Seasonal pattern of speleothemic lamination in the Ortigosa de Cameros Caves (La Rioja): an experimental approach

Monitoring of both carbonate precipitation process and environmental parameters inside two caves in Ortigosa de Cameros (La Rioja, Spain) has allowed us to establish the seasonality of speletohem lamination in these caves. Temperature record shows a minimum in March-June and a maximum in August with little oscillation (< 1ºC). Drip water flow is maximum in autumn and spring. The carbonate record displays white porous laminae (WPL) and dark compact laminae (DCL) of seasonal origin. DCL are organic matter rich and form in high drip water flow periods, when soil organic matter is flushed into the caves. Stable isotope analyses of drip water (δ18O and δD) and carbonate (δ18O and δ13C) confirm the seasonal pattern: δ13C minimus correspond to the warm seasons (WPL) while δ18O pattern can be explained on the basis of the corresponding drip water δ18O variation

Tufa sedimentation in changing hydrological conditions : the River Mesa (Spain)

The processes controlling tufa deposition along the River Mesa (NE Spain) were studied from April 2003 to September 2009, based on six-monthly monitoring of physical and chemical parameters of the river water and sedimentological characteristics, including deposition rates on tablets. With a mean annual discharge around 1.5m3 /s, the sedimentation rate (mean 2mm/yr) recorded important spatial, seasonal and interannual variations. The river waters are of the calcium bicarbonate type. In this study, three distinct river stretches were distinguished based on the steady groundwater inputs, some of low-thermal nature. Groundwater discharges controlled the water chemical composition, and some sedimentation features too. At each stretch, an increase in pCO2 and conductivity was measured around the spring sites. Decreasing trends in conductivity or alkalinity with high enough saturation values with respect to calcite were only clearly observed in the intermediate stretch, which had higher tufa deposition rates than the other two. Tufa deposition rates were higher in cool (autumn+winter) than in warm (spring+summer) periods. In some low-rainfall warm periods, tufa deposition was inhibited or limited due to the low flow -mainly from groundwater inputs- and to the dryness of some river sites, which indeed favoured erosion during flooding. A decrease in yearly deposition rates from April 2006 onwards paralleled an important reduction in the river discharge. Groundwater inputs, drought periods and flood events should therefore be considered to understand fluvial tufa sedimentation in semi-arid conditions

Geoquímica de elementos trazas en espeleotemas con laminación estacional de las cuevas de Ortigosa de Cameros (La Rioja)

The concentration of several trace elements (Mg, Ba, Sr,Al, Si and P) has been analyzed in two speleothems, corresponding to MIS-5 and MIS-1 according to U/Th dating, and one recent deposit, experimentally recorded. All them belong to La Paz cave in Ortigosa de Cameros (La Rioja). The analyzed trace element content displays a seasonality that agrees with the speleothem lamination.Trace element concentration is higher in the dark laminae, formed during the fall-winter season. This content is linked to the flushing into the cave of organic matter from soil activity, in fall, when precipitation resumes. Mg/Ca and Sr/Ca evolutions point to a decrease of humidity during MIS-5 with respect to MIS-1, whereas at present aridity increases, probably in relation to an enlarging of the seasonal contrast. Se estudia la concentración de varios elementos traza (Mg, Ba, Sr,Al, Si y P) en dos espeleotemas, datados por U/Th como MIS-5 y MIS-1, y en un depósito actual, de origen experimental, todos ellos de la cueva de La Paz en Ortigosa de Cameros (La Rioja). Los elementos analizados muestran una estacionalidad acorde con la laminación de los depósitos. La concentración de trazas es mayor en las láminas oscuras, correspondientes a otoño-invierno, asociada a la materia orgánica procedente de la actividad edáfica, que es introducida por las precipitaciones de otoño, tras la sequía estival. Las evoluciones de Mg/Ca y Sr/Ca indican una disminución de la humedad durante el MIS-5 respecto al MIS-1, mientras que en la actualidad hay un aumento de la aridez. Estas variaciones podrían estar influenciadas por modificaciones del contraste estacional

First monitoring results in the El Recuenco Cave (Ejulve, Teruel)

