oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 36 )

2018 ( 181 )

2017 ( 126 )

2016 ( 191 )

Custom range...

Search Results: 1 - 10 of 4202 matches for " Guadalquivir basin "
All listed articles are free for downloading (OA Articles)
Page 1 /4202
Display every page Item
Caracterización y origen de la facies glauconítica de la cuenca del Guadalquivir
Galán, E.,González, I.,Mayoral, E.,Vázquez, M. A.
Estudios Geologicos , 1989, DOI: 10.3989/egeol.89453-4489
Abstract: Occurrences of glauconite in Tertiary materials of the Guadalquivir basin have been known nearly a century. Recent studies indicate that the glauconite is stratigraphically concentrated in two levels: the lower one (Miocene) being at the boundary between a detrital-carbonate formation and the Blue Clays ; the higher one (Pliocene) at the transition between the Blue Clays and the Huelva Sand Formation. Different glauconitizacion degrees of organic remains have been observed in both glauconitic level studied. The environmental conditions during sedimentation of glauconite materials as deduced from palaeontological and sedimentological data, suppose that glauconite pellets may have formed in an open-sublitoral environment at around 50 m deep. La presencia de glauconita en los materiales terciarios de la Cuenca del Guadalquivir se conoce desde hace casi un siglo. Estudios recientes la sitúan estratigráficamente en dos niveles: uno inferior (Mioceno) en el tránsito de una facies detrítico-carbonatada y las Margas azules, y otro superior (Plioceno) entre las Margas azules y la Formación Arenas de Huelva. En el presente trabajo se ha realizado una caracterización mineralógica y genética de la glauconita, encontrándose un diferente grado de evolución para cada nivel, y condiciones de sedimentación propias de un medio marino sublitoral, con una profundidad < 50 m, a partir de datos sedimentológicos y paleontológicos. Por último, se interpreta además su significado paleogeográfico en la evolución general de la Cuenca del Guadalquivir.
Braquiópodos neógenos del suroeste de la depresión del Guadalquivir (sur de Espa?a)
Toscano-Grande, Antonio;García-Ramos, Diego;Ruiz-Mu?oz, Francisco;González-Regalado, María Luz;Abad, Manuel;Civis-Llovera, Jorge;González-Delgado, José ángel;Rico-García, Alberto;Martínez-Chacón, María Luisa;Xiomara García, Edith;Pendón-Martín, José Gabriel;
Revista mexicana de ciencias geológicas , 2010,
Abstract: this paper analyzes the first brachiopod record of three neogene formations of the southwestern guadalquivir basin (huelva province, sw spain) with a wide cartographical distribution. samples obtained in five sections of these formations have allowed to recognize three species belonging to the genera terebratula, maltaia and cryptopora, the latter being the first record of this genus in spain. in addition, the biostratigraphical distribution and palaeoecological context of these species and others present in upper neogene sediments (tortonian-lower pliocene) of south spain are discussed.
Contribución de la mineralogía de arcillas a la interpretación de la evolución paleogeografica del sector occidental de la Cuenca del Guadalquivir
Galán, E.,González, I.
Estudios Geologicos , 1993, DOI: 10.3989/egeol.93495-6354
Abstract: Marine tertiary materials of the Guadalquivir basin consist of four mayor depositional sequences of great continuity in the whole basin which are separate by unconformities. The lower outcroping unit (unit 2) ineludes glauconite-rich sandstones and marly limestones (Fm. Calcarenitas de Niebla, Tortonian-Messinian) and Olisthostromic materials. This unit lies discordantly over the Paleozoic, and was sedimented in a shaUow marine platform. Olisthostromic materials (Mesozoic and Miocene), composed of sand and elayey sand, were deposited during Tortonian-Messinian times. As a consequence of a transgressive pulse, the sedimentation of a thick marly series (Fm. Arcillas de Gibraleón) ofthe Messinian-Low Pliocene age took place. In the last stages of the filling of the basin (Pliocene) a regression began, and sands and silts were deposited (Fm. Arenas de Huelva and Fm. Arenas de Bonares). Also, and as a final consequence of the regression stage, lacustrine sedimentary deposits (Upper Pliocene) occur at the south of the basin, which are composed of marly limestone and greenish palygorskite and sepiolite marls. From a mineralogical point of view, autochthonous materials from this marine detritalcarbonate series, are mainly composed of calcite, quartz and phyUosilicates with minor dolomite and feldspars, and secondary gypsum. The elay minerals present are illite and smectite with minor kaolinite and chlorite. The evolution of the elay minerals associations varies from bottom to top as foUows: Illite or Clauconite >> Smectite > Chlorite/Kaolinite (Fm. Calcarenitas de Niebla); Smectite a ¥ Illite > Kaolinite (Lower Fm. Arcillas de Gibraleón); Illite > Smectite a ¥ Kaolinite/Chlorite) (Upper Fm. Arcillas de Gibraleón), and Smectite > Illite > Kaolinite (Fm. Arenas de Huelva y Fm. Arenas de Bonares). This vertical variation confirms a stratigraphical discontinuity (paraconformity) into the Fm. Arcillas de Gibraleón, which was observed by others from stratigraphical and paleontological data, and supports a new mineralogical change between the Fm. Arcillas de Gibraleón y Fm. Arenas de Huelva. Sedimentation of those materials above described took place in a shallow marine environment which was more superficial upward, according to palaeontological data. The illite crystal-chemistry characteristics, suggest that metamorphic and igneous rocks from the South Iberian Massif should be the source area for these sediments. The mineralogical composition of allochthonous materials are quartz, opal-A and opalCT, phyllosilicates, and calcite. The clayminerals are predominantly smec
Las formaciones Plio-Cuaternarias de El Abalario, en el litoral de la provincia de Huelva
Salvany, J. M.,Mediavilla, C.,Rebollo, A.
Estudios Geologicos , 2010, DOI: 10.3989/egeol.39953.072
Abstract: The study of new and ancient boreholes in El Abalario area (Lower Guadalquivir basin) permitted to identify four main plio-quaternary formations above the Miocene marls, namely: Huelva Sands, Bonares Sands, Almonte Sands and Gravels, and El Abalario Sands. Respectively, they are interpreted as shallow marine, deltaic, alluvial and eolian sediments, together forming a marine to continental sequence that reaches a thickness of more than 250 metres. All sediments are arranged as a gentle dipping and thickening structure to the southeast. Only a few boreholes of the western border of El Abalario reach the top of the Miocene marls. In the rest of the Abalario area the Miocene marls are confined to an unknown level bellow the deepest boreholes. Upward, the marls grade to the Huelva sands, without any appreciable break in the sediments. To the north, the upper part of the Huelva formation grades to the Bonares sands, which is mainly developed outside the study area. Both formations are covered by the coarse clastic deposits of the Almonte formation. At the top, El Abalario sands recover all previous deposits and configure the current relief. The study performs the early existing geology profile and the connection with the surrounding areas. El estudio de nuevos y antiguos sondeos en El Abalario (Bajo Guadalquivir) permite identificar por encima de las margas miocenas, cuatro principales formaciones plio-cuaternarias, denominadas: Fm. Arenas de Huelva, Fm. Arenas de Bonares, Fm. Arenas y Gravas de Almonte, y Fm. Arenas de El Abalario, respectivamente interpretadas como sedimentos marinos someros, deltaicos, aluviales y eólicos. En conjunto forman una potente sucesión de más 250 metros de espesor, de estructura ligeramente inclinada y de espesor creciente hacia el sureste. Sólo algunos sondeos de la parte occidental de El Abalario alcanzan las margas miocenas. En el resto del área de El Abalario, las margas están a una profundidad desconocida, por debajo de los sondeos más profundos. Sobre ellas se disponen gradualmente los depósitos arenosos de la Fm. Huelva, sin ninguna apreciable ruptura sedimentaria. Hacia el norte, la parte superior de la Fm. Huelva grada lateralmente a los depósitos arenosos de la Fm. Bonares, principalmente desarrollada fuera del área de estudio. Ambas formaciones quedan cubiertas por los sedimentos clásticos más gruesos de la Fm. Almonte. Por encima se desarrollan las arenas de la Fm. El Abalario, que configuran el relieve actual. El estudio mejora el modelo geológico existente y la conexión de unidades con los sectores vecinos.
Composición modal de las arenas de la Cuenca del Guadalquivir: evaluación de su procedencia
Palomares, M.
Estudios Geologicos , 1990, DOI: 10.3989/egeol.90465-6467
Abstract: The sedimentation of the Guadalquivir neogene basin between Córdoba and Sevilla towns gave place to a thick marly succession which included several sandstone units: Arenas Basales, Arenas de Ubeda, Arenas del Guadalquivir, Arenas de Ecija, Arenas de Cuesta el Espino (all of them of upper Tortonian age), Arenas de Guadarcázar, Calcarenitas de Carmona (both of Messinian age) and pliocene sands. Arenas Basales have a lithic composition, showing high percentages of metamorphic rock fragments, and derived from metamorphic complexes of the paleozoic Macizo Hespérico located in the N of the basin. Arenas del Guadalquivir and Arenas de Ecija are litharenites and sublitharenites; their rock fragments are mainly carbonatic and derived from neogene sandy formations that cropped out in the N because of the progressive reduction of the basin. Arenas de Ecija derived from the betic mantles that were emplaced in the S of the basin at that time. Arenas Basales and Arenas del Guadalquivir are plataform deposits and Arenas de Ecija are sediments in subsea fans. Finally, Arenas de Guadarcázar and the pliocene sands are quartzarenites and sublitharenites and derived from the underlying sandy formations. The high compositional and textural maturity of Arenas de Guadarcázar was due to the reworking of these sands in a beach environment. The succession reflects an initial stage with first cycle contributions of metamorphic rocks from a stable craton and a later stage in which the source area is formed of sedimentary rocks related to a recycled orogen. In the eastern part of the basin Arenas del Guadalquivir and Arenas de Ecija are litharenites whilst the Arenas de Cuesta el Espino are sublitharenites; the former derived from a recycled orogen, and the latter from a continental block or a stable craton. The compositional evolution of the sands in this side of the basin could indicate a basin edge zone. La sedimentación de la cuenca neógena del Guadalquivir entre las provincias de Córdoba y Sevilla está formada por una potente sucesión margosa en la que se intercalan varias unidades arenosas que, de base a techo, se denominan: Arenas Basales, Arenas de Ubeda, Arenas del Guadalquivir, Arenas de Ecija, Arenas de Cuesta el Espino (todas ellas de edad Tortoniense superior), Arenas de Guadarcázar, Calcarenitas de Carmona (de edad Messiniense) y arenas pliocenas. Arenas Basales tienen una composición lítica, con alto porcentaje en fragmentos de roca metamórficos, y proceden de los complejos metamórficos del Macizo Hespérico paleozoico situado al N de la cuenca. Arenas del Guadalquivir
Implicaciones etologicas y significado de la estereotipicidad de Oichnus Bromley durante el plioceno en la cuenca del bajo Guadalquivir (SO Espa a)
Mayoral, E.
