Research

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Our research in the Iberian Peninsula is integrated within several projects of the Pyrenean Institute of Ecology and the Experimental Station of Aula Dei (CSIC) funded by regional (Diputación General de Aragón,  the Regional Aragonese Goverment), national (CICYT, the Spanish National Science Foundation) and European (European Comission) agencies. We highlight here the main projects and research lines in the Iberian Peninsula:

1.- Limnocliber project

2.- Iberarid project

3.- Saline Lakes from the Central Ebro basin

4.- Previous work in the Iberian Peninsula

Project: CLIBER (Variabilidad climática y su impacto en la Península. Ibérica desde el último máximo glacial: correlación de registros continentales y marinos e implicaciones para el entendimiento del clima presente y futuro).

Period: Dec 2003 - Dec 2006

Funding: CICYT, Ministerio de Ciencia y Tecnología, Spain

Main researchers: Francisca Martínez Ruíz and Blas L. Valero Garcés

Lago Enol (Covadonga National Park) in April 2004 during the coring expedition

The CLIBER project is divided in two subprojects, one dealing with marine sediments and the other related to lake cores (LIMNOCLIBER). CLIBER project aims to reconstruct the climatic variability of the Iberian Peninsula since the Last Glacial Maximum (LGM) from high-resolution marine and lacustrine archives. The selected marine records come from the Alboran and Surbalear Seas in the western Mediterranean, and from the link areas with the Atlantic; the lake cores come from karstic lakes in the Pre-Pyrenees, Iberian Range and Andalucia. All the sites have been selected to ensure records with high sedimentation rates and absence of sedimentary discontinuities from key regions to understand climate variability in the Iberian Peninsula. In order to unravel climate dynamics at higher timescales than those provided by instrumental and historical data, these records are extremely important. They also provide the needed reconstructions to validate future climate change scenarios. The scientific strategy of the coordinated team is based in a multidisciplinary analysis including physical, sedimentological, chemical, mineralogical and biological techniques. The project goals include: i) to evaluate the ocean-continent interactions, ii) to reconstruct the climate since the LGM, with particular emphasis on abrupt and rapid event, iii) to assess the response of the different climate subsystems and the natural and human-related factors, and iv) to contribute to the prediction of future climate change and its impacts on geographic regions of national interest.

In the framework of the LIMNOCLIBER project up to eight lakes were cored in Spain during Spring 2004. Here you can see a map with the location of the studied lakes. The field expedition was carried out with the coring kullemberg platform from the Limnological Research Center and the help of many people from different universities in Spain. A general poster about the LIMNOCLIBER project can be downloaded from here.

A total of 200 m of lake sediments were recovered during the field expedition. Here is a table with the summary of the recovery cores. For more information about the available material and possible collaborations, please contact Dr. Blas L. Valero Garcés. After the coring expedition, cores were sent to the Limnological Research Center where they were stored in cold rooms at 4ºC. Several months later (in Sept-Oct, 2004) we went to Minneapolis to open and describe the obtained cores. Smear slides were produced and observed at the microscope to define the sedimentary facies.

Spliting a core at the LRC laboratory

Additionally, continuous measurements of physical properties were carried out with a GEOTEK multi-sensor system and color pictures were taken.

One or two representative cores from every lake were sent back to Spain and are now stored in the IPE laboratory. Several of these cores have already been sampled in the IPE laboratory for different analyses since November 2004. Here you can see several pictures of the sampling procedures.

Color picture from a core of El Tobar lake (Cuenca) with several finely laminated intervals

Three phD thesis are now in progress in the framework of LIMNOCLIBER project:

- Mario Morellón (Instituto Pirenaico de Ecología). Paleohidrología y cambios climáticos abruptos en la Península Ibérica desde el último máximo glacial: el registro lacustre de Estaña. Dirigida por Dr. Blas Valero Garcés.

- Celia Martín (Universidad de Cádiz). Cambio global desde el último máximo glaciar en el sur de España: el registro paleoclimático y paleoambiental de la Laguna de Zoñar (Córdoba). Codirigida por los Drs. Blas Valero Garcés y Pilar Mata.

