Evolution of the Júcar-Cabriel fluvial system on the Mediterranean watershed of the Iberian Peninsula (Valencia, eastern Spain)

This study presents the characterization and chronology of the Quaternary terrace sequence developed in the confluence zone of the Júcar and Cabriel river valleys. The study area covers a radius of 10 km from the confluence of the two valleys near the locality of Cofrentes (Valencia). It is located in the northern zone of the Ayora-Cofrentes Graben in the northeastern sector of the External Prebetic Zone adjacent to southern Iberian Chain. This N-S graben is an inherited tectonic feature with an axial salt wall subject to different periods of fluvial dissection and refilling since at least the end of the Messinian Salinity Crisis (MSC). Regional isostatic uplift and local uplift and subsidence processes related to salt flow and dissolution during the Quaternary period, favored by fluvial entrenchment and terrace development. The terrace system and the previous pre-incision erosional and depositional surfaces are analyzed from a geomorphological point of view. The terrace system only develops within the soft Mio-Pliocene sedimentary fill of the graben, whilst upstream and downstream this zone the studied valleys develop important gorges (canyons) carved in the Cretaceous tablelands (Caroch Massif) and Mio-Pliocene deposits (Llanura Manchega). The geochronological control is established from 20 numerical ages obtained by different dating methods, such us Electron Spin Resonance (ESR), Optically Stimulated Luminescence (OSL) in detrital sequences and Th/U series in calcareous tufa deposits. Additionally, four K/Ar dates available for volcanic materials disrupting the upper and oldest terrace have been considered. A total of 14 terrace levels were identified between +130–135 m (T1) and +3–4 m (T14) of relative height above the river thalwegs. The T1 has an approximate age of c. 1.6–2.0 M.a. as indicate the age of the volcanic materials from the Agras Volcano intruded in the terrace, marking the onset of Quaternary fluvial dissection in the zone. The obtained geochronological data indicate that the Lower-Middle Pleistocene boundary is slightly above T6 (+60–65 m), which has an ESR age of 577 ± 43 ka. This terrace also documents the onset of the most important period of rise of the salt within the graben interfering drainage development. The geochronological data indicate the occurrence of a second eruptive event during the second half of the Middle Pleistocene related to the terraces T7 (+50 m) and T8 (+35–40 m), updating the volcanic activity in the zone. The beginning of the Upper Pleistocene is recorded by the top sequences of the T9 terrace (+25–30 m) where numerous OSL and Th/U data have been obtained with ages between ca. 105 and 81 ka (MIS 5). However, these young terraces (T8 to T13) are thickened (8–10 m) recording Middle Pleistocene sediments in their basal sequences with ages between ca. 193 and 137 ka (MIS 6). The study provides important data on valley evolution under the interference of volcanic activity, salt –related deformation (diapirism, solution subsidence) and fluvial incision fostered by the rise of the axial diapir (salt wall) protruding the graben since at least the Brunhes-Matuyama boundary. The analyzed fluvial evolution documents interesting cases of river capture, drainage antecedence and tectonic adaptation of the drainage throughout the Quaternary Period. The paper also poses interesting geochronological data on the long-term Quaternary evolution of Mediterranean valleys in the Iberian Peninsula, poorly explored to the dat

Multi-level alkerdi-zelaieta cave system (Urdazubi/Urdax, Navarre): Base-level incision versus (re)sedimentation