Estudios Geologicos , 1990, DOI: 10.3989/egeol.90463-4463
Abstract: The analysis of the stereotypy in the Oichnus-type borings on Bivalvia (epi and infaunal) from different Pliocene stratigraphic horizons in the Southwestern sector of the Guadalquivir Basin, has allowed to show sorne changes about the predatory behaviour. These have an effect on two levels: on a small scale, when the changes between juvenil and mature state of the preys are considered and on a larger scale, when the environmental conditions of every stratigraphic horizons are estimated. The variability on the first case are due to internal factors to the predatory-prey system: morphology, size and ornamentation of the preys. On the second one, are related with loss or increase in external factors on system: environmental selective pressure (kind of substrate, energy, ecologic competition). Wel1 defined behaviour patterns have been revealed by differences in the stereotypy of several Oichnus-type (O. paraboloides Bromley and O. simplex Bromley). This fact establish also various trace-makers for the latter. El estudio de la estereotipicidad de las perforaciones del tipo Oichnus Bromley, realizado sobre representantes de Bivalvia (epi e infauna) en diferentes horizontes estratigráficos del Plioceno del sector SO de la Cuenca del Guadalquivir ha permitido evidenciar cambios en la conducta depredadora de los organismos. Estas variaciones se detectan a peque a escala al considerar los cambios que se producen en el desarrollo del estado juvenil al estado adulto de las presas y a una escala mayor, cuando se estiman las transformaciones medioambientales inherentes a cada uno de los horizontes estratigráficos estudiados. En el primer caso, las variaciones están en función de factores internos al sistema depredador- presa: morfología, tama o y ornamentación de estas últimas. En el segundo caso se relacionan con la pérdida o adquisición de factores externos al sistema: presión selectiva ambiental (naturaleza del sustrato, energía, competición ecológica). Las diferencias observadas en la estereotipicidad de los distintos tipos de Oichnus (O. paraboloides Bromley y O. simples Bromley), prueban, en aquellos casos que ha sido posible, que su origen y producción se llevaron a cabo mediante modelos de conducta diferentes.
Microperforaciones (Tallophyta) sobre bivalvia del Plioceno del Bajo Guadalquivir. Importancia paleoecologica
Mayoral, E.
Estudios Geologicos , 1988, DOI: 10.3989/egeol.88443-4548
Abstract: The vegetal microborings in the characteristic communities of bivalves of the Pliocene (Bajo Guadalquivir Basin) are studied. Two basic morphotypes of algal origín and one fungoid are recognized from their size and boring system. The preferential siting and the degree of intensity are exposed together with their paleoecologic significance. Se estudian los principales tipos de microperforaciones atribuidas a la acción de organismos vegetales (Tallophyta) sobre las comunidades características de bivalvos del Plioceno en el Bajo Guadalquivir. En base a su tama o y modelo de perforación se han distinguido dos morfotipos básicos de origen algal y uno de origen fungoide. Se expone la ubicación preferencial y el grado de intensidad de estas microperforaciones y se analiza su significado paleoecológico.
Gyrolithes vidali nov. icnocsp. (Plioceno marino) en el sector Suroccidental de la cuenca del Guadalquivir (área de Palos de la Frontera, Huelva, Espa a).
Mayoral, E.
Estudios Geologicos , 1986,
Abstract: A new ichnospecies Gyrolithes vidali, is defined for the marine Lower Pliocene at the South-western Sector of the Guadalquivir Basin. The size, helial and vertical desviation angle, internal structure and external wall ornamentation as well as a lower basal camera ending whole the system, are indicatives for their distinction. A pattern of burrowing behavior is proposed. This is made by means of a longitudinal and vertical helical movement. A paleoenvironmental significance is showed. The ichnocoenosis assemblage as settled within a protective offshore environment under a continuous, slow sedimentation rate. The tracemaker of Gyrolithes vidali is discused and a callianasid or thalassinid shrimp origin in assumed. Se define Gyrolithes vidali una nueva icnoespecie para el Plioceno inferior marino en el sector más Suroccidental de la cuenca del Guadalquivir. Esta distinción se realiza a partir de su tama o, ángulos de desviación verticales y helicoidales, estructura interna y ornamentación exterior de las paredes, así como por la presencia de una cámara basal en la parte inferior del conjunto que completa todo el sistema. Se propone un modelo de excavación que consiste en un movimiento helicoidal con dos componentes, una longitudinal y otra vertical. El medio de sedimentación se interpreta como de muy baja energía en un área de offshore protegida. Se discute el posible organismo constructor de esta galería y se concluye que su origen puede ser debido a la acción crustáceos decápodos del grupo de los callianásidos o thalasinídeos.
