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

Discerning the interactions between environmental parameters reflected in d13C and d18O of recent fluvial tufas: Lessons from a Mediterranean climate region

d13C and d18O of recent, continuous tufa records, obtained during a monitoring period spanning 3 to 13 years, are compared with the corresponding, known environmental conditions. Three rivers in NE Iberia (located along a 200-km N–S transect) are used for this comparison. The isotopic variations through space and time are discussed in terms of the environmental and geological parameters that operate on different scales, focusing on discerning the interactions between these parameters and providing examples of possible misinterpretation of climatic conditions, which is important to past climate studies based on isotopic data. The calculation of the actual isotopic fractionation coefficients, and the comparison with the literature-derived coefficients, demonstrates that the studied tufa formation was close to isotopic equilibrium to reflect the water temperature. The difference between mean measured water temperature (Tw) and mean calculated Tw (based on d18Ocalcite and measured d18Owater) is less than 2.7 °C. Tendencies of these calculated Tw are similar to the regional air temperature (Tair) tendencies through time, in particular in the case of the 13-year record, although certain deviations exist over shorter time spans. The best agreement between measured and calculated Tw and between d18Ocalcite-based Tw tendencies and Tair tendencies corresponds to the tufa stromatolite facies. Differences between the d18Ocalcite records of the three rivers cannot be attributed to temperature changes, but to the varying influences of groundwater inputs and isotopic rainfall composition in each river.Without considering these parameters, d18Ocalcite-based Tw calculations yield inaccurate results when comparing the study sites. d13Ccalcite values do not exhibit distinct patterns over time, and d13Ccalcite variations are likely caused by local processes that do not reflect general environmental changes. These findings underscore the significance of accounting for both groundwater behaviour and rainfall stable isotope composition when interpreting climate parameters in carbonate systems, particularly when differences between the isotopic signatures of deposits exist in the same region

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

Seasonal temperatures from δ18O in Recent Spanish tufa stromatolites: Equilibrium redux!

This study focuses on recent debate over the value of stable-isotope-based environmental proxies recorded in riverine tufa-stromatolites. We recovered a 12-year record (1999-2012) of river-bed tufa stromatolites in the River Piedra (NE Spain) along with a partly overlapping 15-year record (1994 to 2009) of accumulations in a drainage pipe: both deposits formed in water with near identical physico/chemical parameters. Measured water temperature (Tw) data and near constant δ18Owater composition allowed selection of an ‘equilibrium’ palaeotemperature equation that best replicated actual temperatures. We found, as other have, that both the Epstein et al. (1951) and Kim & O’Neil (1997) formulas for Tw calculation from equilibrium calcite δ18O compositions were appropriate for the River Piedra where tufa deposition rates are high, means between 5.6 and 10.8 mm in six months. δ18Ocalcite in both the river and the pipe deposits record essentially the full actual seasonal Tw range. Only the coldest times (Tw < 10ºC), when calcite precipitation mass decreased to minimum, are likely to be unrepresented, an effect most noticeable in the pipe where depositional masses are smaller and below sample resolution. While we cannot rule out kinetic effects on δ18Ocalcite-based calculated Tw, the good fit between measured Tw and δ18Ocalcite-calculated Tw indicates that temperature is the principal control. Textural and deposition rate variability between the river and pipe settings are caused by differences in flow velocity and illumination. In the river, calcification of growing cyanobacterial mat occurred throughout the year, producing composite dense and porous laminae, whereas in the pipe, discontinuous cyanobacterial growth in winter promoted more abiogenic calcification. High-resolution δ18Ocalcite data from synchronous pipe and river laminae show that reversals in Tw occur within laminae, not at lamina boundaries, a pattern consistent with progressive increase in calcite precipitation rate as cyanobacterial growth re-established in spring

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

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

Las tobas cuaternarias del río Añamaza (provincia de Soria, Cordillera Ibérica): aproximación cronológica

High-gradient, stepped fluvial tufa systems with dammed areas existed in the River Añamaza valley (NW Iberian Ranges, Spain) during Quaternary times. Single deposits range from a few meters to about 70 m thick, in which prograding-aggrading wedges separated by erosional surfaces exist. Several episodes of tufa formation have been distinguished by means of U-series, Amino-acid racemization and radiocarbon techniques. These correlate to MIS 8, 7, 5 and 1. The presence of MIS 9 is uncertain, as chronological data may also correspond to older stages. Most tufas in this area formed in MIS 5. Distinct tufa episodes can also be distinguished in the Holocene. These are the first chronological data presented for one of the northernmost Quaternary tufa systems in the Iberian Ranges

Análisis preliminar de las tobas cuaternarias del río Ebrón (Castielfabib, Valencia, Cordillera Ibérica)

In this paper the Alpine cleavage affecting the Permo-Triassic series of the Espadan Range (Castellón) is studied. Cleavage affects to argillites and sandstones in Saxonian and Buntsandstein facies. At cartographic scale it is linked with the Espadan box anticline with constant ONO-ESE trend. At microscoscopic scale it constitutes a “spaced cleavage” with a predominance of pressure solution and passive rotation mechanisms. At outcrop scale the cleavage characterizes by a sigmoidal geometry linked both the post-cleavage flexural slip as a cleavage-related flexural flow mechanism. The proposed kinematic model to explain its origin includes three main stages: 1) incipient development of cleavage linked to layer-parallel shortening, 2) buckling and increasing of cleavage penetrativity and 3) folfing amplification and layer-parallel shear. RESUMEN Se estudia la esquistosidad alpina que afecta a la serie Permo-Triásica de la Sierra de Espadán, (Castellón). La esquistosidad afecta a los tramos argilíticos y areniscosos en facies Saxoniense y Buntsandstein, con distinto grado de penetratividad. A escala cartográfica se asocia al anticlinal de Espadán con geometría en cofre y orientación ONO-ESE. A escala microestructural se clasifica como esquistosidad espaciada con predominio de los mecanismos de disolución por presión y rotación mecánica de filosilicatos. A escala de afloramiento destaca la geometría sigmoidal de las superficies de esquistosidad atribuida tanto a un mecanismo post-esquistoso de flexodeslizamiento en las capas competentes como a flexofluencia sin-esquistosa en capas incompetentes. El modelo cinemático para su génesis contempla tres estadios: 1) desarrollo incipiente de esquistosidad en relación a acortamiento paralelo a las capas, 2) buckling e incremento del grado de penetratividad y 3) amplificación de los pliegues y cizalla simple paralela a las capa

Ensayo cronológico de las tobas cuaternarias del río Piedra (Cordillera Ibérica)

A preliminary absolute chronology for the Quaternary calcareous tufa deposits from the Piedra River valley (Iberian Range, NE Spain) has been carried out based on U series dating, Amino Acid Racemization, Optically Stimulated Luminescence and Radiocarbon dating techniques. Although the age uncertainties of the obtained dates are substantial, four stages of tufa accumulation correlated to MIS 9, 7-6, 5 and 1 can be distinguished. The most favourable period for tufa accumulation is located around the isotopic stage

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