Resumen: El sistema kárstico de Alkerdi-Zelaieta tiene un desarrollo de más de 5878 m. En él se engloban distintas cuevas que están genéticamente unidas, pero separadas por la colmatación de las galerías por sedimentos o colapsos. En todo caso, la organización de las galerías formadas en condiciones freáticas indica una mínima disposición de 6 niveles de cuevas, que se han formado en un contexto general de bajada del nivel freático. La formación de cada nivel de cueva está relacionada con procesos paragenéticos, que se deben a un incremento de la carga sedimentaria respecto al caudal hídrico. La variación en el aporte sedimentario se relaciona con cambios climáticos, de forma que cada vez que se repiten las condiciones climáticas propicias se produciría el aumento en la disponibilidad sedimentaria, y con ello, el desarrollo de niveles de cueva en el sistema kárstico. El área fuente de los sedimentos se localiza fundamentalmente en materiales paleozoicos y triásicos del entorno. En este sentido, una vez un nivel de cueva pasa a estar en condiciones vadosas, el sedimento depositado en ella comienza a erosionarse y redepositarse en el nivel inferior que se está formando, reciclándose una y otra vez hasta salir del sistema.Abstract: The Alkerdi-Zelaieta cave system is longer than 5878 m. It is composed by genetically connected caves, which are currently separated by sedimentary filling or collapses. Nevertheless, the disposition of the different subhorizontal passages formed under phreatic conditions shows at least 6 cave-levels, which have been developed in a widespread base-level falling context. The speleogenesis of each cave-level is due to paragenesis, given by an increment on sediment input regarding the stream flow. Changes in sediment input rates are due to climatic changes. Therefore each time that those climatic conditions were reproduced, cave-levels would have been formed. The origin of the sediments are from Paleozoic and Triassic formations of the area. As such, using the meandering conduits that connect different cave-levels, sediments that filled the abandoned galleries were removed and deposited in a lower cave-level that was forming at the moment, being recycled repetitively until they leave the cave-system

First chronostratigraphic framework of fluvial terrace systems in the eastern Cantabrian margin (Bay of Biscay, Spain)

Reported here is the first chronostratigraphic study of the Quaternary fluvial terrace deposits of three different valleys (Deba, Nerbioi, Oiartzun) located in the eastern Cantabrian margin (northern Spain), designed to understand long-term fluvial dynamics of this region. Fourteen samples were collected for numerical dating purpose, in the lowest terrace levels from 5 m to 63 m above current river channel. Optically Stimulated Luminescence dating was performed using the SAR protocol. For samples from terraces > 20 m above the current river channel, over 20% of measured aliquots were above saturation of the OSL signal. Consequently, only minimum ages could be estimated. Five samples also underwent Electron Spin Resonance (ESR) dating following the Multiple Centre approach. The ESR signals of the Aluminium and Titanium (Ti -Li and Ti -H) centres were systematically measured in each sample. In particular, the ESR signal of the Ti -H centre was strong enough to derive reliable and meaningful dose estimates. Obtained age results range between similar to 140 and similar to 400 ka for the terrace levels from + 10 to + 25 m. They suggest phases of aggradation during MIS 6, MIS 8 and MIS 10, for terrace levels T + 10m, T + 20m and T + 25m, respectively

La protección, gestión y ordenación de los paisajes de Álava. El catálogo de paisaje de la llanada alavesa (País Vasco)

[ES] La presente comunicación expone el esquema metodológico y los primeros resultados de dos proyectos de investigación. Uno de ellos, elaborado al amparo de un convenio con la Diputación Foral de Álava, está destinado a la exploración de alternativas metodológicas para la elaboración de los denominados Catálogos del Paisaje y a la realización del catálogo correspondiente a la Llanada Alavesa. El segundo es el denominado “Valoración paisajística, ambiental y socioeconómica de los espacios agrarios de alto valor natural de la Comunidad Autónoma de Euskadi. (GIU10/07)”. En ambos, el objetivo es obtener y elaborar información útil para la elaboración de instrumentos para la protección, gestión y ordenación del paisaje y para la política territorial, en especial de aquellos espacios agrarios que están sufriendo una profunda transformación económica, social, ambiental y territorial. Es el caso de La Llanada Alavesa, en cuyo estudio se utiliza una metodología de valoración paisajística integral y consensuada mediante mecanismos de participación ciudadana.[EN] This paper describes the methodological aspects and the first results of two research projects. One of them, drawn up with the help of a collaboration agreement with the Diputación Foral of Álava, is intended to explore methodological alternatives for carrying out the landscape catalogues and to make a landscape catalogue of the Llanada Alavesa. The second is called “Landscape, environmental and socio-economic assessment of agricultural areas of high natural value of the autonomous community of Basque country.” (GIU10/07). In both, the objective is to generate useful information in developing tools for the landscape protection, management and planning and for the territorial policy, particularly in agricultural areas experiencing an economic, social, environmental and territorial deep crisis. This is the case of the Llanada Alavesa, whose study uses a methodology of comprehensive and consensual landscape assessment through citizen participation procedures

