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Ferreira Ó. - One of the best experts on this subject based on the ideXlab platform.

  • Multi-proxy evidence of rainfall variability recorded in subaqueous Deltaic Deposits off the Adra River, southeast Iberian Peninsula
    'Elsevier BV', 2015
    Co-Authors: Lobo F.j., Fernández-salas, L.m. Miguel), López-gonzález N., Bárcenas P., Schönfeld J., Ferreira Ó.
    Abstract:

    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 expression of recent climatic cycles and anthropogenic interventions in the river basin. Periods of increased Deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770e1810 and 1860 e1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the proDeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous Deltaic Deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions.En prensa2,247

  • Multi-proxy evidence of rainfall variability recorded in subaqueous Deltaic Deposits off the Adra River, southeast Iberian Peninsula
    'Elsevier BV', 2015
    Co-Authors: Lobo F. J., López-gonzález N., Bárcenas P., Fernández-salas L. M., Schönfeld Joachim, Ferreira Ó.
    Abstract:

    Highlights • Multi-proxy evidence of rainfall variability in subaqueous Deltaic Deposits. • Low absolute abundances related with rainfall-driven periods of increase supply. • Raise of colonizers and opportunistic species during dry periods. • Human activities led to a drastic reduction of sedimentation rates. Abstract 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 expression of recent climatic cycles and anthropogenic interventions in the river basin. Periods of increased Deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770–1810 and 1860–1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the proDeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous Deltaic Deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions

Tanya N Harrison - One of the best experts on this subject based on the ideXlab platform.

  • hypotheses for the origin of the hypanis fan shaped Deposit at the edge of the chryse escarpment mars is it a delta
    Icarus, 2019
    Co-Authors: J Adler, J F Bell, P Fawdon, J M Davis, Nicholas H Warner, E Seftonnash, Tanya N Harrison
    Abstract:

    Abstract We investigated the origin of the fan-shaped Deposit at the end of Hypanis Valles that has previously been proposed as an ExoMars, Mars 2020, and human mission candidate landing site, and found evidence that the landform is an ancient delta. Previous work suggests that the Deposit originated from a time of fluvial activity both distinct from and prior to catastrophic outflow, and crater counting placed the Deposit’s age at  ≥ 3.6 Ga. We found over 30 thin sedimentary strata in the proposed delta wall, and from our slope analysis conclude that the fluvial sequence is consistent with a lowering/retreating shoreline. We measured nearly horizontal bedding dip angles ranging from 0° to 2° over long stretches of cliff and bench exposures seen in HiRISE images and HiRISE stereo DTMs. From THEMIS night IR images we determined that the fan-shaped Deposit has a low thermal inertia (150–240 Jm−2K−1s−1/2) and the surrounding darker-toned units correspond to thermal inertia values as high as 270–390 Jm−2K−1s−1/2. We interpret these findings to indicate that the fan-shaped Deposit consists mostly of silt-sized and possibly finer grains, and that the extremely low grade and large lateral extent of these beds implies that the Depositional environment was calm and relatively long-lived. Our assessment of the geomorphology and composition seems to indicate that the alluvial fan and mudflow hypotheses are less compatible. From our stratigraphic mapping we interpret the order of events which shaped the region. After the Chryse impact, sediment filled the basin, a confined lake or sea formed allowing a large delta to be Deposited near its shoreline, the water level receded to the north, darker sedimentary/volcanic units covered the region and capped the light-toned Deposit as hydro-volcanic eruptions shaped the interior of Lederberg crater, freeze/thaw cycles and desiccation induced local fracturing, and finally wrinkle ridges associated with rounded cones warped the landscape following trends in degraded crater rims and existing tectonic features. The ancient Deltaic Deposit we observe today was largely untouched by subsequent catastrophic outflows, and its surface has been only moderately reshaped by over 3 billion years of aeolian erosion.

El Hassan Chellai - One of the best experts on this subject based on the ideXlab platform.

  • facies and sequence stratigraphy of a late barremian wave dominated Deltaic Deposit agadir basin morocco
    Sedimentary Geology, 2002
    Co-Authors: Mohammed Nouidar, El Hassan Chellai
    Abstract:

    Abstract The late Barremian succession in the Agadir Basin of the Moroccan Western High Atlas represents wave-dominated Deltaic Deposits. The succession is represented by stacked thickening and coarsening upwards parasequences 5–15 m thick formed during fifth- or fourth-order regression and building a third-order highstand systems tract. Vertical facies transitions in parasequences reflect flooding followed by shoaling of diverse shelf environments ranging from offshore transition interbedded mudstones, siltstones and thin sandstones, lower shoreface/lower delta front hummocky bedforms to upper shoreface/upper delta front cross-bedded sandstones. The regional configuration reflects the progradation of wave-dominated deltas over an offshore setting. The maximum sea-level fall led to the development of a sequence boundary that is an unconformity. The subsequent early Aptian relative sea-level rise contributes to the development of an extensive conglomerate lagged transgressive surface of erosion. The latter and the sequence boundary are amalgamated forming a composite surface.

Brady Z. Foreman - One of the best experts on this subject based on the ideXlab platform.

