Person:
Antón López, Loreto

First Name

Loreto

Last Name

Antón López

URI

https://hdl.handle.net/20.500.14352/82688

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Area

Geodinámica Interna

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Now showing 1 - 10 of 18

Controles tectónicos y estructurales de la incisión fluvial en el centro-oeste de la Cuenca del Duero, NO de Iberia
(Geogaceta, 2007) Antón López, Loreto; Muñoz Martín, Alfonso
The present work approaches incision rates quantification of Duero River in the central- west par t of Iberia and implications of tectonics in the evolution and change of drainage patterns. For this aim we calculate incision rates from the two main geomorphological surfaces defined in the area. Comparing fluvial incision rates and fracture pattern a strong structural control is shown; either in the orientation of drainage network, either in the incision rates distribution. Drainage pattern shows two main orientations, NW-SE following the hercinian structure of the area and NE-SW to N-S matching with the main fracture sets (Duero, Almendra, Almeida-Valderaduey faults, as example). Fluvial incision is mostly controlled by the great faults and faults systems NE-SW to N-S oriented.
Quantifying the erosional impact of a continental-scale drainage capture in the Duero Basin, northwest Iberia
(Quaternary Research, 2018) Antón López, Loreto; Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo
Formerly closed drainage basins provide exceptional settings for quantifying fluvial incision and landscape dissection at different time scales. Endorheic basins trap all the sediment eroded within the watershed, which allows estimates of post–basin opening erosion patterns. The Duero Basin was a former closed basin and is presently drained by the Duero River into the Atlantic Ocean. During the Cenozoic, the basin experienced a long endorheic period, marked by the formation of continental carbonates and evaporites. The retrogressive erosion of the Atlantic drainage coming from the Portuguese coast subsequently captured the internal drainage, and significant fluvial dissection occurred. Presently, the basin contains a relatively well-preserved sedimentary fill. Gridding and surface fitting in this paper provide the first attempt to reconstruct the surface of the top of the former endorheic sedimentary sequence to quantify the erosional impact of the basin opening. At least 2251±524 km3 of sediment was removed from the formerly closed basin following the start of exorheism. This volume represents a mean basin-surface lowering of 65±13 m. Erosion estimates and landscape dissection patterns are consistent with geologic evidence of progressive establishment of an outward drainage system.
Exceptional river gorge formation from unexceptional floods
(Nature Communications, 2015) Antón López, Loreto; Mather, A.E.; Stokes, M.; Muñoz Martín, Alfonso
An understanding of rates and mechanisms of incision and knickpoint retreat in bedrock rivers is fundamental to perceptions of landscape response to external drivers, yet only sparse field data are available. Here we present eye witness accounts and quantitative surveys of rapid, amphitheatre-headed gorge formation in unweathered granite from the overtopping of a rock-cut dam spillway by small-moderate floods (B100–1,500m3 s�1). The amount of erosion demonstrates no relationship with flood magnitude or bedload availability. Instead, structural pattern of the bedrock through faults and joints appears to be the primary control on landscape change. These discontinuities facilitate rapid erosion (4270m headward retreat; B100m incision; and B160m widening over 6 years) principally through fluvial plucking and block topple. The example demonstrates the potential for extremely rapid transient bedrock erosion even when rocks are mechanically strong and flood discharges are moderate. These observations are relevant to perceived models of gorge formation and knickpoint retreat.
Using river long profiles and geomorphic indices to evaluate the geomorphological signature of continental scale drainage capture, Duero basin (NW Iberia)
(Geomorphology, 2013) Antón López, Loreto; De Vicente Muñoz, Gerardo; Muñoz Martín, Alfonso; Stokes, Martin
