Mostrando recursos 1 - 20 de 177

  1. The continental shelf off the Guadiana estuary

    Mendes, I.; Rosa, Francisca
    The Continental shelf is the seafloor area around a large land mass where the sea is relatively shallow compared with the open ocean.This major physiographic domain is comprised between the shoreline and the shelf break located at variable water depths (generally, around 200 m water depth) and variable extensions (average width of about 80 km). The continental shelf off the Guadiana estuary is the area in front of the Guadiana River mouth,which is influenced by the discharges of the Guadiana River Basin.This area is located in the southern border between Portugal and Spain, in the middle part of the northern Gulf of Cadiz continental shelf, southwestern Iberian...

  2. Inner shelf paleoenvironmental evolution as a function of land–ocean interactions in the vicinity of the Guadiana River, SW Iberia

    Mendes, I.; Rosa, F.; Dias, J. A.; Schönfeld, J.; Ferreira, Óscar; Pinheiro, J. P.
    This study investigates the land-ocean interactions along the northern margin of the Gulf of Cadiz in the vicinity of the Guadiana River. Benthic foraminifera and sedimentological characteristics were analysed in a sedimentary sequence spanning ca. 5000 years (core 8, 22 m water depth) retrieved from the inner shelf prodeltaic wedge. The analyses were integrated in a temporal framework based on accelerated mass spectrometry radiocarbon dating. Paleoenvironmental changes and sediment transfer mechanisms from the continent to the shelf were investigated and related to climatic oscillations and anthropogenic impact in the region. The results allowed the identification of two main periods of deposition....

  3. Living, dead and fossil benthic foraminifera on a river dominated shelf (northern Gulf of Cadiz) and their use for paleoenvironmental reconstruction

    Mendes, I.; Dias, J. A.; Schönfeld, J.; Ferreira, Óscar; Rosa, F.; Lobo, F. J.
    Same-area comparison between patterns of Recent (living) and Holocene benthic foraminiferal assemblage composition is essential to validate their utility as proxies for paleoenvironmental reconstructions. Such reconstructions have scarcely been attempted in shelf environments. In this study, we compared living (stained), dead and Holocene benthic foraminiferal assemblages from the Gulf of Cadiz continental shelf off the Guadiana River. On average, 99% of the living benthic foraminiferal species were preserved in the dead assemblage and 95% in the fossil record. Several common species were assessed as indicators for certain environmental factors, including river discharge, supply of terrestrial organic matter, heavy metal concentrations,...

  4. Multi-proxy evidence of rainfall variability recorded in subaqueous deltaic deposits off the Adra River, southeast Iberian Peninsula

    Mendes, I.; Lobo, F. J.; Fernández-Salas, L. M.; López-González, N.; Bárcenas, P.; Schönfeld, J.; Ferreira, Óscar
    The Adra River deltaic system, southeast Iberian Peninsula, shows a steep topography and is subjected to strong climatic seasonality. This system has been affected by alternating wet and dry periods, and it has also undergone numerous anthropogenic activities such as deforestation, mining activities, river channel deviations and dam construction, particularly during the last two centuries. Two sediment cores were retrieved off the Adra River, from the western (MS_V9) and eastern (MS_V4) lobes of the subaqueous deltaic deposit. A multi-proxy study was carried out, including grain size, benthic foraminiferal assemblages, magnetic susceptibility and geochemical element analyses, in order to understand the sedimentary...

  5. Resumos das comunicações apresentadas na conferência internacional "Desenvolvimento sustentavel dos Oceanos: uma utopia útil". Homenagem ao Professor Mário Ruivo


    info:eu-repo/semantics/publishedVersion

  6. Resumos das comunicações apresentadas na conferência internacional "Desenvolvimento sustentável do Oceano: uma utopia útil". Homenagem ao Professor Mário Ruivo


    info:eu-repo/semantics/publishedVersion

  7. Mudança do nível do mar no golfo de Cádiz durante o Plistocénico tardio e Holocénico

    Boski, T.; Moura, Delminda; Sousa, Carlos; Gomes, Ana; Pereira, Laura; Oliveira, Sónia; Santana, Paulo
    The multiproxy information data set obtained from borehole sequences permitted to establish a robust chronology of events, which led to the post glacial infilling of the terminal stretches of regional river palleovaleys. The paleoecological reconstructions combined with 14C age model of Guadiana Estuary sedimentary record revealed the fast sea level rise period since ca 13.5 kyr cal BP, halted during the Younger Dryas and resuming at ca 11500 yr cal BP. The Holocene history of coastal evolution is also well documented in the Estuary of Arade and in Ria Formoza, pointing to the sea level stabilization at ca 7500 cal BP...