Analysis of Stakeholders’ Attitudes towards Water Markets in Southern Spain
Giacomo Giannoccaro,Verónica Pedraza,Julio Berbel
Water , 2013, DOI: 10.3390/w5041517
Abstract: This research examines stakeholders’ perceptions of and preferences for water markets in agriculture, focusing on the likely barriers that might refrain them from participating in such markets. The research was carried out on the Guadalquivir River Basin and involved semi-quantitative methods, combining a structured survey and focus group discussions. A very simple questionnaire was administered to each irrigation stakeholder ( i.e., managers, water right holders and non-holders). The main result is that stakeholders will only keep selling water seasonally as the rights remain linked to the land. Nonetheless, some relevant differences among stakeholders were found. Managers seem to be more interested in selling water than farmers. Another important discrepancy was found between water rights holders and non-holders. Access to a water rights system, types of existing infrastructure, and legal and administrative aspects are also important factors influencing the acceptability of water trading in the study area. These results might be helpful to policymakers who are currently evaluating the potential for water markets in Europe and have little observable market data to work with.
Resultados paleoceanográficos deducidos a partir del contenido en diatomeas de los sedimentos siliceos miocenos ( moronitas ) en la Cuenca del Guadalquivir
López García, M?a J.
Estudios Geologicos , 1995, DOI: 10.3989/egeol.95511-2281
Abstract: During a part of the Miocene (Langhian middle-middle Tortonian) diatom bearing sediments, named moronitas , were deposited in the Guadalquivir Basin. This sedimentation was the result of a highly productive coastal upwelling regime in the area. At this time, the oceanic circulation in the nord-betic strait was under stuarine conditions and the nutrients carne from deep Atlantic currents. The intensity of the circulation of deep water in oceans is usually related to global climatic changes. Coastal upwelling is not an effective process to bring up nutrient-rich deep waters to the surface. A complex hidrological process must occur to bring up deep water firstly to intermediate leveIs and then the nutrients may be upwelled from subsurface waters. It is necessary to take into account local factors related to the basin morphology and the changes that it has gone through in arder to place the ancient upwelling centers in the basin. The percentajes of the most common species (Crucidenticula nicobarica + Crucidenticula punctata, Denticulopsis hustedtii, Thalassionema nitzschioides, Thalassionema nitzschioides var. parva, Thalassiothrix longissima + Thalassionema bacillaris) and the biosilicic global content of the rocks has made possible the recognition of a change in the temperature of superficial waters and upwelling intensity in time. The interpretation of the A..P.C. graphics gives a paleoecological significance to the A.P.C. first two factors. In this way different productivity situations in response to different locations and intensity of the ancient upwelling centers in time have been identified. Durante una parte del Mioceno (Langhiense medio-Tortoniense medio) tuvo lugar en actual Cuenca del Guadalquivir la formación de sedimentos con diatomeas ( moronitas ). Esta sedimentación fue consecuencia de la formación de un área de alta productividad biogénica ocasionada por corrientes ascensionales costeras (coastal upwelling). La existencia en esa época de una circulación de tipo estuarino en la zona, permite suponer que los nutrientes procedían, inicialmente, de las aguas profundas atlánticas, cuya circulación estaba ligada a situaciones climáticas globales. Las corrientes ascensionales costeras no constituyen por sí solas un mecanismo efectivo para llevar a la superficie aguas oceánicas profundas. Por ello debió tener lugar un mecanismo hidrológico complejo que llevara, en primer lugar, las aguas oceánicas profundas a niveles intermedios. Desde allí esas aguas ricas en nutrientes serían traídas a la superficie por las corrientes ascensionales, desde ni
Page 1 /4202
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.