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- Early and Middle Jurassic palynostratigraphy of the Lusitanian Basin in the proto-Atlantic contextPublication . Correia, Vânia; Pereira, Zélia; Riding, James; Duarte, L. V.; Henriques, Maria Helena; Fernandes, PauloSUMMARY: A palinologia é uma ferramenta muito útil nos trabalhos de bioestratigrafia e interpretações paleoambientais, e que pode ser aplicada no conhecimento da geologia da Bacia Lusitânica. Assim, foi desenvolvido um estudo palinoestratigráfico de alta-resolução em 8 cortes do Jurássico Inferior e Médio (Sinemuriano superior—base do Batoniano) da Bacia Lusitânica e, neste trabalho, são apresentados os intervalos de ocorrência e bioeventos associados aos principais taxa identificados, nomeadamente no grupo dos quistos de dinoflagelados.
- A re-assessment of the organic maturation and palynostratigraphy of the wells Ruivo-1 and Corvina, offshore Algarve Basin PortugalPublication . Fernandes, Paulo; Borges, Marisa; Rodrigues, B.; Matos, V.The Algarve Basin is the southernmost geological province of portugal. The nowledge of its offshore geology is limited to a few hydrocarbon exploration wells and seismic profiles. Two of these wells, Ruivo-1 and Corvina, were studied in order to assess its organic maturation levels and age using the biostratigraphy of dinoflagellate cysts. The well Ruivo-1 intercepted a thick Callovian succession whereas the well Corvina intercepted a thick Oxfordian succession. Both Jurassic successions are within the oil-window.
- New data on the late Famennian miospore assemblage of the Cercal Anticline, westernmost Iberian Pyrite Belt area, PortugalPublication . Pereira, Zélia; Matos, João Xavier; Fernandes, Paulo; Oliveira, José TomásThe Cercal Anticline (CA) is located in the westernmost region of the Iberian Pyrite Belt (IPB). The exposed stratigraphic sequence includes, in ascending order, the Volcano-Sedimentary Complex (VSC) followed by the Xistos das Abertas Fm, which passes gradually to the flysch sequence of the Mira Formation (Carvalho, 1976). The VSC is composed from base to top by: Felsic Volcanics (Vα), that comprehends lavas, pumice and volcaniclastic beccias with intercalations of volcanogenic shales; diabases and intermediate/basic subvolcanics (Vβ); jaspers and the S. Luís Formation (SL), a unit composed of shales, phyllites, siliceous shales and volcanogenic sediments. About 500m NW of São Luís village, at the base of this last unit, brachiopods ascribed to the late Strunian were found (Quiring, 1936). This determination led Carvalho (1976) to assume that the volcanics of the VSC are older than the Strunian, meaning so that this volcanism is the oldest in the Portuguese IPB. The stratigraphic succession of the CA is still poorly constrained, in terms of lithostratigraphy and age. In fact, three boreholes carried out in the hinge zone of the anticline by the Elf Aquitane company, about 1km NW of São Luis village, showed that below the felsic volcanics a thick (>250m) succession of dark shales and siltstones occur. These shales yielded very well preserved specimens of Grandispora echinata together with Ancyrospora spp., Apiculiretusispora sp., Auroraspora macra, Cristicavatispora dispersa, Diducites poljessicus, D. mucronatus, D. versabilis, Emphanisporites annulatus, Grandispora cornuta, Punctatisporites spp., Retispora cf. macroreticulata, Retusotriletes phillipsii, R. planus, R. triangulatus, R. rugulatus, Rugospora explicata and R. radiata. This assemblage indicates the VH Biozone of late Famennian age. It is similar to those found in shales interbedded in felsic volcanics in several regions of the Portuguese Pyrite Belt (Neves Corvo Mine, Albernoa Anticline, São Domingos Mine). Palynostratigraphic research in the CA is currently still in progress. However, these preliminary results show that the age of the CA felsic volcanics is similar to that obtained in the northeastern branches of the Portuguese Pyrite Belt and no prove that the volcanism migrated in time to the NW, as suggested by Carvalho (1976), could be detected.
- New Lower Givetian age Miospores of the Phyllite-Quartzite Group, São Francisco da Serra anticline, Iberian Pyrite Belt, PortugalPublication . Pereira, Zélia; Matos, João Xavier; Fernandes, Paulo; Jorge, Raul CG Santos; Oliveira, José Tomás
- Idade e ambientes deposicionais da sucessão do Karoo Inferior da Bacia Carbonífera de Moatize em Moçambique: compreenções sobre a história pós-glacial do Gondwana centralPublication . Fernandes, Paulo; Hancox, J.; Mendes, Márcia; Pereira, Zélia; Lopes, Gilda; Marques, João; Jorge, Raul CG Santos; Albardeiro, Luís
- New palynological data from the Ruivo-1 and Corvina wells, offshore Algarve Basin, Portugal - implications for future hydrocarbon explorationPublication . Borges, Marisa; Riding, James B.; Fernandes, Paulo; Pereira, Zélia; Matos, Vasco
- CIMP Faro'09 : II Joint Meeting of Spores-Pollen and Acritarch Subcommissions. AbstractsPublication . Fernandes, Paulo; Pereira, Zélia; Oliveira, José Tomás; Clayton, G.; Wicander, R.
