Models of landscape evolution of the Spanish Sistema Central Range: Morphotectonics implications

[Abstract] The characteristic morphostructure of the Spanish Central System corresponds to that of an ancient leveled massif, reactivated during the Tertiary Age by tectonic impulses related to the Alpine Orogeny; that is to say, it forms a block organized mountainous massif, or a «block mountain» o Although noumerous genetic models about the formation ofthe morphostructure ofthese mountains have been proposed, only three ofthem could be considered to be fundamental: the first one proposes a «polycyclic» or «hemicyclic» denudational and tectonic-uplift sequence; but, at the same time, it clearly shows a «stair-like» physiognomy shape (Piedmont bendlanch orPiedmonttreppen); the second one describes a «cyclic» or «bicyclic» model which could be in conection with a «block mountain» physiognomy; the last model suggests a denudational and tectonic-uplift interaction sequence, with an increase of the tectonic activity and an «etchplain» process development during the Tertiary periodo According to the three basic models pointed to aboye, two main possibilities can be taken into account to find out the tectonic implications in the evolution of the Spanish Central System landscape: the former implies that the tectonic movements and the denudational processes are alternative events in time; the latter implies that the tectonic and the denudational effects have a succesive and continous occurrenceo So, the most interesting thing would be to conclude something related to this issue; as has been stated, it would be necesssary to make a global interpretation of the tectonic setting and, as a consequence, of the reactivated landscapes formation of the Meseta Region in Central Spain. Therefore, it would be essential to consider the following aspects: the behaviour of the tectonic movements during the reactivation, the geographical and chronological distribution ofthe tectonic impulses, the origin ofthe stresses and their way of transmission, and the precise control of the present and the near present day tectonic movements in order to define the uplift and subsidence rates

Morphogenesis of the Central Range (Spain) and its relation with granite morphologie

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasFALSEpu

Un enfoque múltiple para resolver problemas geoarqueológicos: inferencias de la minería de oro romana en el valle del Eria (León)

The Eria River valley exhibits one of the largest gold mining complexes in NW Iberia from Roman age. In this study, a geoarchaeological work is presented, combining a multiapproach based on airborne LiDAR remote sensing, descriptive geology and radiocarbon dating. The studied area is characterized by the presence of a mining infrastructure comprised of hydraulic canals driving the water at different levels to the mines. Mining works were associated with Plio-Quaternary raña deposits and Quaternary materials consisting of hillside and periglacial deposits, and fluvial terraces. The washing of the gold deposits used the hydraulic force to break up and drag out the sediment, giving rise to three different types of exploitation depending on the characteristics of the different materials. The results shed light on the geological materials exploited and other geographical aspects that conditioned the exploitation techniques. The work contributes to improving the knowledge about Roman gold mining and its geological context in northwest IberiaEl valle del río Eria presenta uno de los mayores complejos de minería aurífera de época romana del noroeste de la península ibérica. En este trabajo se presenta un estudio geoarqueológico que combina un enfoque multidisciplinar basado en el análisis por teledetección con LiDAR aerotransportado, geología descriptiva y datación radiocarbónica. La zona estudiada presenta un entramado minero compuesto por una red de canales que dirigían el agua a distinta cota hasta las explotaciones. Los desmontes fueron realizados sobre materiales plio-cuaternarios de tipo raña y cuaternarios constituidos por depósitos de ladera, periglaciares y terrazas fluviales. El lavado de los depósitos auríferos empleó la fuerza hidráulica para deshacer y arrastrar el sedimento, dando lugar a tres tipos distintos de explotación en función de las características que presentan los diferentes depósitos. Los resultados arrojan luz sobre los materiales geológicos explotados y otros aspectos geográficos que condicionaron las técnicas de explotación de los yacimientos. El trabajo contribuye a mejorar el conocimiento sobre la minería aurífera del noroeste y su contexto geológic

Evolución cenozoica de la fosa de Garganta del Villar (Sistema Central español)

La fosa de Garganta del Villar (Sistema Central español) es una depresión tectónica subromboidal sobre zócalo cristalino, que localmente contiene depósitos cenozoicos (Paleógeno-Cuaternario). La interpretación geomorfológica, sedimentológica y de la mineralogía de arcillas, permite aportar nuevos datos sobre la evolución geodinámica durante el Cenozoico de este área del Macizo HercÍnico. Las etapas que configuran dicha evolución son correlacionables, en gran medida, con aquéllas establecidas por otros autores en la zona de contacto entre las grandes cuencas sedimentarias (Duero y Tajo) y el Sistema Central. Sin embargo, un buen registro de morfologías y depósitos cuaternarios de la fosa, han hecho posible matizar y complementar la sucesión de eventos pleistocenos de la misma, que evolucionó con cierta independencia respecto al resto del macizo montañoso

Snow avalanche susceptibility of the Circo de Gredos (Iberian Central System, Spain)

We present a detailed snow avalanche susceptibility map at scale 1:20,000 of the Circo de Gredos in the Sierra de Gredos (Iberian Central System, Spain). This cirque-shaped landscape is one of the most popular spots for winter sports in the region. However, no snow avalanche activity assessment has been conducted to date. We have, therefore, produced a snow avalanche susceptibility map based on aerial and satellite imagery, newspaper reviews and field work, including avalanche features recognition and interviews with frequent backcountry users. We extracted the spatial distribution of necessary and enhancer factors for triggering slab, wet and loose snow avalanches from a digital elevation model. Finally, calculations to evaluate each snow avalanche type susceptibility were performed using a Geographical Information System. By combining our map collection, we concluded that most of the area in the Circo de Gredos is highly susceptible to snow avalanches, especially slab and wet snow types

Near surface geophysical analysis of the Navamuño depression (Sierra de Béjar, Iberian Central System): geometry, sedimentary infill and genetic implications of tectonic and glacial footprint

© 2018. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The geometric and genetic characterization of the Navamuño depression peatland system (Iberian Central System) is presented here using results from a geophysical survey. This depression is a ~30¿ha pseudo-endorheic flat basin over granitic bedrock. Three geophysical techniques were used to map the subsurface geology, and identify and describe the infill sequence: shallow seismic refraction (SR), Magnetic Resonance Sounding (MRS) and electrical resistivity measurements (VES and ERT). The three main geoelectrical layers (G1, G2, G3) identified in previous research, have also been identified in the present work. Using the data obtained in this new research we have been able to analyse these three geological layers in detail and reinterpret them. They can be grouped genetically into two sedimentary units: an ancient sedimentary body (G3), of unknown age and type, beneath an Upper Pleistocene (G2) and Holocene (G1) sedimentary infill. The facies distribution and geometry of the Upper Pleistocene was examined using the Sequence Stratigraphy method, revealing that the Navamuño depression was an ice-dammed in the last glacial cycle resulting in glaciolacustrine sedimentation. A highly permeable sedimentary layer or regolith exists beneath the glaciolacustrine deposits. Below 40¿m depth, water content falls dramatically down to a depth of 80¿m where unweathered bedrock may be present. The information obtained from geophysical, geological and geomorphological studies carried out in this research, enabled us to consider various hypotheses as to the origin of this depression. According to these data, the Navamuño depression may be explained as the result of a transtensional process from the Puerto de Navamuño strike-slip fault during the reactivation of the Iberian Central System (Paleogene-Lower Miocene, Alpine orogeny), and can be correlated with the pull-apart type basins described in these areas. The neotectonic activity of this fault and the ice-dammed processes in these areas during the Last Glacial Cycle (MIS2) were the main causes of recent sedimentary infill in this depression.Peer ReviewedPostprint (author's final draft

Contesting the role of regional geomorphology in spatial planning through non-eucledian geometries and fuzzy clustering methodologies

Regional Geomorphology is defined as the scientific discipline in charge of explaining the spatial distribution oflandforms at both regional and sub-regional scales, and has been traditionally considered by land use and spatialplanners, as an essential scientific field when attempting to define both landscape character and dynamics. The useof landforms, and land-units, to delimit and define planning units useful for land and natural resource managementis a classic procedure intensively and extensively employed on classic Spatial planning science. Such relation-ship(geomorphology/planning) has traditionally been approached through the design and application of eitherphysiographic (synthetic) or parametric (analytical) landform-based methodologies. Either by using a syntheticor analytical approach, the definition and delimitation of homogeneous land units is as essential step to define aproper planning strategy and geographically delimit decision-making. Nevertheless, the once high importance thatwas once attributed to landforms on regional definition and characterization, has recently suffered from a continu-ous decrease in both scientific and operational (political/administrative) popularity, and is actually reduced almostexclusively to very specific, and exclusively specialized planning procedures (e.g. watershed planning, naturalhazard mitigation, landscape impact assessment...). Out of the multiple causes that might explain the aforemen-tioned decrease on the importance of regional geomorphology within Spatial Planning, there should be speciallyhighlighted the recent trend that is refocusing Spatial Planning towards a more complex socio-environmental,and progressively less exclusively land-use-centred, discipline, thus progressively shifting Its main focus towardsunravelling the complex dynamics that define humanenvironmental systems. Therefore, and in order to properlyaddress Its new complex objectives, Spatial planning needs to embrace the socio-environmental paradigm and Itsassociated principles, therefore inevitably assuming the importance of concepts such as the complexity and uncer-tainty of Land-Systems. This paper discusses the applicability of a conceptual methodology specifically designedto provide Regional Geomorphology with both the epistemic foundations and practical tools, necessary to demon-strate Its ability to act as a complex science, and thus get back to the core of Spatial Planning decision making.For such purpose, a number of quantitative indicators of complexity and uncertainty in landforms and land-unitswere designed, tested and implemented, using the theoretical basis provided by tools such as fractal and com-plex geometric analysis, and fuzzy clustering methodologies. The possibility to obtain fuzzy metrics and limits oflandforms and land-units, and to quantify the spatial uncertainty associated with their delimitation and definition,intends to contribute, both epistemologically and from an applied perspective, to generate more flexible and lesserratic methodologies for Spatial Planning, adding reliability and accuracy to land-system-based decision making