  8. Mudança do nível do mar no golfo de Cádiz durante o Plistocénico tardio e Holocénico

    Boski, T.; Moura, Delminda; Sousa, Carlos; Gomes, Ana; Pereira, Laura; Oliveira, Sónia; Santana, Paulo
    The multiproxy information data set obtained from borehole sequences permitted to establish a robust chronology of events, which led to the post glacial infilling of the terminal stretches of regional river palleovaleys. The paleoecological reconstructions combined with 14C age model of Guadiana Estuary sedimentary record revealed the fast sea level rise period since ca 13.5 kyr cal BP, halted during the Younger Dryas and resuming at ca 11500 yr cal BP. The Holocene history of coastal evolution is also well documented in the Estuary of Arade and in Ria Formoza, pointing to the sea level stabilization at ca 7500 cal BP...

  9. Moving sands along a headland-embayed beach system (Algarve, Southern Portugal)

    Oliveira, Sónia; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, C.; Moura, Delminda
    Resilience of embayed and pocket beaches located at the southernmost coast of Portugal is currently a major question to coastal management of this region. In fact, several among those beaches have been artificially fed aiming to increase the width of the beach allowing people to maintain a safe distance to the unstable rocky cliffs.

  10. Moving sands along a headland-embayed beach system (Algarve, Southern Portugal)

    Oliveira, Sónia; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, C.; Moura, Delminda
    Resilience of embayed and pocket beaches located at the southernmost coast of Portugal is currently a major question to coastal management of this region. In fact, several among those beaches have been artificially fed aiming to increase the width of the beach allowing people to maintain a safe distance to the unstable rocky cliffs.

  11. Modelling the hydrodynamic and morphosedimentary response of an beach-headland system (Algarve, Southern Portugal)

    Horta, João; Oliveira, Sónia; Moura, Delminda
    Future behaviour of beaches within a headland-beach system is of fundamental interest on coastal evolution since they act as a buffer between the waves’ attack and the cliffs backing them. The beaches at the cliffs’ foot anchored between headlands are space-limited environments to morphosedimentary processes.

  12. Modelling the hydrodynamic and morphosedimentary response of an beach-headland system (Algarve, Southern Portugal)

    Horta, João; Oliveira, Sónia; Moura, Delminda
    Future behaviour of beaches within a headland-beach system is of fundamental interest on coastal evolution since they act as a buffer between the waves’ attack and the cliffs backing them. The beaches at the cliffs’ foot anchored between headlands are space-limited environments to morphosedimentary processes.

  13. O registo de diatomáceas e foraminiferos da Ria Formosa (Sul da Península Ibérica): uma contribuição para a compreensão da evolução Holocénica do sistema lagunar.

    Gomes, Ana; Pereira, Laura; Boski, T.; Connor, Simon; Sousa, Carlos; Oliveira, Sónia; Santana, Paulo
    As part of a multi-proxy study to reconstruct the Holocene evolution of the Ria Formosa Lagoon, diatom and foraminifera assemblages were analyzed in a ca. 24.6-m-deep borehole, which crossed the entire infill sequence of the local paleovalley. Except in a few samples, diatom assemblages were generally poorly preserved, whereas foraminiferal assemblages were mostly well preserved. In the core depths interval from 23.5 and 3.2 m, both proxies indicate a marine environment installed during the progressive flooding of the fluvial valley during the Holocene. Above 3.2-m, both proxies

  14. O registo de diatomáceas e foraminiferos da Ria Formosa (Sul da Península Ibérica): uma contribuição para a compreensão da evolução Holocénica do sistema lagunar.

    Gomes, Ana; Pereira, Laura; Boski, T.; Connor, Simon; Sousa, Carlos; Oliveira, Sónia; Santana, Paulo
    As part of a multi-proxy study to reconstruct the Holocene evolution of the Ria Formosa Lagoon, diatom and foraminifera assemblages were analyzed in a ca. 24.6-m-deep borehole, which crossed the entire infill sequence of the local paleovalley. Except in a few samples, diatom assemblages were generally poorly preserved, whereas foraminiferal assemblages were mostly well preserved. In the core depths interval from 23.5 and 3.2 m, both proxies indicate a marine environment installed during the progressive flooding of the fluvial valley during the Holocene. Above 3.2-m, both proxies

  15. The morphosedimentary behaviour of a headland–beach system: Quantifying sediment transport using fluorescent tracers

    Oliveira, Sónia; Moura, Delminda; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, C.
    Embayed beaches occurring along rocky coasts with headlands controlling hydrosedimentary processes are considered to be constrained sedimentary systems with little longshore sediment transfer between them. Such beaches are likely to narrow under rising sea level and a deficit of fluvial sediment, and because beaches act to dissipate wave energy, cliff erosion is expected to increase. Knowledge of hydrosedimentary processes in fetch-limited environments such as embayed beaches is therefore a fundamental management tool in erosionprone coastal areas such as the Algarve region (southern Portugal). Themain objective of this work is to quantify longshore sediment transport (LST) using a sedimentary tracer and compare the resultswith the ones derived...

  16. The morphosedimentary behaviour of a headland–beach system: Quantifying sediment transport using fluorescent tracers

    Oliveira, Sónia; Moura, Delminda; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, C.
    Embayed beaches occurring along rocky coasts with headlands controlling hydrosedimentary processes are considered to be constrained sedimentary systems with little longshore sediment transfer between them. Such beaches are likely to narrow under rising sea level and a deficit of fluvial sediment, and because beaches act to dissipate wave energy, cliff erosion is expected to increase. Knowledge of hydrosedimentary processes in fetch-limited environments such as embayed beaches is therefore a fundamental management tool in erosionprone coastal areas such as the Algarve region (southern Portugal). Themain objective of this work is to quantify longshore sediment transport (LST) using a sedimentary tracer and compare the resultswith the ones derived...

  17. Holocene history of Ria Formosa coastal lagoon system (Southern Portugal): borehole evidence and threedimensional paleotopography

    Sousa, Carlos; Boski, T.; Gomes, Ana; Pereira, Laura; Lampreia, João; Oliveira, Sónia
    A paleotopographic model of Ria Formosa is presented based on two borehole campaigns and a systematic comparison with previous works, revealing the existence of a complex network of fluvial valleys. Vertical sediment profiles showed a mosaic of changing depositional environments, resulting from local hydrodynamics, sedimentary sources and, to an extent, by the structurally inherited accommodation space. Sedimentological, geochemical and micropaleontological data were put in the context of an age model obtained from 14C datings, pointing to the existence of an estuarine environment subjected to a rapid coastal flooding from ca. 10000 to 7500 cal. years B.P., followed by a period...

  18. Holocene history of Ria Formosa coastal lagoon system (Southern Portugal): borehole evidence and threedimensional paleotopography

    Sousa, Carlos; Boski, T.; Gomes, Ana; Pereira, Laura; Lampreia, João; Oliveira, Sónia
    A paleotopographic model of Ria Formosa is presented based on two borehole campaigns and a systematic comparison with previous works, revealing the existence of a complex network of fluvial valleys. Vertical sediment profiles showed a mosaic of changing depositional environments, resulting from local hydrodynamics, sedimentary sources and, to an extent, by the structurally inherited accommodation space. Sedimentological, geochemical and micropaleontological data were put in the context of an age model obtained from 14C datings, pointing to the existence of an estuarine environment subjected to a rapid coastal flooding from ca. 10000 to 7500 cal. years B.P., followed by a period...

  19. Aplicação multimédia sobre a Ria Formosa e seus fins educacionais (ForDid)

    Oliveira, Sónia; Boski, T.; Moura, Delminda; Sousa, Carlos; Gomes, Ana; Pereira, Laura
    Na atualidade torna-se inquestionável a necessidade de integrar a aprendizagem com as novas tecnologias de modo a cativar e facilitar a compreensão dos temas abordados através de aplicações didáticas. Durante a última década o Centro de Investigação Marinha e Ambiental (CIMA) assumiu a responsabilidade de criar meios eficazes de comunicação entre o público em geral e a comunidade científica, através de plataformas multimédia interativas. Foram objecto destas aplicações didáticas as várias vertentes do património natural do Algarve. Após o sucesso das primeiras aplicações GuaDid e MonDid visando o Estuário do Rio Guadiana e a Serra de Monchique respectivamente, o desafio de criar e inovar foi acrescido, resultando numa...

  20. Aplicação multimédia sobre a Ria Formosa e seus fins educacionais (ForDid)

    Oliveira, Sónia; Boski, T.; Moura, Delminda; Sousa, Carlos; Gomes, Ana; Pereira, Laura
    Na atualidade torna-se inquestionável a necessidade de integrar a aprendizagem com as novas tecnologias de modo a cativar e facilitar a compreensão dos temas abordados através de aplicações didáticas. Durante a última década o Centro de Investigação Marinha e Ambiental (CIMA) assumiu a responsabilidade de criar meios eficazes de comunicação entre o público em geral e a comunidade científica, através de plataformas multimédia interativas. Foram objecto destas aplicações didáticas as várias vertentes do património natural do Algarve. Após o sucesso das primeiras aplicações GuaDid e MonDid visando o Estuário do Rio Guadiana e a Serra de Monchique respectivamente, o desafio de criar e inovar foi acrescido, resultando numa...

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