, 23 Mar 2026 08:54:14 GMT 2026-03-23T08:54:14Z http://hdl.handle.net/10174/41486 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). Fri, 31 Mar 2023 23:00:00 GMT http://hdl.handle.net/10174/41486 2023-03-31T23:00:00Z http://hdl.handle.net/10174/41421 Title: Fracture Network Modelling in a geological complex considered for carbon dioxide (CO2) injection in the offshore area of the Lusitanian Basin. Authors: Barata, Madalena Abstract: The following thesis focuses on developing conceptual models of fracture networks to be used as analogues for a geological complex targeted for carbon dioxide (CO2) storage in the offshore area of the Lusitanian Basin. This work presents a fracture interpretation and characterization, followed by a statistical analysis of the identified fractures, leading to the development of several fracture network scenarios. The main objective is to characterize and model fractures in the sealing formation and assess how these fracture networks could impact the feasibility of CO2 storage. The study's main data source is the 3D seismic volume of Cabo Mondego, which allowed the creation of comprehensive conceptual models, given the data limitations in the target area. Developing conceptual fracture network models provided an extensive characterization of the fractures within the study area by proposing different potential scenarios of their occurrence. The models derived from these scenarios allowed the visualization of possible fracture distributions, considering the main fracture characteristics, and offering a useful analogue for understanding their behavior in the target area. This thesis is aligned with the PilotStrategy project, which aims to improve the understanding of deep saline aquifers for CO2 storage across Europe. Integrating this work with the broader project by considering the fracture scenarios in the dynamic simulations, provides valuable insights into the dynamic behavior of the target area and the CO2 storage potential within the offshore Lusitanian Basin Fri, 01 Nov 2024 00:00:00 GMT http://hdl.handle.net/10174/41421 2024-11-01T00:00:00Z http://hdl.handle.net/10174/41420 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. Tue, 30 Apr 2024 23:00:00 GMT http://hdl.handle.net/10174/41420 2024-04-30T23:00:00Z http://hdl.handle.net/10174/41419 Title: Marcadores tectónicos, ambientais e cronológicos em rochas sedimentares do Paleozóico, Triásico, Jurássico e Quaternário do Algarve Ocidental - Guia de Campo Authors: Terrinha, Pedro; Duarte, João; Ribeiro, Carlos; Pereira, Helder; Correia, Gina; Sousa, Monica Abstract: Na Bacia Algarvia, sector ocidental de Sagres-Lagos encontra-se o registo tectonoestratigráfico de rifting, do Triásico (~220 Ma) ao Cretácico inferior terminal (Albiano, ~100Ma). As séries estratigráficas deste sector da Bacia Algarvia são condensadas, registando numa espessura inferior a 0.5 km o registo sedimentar Mesozóico local de 120 milhões de anos. Por oposição na Bacia offshore no Algarve Central o registo equivalente pode estar registado numa série de espessura da ordem de 4 km. No Mesozóico o Algarve situava-se próximo da junção tripla de dois oceanos em expansão, o Atlântico norte e o Neotétis (prolongamento ocidental do Tétis). Ambos estes segmentos oceânicos estavam associados a estruturas distensivas do tipo dorsal média oceânica. Não obstante, a interação dinâmica entre a deriva continental da África, Eurásia e América do Norte provocou campos de tensão compressiva locais. Estas séries condensadas permitem a datação de estruturas de três fases de rifting (Triásico-Jurássico inferior, Jurássico médio e Jurássico superior-Cretácico inferior), dolomitização (Jurássico inferior e Jurássico superior) e vários episódios de inversão tectónica, ou seja, momentos em que o campo de tensões se inverteu de distensivo para compressivo, causando crises sedimentares e ecológicas marinhas, devido a modificações ambientais, nomeadamente variações na posição da linha de costa e da altura da coluna de água (profundidade do mar). Estas modificações ambientais estão claramente patentes na litostratigrafia e sua relação com as descontinuidades estratigráficas (alostratigrafia). A costa Algarvia situa-se próximo do limite de placas litosféricas Eurásia-África que tem capacidade para gerar sismos de magnitude superior a M8. Estes sismos têm capacidade para gerar grandes tsunamis. O sismo e o tsunami de 1 de novembro de 1755 são disso o melhor exemplo histórico da Europa ocidental. O regime tectónico atual responsável pela geração de sismicidade atípica no oeste da Eurásia continental é, no Presente, um regime compressivo. Mais especificamente, um regime compressivo causado pela colisão oblíqua dextrogira da África contra a Ibéria. As estruturas tectónicas encontram-se bem representadas essencialmente no corredor transcorrente SWIM (SouthWest Iberia Margin) de orientação WNW-ESSE de cerca de 600 km de comprimento, 80 km de largura e que passa cerca de 150 km a sul de Sagres. Este campo de tensões instalado no Pliocénico de compressão orientada WNW-ESE sucede ao campo compressivo do Miocénico (NW-SE e do Paleogénico (~N-S). Diferentes aspectos morfológicos da costa podem ainda ser observados na região de Sagres-Lagos. Alguns destes aspetos são resultado da alteração do campo de tensões e das variações Plio-Quaternárias do nível do mar. Tue, 30 Apr 2024 23:00:00 GMT http://hdl.handle.net/10174/41419 2024-04-30T23:00:00Z