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- Silurian to Lower Devonian Palynomorphs from the Barrancos region, Ossa Morena Zone, PortugalPublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Piçarra, J. M.; Oliveira, José TomásNew miospore results were obtained from the Palaeozoic stratigraphic succession present in the Barrancos region, Portugal. The studied formations comprise the Silurian carbonaceous shales intercalated with cherts and rare lenticular carbonates of the Xistos com Nódulos Formation, as well as, the dark shales that alternates with thin psammit beds of Late Silurian to Early Devonian age from the Xistos Raiados Formation. Two miospore biozones were identified: the cf. protophanus verrucatus Miospore Biozone, of the Lower Wenlock (Homerian) (Richardson &McGregor, 1986) and the Verrucosisporites polygonalis (Po)Miospore Biozone of the Lower Pragian (Streel et al., 1987). For the first time cryptospores are reported. Rare acritarchs and chitinozoans are also present. This new preliminary data allow correlation with the graptolite biozonation already established in this region (Piçarra, et al., 1995, 1998; Piçarra, 2000) and completes previous palynological studies (Pereira et al., 1999). Even so, detailed palynostratigraphic research is needed and is currently being undertaken to better understand the complex geology of the region.
- 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).
- Resultados preliminares do registo isotópico de carbono orgânico (d13C org) do Silúrico da região de Barrancos, Zona de Ossa Morena, PortugalPublication . Lopes, Gilda; Fernandes, Paulo; Goodhue, R.; Pereira, Zélia; Piçarra, J. M.A região de Barrancos apresenta uma das sessões mais complexas de Silúrico na zona da Ossa Morena.
- A importância dos palinomorfos remobilizados no Complexo Vulcano-Sedimentar da Toca da Moura - Implicações para a evolução geodinâmica da Zona de Ossa Morena, PortugalPublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Wicander, Reed; Matos, João Xavier; Rosa, Diogo; Oliveira, José TomásO estudo palinostratigráfico da sondagem SDJ11 permitiu a recuperação de associações in situ de palinomorfos do Carbónico assim como associações de palinomorfos remobilizados do Câmbrico médio ao Devónico inferior e Câmbrico médio ao Tournaisiano.
- Palynostratigraphic study of Lower Karoo rocks in the Moatize-Minjova coal basin, Mozambique - preliminary resultsPublication . Lopes, Gilda; Pereira, Zélia; Fernandes, Paulo; Marques, JoãoThe Karoo Supergroup (KSG) is one of the most important geological units of Southern Africa. The KSG is well represented in the Tete Province along the Zambezi River in several horst and graben basins.
- The timing of the Svalbardian Orogeny in Svalbard: a reviewPublication . Koehl, Jean-Baptiste P.; Marshall, John E. A.; Lopes, GildaIn the Late Devonian to earliest Mississippian, Svalbard was affected by a short-lived episode of deformation named the Svalbardian Orogeny. This event resulted in intense folding and thrusting in Devonian sedimentary successions. Deformation stopped prior to the deposition of Carboniferous to Permian sedimentary strata of the Billefjorden and Gipsdalen groups, which lie unconformably over folded Devonian strata. Later on, presumed Svalbardian structures were reworked during Eurekan tectonism in the early Cenozoic and partly eroded. At present, records of Svalbardian deformation are only preserved in narrow N–S-trending belts in central, northern, western, and southern Spitsbergen. Despite extensive field studies, the timing of the Svalbardian Orogeny is poorly constrained and remains a matter of debate in places because of conflicting ages and because of the complex tectonic history of Svalbard. The present contribution aims at reviewing and discussing all available age constraints for Svalbardian tectonism, including notably palynological, paleontological, and geochronological evidence. This has great implications for the plate tectonic reconstructions of Arctic regions and for the tectonic history of Svalbard. Palynological and paleontological evidence suggest that the Mimerdalen Subgroup is upper Givetian to lower Frasnian (ca. 385–380 Ma) in age and that the Billefjorden Group is mid-Famennian to Upper Mississippian (ca. 365–325 Ma) in age, constraining the Svalbardian event in central and northern Spitsbergen to 383–365 Ma if it ever occurred.
- The Late Permian in the Muarádzi Sub-basin, Moatize-Minjova Basin, Mozambique – multidisciplinary palaeoenvironmental characterizationPublication . Lopes, Gilda; Pereira, Z.; Fernandes, Paulo; Mendes, M.; Marques, J.; Jorge, R.C.G.S.A study involving lithofacies, palynofacies, and palynological analysis is presented for the Muarádzi Sub-basin. This sub-basin is part of the Moatize-Minjova Basin (MMB), a crucial Karoo aged coalfield in Mozambique previously situated in the southern-central part of Gondwana.
- 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 TomásThe borehole SDJ1, with a total depth of 404.5 meters, was drilled in 1991 by the Serviço de Fomento Mineiro to investigate an Electromagnetic TEM conductor (Oliveira & Matos 1991). This hole is located in the eastern sector of the Santa Susana/Moinho da Ordem coal mine (1927-1944), in the Jongeis mine sector. The borehole log indicates that it cuts lithologies of the Carboniferous Toca da Moura Complex (TMC) and the Santa Susana Formation (SSF).
- Investigação em palinologia e isótopos estáveis do Paleozoico da zona centro-ibérica (Buçaco, Dornes, Mação e Portalegre) e zona de Ossa-Morena (Toca da Moura e Barrancos), Portugal: implicações paleogeográficas e paleoambientaisPublication . Lopes, Gilda; Fernandes, Paulo; Pereira, Zélia; Goodhue, RobbieEste trabalho apresenta os estudos palinostratigráfico (algas prasinófitas, acritarcas, criptosporos, esporos trilete), de geoquímica de isótopos estáveis e maturação, das sucessões do Paleozoico da Zona Centro-Ibérica (Buçaco; Dornes; Mação; Portalegre) e Zona de Ossa- Morena (Barrancos; Bacia de Toca da Moura). Foram recolhidas 485 amostras para palinologia, provenientes de 33 sucessões, de uma sondagem (SDJ1) e, de amostras do Museu Geológico do LNEG. As amostras provenientes de afloramentos revelaram-se pobres em palinomorfos devido à má preservação originada pelo elevado grau de maturação medido. No total foram identificadas 194 espécies e 148 géneros. No Buçaco foram recuperadas associações do Dobrotiviano ao Kosoviano e, do Gorstiano médio à base do Pridoli. Em Dornes os dados recuperados foram escassos, apenas complementando associações anteriores do limite Silúrico/Devónico. Em Mação apenas foram identificados alguns exemplares de algas prasinófitas. Em Portalegre, foram recuperadas associações da base do Pridoli e, topo do Viseano. Em Barrancos foram recuperadas associações do Arenigiano superior, Gorstiano, limite Pridoli/Lochkoviano e, Pragiano inferior. As associações recuperadas da sondagem SDJ1 forneceram idades do Carbónico e, associações de remobilizados do Câmbrico médio ao Carbónico inferior. Cinco secções, num total de 199 amostras, foram estudadas para isótopos estáveis de carbono. Os resultados obtidos em três perfis (Dornes e Barrancos) do Kosoviano ao Pridoli basal, permitiram inferir que as excursões poderão estar relacionadas com a ocorrência de eventos de extinção e, com a mudança dos ambientes de deposição. Os estudos de maturação foram realizados em 22 amostras do Ordovícico, Silúrico e Carbónico, pertencentes à região do Buçaco, Mação, Portalegre e Barrancos. No geral, observou-se um grau de maturação muito elevado (1,48% a 7,32%) e, em todas as amostras a matéria orgânica está matura a sobrematura. Os resultados obtidos permitem refletir sobre as condições de subsidência e o contexto tectónico ao qual as amostras estiveram sujeitas aquando da Orogenia Varisca.
- New palynostratigraphic data of the Irati (Assistencia Member) and the Corumbatai formations, Parana Basin, Brazil, and correlation with other south American basinsPublication . Rocha, H., V; Mendes, M.; Pereira, Z.; Rodrigues, C.; Manuel Carvalho Fernandes, Paulo; Lopes, Gilda; Sant'Anna, L. G.; Tassinari, C. C. G.; Lemos de Sousa, M. J.This research presents the palynostratigraphy of organic-rich shales from the Irati and the Corumbatai formations, Parana Basin (PB), Southeastern Brazil, as part of an unconventional hydrocarbon source rock and CO2 reservoir assessment study. Thirty-four samples from the Corumbatai Formation and the Assistencia Member of the Irati Formation were collected in the states of Goias (northern border of the PB), Sao Paulo and Parana (eastern and southern border of the PB, respectively). The acquired data allowed to establish a comprehensive palynostratigraphic study across the basin where a total of 18 pollen genera (34 pollen species), seven spore genera, four microplankton genera (1 species), and Chlorophyceae algae species where identified. The palynostratigraphic analysis also reveals a clear dominance of bisaccate pollen grains such as Corisaccites alutas, Lueckisporites virkkiae, and Weylandites lucifer. The Lueckisporites virkkiae zone was identified in the upper part of the Irati Formation (Assistencia Member) and the lowermost part of the Corumbatai Formation, indicating a Kungurian to Roadian age for this part of the succession. Differences in the Guttulapollenites hannonicus and Tornopollenites toreutos biostratigraphic ranges, recovered in the Corumbatai Formation, suggest an earlier development of these species in the Parana Basin during the middle Permian. Therefore, to evaluate the differences in the first occurrences of key species within the Parana Basin, a close palynostratigraphic correlation between the main Guadalupian-Lopingian South American Gondwana basins is tentatively established.