Contexto paleoambiental del yacimiento Neolítico de Los Cascajos (Navarra, España): Quimioestratigrafía de la secuencia sedimentaria holocena del río Odrón

[ES] El conocimiento de los cambios climáticos y ambientales del inicio del Holoceno y su incidencia en las poblaciones y culturas humanas es clave para la comprensión de la evolución tanto pretérita como futura de éstas. En este sentido, el estudio mediante zanjas y sondeos del registro arqueosedimentario holoceno en el área del yacimiento neolítico de Los Cascajos (Los Arcos, Navarra), aporta una valiosa información no sólo para el establecimiento de la evolución ambiental de esta zona, sino también para el conocimiento de las actividades que los pobladores del yacimiento realizaron en los márgenes del río Odrón. En este trabajo se presentan los resultados del estudio estratigráfico, sedimentológico y geoquímico mediante XRF-CS de alta resolución del sondeo LAC1. Los datos obtenidos denotan una tendencia hacia la aridificación a lo largo del Holoceno, representada por un ciclo de agradación-incisión en la evolución fluvial del río Odrón. En el registro sedimentario fluvial se detectan también indicadores de actividad antrópica coetánea al asentamiento de Los Cascajos, lo que permite situar su ocupación en momentos hidrológicamente más húmedos que el actual, y evidenciar la posterior aridificación de esta zona del valle del Ebro a lo largo del Holoceno reciente (Megalayense).[EN] The knowledge of climatic and environmental changes at the onset of the Holocene and its impact on human populations and cultures is key for the understanding of their both past and future evolution. In this sense, the study through trenching and cores of the Holocene archaeosedimentary record in the surroundings of the Los Cascajos Neolithic archaeological site (Los Arcos, Navarra), provides valuable information not only for the establishment of the environmental evolution of this area, but also for the knowledge of the activities that the inhabitants of the settlement developed in the Odrón riverbanks. In this work the results of the stratigraphic, sedimentological and geochemical study (XRFCS) of the LAC1 core are presented. The obtained data denote a trend towards longterm aridification throughout the Holocene, recorded by an aggradation-incision cycle in the fluvial evolution of the Odrón River. In the fluvial sedimentary record, anthropic activity proxies coetaneous to Los Cascajos settlement are also detected during a relatively more humid period than nowadays, this fact evidences the subsequent aridification of this area of the Ebro valley along the late Holocene (Meghalayan).Los autores agradecen a la Dirección General de Cultura-Institución Príncipe de Viana del Gobierno de Navarra la subvención de las tareas de investigación realizadas a lo largo de este proyecto. Agradecemos también la labor del Dr. Ángel Carrancho (UBU, Editor Invitado); a C. Tejedor-Rodríguez e I. García-Martínez de Lagrán, investigadores del Programa “Juan de la Cierva” del Ministerio de Ciencia, Innovación y Universidades; y las correcciones y sugerencias de la Dra. Arantxa Aranburu (EHU/UPV) y un revisor anónimo que han contribuido a mejorar el manuscrit

Calcretas, espeleotemas y depósitos aluviales: tres registros de una misma historia geológica (Nerja, Málaga)

In this work we study the genetic link between calcretes, speleothems and alluvial deposits developed on the epikarst and endokarst of the Nerja Cave (Nerja, Málaga, Spain) and the adjacent Quaternary (Pleistocene) alluvial fan. Field and petrographic observations, and δ.18O and δ.13C isotopic data analysis of the host rock, distinct calcrete types and epikarst speleothems indicate that these deposits are the result of arid and more humid climatic episodes. Epikarstic and endokarstic speleothem U/Th absolute dating indicate that both endokarstic and epikarstic development of the Nerja Cave was coetaneous and genetically linked to the sedimentation of the adjacent Pleistocene alluvial fan, as a response to climatic changesAgradecimientos: A la Fundación Pública de Servicios Cueva de Nerja y a su Instituto de Investigación por su apoyo y financiación al proyecto “Estudio geológico de la Cueva de Nerja (Maro, Nerja)”, así como al Grupo de Investigación IT1029-16 del Gobierno Vasco. Queremos agradecer especialmente el apoyo y la colaboración incansable de D. Luis-Efrén Fernández, Conservador de la Cueva de Nerja.Peer reviewe

Geological risk assessment for rock art protection in karstic caves (Alkerdi Caves, Navarre, Spain)

This paper sets out a methodology for calculating the potential zone of damage to which an Item of Cultural Interest (ICI) located in a karst environment is exposed. An itemised study of the geological characteristics of the cave environment is proposed: lithological cartography, endokarst and exokarst geomorphology and the study of fracturing of the limestone massif. Based on these data and using a Geographical Information System (GIS), it was possible to calculate the degree of the geological threats on a susceptibility map, according to the vulnerability of the heritage item to be protected and its exposure to the identified hazardous geological processes. By combining these parameters, the existing geological risk was calculated and mapped and the necessary protection area for conservation of the cultural heritage was defined. This methodology was applied in the Alkerdi caves located in the municipal area of Urdazubi/Urdax (Navarre, northern Spain)

Estudio interdisciplinar del macizo kárstico de Alkerdi: rasgos geológicos, evolución kárstica y contenido arqueopaleontológico

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/8869/thumbnail.jp

Estudio interdisciplinar del macizo kárstico de Alkerdi: rasgos geológicos, evolución kárstica y contenido arqueopaleontológico

El estudio interdisciplinar realizado en el Macizo de Alkerdi (Urdazubi, Nafarroa), ha puesto de manifiesto la existencia de un complejo sistema kárstico desarrollado en dos unidades litoestratigráficas calcáreas de edad cretácica con aproximadamente 3 km de desarrollo y estructurado en cuatro pisos kársticos de dirección SW-NE. Los tres pisos superiores, más antiguos, están en condiciones vadosas y presentan rasgos de un karst evolucionado, con evidencias de fracturación y colapso de techos y paredes, más o menos tapizados por espeleotemas o fases de relleno/vaciado sedimentario. Las labores arqueológicas realizadas en estos pisos elevados han ofrecido unos resultados positivos. Cabe destacar el hallazgo de arte parietal paleolítico en la cueva de Alkerdi 2, incluyendo motivos geométricos pintados en rojo y negro y animales grabados. A ello se une la localización en posición primaria de material arqueológico (industria lítica, fauna, carbones) en el suelo de las áreas decoradas

MIS5-MIS3 Neanderthal occupations at Amalda III cave (Northern Iberian Peninsula)

The arrival, occupation, and disappearance of Neanderthals in the Cantabrian region is the subject of a long-running debate that continues to this day. Knowledge of the evolution of Neanderthal societies since the end of the Middle Pleistocene in the north of the Iberian Peninsula is greatly impacted by the scarcity of a good chronological framework. This absence of good data creates difficulties in evaluating the cultural adaptations of these populations to environmental changes and their historical dynamics. The Amalda III cave, surveyed in 1983-84, contains a sequence of occupations ranging from the end of MIS5 (Levallois with Mousterian points and bifaces) to the beginning of MIS3 (Vasconian). It is possible to observe substantial changes in the environmental conditions and cultural responses of Neanderthal groups that inhabited the cave. Here we present the first results of the Amalda III sequence, which is currently being excavated by an interdisciplinary team. Our objective is to test, enrich and refine the regional environmental and Neanderthal cultural framework and the transformations that took place between the MIS5 and the MIS3. These new data are compared with the information available from several Middle Paleolithic sites in the region, advancing our understanding of the behavioural adaptations of Neanderthals to different ecological and socio-cultural situations between ca. 100 and 45 kyr BP in the Eastern Cantabrian region. In this way, we will be able to deepen our interpretation of the processes of cultural change of the last groups of Neanderthals that inhabited this region.Gipuzkoako Foru AldundiaAyuntamiento de ZestoaMinisterio de Ciencia e InnovaciónNext Generation European FundsMCIN/AEI/10.13039/501100011033/and “FEDERERC Subsilience projectDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu