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- 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
- 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.
- Dados palinoestratigráficos preliminares do Gorstiano, Silúrico, da Formação de Sazes, Sinclinal do Buçaco = Preliminary palynostratigraphic data from the Gorstian, Silurian, Sazes Formation, Buçaco SynclinePublication . Lopes, Gilda; Vaz, Nuno; Sequeira, António J. D.; Piçarra, José Manuel; Fernandes, Paulo; Pereira, ZéliaNovos dados bioestratigráficos foram obtidos na sucessão estratigráfica do Paleozóico Inferior da região do Buçaco. A Formação de Sazes (Silúrico) está a ser estudada ao nível palinológico (miosporos e quitinozoários) e de macrofósseis (graptólitos), com o intuito de rever e complementar dados bioestratigráficos anteriormente descritos. Com base nos dados palinológicos, parte da Fm. de Sazes foi datada com mais precisão como pertencendo ao Gorstiano e, pela primeira vez nesta região, também foram identificados criptosporos. Novos dados são esperados com a continuação deste estudo.
- Preliminary account of the Silurian carbon isotope record from the Barrancos region, Ossa Morena Zone, PortugalPublication . Lopes, Gilda; Fernandes, Paulo; Goodhue, Robbie; Pereira, Zélia; Piçarra, José Manuel
- Late Permian palaeoenvironmental evolution of the Matinde Formation in the Muarádzi Sub-basin, Moatize-Minjova Basin, MozambiquePublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Mendes, Márcia; Marques, João; Jorge, Raul CG SantosABSTRACT:A multidisciplinary study involving lithofacies analysis, palynofacies, and palynology is presented for the Muaradzi Sub-basin. This sub-basin is part of the Moatize-Minjova Basin (MMB), an important Karoo aged coalfield in Mozambique. A total of 99 core samples from 3 coal exploration boreholes (DW11, DW21, and DW141) were analysed and all the successions were assigned a Lopingian age based on palynology. According to the data, in the Muar ' adzi Sub-basin, a vast lowland fluvial setting existed with floodplains and wetlands, in an area controlled by tectonic movements associated with a continental rifting phase. Typical vegetation of the Glossopteris Province is recorded in the palynological assemblages of this sub-basin, which allowed for the characterization of a flora dominated by glossopterids (Protohaploxypinus and Striatopodocarpites) and gymnosperm pollen (Alisporites). Other palynomorphs revealed the presence of gingkoales, ferns (Filicopsida), sphenopsids, and lycopsids in the area, indicating a typical lowland setting. Humid and warm climates, associated with higher CO2 atmospheric levels, promoted the growth of widespread vegetation that led to the development of the thick coal beds in anoxic to dysoxic depositional environments.
- Permian stratigraphy and palynology of the Lower Karoo Group in Mozambique: a 2020 perspectivePublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Marques, João; Mendes, Márcia; Götz, Annette E.ABSTRACT: In the past decade, the increase in the number of palynological works in Mozambique documents the significance of palynology in dating the late Palaeozoic basins in this region of southwestern Gondwana. The new information gained mainly from the study of the Moatize-Minj ova Coal Basin is the basis for a better understanding of the regional biostratigraphy, as well as of palaeoenvironmental and palaeoclimatic conditions during the Permian. Here we provide a review on the Permian palynostratigraphy and its implications for lithostratigraphic correlation of Lower Karoo basins in Mozambique. The new biostratigraphic information leads to the conclusion that an age update for the lithostratigraphic units established for the Lower Karoo in Mozambique (Virzi, Moatize, and Matinde formations) is most needed. The Cisuralian palynological association in Mozambique is characterized by long-range taxa recorded since the middle Cisuralian (Sakmarian to Artinskian) (Alisporites spp., Cannanoropollis spp., Horriditriletes spp., Laevigatosporites spp., Potonieisporites spp., Protohaploxypinus spp.). Several first occurrences are also recorded in the late Cisuralian (Kungurian) (e. g., Cirratriradites africanensis, Marsupipollenites triradiatus, and Vittatina spp.). The Guadalupian association is mainly characterized by taxa that extend their range since the Cisuralian (e. g., Alisporites spp., Cirratriradites africanensis, Guttulapollenites hannonicus, Horriditriletes ramosus, Kraeuselisporites enormis, Lueckisporites virkkiae, Limitisporites monstruosus, Marsupipollenites striatus, M. triradiatus, Pakhapites fusus, Platysaccus papilionis, Thymospora pseudothiessenii, and Weylandites lucifer), with only few first occurrences (Lueckisporites virkkiae, Striatopodocarpites cancellatus, and S. fusus) and last occurrences (Cirratriradites africanensis, Limitisporites monstruosos) being recorded. The Lopingian palynological association includes most of the taxa described for the Guadalupian. In contrast, Corisaccites alutas, Indotriradites niger, Klausipollenites schaubergeri, Lunatisporites pellucidus, Osmundacidites senectus, Polypodiisporites spp., P. mutabilis, and Protohaploxypinus microcorpus are recorded for the first time. Indication of the proximity to the Permian-Triassic Boundary is supported by the occurrence of Klausipollenites schaubergeri, Protohaploxypinus microcorpus, and Osmundacidites senectus in the upper part of the Matinde Formation. Based on the palynological data, the oldest rock unit, the Virzi Formation, was deposited in the Permian (middle Cisuralian), and no older sedimentary rocks are currently known for the Lower Karoo Group in Mozambique. The palynological associations described also indicate that the Authors' deposition of the Moatize Formation occurred from the middle Cisuralian to the latest Guadalupian/early Lopingian, whilst the deposition of the Matinde Formation lasted from the late Guadalupian to the latest Lopingian. Thus, the boundary between both formations is assumed to be diachronous.
- The significance of reworked palynomorphs (middle Cambrian to Tournaisian) in the Visean Toca da Moura Complex (South Portugal). Implications for the geodynamic evolution of Ossa Morena ZonePublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Wicander, Reed; Matos, João Xavier; Rosa, Diogo; Oliveira, José TomásThe 404.5 m deep SDJ1 borehole is located in the Jongeis mining sector of the Santa Susana Basin (SSB), and has been palynostratigraphically studied. The SSB is a Carboniferous coal-bearing basin developed along the suture contact between the Ossa Morena Zone (OMZ) and the South Portuguese Zone (SPZ). The recovered palynologic assemblages are assigned to the NM Miospore Biozone of mid Visean age, with the lowermost 6.8 m of the borehole yielding an in situ miospore assemblage assigned to the SL Miospore Biozone of mid Moscovian age. All of the studied samples contained more than 90% of reworked palynomorphs ranging in age from the middle Cambrian to the early Tournaisian (0–397.7 m depth), with the first 6.8 m (397.7–404.5 m depth) yielding reworked palynomorphs from the middle Cambrian to the mid Moscovian. This particular palynologic signature provides further evidence for the interpretation of the reworked palynomorphs in the Toca da Moura Complex (TMC) and its importance in the geodynamic evolution of the OMZ, regarding the probable provenance areas of the reworked palynomorphs within the OMZ and SPZ. Six reworked sub-assemblages were discriminated: i. middle to (?)upper Cambrian; ii. Lower to Middle Ordovician; iii. middle to upper Silurian; iv. Lower Devonian; v. Upper Devonian and vi. lower Carboniferous. From the study of the palynomorph assemblages (both in situ and reworked) recovered from the SDJ1 borehole samples, new inferences are made regarding the recognition of the subsurface extension of the Toca da Moura Complex and its structural relationship to the Pennsylvanian continental coal-bearing SSB. These new data, together with the palynologic study of a control sample (STS15) from the Jongeis old coal mine, housed in the LNEG Geological Museum, in Lisbon, makes possible new interpretations concerning the evolution of the SSB.
- The geodynamic importance of the Late Cambrian to Late Devonian reworked palynomorphs from the borehole SDJ1, Santa Susana region, Ossa Morena Zone (OMZ), PortugalPublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Matos, João Xavier; Rosa, Diogo; Oliveira, José Tomás
- The Permo-Triassic boundary in the N’Condédzi sub-basin, Moatize- Minjova Coal Basin, Mozambique: palynology, 𝛿13Corg variation and paleoenvironmentsPublication . Pereira, Zélia; Fernandes, Paulo; Mendes, Márcia; Lopes, Gilda; Marques, João; Jorge, Raul CG Santos; Albardeiro, LuísSUMÁRIO: A Bacia carbonífera de Moatize-Minjova em Mozambique, compreende a sub-bacia de N’Condédzi. Esta última possui um registo sedimentar, importante para compreender as principais alterações ambientais ocorridas durante a fronteira Permo-Triasico. Para o estabelecimento da idade da sequência estratigráfica e a identificação dos ambientes deposicionais, foi realizada a revisão do estudo palinoestratigráfico da sondagem CIMT-14, combinada com a análise da variação 𝛿13Corg e complementada com novos dados de palinofácies. As espécies-guia de esporomorfos reconhecidas possibilitaram a identificação de quatro associações, de idade compreendida entre o Pérmico superior (Lopingiano) e o Triásico Superior (Carniano). Os dados de palinologia e as variações de 𝛿13Corg, no limite Permo-Triasico, assinalam uma mudança abrupta dos ambientes deposicionais. Os ambientes dominados por vastos pântanos, onde se depositou o carvão, associado a climas húmidos e quentes, sofreram uma abrupta reorganização para sistemas fluviais em climas áridos e semi-áridos, que marcam o Triasico inicial. O contacto Permo-Triasico é assinalado por uma excursão negativa de 𝛿13Corg, seguido por uma recuperação lenta da variação 𝛿13Corg e da microflora.
- Carboniferous palynostratigraphy of the borehole SDJ1 from the Santa Susana region, Ossa Morena Zone, PortugalPublication . Pereira, Zélia; Lopes, Gilda; Fernandes, Paulo; Matos, João Xavier; Rosa, Diogo; Oliveira, José Tomás
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