Well-constrained case studies of transient landscape responses are needed to improve our understanding of erosion processes associated with drainage captures. The Duero basin is an excellent location for such a study because the landscape is currently undergoing pronounced geomorphological changes resulting from the opening of a former closed drainage. The present-day continental interior basin (N50,000 km2) drains to the Atlantic Ocean via the Duero River, but during the Cenozoic the basin experienced a long endorheic period marked by the formation of evaporites. Currently, the entire continental interior is an area of relative tectonic quiescence, characterised by a relict low-relief upland topography (Meseta). Systematic variations in lithology and a well-constrained tectonic setting throughout the basin and adjacent areas allow for the comparison of channel morphology between the Cenozoic Duero basin and its western fringe. To explore the signal of transient geomorphic response to capture and opening of the former endorheic basin, the main channel and 24 tributaries were analysed in terms of their longitudinal profiles and the application of geomorphic indices (concavity index [Ci], valley floorwidth-to-height ratio [Vf], and stream-length gradient index [SL]). The analysis reveals two zones with distinctive morphologies: (1) an upper reach domain consisting of broad flat valleys and low-gradient streams where concave longitudinal profiles dominate and (2) a middle reach domain characterised by steep, deeply incised canyons where a convex long profile dominates marking a major kinckzone. The quantitative information on channel shapes and long profile geometries allows the interpretation of these patterns in terms of driving forces for fluvial landscape development. Large-scale morphometric analysis highlights the transient response of the entire basin to a capture-related base level lowering and illustrates the importance of drainage captures as potential internal drivers of landscape modification and topographic adjustments. Furthermore, the Duero basin case study also emphasises that well-constrained bedrock geology and tectonic patterns are essential to avoid misinterpretation of geomorphic indexes.
Quantification of fluvial incision in the Duero Basin (NW Iberia) from longitudinal profile analysis and terrestrial cosmogenic nuclide concentrations
(Geomorphology, 2012) Antón López, Loreto; Rodés, Ángel; De Vicente Muñoz, Gerardo; Pallàs, Raimon; García Castellanos, Daniel; Finlay M., Stuart; Régis, Braucher; Didier, Bourlès
The Duero Basin is one of the largest Cenozoic basins in Iberia and contains a relatively well-preserved sedimentary infill. The top of the sedimentary sequence crops out at elevations up to 900 m above sea level. The present-day basin drains to the Atlantic Ocean via the Duero River through the Arribes Gorge, but during the Cenozoic the basin experienced a long endorheic period marked by the formation of evaporites. The time the basin opened to the Atlantic Ocean and the formation of the modern Duero River drainage system remains poorly constrained. In this study we quantify the spatial distribution of river incision within bedrock and sedimentary units by comparing the nearly relict higher reaches with the lower deeply incised reaches of the tributary system. Results show an abrupt increase in stream incision westward, reaching a minimum bedrock incision depth of 600 m in the Arribes Gorge. Using cosmogenic 10Be and 21Ne data we estimate exposure ages for erosion surfaces at various levels in the incised Duero River. The cosmogenic nuclide dataset suggests that the final 2–300 m of fluvial incision in the Arribes Gorge occurred at a rate of 2–3 mm/yr over the last ~ 100 ka.
Análisis de la fracturación en un área granítica intraplaca : el Domo de Tormes
(2004) Antón López, Loreto; Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de
La presente Tesis aborda el estudio de la fracturación frágil en un área granítica intraplaca, localizada sobre la megaestructura hercínica conocida como el Domo del Tormes, situada en el NO de la Península Ibérica. En primer lugar se ha realizado una síntesis geológica del área de estudio, que ha permitido describir las características litológicas y los diferentes elementos estructurales que la configuran. El análisis macroestructural se ha desarrollado mediante la confección de un modelo digital del terreno y con el apoyo de diferentes cartografías estructurales. A partir de estos elementos se han descrito los principales rasgos morfoestructurales del área y su entorno, con especial énfasis en la red de fracturación (características principales, orientaciones, tamaños y distribución). Adicionalmente, la interpretación conjunta de la gravimetría y de las cartografías geológica y estructural ha permitido analizar la estructuración del área en profundidad y definir una serie de anomalías que pueden asociarse a grandes fracturas de carácter cortical, algunas de ellas con reflejo en superficie. Posteriormente se ha abordado el estudio de la fracturación a escala mesoestructural, con trabajos de campo que han aportado un número suficiente de datos para la aplicación de diferentes métodos de análisis poblacional de fallas. A partir de los resultados obtenidos se han definido una serie de campos de paleoesfuerzos responsables de la fracturación frágil presente en la zona, y que explican su evolución cinemática y dinámica desde el fina de la Orogenia Hercinica y durante la Alpina. El hecho de que los estudios se hayan centrado mayoritariamente en materiales graníticos de edad hercínica ha dificultado la ordenación temporal de los eventos definidos, por lo que ha sido necesario recurrir a técnicas complementarias para determinar su edad de actuación. De este modo, se ha ampliado el análisis a los bordes de las cuencas sedimentarias cenozoicas que rodean el área (Cuenca del Duero y Fosa de Ciudad Rodrigo), para apoyar con criterios estratigráficos la datación de los eventos propuestos. Adicionalmente, se ha determinado, mediante geocronología K-Ar, la edad de actuación de varias estructuras, a partir de muestras de arcilla de falla recolectadas en campo. La definición de la actividad tectónica reciente se ha completado con un análisis de las cartografías geológica, geomorfológica y estructural, con especial énfasis en las relaciones entre fracturación y red de drenaje y en la determinación de las familias de fracturas que afectan o condicionan la disposición de los materiales cenozoicos en la zona. Finalmente, se han recopilado y discutido las evidencias de sismicidad actual.
Distribución y características de los depósitos fluviales pleistocenos del subsuelo de la Bahía de Cádiz
(Geotemas, 2004) Mediavilla López, Rosa María; Antón López, Loreto; Dabrio González, Cristino José; Perucha, M.A.; Santisteban Navarro, Juan Ignacio; Mediato Arribas, José F.; Barnolas Cortina, A.; Llave, E.
Middle to Upper Pleistocene fluvial sediments of the Cádiz Bay occur fifling partly two disconnected sub-basins excavated into shallow marine deposits of Pliocene to Lower Pleistocene age, and are buried under fluvial and estuarine Hofocene deposits. Subsurface, drill cores, and surface informatio indicate that the area of the Bay was occupied by a more or less continuous basin during the Late Pliocene-Lower Pleistocene, but the pattern changed during Middle to Late Pleistocene as revealed by facies analysis and palaeogeographical reconstruction of the fluvial environments. Fluvial deposits are laterally discontinuous, with variable rhickness and elongated troughs occupied by the coarsest sediments available. Our paleogeographical reconstruction for this periad shows a landscape with two subaerial sub-basins that acted as Fluvial valleys during glacially-forced lowstands, with two main Fluvial systems flowing constrained by topographical highs. This configurarion records the coincidence of very low sea level (regressive conditions) during glacial periods and active neotectonics. The valleys were flooded during the postglacial Holocene transgression and sea level surpassed the elevations separating the former valleys leading to the apparently simple configuration of the bay.
La deformación alpina en el Sistema Central Español
(Geo-guías, Rutas geológicas por la Península Ibérica, Canarias, Sicilia y Marruecos, 2019) De Vicente Muñoz, Gerardo; Muñoz Martín, Alfonso; Olaiz, A.J.; Vegas Martínez, Ramón; Antón López, Loreto; Martín Velázquez, Silvia; Giner Robles, Jorge Luis; Rodriguez Pascua, M.A.
La idea del origen compresivo del Sistema Central (SC) se debe a Birot y Solé Sabarís (1954) [1], antes del establecimiento del papel que la tectónica de placas juega en el desarrollo de las estructuras intraplaca. Sin embargo, sus observaciones de campo no fueron tenidas en cuenta y, durante mucho tiempo, el SC fue considerado como una estructura extensiva [2]. Los primeros modelos de estructura del SC, en un contexto compresivo intraplaca, fueron propuestos por Vegas y Suriñach (1987) [3], que calcularon un engrosamiento cortical de 5 km, mientras que Warburton y Álvarez (1989) [4] construyeron una sección transversal con el desarrollo de una tectónica de piel fina asociada a un detachment intracortical proveniente de las Béticas y con un acortamiento asociado de 50 km. Esta idea fue también propuesta con menos detalle para el sector portugués, pero en relación a un estilo tectónico de piel gruesa y un acortamiento menor [5]. No obstante, estos trabajos carecían de observaciones de campo. En concreto, la sección de Warburton y Álvarez adolece de numerosas inconsistencias. El estilo tectónico propuesto durante la celebración de la III reunión de la Comisión de Tectónica de la SGE, que es el que se tiene en cuenta hoy en día, fue el de una tectónica de piel gruesa, sin despegues en la cobertera, con la formación de cabalgamientos imbricados de piel fina con implicación del basamento y pop ups dentro del basamento varisco de direcciones NE-SO a E-O. El acortamiento asociado se calculó en un 14% (20 km) [6, 7].
Mapa de esfuerzos activos en línea de la Península Ibérica a partir de Mecanismos Focales calculados desde el Tensor de Momento Sísmico
(Geotemas, 2012) Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo; Olaiz Campos, Antonio José; Antón López, Loreto; Vegas Martínez, Ramón; Granja Bruña, José Luis
This work shows a new on-line stress map for Iberian Peninsula obtained from the inversion of earthquakes focal mechanisms calculated with the centroid moment tensor. An amount of 299 focal mechanisms have been selected with several quality criteria from different catalogues (CMT Harvard, ETH, Med-Net, I.G.N. and I.A.G.) from 1973 to January 2012. Values for the maximum horizontal stress and the shape factor of the ellipsoid (horizontal/vertical stress) have been calculated following De Vicente et al. (2008).. The local results have been interpolated to a 10’ regular grid in which the relation between tectonic horizontal stress and vertical load has been taken into account. The final map shows a good correlation with the primary tectonic forces generated in the plate boundaries and the local perturbations related with main crustal heterogeneities. Both the maps and data are free for download from http://www.ucm.es/info/lta/lta.html Applied Tectonophysics Group WebSite). [RESUMEN]Este trabajo muestra el nuevo mapa en línea de esfuerzos activos para la Península Ibérica obtenido a partir de la inversión de mecanismos focales de terremotos (MF) calculados con Tensor de Momento Sísmico (TMS). Un total de 299 MF han sido seleccionados con varios criterios de calidad de diferentes catálogos (CMT Harvard, ETH, Med-Net, I.G.N. e I.A.G.), para un periodo comprendido entre 1973 y enero de 2012 y profundidades menores de 60 km. Los valores de la dirección de máximo acortamiento horizontal (Dey) y el factor de forma (carga horizontal/vertical) han sido calculados siguiendo a De Vicente et al. (2008). Los resultados obtenidos se han interpolado a una malla regular de 10’, teniendo en cuenta las orientaciones de las componentes horizontales de esfuerzo, y el factor de forma. Los mapas finales muestran una buena correlación con indicadores geológicos y cinemáticos. Las orientaciones de los esfuerzos horizontales se relacionan con las fuerzas primarias provenientes de los límites de placas, y con perturbaciones locales relacionadas con heterogeneidades de primer orden a nivel cortical. Tanto los mapas, como los datos procesados son accesibles a través de la Web del Grupo de Tectonofísica Aplicada de la UCM http://www.ucm.es/info/lta/lta.html.
Iberia, a natural laboratory for the quantification of the large scale erosional response to the fluvial capture processes
(8º Congresso Nacional de Geomorfologia - Geomorfologia 2017, Congresso Nacional de Geomorfologia (8. 2017. Porto), 2017) Antón López, Loreto; Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo De; Alberto Gomes, António; Teixeira, José; Soares, Laura
Due to its geological location and diversity, Iberia is a key natural laboratory for the study of tectonic and geological processes. Within those it is especially suitable for the study of large-scale fluvial capture processes, and their influence on topography and landscape evolution. Nowadays, Iberia is characterized by the presence of highly elevated extensive flat surfaces (Iberian Mesetas). Those high plains correspond to planation surfaces developed mainly on Palaeozoic and Mesozoic rocks, and sedimentation surfaces of Neogene rocks. These last mostly represent the sedimentary deposits related to infill of the, formerly closed Foreland Basins. Three main rivers (Duero, Ebro and Tajo) which watersheds cover an area over 250 km2, drain almost half of the total Iberia surface. For these basins the development of the present-day drainage network was related to the opening of formerly closed fluvial systems, developed within ancient Cenozoic basins. In The Iberian Peninsula, the signature of that change in drainage conditions is still preserved in some areas, and can be studied through the analysis of longitudinal profiles shapes and the relief characterization. The analysis of present and former topography represents a powerful qualitative tool for a relative quantification of fluvial dissection and basin denudation, allowing to illustrate the spatial distribution of surface erosion, associated to the exorheic history of the basins. This work approaches the analysis of the denudation processes for the main formerly endorheic Iberian basins.