Browsing by Author "Descamps, G.S."
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- Lower Cretaceous palynology and palaeoenvironments of Algarve Basin: the Arrifes sectionPublication . Mendes, Márcia; Descamps, G.S.; Fernandes, Paulo; Lopes, Gilda; Jorge, Raul CG Santos; Pereira, ZéliaSUMÁRIO: Uma análise sedimentológica e palinológica detalhada foi realizada na secção dos Arrifes, uma sucessão do Cretácico Inferior da Bacia do Algarve (sul de Portugal). A sucessão estudada é composta por calcários fossilíferos intercalados, calcários margososos e margas, sendo que os palinomorfos identificados indicam uma idade entre o Hauteriviano superior e o Barremiano superior. As principais características deposicionais e palinológicas documentadas na secção dos Arrifes sugerem uma deposição geral sob condições rasas subtidais e intertidais, marcadas por pequenas mudanças climáticas com múltiplas oscilações do nível do mar. Face a estes novos resultados, a área foi correlacionada com outras secções circundantes do Cretácico Inferior, sugerindo uma influência Tethyana durante o Hauteriviano superior, prolongando-se até ao final do Barremiano.
- The upper Hauterivian Barremian (Lower Cretaceous) Arrifes section (Algarve Basin, Southern Portugal): a palynostratigraphic and palaeoenvironmental approachPublication . Mendes, Márcia; Descamps, G.S.; Fernandes, Paulo; Lopes, Gilda; Jorge, Raul CG Santos; Pereira, ZéliaABSTRACT: Integrated sedimentological, palynological, and palynofacies analyses of the Arrifes section in the central Algarve Basin (southern Portugal) provided new information on the age and environments of this Lower Cretaceous sequence. The sedimentary succession at the Arrifes section consists of fossiliferous interbedded limestones, marly limestones, and marls, dated as latest Hauterivian to late Barremian age (Lower Cretaceous) based on key dinoflagellate taxa. During this interval, the Arrifes area records climatic shifts and, multiple sea-level fluctuations; overall deposition was in shallow subtidal to intertidal settings, with deposition of carbonate and marly sediments. During the latest Hauterivian to earliest Barremian interval, an evident sea-level fall culminated in the subaerial exposure of the local carbonate ramp with increased influx of clastic sediments. However, during the Barremian, both sedimentological and palynological analyses suggest an overall deepening of the water depth towards the top of the section. These overall increase in the water column are confirmed by oscillation of terrestrial/marine palynomorph groups and supported by dinosaur track levels at the top of the succession; the latter indicate that sedimentation occurred in intertidal to subtidal environments. Finally, an attempt was made to correlate the Arrifes section with other sections from the Algarve Basin, as well as with broader region. These new data suggest a setting in the Tethyan basin influenced during the latest Hauterivian to the end of the Barremian. These new data allow local correlations and new palynological ages and paleoenvironmental interpretations for the Lower Cretaceous succession of the Algarve Basin.