- Noemí Fuentes (Universidad de Murcia). Codirigida por los Drs. José S. Carrión y Penélope González Sampériz.

Preliminary results will be presented in the EGU General Assembly in Vienna (see below). In addition, a power point presentation about our field expedition and the obtained cores can be downloaded from here (warning!!: it´s 190 Mb).

Abstract for the EGU General Assembly, 24-29 April, 2005, Vienna, Austria:

Blas L. Valero-Garcés(1), Ana Moreno (1) , Penélope González-Sampériz(1), Mario Morellón(1) , Ana Navas(2), Javier Machín(2), Pilar Mata(3), Celia Martín(3), Antonio Delgado-Huertas(4), Roberto Bao(5), Antonio González-Barrios(6) , Doug Schnurrenberger(7), Anders Norens(7), Mark Shapley(7). LIMNOCLIBER: A Transect of High-Resolution Lacustrine Records of Climate and Environmental Variability in Spain since the Last Glacial Maximum

1 Pyrenean Institute of Ecology- CSIC, Apdo 202, E-50080 Zaragoza, Spain; 2 EEAD-CSIC, Apdo 202, E-50080 Zaragoza, Spain; 3 Cadiz University, Cadiz, Spain; 4 EEZ- CSIC, Prof. Albareda 1, Granada, Spain; 5 Facultade de Ciencias, Universidade da Coruña, Campus da Zapateira s/n, E-15071 A Coruña, Spain; 6Córdoba University, Córdoba, Spain; 7 LRC, University of Minnesota, Minneapolis MN-55455, USA

The LIMNOCLIBER project represents a multidisciplinary, international effort to recover, for the first time, long paleoenvironmental and paleoclimate records from relatively deep lakes in Spain. New records from the Iberian Peninsula during the last decade have changed our views on Holocene history from a generally benign climate punctuated by dry mid Holocene period and an amelioration afterwards, to a complex fluctuation of arid and humid periods. Lateglacial reconstructions have also shown large variability and a multifaceted regional pattern in the Iberian Peninsula. The fact that the maximum extent of mountain glaciers occurred much earlier than the global Last Glacial Maximum (LGM,) also underlines the differences in timing of the main climatic events in Southwestern Europe.
To resolve the contradictory interpretations of available records and to reconstruct the effective moisture history of the region since the global LGM, long, high resolution, well-dated records from hydrologically-sensitive regions in Spain are needed. Although deep lakes are not common in Spain, numerous, relatively deep (up to 20 m), karstic lakes with carbonate-rich sediments occur in the Iberian Range and the Pyrenees, and deep terminal-moraine lakes appear in the mountains of northern and western Spain. During the spring of 2004, over 200 m of lacustrine sediment cores were retrieved from eight lakes in Spain using a modified Kullenberg piston coring platform from the Limnological Research Center (U. of Minnesota, USA). The lakes were selected based on several criteria: accessibility, sedimentology (presence of authigenic carbonates) and limnology (karstic lakes deeper than 10 m), aimed to assure the presence of long, continuous paleoclimate records (> 20000 years) along a climatic and ecological transect in Spain. Three of them (Caicedo-Arreo, Estaña and Montcortes) follow a W-E transect in the Pre-Pyrenean Range. Laguna Taravilla, and El Tobar are karstic lakes in the Iberian Range. El Tobar is a saline, meromictic lake with a finely laminated sedimentary record. Preliminary studies based on 210Pb and AMS 14C- dated short cores from Taravilla have shown the potential of the lake system as an archive of paleohydrological events. Laguna Zoñar is the only accessible and relatively deep karstic lake in southern Spain, and short cores previously obtained had already shown the complex interplay of human impact and climate variability during the last 1000 years. The Lago de Sanabria, the largest glacial lake in Spain, lies behind a large terminal moraine complex deposited during the LGM in NW Spain. Lago Enol is also a glacial lake located in the Cantabrian mountains.
Preliminary analyses and some dating have been performed in selected cores from the eight lakes. Magnetic and physical properties were measured with a GEOTEKTM Multi-Sensor Core Logger (MSCL). The cores have been split and imaged with a high-resolution scanner. Detailed sedimentological descriptions have allowed identification and interpretation of sedimentary facies and preliminary reconstructions of the depositional history of the lakes. Other paleohydrological-sensitive techniques are in progress: chemical composition of carbonate phases, stable isotopes of carbonates and organic matter, and a variety of biological indicators (pollen, diatoms, ostracods and chironomids). A detailed chronological framework based on AMS14C and U/Th analyses is in progress.
Our goal is to provide long, high resolution, paleohydrological reconstructions from a region extremely sensitive to changes in effective moisture and atmospheric dynamics. The multiproxy-based reconstructed curves will provide new data to identify and date the main climate events, and to characterize the climate variability at century and millennium scale since the LGM. The regional distribution of the sites will enable us to discuss the climate and effective moisture patterns in Iberia during Last Glacial Maximum. The high resolution reconstructions will provide data for the timing, duration and geographical distribution of the cold and arid intervals during deglaciation, and the correlation of the Iberian Holocene arid episodes with world-wide periods of abrupt climate change Our reconstructions will help to test possible causes for aridity in Iberia (enhancement of the north Atlantic High, a southwards displacements of the Azores high and the Mediterranean winter belt, local monsoonal-enhanced climate effects). Finally, the occurrence of finely laminated intervals provides an opportunity to understand the significance of high frequency climate variability (NAO, ENSO) in the climate of the Iberian Peninsula.
Lacustrine time-series are response records of sensitive regional systems to past global changes and the understanding of their natural variability and their thresholds will help and inspire our understanding of future climate changes. The LIMNOCLIBER project contributes to this global effort by focusing in the integration of sedimentological, biological and geochemical proxies for a number of time-series from the Iberian Peninsula, aimed to develop a coherent, comparative synthesis of the regional pattern.