Regional Geomorphology and Land-Use Planning: New possibilities for its application based upon uncertainty and complexity of landforms. The example of the Bullaque river basin (Toledo Mountain Range, Spain)

La Geomorfología Regional, definida como ciencia que se ocupa de describir y explicar la distribución espacial de las formas del terreno a escala regional y sub-regional, ha sido considerada por la planificación física y la ordenación del territorio más clásicas, como la única disciplina capaz de analizar las “líneas maestras” que definen el carácter complejo del territorio y del paisaje. La utilización del relieve como base física para la delimitación y definición de unidades territoriales integradas, básicas para gestionar el territorio y sus recursos, ha constituido además uno de los métodos tradicionalmente empleados por algunas de las disciplinas ambientales que en mayor medida han contribuido al acercamiento de la planificación física clásica hacia la nueva ordenación integral; es el caso de la Ecología del Paisaje, la Ecología Humana y la Geografía Ambiental. Paradójicamente, la importancia de los criterios fisiográficos y geomorfológicos de regionalización en planificación se ha ido reduciendo en la nueva “ordenación integral”, quedando relegados a determinados procedimientos de planificación sectorial. Entre los sectores en los que la Geomorfología ha conseguido mantener su peso, destacan la gestión de recursos hídricos, de Espacios Naturales Protegidos, de riesgos naturales e inducidos y del paisaje. En este sentido, es a partir del reciente auge de una serie de teorías y modelos en planificación territorial asociados al paradigma socio-ambiental, entre los que sobresalen particularmente la complejidad e incertidumbre de los sistemas territoriales, cuando se ha generado una crítica generalizada hacia las ciencias naturales más clásicas que, como la Geomorfología, han sido incapaces de generar propuestas actualizadas. Por ello, la Geomorfología aplicada a la planificación ha sido genéricamente acusada de inmovilista cuando no, incluso, de determinista. En el presente artículo se analiza la eficacia y posibilidades de implementación de una metodología de análisis geomorfológico regional, con base en los principios de incertidumbre y complejidad de las formas del terreno, que fue ensayada con resultados positivos en la “región-plan” (la cuenca del río Bullaque; Ciudad Real-Toledo).Regional Geomorphology is defined as the scientific study of the spatial distribution of landforms at both regional and subregional scales, and has been traditionally considered by land use planners, as the discipline capable to explain the master lines that define the character of both territory and landscape. The use of landforms and land-units to delineate and define territorial units useful for land and resource management is a classical procedure used by both Land-Use and classic Spatial Planning. The design and use of either physiographic (synthetic) or parametric (analytical) landform-based methodologies to define homogeneous regions is a classic procedure, developed and used by sciences such as regional geography, landscape ecology and environmental geomorphology. Nevertheless, the former importance of the diverse existing regionalization criteria based upon physiographic and geomorphologic features, has recently suffered from a continuous decrease in both their technical and political popularity, being presently reduced almost exclusively to certain sectorial planning procedures. Amongst the territorial components and processes whose planning strategies have managed to retain the importance of landforms and land units specially outstand watersheds, Natural Protected Areas, natural and induced Hazards and Landscape. One of the main causes explaining the aforementioned decrease might probably lye upon the recent trend that is redirecting Spatial Planning towards a more complex socio-environmental, and each time less land-use-based, discipline. Even if Land-Use Planning still constitutes a very central component of complex modern Spatial Planning, it is no longer considered as its main core. Instead, issues such as the creation of places, public participation and governance-related strategies, and the capacity to link together the diverse actors, policies, scales and interests involved on sectorial planning in order to attain a sustainable development, have arisen as the main goals to achieve. In order to adapt to such new tendencies, land-use planning has evolved based upon the newest socio-environmental paradigms, assuming therefore the importance of concepts such as complexity and uncertainty. Even if these changes have taken place mostly from within a theoretical perspective, certain traditional sciences, such as landscape and spatial ecology, earth-system sciences, human and regional geography and applied sociology, have all been able to generate new models that are easily adaptable to the newest planning purposes. Clearly contrasting with the former, some more classic natural sciences, including Geomorphology, have shown a much stronger reticence to adapt to such changes, from both a theoretical and applied point of view. On the present article, the results of the methodology designed to provide Regional Geomorphology with both the epistemic foundations and practical tools necessary to become a complex science useful to the aforementioned newest tendencies in planning, are discussed. For such purpose certain indicators of complexity and uncertainty in landforms were designed, and discussed, using the theoretical basis provided by broader concepts such as fractal and complex geometries and fuzzy methodologies. The utility of such indicators and methodologies from within a planning perspective were positively essayed at the Bullaque river basin (Ciudad Real-Toledo), a region characterized by the high diversity and complexity of its landscape and territorial features and values. The results obtained also served to prove the miss-accuracy of the most traditional Regional Geomorphology–based planning methodologies. The possibility to obtain fuzzy indicators of landforms, made it possible, both epistemologically and from an applied perspective, to generate more flexible and less technocratic methodologies for planning in accordance with the present principles implied by the assumption of the socio-environmental paradigm.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUECastilla-La Mancha. Junta de Comunidades. Consejería de Medio Ambiente y Desarrollo Ruralpu