Mostrando recursos 1 - 20 de 87

  1. Benthic foraminiferal and sedimentological response to the evolution of the Adra submarine delta, northern Alboran Sea

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Rosa, F.; Bárcenas, P.; Fernandez-Salas, L. M.; López-González, N.; Dias, J. A.
    The Adra submarine delta is located on the northern Alboran Sea shelf in the western Mediterranean Sea. The genesis of this deltaic system is associated with the discharges of the short and mountainous Adra River. The area is under the influence of a Mediterranean climate with sporadic winter torrential flows and increased summer aridity. Major anthropogenic activities in the river system occurred in 1872 AD, with the deviation of the main fluvial course to the east. The channel was silted up in 1910 AD as result of a flood event and relocated further west, at its present position. These artificial changes...

  2. Benthic foraminiferal and sedimentological response to the evolution of the Adra submarine delta, northern Alboran Sea

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Rosa, F.; Bárcenas, P.; Fernandez-Salas, L. M.; López-González, N.; Dias, J. A.
    The Adra submarine delta is located on the northern Alboran Sea shelf in the western Mediterranean Sea. The genesis of this deltaic system is associated with the discharges of the short and mountainous Adra River. The area is under the influence of a Mediterranean climate with sporadic winter torrential flows and increased summer aridity. Major anthropogenic activities in the river system occurred in 1872 AD, with the deviation of the main fluvial course to the east. The channel was silted up in 1910 AD as result of a flood event and relocated further west, at its present position. These artificial changes...

  3. Last ca. 250 years shifts of benthic foraminiferal assemblages in response to natural and anthropogenic impacts, northern Alboran Sea

    Mendes, I; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Rosa, F.; Bárcenas, P.; Fernandez-Salas, L. M.; López-González, N.; Dias, J. A.
    Benthic foraminifera have a wide distribution in space and time and also respond rapidly to environmental changes. The northern Alboran Sea is influenced by a torrential regime with sporadic, intense rainfalls and extended periods of aridity. In addition, anthropogenic activities such as river channel deviation have taken place during the last ca. 150 years. In order to understand the interaction between natural and anthropogenic impacts through time, shifts of most abundant benthic foraminiferal species, species richness and diversity indices were combined with sedimentological analyses and radiocarbon dating of sediment cores collected from the Adra shelf prodeltaic deposit, in the northern...

  4. Last ca. 250 years shifts of benthic foraminiferal assemblages in response to natural and anthropogenic impacts, northern Alboran Sea

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Rosa, F.; Bárcenas, P.; Fernandez-Salas, L. M.; López-González, N.; Dias, J. A.
    Benthic foraminifera have a wide distribution in space and time and also respond rapidly to environmental changes. The northern Alboran Sea is influenced by a torrential regime with sporadic, intense rainfalls and extended periods of aridity. In addition, anthropogenic activities such as river channel deviation have taken place during the last ca. 150 years. In order to understand the interaction between natural and anthropogenic impacts through time, shifts of most abundant benthic foraminiferal species, species richness and diversity indices were combined with sedimentological analyses and radiocarbon dating of sediment cores collected from the Adra shelf prodeltaic deposit, in the northern...

  5. The evolution of the Guadalfeo submarine delta (northern Alboran Sea) during the last ca. 200 years.

    Mendes, I.; López-González, N.; Lobo, F. J.; Bárcenas, P.; Fernández-Salas, L. M.; Schönfeld, J.; Ferreira, Óscar
    The Guadalfeo submarine delta is located on the northern Alboran Sea shelf in the western Mediterranean Sea. The sedimentary dynamics of the deltaic system is governed by the discharge of one of the major rivers in this area draining the western sector of the near-coastal Sierra Nevada Mountains. The area is under the influence of a Mediterranean climate, with high spatial and temporal (i.e., inter- and intra-annual) rain variability. Major anthropogenic forcing affected the river system during the 1930’s, with the deviation of the main river channel 2.5 km to the west, to its present position. More recently, the construction...

  6. The evolution of the Guadalfeo submarine delta (northern Alboran Sea) during the last ca. 200 years.

    Mendes, I.; López-González, N.; Lobo, F. J.; Bárcenas, P.; Fernández-Salas, L. M.; Schönfeld, J.; Ferreira, Óscar
    The Guadalfeo submarine delta is located on the northern Alboran Sea shelf in the western Mediterranean Sea. The sedimentary dynamics of the deltaic system is governed by the discharge of one of the major rivers in this area draining the western sector of the near-coastal Sierra Nevada Mountains. The area is under the influence of a Mediterranean climate, with high spatial and temporal (i.e., inter- and intra-annual) rain variability. Major anthropogenic forcing affected the river system during the 1930’s, with the deviation of the main river channel 2.5 km to the west, to its present position. More recently, the construction...