El Recuenco Cave (Ejulve, Teruel, NE Spain) is developed with a complex topography in Upper Cretaceous dolomitic limestones. A monitoring survey is in progress in the cave (covering now the 1st semester of 2013) in order to know the isotopic path from rainfall to dripwater and in-situ farmed calcite. Rainfall results show that δ18O values reveal a clear seasonality (-12,73‰V-SMOW in winter, -8,94‰V-SMOW in spring). Dripwater values are mainly influenced by homogenization processes in the epikarst and also reveals seasonality in δ18O values (-10,9‰ V-SMOW in winter, -9,8‰ V-SMOW in spring). Finally, isotopic values of in-situ farmed calcite confirm this seasonality pattern (in δ18O values, -8,17‰ PDB in winter, -8,11‰ PDB in spring; also in δ13C values, -9,84‰ PDB in winter, -9,68‰ PDB in spring). Nonetheless, new monitoring tasks are needed to confirm this preliminary pattern. These conclusions will help to better interpret of speleothem records in this cave for paleoclimatic reconstructionsLa cueva de El Recuenco (Ejulve, Teruel) presenta una topografía compleja desarrollada en calizas dolomíticas del Cretácico superior. En ella se ha efectuado un seguimiento instrumental del desarrollo espeleotémico actual (primer semestre de 2013) de cara a evaluar el recorrido isotópico desde el agua de lluvia, pasando por el goteo interno hasta el carbonato precipitado. Los resultados del agua de lluvia evidencian que el δ18O muestra una clara estacionalidad (-12,73‰ V-SMOW en invierno, -8,94‰ V-SMOW en primavera). Los valores isotópicos del goteo se encuentran controlados por la homogeneización producida en el epikarst,mostrando de nuevo cierta estacionalidad en δ18O (-10,9‰V-SMOW en invierno, -9,8‰V-SMOW en primavera). Finalmente, la señal isotópica del carbonato resultante confirma este patrón de estacionalidad (en δ18O, -8,17‰ PDB en invierno, -8,11‰ PDB en primavera; en δ13C, -9,84‰ PDB en invierno, -9,68‰ PDB en primavera). No obstante, es necesario ampliar el seguimiento temporal para confirmar este patrón estacional preliminar. Estas consideraciones ayudarán a una mejor interpretación de los registros espeleotémicos en esta cueva de cara a realizar reconstrucciones paleoclimática

Caracterización de carbonatos criogénicos en una cueva helada del Pirineo

Se aportan datos micromorfológicos, isotópicos y cronológicos de carbonatos criogénicos CCC) de la cueva helada Sarrios-6, situada a 2780 m s.n.m. en el macizo de Monte Perdido (Pirineo central). Es el primer estudio de este tipo de espeleotemas en la Peninsula Ibérica. En una masa de hielo aparecen cristales romboédricos de calcita de tamaño milimétrico constituidos por un núcleo interno de cristales esqueléticos rodeados por un crecimiento externo de color pardo-rojizo. Indican una fase rápida inicial de precipitación de calcita y otra posterior más lenta. Los dos tipos de calcita presentan composición isotópica diferente (núcleo: valor medio de δ13C = 4,8‰VPDB, valor medio de δ18O = -20,8‰VPDB; crecimiento externo: valor medio de δ13C = 5,3‰ VPDB, valor medio de δ18O = -21,3‰ VPDB). La datación de una semilla incluida en la masa de hielo indica que la formación de la CCC tuvo lugar durante la Anomalía Climática MedievalWe provide micromorphological, isotopic and chronological data on cryogenic cave carbonates (CCC) from Sarrios-6 ice cave (2780 m a.s.l.) in the Monte Perdido Massif (central Pyrenees). It is the first report of such speleothems on the Iberian Peninsula.Millimeter-sized white skeletal calcite rhombohedrons overgrown by brown rhombohedral crystals are present within a perennial ice body. The morphology of two carbonate generations suggests an early stage of fast carbonate precipitation followed by a second phase formed at a slower precipitation rate. The two generations show distinct isotopic compositions (skeletal cores:mean δ13C = 4.8‰,mean δ18O = -20.8‰; overgrowths: mean δ13C = 5.3‰, mean δ18O = -21.3‰). A preliminary radiocarbon date of a seed found in the same ice layer suggests that the precipitation of CCC likely occurred during the Medieval Climate Anomal

Evolución estacional y decenal de isótopos estables registrada en tobas recientes depositadas en substratos artificiales en el Parque del Monasterio de Piedra (NE España)

Identification of six-month intervals in carbonate deposits formed on tablets installed in several fluvial subenvironments of the Monasterio de Piedra Natural Park, from 1999 to 2009, allowed six-monthly stable-isotope analysis of such records. Slight differences in δ13C and δ18O exist between stromatolites (fast-flowing water areas) and moss-bearing deposits (cascades). Sediment δ13C values did not show clear regular variations through time. A chiefly cyclic pattern of sediment δ18O values reflected the seasonal variations in temperature. The calculated water temperature values were consistent with measured air and water temperature values. The increasing tendency of air temperature is closely reflected by the estimated temperature tendencies. The isotopic results stress the validity of the seasonal variation pattern detected through thickness measures, and underscore the environmental significance of tufas, which accounts for the use of this type of analysis in climate interpretation from ancient tufa recordsLa identificación de intervalos semestrales en depósitos carbonatados formados sobre losetas instaladas en diversos subambientes fluviales del Parque Natural del Monasterio de Piedra, desde 1999 hasta 2009, ha permitido el análisis semestral de isótopos estables de dichos registros. Existen pequeñas diferencias en δ13C y δ18O entre las facies estromatolíticas (áreas de flujo rápido) y las ricas en musgos (cascadas). Los valores de δ13C no muestran variaciones temporales regulares. Los valores de δ18O presentan una pauta cíclica que refleja las variaciones estacionales de temperatura. Los valores calculados de la temperatura estacional del agua son acordes con las temperaturas medidas de aire y agua. La tendencia creciente de la temperatura del aire se refleja en las tendencias de temperatura estimadas. Estos resultados refuerzan la validez del patrón estacional detectado mediante la medida de espesores de los depósitos, y confirman la utilidad de este tipo de análisis en la interpretación climática de tobas antigua

Palaeoenvironmental interpretation of Late Pleistocene–Holocene morphosedimentary record in the Valsalada saline wetlands (Central Ebro Basin, NE Spain)

22 páginas, 6 figuras, 1 tablaThis work presents a palaeoenvironmental interpretation of the Upper Pleistocene–Holocene sedimentary sequence recorded in the Valsalada saline wetland system (Monegros, Central Ebro Basin). This morphosedimentary system developed on karstified, gypsiferous bedrock and was mainly fed by local saline groundwater. Based on geomorphological, sedimentological, palynological and radiocarbon data, three depositional units have been differentiated: 1) a lacustrine unit, which accumulated under cold/cool and humid environmental conditions at 41–40 kyr cal BP, 2) a fluvial unit that was deposited under arid climatic conditions with cold episodic periods from 14 to 3.5 kyr cal BP, and 3) an alluvial slope unit associated with arid climate with human influence during the Late Roman Period (1.5 kyr cal BP). The morphosedimentary evolution of the Valsalada system is strongly influenced by the geomorphic setting (small catchment with karstic depressions and low gradient slopes on gypsum), the hydrological availability (runoff and groundwater discharges) related to climate variability during the Late Pleistocene–Holocene, and the human activities developed in the area during historical times. The response of the Valsalada system displays a low sensitivity to short-term climatic changes but responds to major long-term climatic conditions, improving the regional paleoenvironmental picture of the Late Quaternary in NE Spain.This work was supported by projects CGL2006-08973/BTE, CGL2009-10455/BTE, CGL2009-07992 and CSD2007-00067 of the Spanish Government and the European Regional Development Fund. This is a contribution by PaleoQ, GCC and Cuencas Sedimentarias Continentales groups (Aragón Regional Government). We are grateful to the anonymous reviewers for their helpful comments.Peer reviewe

Geochemical proxies of environmental changes in Holocene alluvial sequences from Bardenas Reales

Geochemical features and Chemical Index of Alteration (CIA), corrected for Ca from calcite, were studied in Holocene alluvial sequences from Bardenas Reales of Navarra. The five sequences, distinguished by using morphochronostratigraphic evidences, show a different geochemical pattern controlled by granulometric characteristics, bedrock weathering and soil processes. Geochemical proxies (CIA) indicate an increase in moisture during some phases of Early and Middle Holocen

Insights into the speleogenesis of Ejulve cave (Iberian Range, NE Spain): quaternary hydrothermal karstification?

We provide first insights into the speleogenesis of Ejulve cave (Teruel province, Iberian Range, NE Spain) by studying cave morphologies and cave deposits, combined with regional geomorphological and hydrothermal observations. Three main hydrogeomorphic evolutionary stages can be distinguised to explain the origin and evolution of the Ejulve endokarstic system. Cave pattern and cave solutional features (calcite vein fillings, tubes with rising ceiling cupolas, pendants and cusps, spongework and micro-corrosion features) suggest that the cave generated in a phreatic environment by ascending water. Cave morphologies and regional hydrothermal springs in this region suggest, but not prove, the involvement of thermal waters and related convection and condensation-corrosion mechanisms in the origin of the cave. Subsequently, the cave underwent a change to epigenic conditions driven by denudation, as a result of regional uplift. Once the karstic system was exhumated, carbonate speleothems formed in a vadose environment. Mineralogical, petrographic, isotopic and chronological (U-series dating) analyses of carbonate speleothems (i.e. stalagmites, flowstones, botryoids, spars, acicular crystals and farmed carbonate) are provided. Calcite, high-Mg calcite and aragonite are the most common minerals, whereas columnar, dendritic, micrite, mosaics and fans are the main fabrics. Mean δO values of − 7.3‰ and δC values of − 9.1‰ indicate carbonate precipitation from meteoric waters without a hydrothermal origin. Carbonate deposits formed at least since 650 ka BP. Our study suggests that hydrothermal fluid flow may explain, although the evidences are not fully conclusive, the speleogenesis of this cave.We acknowledge the predoctoral research Grant from the Government of Aragón (B158/13) and CTM2013-48639-C2-2-R (OPERA) and CGL2016-77479-R (SPYRIT) projects for funding. Fernando Gázquez was financially supported by the “HIPATIA” research program of the University of Almeria

Geochemical differentiation of «Weald» materials of Cameros Basin (Soria - La Rioja)

The Cameros Basin ( N W o f the Iberian Range) is m a in ly composed o f very homogeneous silicic d e tr ita l m aterials in Weald facies. The occurrence o f c h lo rito id , cookeite, p y rite an d muscovite/p aragonite is related to a cretacic very low grade metamorphism. The geochemical analysis of this materials displays differences linked to lithologic features; comparison between metamorphic and no metamorphic materials shows no main differences in the chemical contents, but in the relationships between element