- Thermal history and basin evolution of the Moatize - Minjova Coal Basin (N'Condédzi sub-basin, Mozambique) constrained by organic maturation levelsPublication . Galasso, Francesca; Fernandes, Paulo; Montesi, Giovanni; Marques, João; Spina, Amália; Pereira, ZéliaABSTRACT: Kerogen concentrates obtained from Lopingian (Late Permian) to Upper Triassic mudrock lithologies of seven coal exploration boreholes, drilled in the Moatize – Minjova Coal Basin (N'Condédzi sub-basin, Mozambique), were studied by means of vitrinite reflectance (VR), spore fluorescence and spore colour, in order to constrain the thermal history and basin evolution by organic maturation levels. VR increases with depth, indicating organic maturation related to sediment burial for most of the boreholes. Modelled VR data indicate a regional palaeogeothermal gradient between 35 and 40 °C/km. Lower Jurassic doleritic intrusions observed in three boreholes had only local thermal effects without affecting the regional palaeogeothermal gradient. Two boreholes located near the basin margin show high palaeogeothermal gradients suggesting thermal processes other than heating due to burial were involved. These processes may have involved hot diagenetic fluids circulating through fault zones and/or permeable lithologies, locally elevating geothermal gradients. Circulation of these fluids was induced by lithostatic pressure due to rapid rates of sedimentation. These high sedimentation rates lead to the accumulation of a thick succession (over 2000 m) of Lopingian (Late Permian) to Upper Triassic siliciclastic sediments. All the organic maturation indices measured and the age of the successions indicate that organic maturation occurred during or after Late Triassic times. However, the presence of reworked Permian palynomorphs into Upper Triassic sediments and the absence of Middle Triassic sediments indicate an exhumation and erosion of Permian strata in Middle Triassic times. The organic maturation levels of the reworked palynomorph population are considerably higher than the indigenous Upper Triassic population, indicating that they attained higher burial temperatures prior to being reworked.
- The paleoenvironmental and thermal histories of the Permian Irati formation shale in the paraná basin, Brazil: An integrated approach based on mineralogical and organic imprintsPublication . Rocha, Rocha, H.V.; Sant'Anna, L.G.; Rodrigues, Cristina F.A.; Mendes, Márcia; Pereira, Zélia; Lopes, Gilda; Fernandes, Paulo; Pereira, Egberto; Tassinari, Colombo C. G.; Sousa, M.J. Lemos deABSTRACT: Mineralogical assemblages and organofacies are important sources of information to recover the paleoenvironmental and thermal histories of shale deposits. In this study, a detailed qualitative and quantitative characterization of the Permian Irati Formation (Assistência Member) shale is based on mineralogical (XRD and SEM-EDS) and organic components (TOC, Rock-Eval pyrolysis, organofacies, TAI, fluorescence and vitrinite reflectance measurements) and provides integrated data about sediment provenance, depositional environment, diagenesis, and thermal history, while supporting interpretations on the Paraná Basin (PB), Brazil, paleogeography and its correlation to the southwest Gondwana. The results revealed a prevailing type I/II kerogen, with type III kerogen being also present but mainly confined along the paleoshoreline of the PB. The dominance of fluorescent amorphous organic matter (AOM) combined with framboidal pyrite suggests microbial activity in an anoxic-dysoxic neritic-marine paleoenvironment. Additionally, common to abundant well-preserved phytoclasts, as well as the occurrence of Botryococcus braunii, indicates freshwater influx in a brackish marine depositional setting. Immature to early-oil window thermal maturities prevail across the PB, according to the organic maturation indicators. The combined analysis between the organic matter evolution with clay mineralogy, such as the occurrence of interstratified clays (e.g., I/S) and its positive correlation with depth suggest that burial diagenesis reached the transition to early catagenesis on the north, southeast, and south of the basin, attributing a shale oil potential for the Irati Formation on a regional scale. Local scale imprints of the Early Cretaceous Paraná-Etendeka Large Igneous Province (LIP), and its thermal effect in the Irati Formation shale components, are recorded as clay authigenesis (e.g., smectite webby texture and clay coating development), crystallization of minerals by low to high-grade of thermal alteration (e.g., corrensite, talc, lizardite and diopside), and by local scale gas-window maturities. Such thermal alteration, identified in the proximity to intruded sills and dykes, led to a heterogeneous organic maturation pattern with implications on shale gas and shale oil potential of the Irati Formation shale, demonstrating that these subjects in the Paraná Basin should be assessed locally.
- CIMP Faro'09 : II Joint Meeting of Spores-Pollen and Acritarch Subcommissions. Palynostratigraphic contributions to the understanding the Southwest Portugal and Algarve Basin Geology, Portugal : Post Meeting Field-Trip, 23-24 September 2009Publication . Oliveira, José Tomás; Fernandes, Paulo; Pereira, Zélia; Borges, Marisa