  • Laboratory Experiments of Incised Valley Systems: Influence of Sediment Concentration and Sea Level Rise
    2016
    Co-Authors: Chen Chen, Sébastien Castelltort, Chris Paola, Laure Guerit, Brady Z. Foreman
    Abstract:

    Incised valleys have been widely recognized and studied by many researchers (Cason 1982, Hansen 1984, Dalrymple, Zaitlin et al. 1992, Zaitlin 1994, Posamentier 2001, Li, Wang et al. 2002). The original description of incised valleys of the Mississippi river was established by Fisk in 1944 and later defined as a “fluvial eroded, elongate topographic low that is typically larger than a single channel” (B.A. Zaitlin 1994). Valley fills generally contain a complex range of alluvial architecture linked to laterally amalgamated sandy channel belts in lowstand systems tracts (Martinsen 1994, Zaitlin 1994, Posamentier 2001) to channel avulsion process and backstepping Deltaic Deposit (Harris 1994) during highstand systems tracts. However, some fundamental questions still need to be investigated, in particular 1)what is the influence of upstream controls (e.g., sediment concentration) versus downstream controls (e.g., base level rise) on channel geometrical records in the paleo-valley, and 2) what is the signature of autogenic processes sedimentary records in the incised valley Depositional stratigraphy? To answer these questions, we performed several experiments of incised valley infilling Deposition during a single base-level rise in the Saint Antony Falls Laboratory (SAFL, University of Minnesota). We designed and built a 2m x 0.8m x 0.12m V-shape valley placed into a 5m x 5m basin. The water level of this basin is totally controlled and allows reproducing sea-level rise at different rates. We performed 10 sets of experiments, during which we systematically changed the water discharge and the rate of base level rise. The topography is measured over the whole surface of the valley at regular time intervals (every 10 minutes) by computer-controlled laser scanner. In addition, the geometry of the channel sandbodies is acquired by cross-section photos after each runs. The experimental results are then compared with the stratigraphic record of the paleo-incised valley in the Esplugafreda section of the central Tremp-Graus basin (Spanish South-Pyrenees). This section is composed of sandbodies and well-developed soils (Esplugafreda Fm.) capped by a massive conglomerate (Claret Fm.). Preliminary results suggest that water discharge could influence the variability of sandbodies geometry in the incised valley and the stratigraphic sequence in Esplugafreda Section could the inevitable autogenic signature of valley filling, rather than the record of an upstream perturbation.

  • Laboratory experiments of autogenic fluvial progradation above incised-valley fills during sea-level rise
    2016
    Co-Authors: Chen Chen, Sébastien Castelltort, Chris Paola, Laure Guerit, Brady Z. Foreman
    Abstract:

    Incised valleys have been widely recognized and studied by many researchers (Hansen 1984, Dalrymple, Zaitlin et al. 1992, Zaitlin 1994, Posamentier 2001, Li, Wang et al. 2002). The original description of incised valleys of the Mississippi River was established by Fisk in 1944 and later defined as a “fluvial eroded, elongate topographic low that is typically larger than a single channel” (Zaitlin 1994). Valley fills generally contain a complex range of alluvial architecture linked to laterally amalgamated sandy channel belts in lowstand systems tracts (Martinsen 1994, Zaitlin 1994, Posamentier 2001) to channel avulsion proceses and backstepping Deltaic Deposit (Harris 1994) during highstand systems tracts.

Bárcenas P. - One of the best experts on this subject based on the ideXlab platform.

  • Multi-proxy evidence of rainfall variability recorded in subaqueous Deltaic Deposits off the Adra River, southeast Iberian Peninsula
    'Elsevier BV', 2015
    Co-Authors: Lobo F.j., Fernández-salas, L.m. Miguel), López-gonzález N., Bárcenas P., Schönfeld J., Ferreira Ó.
    Abstract:

    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 expression of recent climatic cycles and anthropogenic interventions in the river basin. Periods of increased Deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770e1810 and 1860 e1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the proDeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous Deltaic Deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions.En prensa2,247

  • Multi-proxy evidence of rainfall variability recorded in subaqueous Deltaic Deposits off the Adra River, southeast Iberian Peninsula
    'Elsevier BV', 2015
    Co-Authors: Mendes Isabel, López-gonzález N., Bárcenas P., Schönfeld J., Lobo F. J., Fernández-salas L. M., Ferreira Óscar
    Abstract:

    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 expression of recent climatic cycles and anthropogenic interventions in the river basin. Periods of increased Deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770e1810 and 1860 e1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the proDeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous Deltaic Deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions.info:eu-repo/semantics/publishedVersio

  • Multi-proxy evidence of rainfall variability recorded in subaqueous Deltaic Deposits off the Adra River, southeast Iberian Peninsula
    'Elsevier BV', 2015
    Co-Authors: Lobo F. J., López-gonzález N., Bárcenas P., Fernández-salas L. M., Schönfeld Joachim, Ferreira Ó.
    Abstract:

    Highlights • Multi-proxy evidence of rainfall variability in subaqueous Deltaic Deposits. • Low absolute abundances related with rainfall-driven periods of increase supply. • Raise of colonizers and opportunistic species during dry periods. • Human activities led to a drastic reduction of sedimentation rates. Abstract 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 expression of recent climatic cycles and anthropogenic interventions in the river basin. Periods of increased Deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770–1810 and 1860–1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the proDeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous Deltaic Deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions