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Terrinha Pedro Pueyo Emilio L. Aranguren Aitor Kullberg José Carlos Kullberg Maria Carla Casas-Sainz Antonio Azevedo Maria do Rosário 《International Journal of Earth Sciences》2018,107(5):1807-1833
International Journal of Earth Sciences - The geometry and emplacement of the ~ 96 km2, Late Cretaceous Sintra Igneous complex (SIC, ca. 80 Ma) into the West Iberian passive... 相似文献
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Forcada A Bayle-Sempere JT Valle C Sánchez-Jerez P 《Marine environmental research》2008,66(5):536-547
Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas. 相似文献
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Fernando D'Eramo José M. Tubía Lucio Pinotti Néstor Vegas Jorge Coniglio Manuel Demartis Aitor Aranguren Miguel Basei 《地学学报》2013,25(5):423-430
This study deals with the structure and emplacement of the Calmayo and El Hongo trondhjemite plutons (Famatinian belt of Córdoba, Argentina). It provides structural data from the granites and the country rocks and a study of the magnetic fabric in the plutons. New U/Pb geochronological data yield intrusion ages of 512.1 ± 3.4 Ma and 500.6 ± 4.5 Ma for the Calmayo and El Hongo plutons respectively. The El Hongo massif and the southern part of the Calmayo trondhjemite preserve magmatic structures, whereas the northern domain of Calmayo shows the imprint of solid‐state deformation. The main foliation in the country rocks outlines a boudin‐like pattern at the map scale and the granites are located along boudin necks, suggesting that the emplacement of these trondhjemite plutons was linked to large‐scale boudinage of the country rocks. 相似文献
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Calciclastic submarine fans are rare in the stratigraphic record and no bona fide present-day analogue has been described to date. Possibly because of that, and although calciclastic submarine fans have long intrigued deep-water carbonate sedimentologists, they have largely been overlooked by the academic and industrial communities. To fill this gap we have compiled and critically reviewed the existing sedimentological literature on calciclastic submarine fans, thus offering an updated view of this type of carbonate slope sedimentary system.Calciclastic submarine fans range in length from just a few to more than 100 km. Three different types can be distinguished: (1) Coarse-grained, small-sized (< 10 km) fans, which are characterized by the abundance of calcirudites and the scarcity of mud. They have relatively long leveed channels and small radial lobes. (2) Medium-grained, medium-sized fans are typified by the abundance of calcarenites and lesser amounts of calcirudites and mud. They have a tributary network of slope gullies, which merge to form a leveed channel that opens to the main depositional site, characterized by extensive lobes and/or sheets, which eventually pass into basinal deposits through a narrow fan-fringe area. These fans are between 10 and 35 km in length. (3) Fine-grained, large-sized fans are rich in calcarenites and mud, but poor in calcirudites. They have wide and long slope channels that feed very extensive calciturbiditic sheets, the total length always exceeding 50 km and generally being close to 100 km. In terms of grain-size distribution the three fan types compare well with sand/gravel-rich, mud/sand-rich and mud-rich siliciclastic submarine fans, respectively. However, they show notable differences in terms of size and sedimentary architecture, a reflection of the different behaviour of their respective sediment gravity flows.Most calciclastic submarine fans were formed on low-angle slopes and were sourced from distally steepened carbonate ramps subjected to high-energy currents. Under these conditions shallow-water loose grainy sediments were transferred to the ramp slope and eventually funnelled into the submarine fan by sediment gravity flows. These conditions seem to have been more easily met on leeward margins in which the formation of reefs was hampered by cool waters, nutrient enrichment or oligophoty. Another circumstance that contributes to the transfer of shallow-water sediments to the distal ramp slope is a low sea level, forcing the carbonate factory closer to the slope break and destabilizing sediments by increased pore-water pressure. However, the most important factor controlling the development of calciclastic submarine fans was the existence of an efficient funnelling mechanism forcing sediment gravity flows to merge downslope and build up a point-sourced sedimentary accumulation. In most cases this occurred through a major slope depression associated with tectonic structures, an inherited topography, or large-scale mass failures. 相似文献
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Contrasting environmental effects of astronomically driven climate change on three Eocene hemipelagic successions from the Basque–Cantabrian Basin 
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下载免费PDF全文 Naroa Martínez‐Braceras Aitor Payros Francesco Miniati Javier Arostegi Gloria Franceschetti 《Sedimentology》2017,64(4):960-986
Several processes can contribute to the formation of hemipelagic limestone–marl alternations as a consequence of astronomically driven climate change. The aim of this study was to decipher which environmental factors governed the formation of three Eocene hemipelagic successions of the Basque–Cantabrian Basin using a comprehensive set of physical and bulk carbonate geochemical data (bed thickness, mineralogy, %CaCO3, δ13C and δ18O). The results show that the significance of several environmental processes varied depending on the palaeogeographic setting and eccentricity‐modulated precessional seasonality. In the Sopelana starved deep‐sea basin, limestones were formed as a consequence of high pelagic carbonate productivity during periods of warm seawater and sluggish circulation, which corresponded with periods of low seasonality (summers at aphelion); conversely, marls accumulated when pelagic carbonate productivity decreased during periods with cooler waters and more vigorous circulation, which occurred when seasonality was higher (summers at perihelion). In the Gorrondatxe submarine fan fringe, marls accumulated when high seasonality produced significant continental rainfall and run‐off, causing the dilution of pelagic carbonate sedimentation with terrigenous supplies. In the Oyambre upper slope, marls also accumulated when seasonality was high, as pelagic carbonate productivity decreased due to both the expansion of low‐salinity waters on the ocean surface and the increase in continentally derived nutrients, which caused detrimental seawater conditions for calcareous plankton. Both in Gorrondatxe and Oyambre, limestones accumulated when boreal summer at aphelion caused low seasonality, which allowed relatively stable conditions to prevail. At minimum eccentricity, when precession‐driven seasonality contrast diminished, changes in pelagic carbonate productivity were significant in the three sections. On the contrary, at maximum eccentricity, when seasonality peaked due to summers occurring at perihelion, the effects of other environmental processes, such as continental and oceanic currents, became influential. However, the influence of these processes minimized when summertime coincided with aphelion at maximum eccentricity and seasonality was weakest. 相似文献
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Fernando D. Hongn José M. Tubía Aitor Aranguren Néstor Vegas Ricardo Mon Gregory R. Dunning 《Journal of South American Earth Sciences》2010,29(2):289-305
The Tastil batholith (Eastern Cordillera, NW Argentina) holds relevant keys for interpreting the tectonic evolution of the Central Andes basement since it has always been interpreted as the subcrop of the Cambrian and Lower Ordovician basins in the Eastern Cordillera. However, in the Angosto de la Quesera section, the batholith intrudes sandstones underlying a fossiliferous Lower Tremadocian conglomerate containing Tastil granite pebbles. The precise assignation of the sandstones intruded by the granite to Cambrian Mesón Group or to the Uppermost Cambrian–Lower Tremadocian Santa Victoria Group is a key for refining the relationships between magmatic and sedimentary units. The ages of 526 Ma and 517 Ma (U/Pb, zircons) obtained from two facies of the batholith are coherent with the proposal of including these sandstones in the Mesón Group. However, the lithologic features and fossil content point to an affinity with the basal units of the Santa Victoria Group according to sedimentologic and stratigraphic studies ruled out by other authors. The intrusive relationships between the Tastil batholith and the Lower Paleozoic sandstones indicates the batholith is coeval with the Mesón and/or Santa Victoria groups basins instead of being its subcrop, which strongly contradicts previous proposals about basement evolution along the Lower Paleozoic margin of Gondwana. Therefore, the genesis and emplacement of the Tastil batholith must be related to the development of the Lower Paleozoic shelf basins rather than with the final stages of Puncoviscana-type basin evolution. The basement of central and northern Argentina records a wide spectrum of sedimentary, deformational, magmatic and metamorphic processes at a variety of crust levels during the Early Paleozoic. Tastil batholith emplacement and exhumation in the Eastern Cordillera represent shallower crustal expressions of the plutonic and high-T–low-P metamorphic events at deeper levels in the basement now exposed mainly in eastern Puna and Pampean Ranges. 相似文献
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A one year long monthly sampling series at a fixed station was combined with a high-spatial resolution survey (May 2003) to investigate factors controlling zooplankton distribution in the south-eastern corner of the Bay of Biscay. Species abundance and gonad maturity for Calanoides carinatus and Calanus helgolandicus were estimated to clarify whether the observed spatial patterns were attributable to increased population growth or to mechanical accumulation. The two studies included distinct oceanographic regimes. The eastern corner of the grid was characterized by Adour river plume waters and the Cap Breton canyon, and the rest of the area by an alternating pattern of physical convergences and divergences. In the river plume, the zooplankton community diversity and abundances were highest in response to the nutrient enriched river plume waters and the submarine canyon. In the rest of the area, distribution and abundance patterns were the result of a combination of behaviour and physical transport. 相似文献
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The influence of astronomically driven short‐term climate change (Milankovitch cycles) on deep‐marine turbidite systems is not well‐known, particularly in the case of long‐term greenhouse intervals with no significant glacio‐eustatic sea‐level fluctuations. This study, carried out at the Gorrondatxe section (Global Stratotype Section and Point for the base of the Lutetian Stage in the western Pyrenees), demonstrates that the characteristics of lower–middle Eocene fan‐fringe/basin‐plain turbiditic and pelagic deposits varied in line with orbitally forced fluctuations in seasonal rainfall, runoff and terrigenous input to the sea. Reduced turbiditic activity during the formation of pelagic limy precessional hemicouplets indicates subdued seasonality and low terrigenous input. Conversely, turbidity currents were more frequent, had greater energy and were more voluminous during the formation of pelagic marly hemicouplets, suggesting precessional hemicycles with strong seasonality and heavy summer rainfall. These differences at precessional time scales were enhanced at maximum eccentricity because turbiditic activity was most intense when boreal summer occurred at perihelion (i.e. maximum seasonality) but declined when it occurred at aphelion. At minimum eccentricity, with relatively weak seasonality throughout one (or more than one) precessional cycle (>21 kyr), turbiditic activity remained relatively low. The pattern observed at the Gorrondatxe fan‐fringe/basin‐plain succession implies that the orbitally forced environmental changes must also have affected the inner and middle parts of the submarine fan. The astronomical influence on terrigenous sediment input also determined the changing characteristics of the pelagic sedimentation. Thus, terrigenous sediment contribution to pelagic sedimentation fluctuated by a factor of five during opposite precessional situations at maximum eccentricity, whereas there was almost no fluctuation at minimum eccentricity. 相似文献
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Naves Acacia Samper Javier Pisani Bruno Mon Alba Dafonte Jorge Montenegro Luis García-Tomillo Aitor 《Hydrogeology Journal》2021,29(8):2655-2669
Groundwater availability, management and protection are great challenges for the sustainability of groundwater resources in the scattered rural areas of the Atlantic regions of Europe where groundwater is the only option for water supply. This report presents a hydrogeological study of the coastal granitic area of Oia in northwestern Spain, which has unique geomorphological and hydrogeological features with steep slopes favoring the erosion of the weathered granite. The hydrogeological conceptual model of the study area includes: (1) the regolith layer, which is present only in the flat summit of the mountains; (2) the slope debris and the colluvial deposits, which are present in the intermediate and lowest parts of the hillside; (3) the marine terrace; and (4) the underlying fractured granite. Groundwater recharge from rainfall infiltration varies spatially due to variations in terrain slope, geology and land use. The mean annual recharge estimated with a hydrological water balance model ranges from 75 mm in the steepest zone to 135 mm in the lowest flat areas. Groundwater flows mostly through the regolith and the detrital formations, which have the largest hydraulic conductivities. Groundwater discharges in seepage areas, springs, along the main creeks and into the sea. The conceptual hydrogeological model has been implemented in a groundwater flow model, which later has been used to select the best pumping scenario. Model results show that the future water needs for domestic and tourist water supply can be safely provided with eight pumping wells with a maximum pumping rate of 700 m3/day.
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