  7. Guadalfeo and Adra submarine deltas evolution in response to sediment supply variations

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; López-González, N.; Bárcenas, P.; Fernandez-Salas, L. M.
    The Guadalfeo and the Adra submarine deltas off the northern coast of the Alboran Sea have been built up under the direct influence of short and mountainous rivers. The area is subjected to strong climatic seasonality, with sporadic winter torrential floods and high summer aridity. In addition numerous anthropogenic activities have affected these systems, mostly during the last two centuries. In order to decode the influence of climatic variability and anthropogenic impacts on sediment supplies during the recent past, five sediment cores were collected from the Guadalfeo and Adra submarine deltas. Benthic foraminiferal and sedimentological analyses, combined with radiocarbon dating,...

  8. Guadalfeo and Adra submarine deltas evolution in response to sediment supply variations

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; López-González, N.; Bárcenas, P.; Fernandez-Salas, L. M.
    The Guadalfeo and the Adra submarine deltas off the northern coast of the Alboran Sea have been built up under the direct influence of short and mountainous rivers. The area is subjected to strong climatic seasonality, with sporadic winter torrential floods and high summer aridity. In addition numerous anthropogenic activities have affected these systems, mostly during the last two centuries. In order to decode the influence of climatic variability and anthropogenic impacts on sediment supplies during the recent past, five sediment cores were collected from the Guadalfeo and Adra submarine deltas. Benthic foraminiferal and sedimentological analyses, combined with radiocarbon dating,...

  9. Benthic foraminifera on the Guadiana inner shelf as indicators of rainfall variability and human impacts on the river basin

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Hanebuth, T.; Lebreiro, S.; Lantzsch, H.; Antón, L.; Reguera, I.
    Prodeltaic depositional systems can be used as high-resolution archives, since they sensitively record environmental changes occurred during their formation. On the inner shelf off the Guadiana River, northern Gulf of Cádiz, the recent deposition is mainly driven by river discharge, which reflects both climate variability and human-induced processes in the river basin. The purpose of this study is to unravel rainfall variability and human impacts on the river basin, recorded on the Guadiana prodeltaic wedge, over the past decades. A multiproxy study including the analyses of benthic foraminiferal assemblages, grain size and geochemical element distribution (X-ray fluorescence core scanning), constrained in...

  10. Benthic foraminifera on the Guadiana inner shelf as indicators of rainfall variability and human impacts on the river basin

    Mendes, I.; Lobo, F. J.; Ferreira, Óscar; Schönfeld, J.; Hanebuth, T.; Lebreiro, S.; Lantzsch, H.; Antón, L.; Reguera, I.
    Prodeltaic depositional systems can be used as high-resolution archives, since they sensitively record environmental changes occurred during their formation. On the inner shelf off the Guadiana River, northern Gulf of Cádiz, the recent deposition is mainly driven by river discharge, which reflects both climate variability and human-induced processes in the river basin. The purpose of this study is to unravel rainfall variability and human impacts on the river basin, recorded on the Guadiana prodeltaic wedge, over the past decades. A multiproxy study including the analyses of benthic foraminiferal assemblages, grain size and geochemical element distribution (X-ray fluorescence core scanning), constrained in...

  11. The record of a high-energy event in a mud entrapment on the inner shelf off the Guadiana river

    Mendes, I.; Lobo, F. J.; Schönfeld, J.; Lebreiro, S. L.; Hanebuth, T.; Lantzsch, H.; Reguera, M. I.; Antón, L.; Ferreira, Óscar
    Recent environmental changes associated with high-energy events and human impacts were investigated in a mud entrapment confined in the paleo-Guadiana incised valley. Those changes were recorded in a gravity core during the last 2500 years. An erosional event seems to have occurred at ca. 500 cal yr BP but it is not clear how much sediment was removed. This event was followed by an increase in river discharges until ca. 465 cal yr BP while the benthic foraminiferal faunas were dominated by species associated with shallow-water sandy sediments. Upward, sedimentological and benthic foraminiferal variations indicated environmental changes, promoted by variable...

  12. The record of a high-energy event in a mud entrapment on the inner shelf off the Guadiana river

    Mendes, I.; Lobo, F. J.; Schönfeld, J.; Lebreiro, S. L.; Hanebuth, T.; Lantzsch, H.; Reguera, M. I.; Antón, L.; Ferreira, Óscar
    Recent environmental changes associated with high-energy events and human impacts were investigated in a mud entrapment confined in the paleo-Guadiana incised valley. Those changes were recorded in a gravity core during the last 2500 years. An erosional event seems to have occurred at ca. 500 cal yr BP but it is not clear how much sediment was removed. This event was followed by an increase in river discharges until ca. 465 cal yr BP while the benthic foraminiferal faunas were dominated by species associated with shallow-water sandy sediments. Upward, sedimentological and benthic foraminiferal variations indicated environmental changes, promoted by variable...

  13. 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...

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

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