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- The actual hydrographic network in SW Portugal - an evolutionary perspectivePublication . Rodrigues, Bruno; Veiga-Pires, C.Both intrinsic factors of hidrographic networks (dynamics changes in the internal fluvial model) and extrinsic factors (climate, tectonics, base level), have an influence in the incision of the valleys and in the formation of fluvial terraces.
- Idades U-Pb de zircões nas areias quaternárias do AlgarvePublication . Veiga-Pires, C.; Moura, Delminda; Rodrigues, Bruno; Machado, Nuno; Campo, Leif; Simonetti, AntonyO objectivo deste trabalho é realçar e quantificar a contribuição das variações geomorfológicas nas modificações da rede de drenagem através de datações de minerais detríticos que permitam a caracterização de fontes de sedimentos desde o Pliocénico.
- The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sourcesPublication . Dinis, Pedro A.; Fernandes, Paulo; Jorge, Raul C. G. S.; Rodrigues, Bruno; Chew, David M.; Tassinari, Colombo G.Detrital zircon U-Pb geochronology data from late Carboniferous to Triassic clastic sedimentary rocks in SW Iberia were used to investigate the regional paleogeography during the transition from Pangea amalgamation to breakup. The major U-Pb zircon age peaks are middle Devonian to Carboniferous (similar to 390-300 Ma), Cambrian Ordovician (similar to 530-440 Ma), Cryogenian-Ediacaran (similar to 750-540 Ma), Stenian-Tonian (similar to 1.2-0.9 Ga) and Paleoproterozoic (similar to 2.3-1.8 Ga). Rapid exhumation of Variscan crystalline rocks at the contact between the South Portuguese zone and Ossa Morena Zone, explains the abundance of late Paleozoic ages in the upper Carboniferous-lower Permian continental successions. The U-Pb zircon data constrain the maximum depositional age of the Santa Susana Basin to c. 304 Ma and the Viar Basin to c. 297 Ma. The Triassic sequences, despite being c. 100 Ma younger than the Variscan tectonothermal events, contain low proportions of late Paleozoic zircon. The major peaks in all zircon spectra closely resemble those found in the adjacent basement rocks, indicating small source areas, mainly located near the rift shoulders. Longer travelled fluvial systems are postulated for the eastern portions of the Algarve Basin, which was closer to the westward advancing Tethys Ocean than the rift basins of West Iberia. Sequences that contain significant proportions of similar to 1.2-0.9 Ga zircon are probably recycled from post-collisional Carboniferous-Permian continental deposits that were more extensive than those found today. (C) 2017 Elsevier B.V. All rights reserved.
- Caracterização da evolução do perfil longitudinal das ribeiras do oeste do Algarve - dados preliminaresPublication . Rodrigues, Bruno; Veiga-Pires, C.; Moura, Delminda; Fernandes, Paulo; Boski, T.A actual rede hidrográfica na região do Algarve, devido à proximidade do mar e ao seu contexto tectónico, teve ao longo da sua formação uma forte influência dos efeitos eustáticos, tendo também o clima regional um papel fulcral na incisão do vales actuais a diferentes escalas temporais.
- Relação entre sedimentos arenosos fluviais e costeiros: estudo dos minerais pesados das areias actuais do Algarve OcidentalPublication . Rodrigues, Bruno; Veiga-Pires, C.; Fernandes, Nuno Machado
- História térmica do grupo do Flysch do Baixo Alentejo, Zona Sul PortuguesaPublication . Rodrigues, Bruno; Chew, Dave; Jorge, R. C. G. S.; Fernandes, PauloCom objectivo de reconstruir a história térmica do Grupo Flysch Baixo Alentejo foi realizado um estudo sistemático com o auxílio de duas metodologias complementares: medição do poder reflector da vitrine e datações de traços de fissão de apatites contidas em grauvaques das formações de Mértola, Mira e Brejeira.
- Organic maturation of the Algarve Basin (southern Portugal) and its bearing on thermal history and hydrocarbon explorationPublication . Fernandes, Paulo; Rodrigues, Bruno; Borges, Marisa; Matos, Vasco; Clayton, GeoffThe Algarve Basin, southern Portugal is under-explored in terms of petroleum geology. Organic maturation levels and the thermal history of this basin have been ascertained, together with their implications for future exploration. Maturity was determined using vitrinite reflectance and spore fluorescence/colour. The succession was extensively sampled (158 onshore samples and 20 samples from two offshore wells). Thermal history was modelled using 1D PetroMod®. A palynostratigraphic study of two offshore wells was also completed, showing thick marl–limestone sequences of Middle and Upper Jurassic age. Hiatuses were identified in the offshore wells within the Jurassic section and between the Jurassic and the Miocene sections. The Mesozoic rocks of the Algarve Basin lie within the oil window. Vitrinite reflectance ranges from 0.52–0.7%Rr in the Lower Cretaceous to 1–1.1%Rr in the Upper Triassic–Hettangian. Miocene rocks that unconformably overlie the Mesozoic strata are immature (0.42–0.47%Rr). Maturation levels increase with increasing age of the strata, indicating that burial was the main process controlling maturation. Thick marl–limestone sequences of the Middle Jurassic (Callovian) and the Upper Jurassic (Oxfordian) are the main source rock intervals. The Miocene successions of both offshore wells contains reworked vitrinite and palynomorphs with maturation levels similar to the Mesozoic rocks of the basin, suggesting exposure and erosion of these rocks during Miocene times. Palaeogeothermal gradients in the onshore Algarve Basin range from 52 °C/km to 24.7 °C/km with pre-Miocene exhumation estimated at 2000–2500 m. The probable age for the removed cover is Upper Cretaceous to Lower Palaeocene(?) and peak temperatures in the Mesozoic rocks were attained during latest Cretaceous–Early Palaeocene times. Modelled palaeotemperatures suggest that the Jurassic entered the oil-window at the beginning of the Cretaceous with peak oil generation in late Cretaceous time.
- Variability of detrital zircons from beaches and rivers in the western Algarve Region-South PortugalPublication . Rodrigues, Bruno; Moura, Delminda; Machado, Nuno; Veiga-Pires, C.Zircon is a common accessory mineral in most rocks and sediments, and although it is ubiquitous, it possesses a considerable petrologic interest. In the scope of CHYNA project, some samples of detrital sediments have been collected in rivers and beaches from Western Algarve region. The present work presents the results of the analyses undergone with the intent to document the existing zircons’ variability in these samples. The zircons from 22 samples have been analysed based on their shape, colour and inclusions. There is predominance of rounded and subrounded grains, generally colourless and without inclusions. Systematic differences between beaches and rivers are not observed, indicating that both environments have the same zircon sources.
- Potencial gerador de hidrocarbonetos dos argilitos carbonosos do Karoo Inferior (Pérmico) da Bacia de Moatize – Minjova, Província de Tete, MoçambiquePublication . Fernandes, Paulo; Rodrigues, Bruno; Jorge, R. C. G. S.; Marques, JoãoA Formação Moatize na Bacia de Moatize – Minjova é uma unidade importante do Karoo de Moçambique, consistindo em argilitos carbonosos, arenitos e camadas de carvão. Os argilitos carbonosos possuem um importante potencial como rochas geradoras de gás, podendo ser considerados como unidades importante de ‘gás de xisto’. Os valores de %Rr medidos indicam um grau de maturação orgânica compatível com o final da janela do petróleo (ca, 1,35 – 1,4 %Rr). A Formação Moatize é caracterizada por possuir querogénio do tipo II-III e do tipo III, com elevados valores de COT e valores de HI médios a elevados, sendo considerada como possuindo elevada capacidade para gerar gás.
- Carbon isotope record (d13Ccarbonate) of the Middle to Late Jurassic (Callovian - Oxfordian) from the Algarve Basin, PortugalPublication . Borges, Marisa; Fernandes, Paulo; Rodrigues, Bruno; Goodhue, R.The Algarve Basin is an important Mesozoic depocentre located in southern Portugal which formed during the succesive phases of the North Atlantic rifting following the break-up of Pangea [1]. Several unconformities related to compressive episodes are observed in the stratigraphic record of the Algarve Basin. One of these episodes ocurred in the transition from Middle to Upper Jurassic times and is marked by an important tectonic episode, observed throughout Iberia [1], that caused the tilting and folding of the Middle Jurassic strata. This situation can be observed at Benaçoitão, where Oxfordian limestones rest unconformably over tilted Middle Callovian marly limestones. In this work we present !13Ccarbonate data across the Middle and Upper Jurassic rocks from the Algarve Basin at Benaçoitão.
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