Iberarid project

In the framework of a previous project called IBERARID funded by the Spanish government three Spanish lakes have been studied: Laguna Zoñar (Córdoba), Taravilla (Guadalajara) and Lagunas de Estaña (Huesca).

Project: IBERARID (Periodos áridos en las zona Mediterránea de la Península Ibérica desde el último máximo glacial: cronología, caracterización e implicaciones paleoclimáticas).

Period: Dec 2000 - Dec 2003

Funding: CICYT, Ministerio de Ciencia y Tecnología, Spain

Main researcher: Blas L. Valero Garcés

This was the introduction to this project, the research strategy and the main objectives established:

Introduction

Paleoenvironmental research in Iberia has been dominated by pollen studies from peat bogs, either in high mountain areas or along the coast. The geographical bias, sensitivity, and low resolution of palynological sites located in pluvial coastal and upland areas have helped to create an image of limited Holocene climate change within Iberia. However, most Iberian lacustrine records document several rapid humid/arid transitions since the Last Glacial Maximum, and the presence of stadials and interstadials in the Lateglacial Iberian pollen sequences is well documented. Several arid/humid transitions during the early (about 8 kyrs), mid (5 Kyrs) and Late Holocene (4-3 kyrs) occurred in most sites. Only two of these arid episodes correlate with marine cooling events (8.2 and 5.2 ky BP). On the other hand, there is a clear teleconnection with the two major dry spells occurred around 8.4-8 and 4.5-4 ka in the northern African monsoon domain and in the eastern Mediterranean. In spite of the new data the teleconnections with abrupt Holocene climate changes detected in northern Europe, North America, and northern Africa are unclear due to low resolution of the paleorecords and lack of detailed chronological control.

During the last five years, we have applied combined sedimentological, geochemical and palynological techniques to several lake record in NE Spain, mostly in the Pyrenees (Tramacastilla, Linás de Broto, Arguisal) and the Ebro Basin (Mediana, Chiprana, La Salineta). All the records document several abrupt arid/humid transitions during the Lateglacial and the Holocene suggestting a millennium-scale climatic variability. The next step in our research is to obtain long, continuous lacustrine cores and to assess their potential as paleohydrological and paleoclimatic indicators. Funding from USA and Spanish agencies has been requested. Our strategy to identify and characterize the main arid/humid abrupt transitions in the Iberian climate is based on:

1) Sites located close to climate zone boundaries and in areas sensitive to effective moisture changes. We have selected several relatively deep, paleohydrologically -sensitive lakes with thick sedimentary sequences in four areas with sharp climatic and vegetational gradients: i) northwestern Iberia, a region between the Atlantic regions with Eurosiberian vegetation and the continental arid Central Plains within the Mediterranean vegetation zone (the Sanabria lake) ii) the Pyrenean foothills, a region between the humid and forested Pyrenees and the Ebro Basin, the most northerly area in Europe with truly semi-arid climate (the Estanya lake); iii) the Serrania de Cuenca in the Iberian Range, characterized by a transition from continental to more humid Mediterranean climate (Lagunas de Cuenca), and iv) the southern regions within a more arid Mediterranean climate but with strong spatial and temporal rainfall fluctuations (Laguna Zoñar).

2) The targeted sites contain long, continuous sediment records but they have not been cored before because of the technological problems involving deep-lake coring.

3) a set of paleohydrologically-sensitive tools (sedimentary facies analyses, mineralogy, chemical composition of carbonate phases and stable isotope of authigenic carbonates and organic matter) applied to the sediment sequences.

Goals

The main objective is to obtain long continuous lacustrine cores and to assess their potential as paleohydrological and paleoclimatic indicators. Sedimentological study of the cores and preliminary dating will produce proxy records from the Iberian Peninsula to test hypotheses concerning the cause and extent of the prolonged Lateglacial and Holocene arid phases and the abrupt humid/arid switching in the Mediterranean region. This research will provide some of the needed mid latitude continental records required to advance the understanding of the causes and ecosystem responses of these rapid changes, which have more immediate importance in predicting future climate changes than the long term variations attributed to orbital forcing. With these records we will address the following scientific questions:

(1) Identification of century-scale arid periods.

(2) Magnitude and timing of the Lateglacial and Holocene arid periods. We will particularly address the following questions:

• what is the timing, duration and geographical distribution of the rapid arid/hummid transitions during the Lateglacial in Iberia?.
• are the Iberian arid episodes synchronous to the five century-scale arid intervals (10230-12480, 7500->7860, 4860-5010, 2830-2990 and 1660-1880 calendar yr BP)described by Lamb et al. (1995) in Morocco ?. Are the most intense arid period synchronous to the major dry spells occurred around 8.4-8 and 4.2-4 ka BP in the northern monsoon African domain (Gasse, 2000)?.
• Climatic mechanisms. Iberian cores will contribute high-quality paleorecords to test hypotheses concerning the cause of rapid arid/humid transitions and prolonged phases of aridity during the Lateglacial and the Holocene. The Lateglacial arid periods have been linked to a southwards displacements of the Atlantic oceanic polar front, the Azores high and the Mediterranean winter belt (Gasse et al., 1990) and to Heinrich events (Sanchez Goñi et al., 1999). The occurrence of a number of abrupt and rapid arid/humid transitions during the Holocene, clearly indicates that other mechanisms besides orbital forcing have controlled the location and intensity of the Azores high, but the causes are not known (Gasse, 2000; deMenocal et al., 2000). They include: a) temporary weakening of the monsoonal circulation (Fontes et al., 1985; Gasse et al., 1987); b) a relationship with Dansgaard-Oeschger cycles (Dansgaard et al., 1993); c) changes in the Atlantic heat transport and the NADW formation (Roberts et al., 1994; Lamb et al., 1995; Broecker et al. 1990; Alley et al., 1997). A detailed chronology of the main climatic episodes in Iberia will help to solve this controversy.

Zoñar

Laguna Zoñar (37º 29' 00" N, 4º 41' 22" W, 300 m a.s.l.) is the deepest (up to 15 m) and largest (37 ha, surface area) of the 10 lakes that belong to the Natural Park of the Southern Córboba. Its origin has been related to tectonic, karstic and diapiric activity (Fernández-Delgado, 1981; Moya, 1984). The elongated lake shape, following the dominant regional tectonic direction (N 45º-50ºE), indicates a clear tectonic control. On the other hand, the location close to Triassic outcrops stresses the importance of diapirism in the genesis of these structures. Finally, an open doline has been mapped between the mouths of the Lobo and Moro creeks to the south and east of the lake (IGME, 1986), raising the possibility of a karstic origin at least for some areas of the Zoñar Basin.

Zoñar lake during the field expedition (Spring 2004)

The Laguna Zoñar watershed was identified and mapped using topographic and geological maps. Water chemical composition, lake level fluctuations and changes in land uses monitored since 1982 by Andalucian Government Environmental Agencies were compiled. A seismic survey was conducted with a 3.5 Khz seismic profiler in June 2002. Unfortunately sediment penetration was extremely poor and only bathymetry and bottom basin morphology could be reconstructed (Valero-Garces et al., 2003). Two sediment cores (ZON-01-1A: 1.72 m, and ZON-01-1B, 1.17 m long) were retrieved in the deepest basin of Laguna Zoñar (14.5 m water depth). The 1.17 cm long core was sub-sampled in the field at 0.5 and 1 cm intervals for 210Pb and 137Cs dating. Magnetic susceptibility was measured with a Bartington magnetic susceptibility bridge every 2 cm. The ZON-01-1A core was split in two halves and sedimentary facies were defined by macroscopic visual description including color, grain-size, sedimentary structures, fossil content, and by microscopic smear slide observations (Schnurrenberger et al., 2003). The core was sampled for organic matter, grain size, mineralogy, trace-element geochemistry, pollen, diatoms, and ostracodes. The chronology is constrained by two AMS 14C dates from the longer core ZON-01-1A (593 ± 38 14C yr B.P. at 124-126 cm depth, and 1771 ± 38 14C yr B.P. at 166-167, Table 1) analyzed at the Arizona Dating Facility and by 210Pb and 137Cs dating in the parallel short core (ZON-01-1B) performed at the St. Croix River Station (University of Minnesota). Both cores were correlated using sedimentary facies, grain size, and organic matter profiles.

For more information, you can read the following references or download a poster presented in the III International Limnogeological Congress, in Tucson (2003):

References:

Valero-Garcés, B. L., Navas, A., Mata, P., Delgado-Huertas, A., Machín, J., González-Sampériz, P., Moreno, A., Schwalb, A., Ariztegui, D., Schnellmann, M., Bao, R., and González-Barrios, A. (2003). Sedimentary facies analyses in lacustrine cores: from initial core descriptions to detailed paleoenvironmental reconstructions. A case study from Zoñar lake (Cordoba province, Spain). In: "Limnología en España: un tributo a Kerry Kelts / Limnogeology in Spain: a tribute to Kerry Kelts” (B. L. Valero-Garcés, Ed.). Consejo Superior de Investigaciones Científicas, Madrid, 14, 385-414.

Valero-Garcés, B.L. Penélope González-Sampériz, Ana Navas, Javier Machín, Pilar Mata, Antonio Delgado-Huertas, Roberto Bao, Ana Moreno, José S. Carrión, Antje Schwalb, & Antonio González-Barrios. Human Impact since Medieval times and Recent Ecological Restoration in a Mediterranean Lake: The Laguna Zoñar (Spain). Journal of Paleolimnology, in review.

Taravilla

Lacustrine and travertine records from Laguna de Taravilla (Iberian Range, Guadalajara province, Spain, 40º 39' N, 1º 59' W, 1100 m a.sl.) have been analysed using sedimentological, mineralogical, geochemical and palynological techniques. A preliminary chronological framework is based on U/Th, 14C AMS, 210Pb and 137Cs dates. Phases of increased travertine growth occurred during the Glacial- Interglacial transitions from isotope stage 6 to 5 and 2 to 1. Short lacustrine cores indicate a lake level and surface area increase after the XVth century, that can be correlated with the end of the Medieval Warm Period. Sandy facies related to flood events are more frequent during the interval ascribed to the Little Ice Age. The growth of littoral vegetation at the mouth of the inlet could have prevented more sandy sediments to reach the center of the lake during the last century.

Taravilla lake during the field expedition (Spring 2004) with a close view of the coring system

For more information you can read the extended abstract presented in the VI Congreso de Geología de España (sorry, only in Spanish). New cores obtained during the Limnocliber field expedition are now going to be studied by several people from the IPE and other institutes.

Sorry, this page is under construction...

Saline lakes from the Central Ebro basin

Several projects have founded our work in the saline lakes from the Central Ebro basin. Among them, we highlight here the project called "Evolución ambiental y efectos del impacto antrópico en el complejo lagunar de Bujaraloz-Sástago. Bases científicas para la conservación y el desarrollo sostenible de las Saladas de Los Monegros" and the "Diagnóstico medioambiental y estudio sedimentológico - isotópico del complejo lagunar de la Salada de Chiprana" both funded by the DGA (regional government). In the framework of those projects, we have studied the sediment record from Mediana, La Salineta and La Playa lakes to reconstruct the paleohydrological changes in the area. A good summary of the work carried out (except of the one from Mediana) can be downloaded here (warning!! it´s a poster of 6 Mb)..

Mediana

The Salada Mediana (41° 30' 10" N, 0° 44' W, 350 m a.s.l.) is a small (main axis about 325 m x 500 m; surface area: 14 ha), seasonal (Zmax: 50-0 cm) playa lake, located 20 km southeast of Zaragoza, in the Central Ebro Basin. The Salada Mediana waters are of a (SO42-)-(Cl-)-(Na+)-(Mg2+) type, with low carbonate and calcium contents, and high Mg/Ca ratios. The sediment record is up to 1.5 m.

Valero-Garcés, B.L., González-Sampériz, P., Delgado-Huertas, A., Navas, A., Machín, J. y Kelts, K.,2000. Late Glacial and Holocene hydrology of Salada Mediana, Central Ebro Basin, Spain. Quaternary International, 73/74: 29-46.

Figure. The Salada Mediana record.

Valero-Garcés, B.L., Delgado-Huertas, A., Navas, A.. Machin, J. González, P., and Kelts, K.,2000. Quaternary sedimentologic and isotopic evolution of a playa lake: Salada Mediana, central Ebro Basin, Spain. Sedimentology, 47: 1135-1156.

ABSTRACT. Sedimentary features, mineralogy, bulk geochemical composition, stable isotope analyses, and pollen data from sediment cores were used to reconstruct the Late Quaternary depositional evolution of the Salada Mediana playa lake (central Ebro Basin, northeastern Spain). The 150 cm-long sediment core sequence is composed of gypsum- and dolomite-rich muds (Lower and Middle sections) and black, laminated, calcite-bearing sediments (Upper section). The Salada Mediana formed as a karstic depression in the Miocene gypsum substratum during the Late Pleistocene. The Lower section was deposited in a sulphate-carbonate saline lake that ended with a period of desiccation, and basin floor deflation. Subsequent deposition (Middle section) took place in a playa-lake system. Two cycles of lower water table and expanded saline mud flats occurred. The Holocene sequence is missing, likely as a result of aeolian erosion. Sedimentation resumed only a few centuries ago, and saline pan environments dominated until modern times. The Salada Mediana facies succession was mainly governed by fluctuations in the hydrological balance, brine composition, and salinity; however, aeolian processes (detrital input and deflation), and recycling of previously precipitated salts also played a significant role.

Valero-Garcés, B.L., Kelts, K., González-Sampériz, P., Delgado- Huertas, A., Navas, A., & Machín, J., 1999. Sedimentary facies analyses as paleohydrological proxies for saline lakes, Central Ebro Basin, Spain. 4th workshop of the European Lake Drilling Programme. Correlations of late Weichselian and Holocene paleoenvironment proxy data. Terra Nostra, 99/10: 101-106.

Chiprana

The Salada Chiprana (N 41° 14’ 30" , W 0° 10’ 50", 150 m a.s.l.), located in the central Ebro basin, is the only permanent (4.2 – 5.6 m deep), hypersaline lake in Iberia, containing a highly diverse flora and fauna including a number of rare and endangered species. The lake’s watershed has been altered by agricultural use over the last centuries and irrigation returns form a significant component of the lake’s hydrological balance.

Valero-Garcés, B.L., Navas, A., Machin, J., Stevenson, T. & Davis, B., 2000. Responses of a saline lake ecosystems in semi-arid regions to irrigation and climate variability. The history of Salada Chiprana, Central Ebro Basin, Spain. Ambio, 26 (6), 344-350.

ABSTRACT. To adequately manage the fragile and changing environments of semi-arid regions it is essential to disentangle human from climate or other environmental impacts over longer timescales than human memory. We investigated sediment cores from Salada Chiprana, a saline lake in the central Ebro basin (Spain), using pollen, charcoal, sedimentological, geochemical and radiometric dating techniques. The sequence indicates a rapid evolution from an ephemeral playa lake during the Late Holocene to a permanent saline lake a few centuries ago. The limnological evolution correlates with changes in agricultural practices and provides evidence of the strong impact of irrigation on the lake’s hydrological balance from the XV century. The work demonstrates that the Salada Chiprana the only permanent, relatively deep, hypersaline lake in Spain has been created by a long history of human interaction with the landscape.

Figure. The Salada Chiprana record.

La Salineta

La Salineta is a small ephemeral playa lake located in the Central Ebro Basin. The core retrieved is the longest in the Ebro Basin (8 meters). The absence of   adequate organic remains makes radiocarbon dating very difficult. Preliminary AMS dating of bulk organic matter suggests that deposition started during the Last Glacial Maximum (around 22 ka), and consequently, the sequence has a great potential to understand the climate evolution of interior Spain.  Palynological (Tony Stevenson, University of Newcastle), geochemical (Ana Navas and J. Machín) and sedimentological studies are already published.

Valero-Garcés, B.L, González-Sampériz, P., Navas, A., Machín, J., Delgado-Huertas, Peña-Monne, J.L., Sancho-Marcén, C., Stevenson, T., y Davis, B. (2004): Paleohydrological fluctutations and steppe vegetation during the last glacial maximum in the central Ebro valley (N.E. Spain). Quaternary International, 122: 43-55. (pdf)

ABSTRACT. Combined analysis of sedimentary facies, geochemistry and pollen from lake sediment records, and sedimentological and palynological studies from slope deposits allow the characterization of vegetation and lake level status during the Last Glacial (LGM) in the central Ebro valley (NE Spain). These records show the presence of phases of increased effective moisture, while regional vegetation was dominated by steppe species. The longest lake record comes from La Salineta, one of the saline lakes in the Los Monegros area; the other lake sequence comes from a sinkhole in the Gállego River floodplain. The slope deposit from Valmadrid is the only periglacial deposit found in the central Ebro valley. Our data indicate that, at least for some intervals during full glacial times, when cold steppe vegetation dominated the region, some lakes experienced more positive water balance than today, and run-off was also high. The data are coherent with the hypothesis that, at least for some periods, the ice-age climate of the western Mediterranean was characterized by cold winters, with relatively higher effective moisture (precipitation minus evaporation ratio) and summer droughts. Increased flow from the Pyrenean rivers during the early deglaciation could also have played a significant role in the paleohydrological cycle in the central Ebro valley. However, La Salineta records also show evidence for arid periods during glacial times, indicating the complex evolution of hydrology and moisture availability in the central Ebro valley during the LGM.

A new core was recovered from the Salineta lake in July 2003. Results are still preliminary. Here are some pictures from the field expedition:

La Salineta lake (Central Ebro Basin) during June 2003

A picture of the saline crust in la Salineta lake (June 2003)

Previous work in the Iberian Peninsula

Some of our previous work in the Iberian Peninsula was by collaborating in the project "Isotope sedimentology of 40 ka time - series from Iberian sites as a test for abrupt arid/humid switching within the Mediterranean climate zone" funded by the USA National Science Foundation. This project, based at the University of Minnesota, is part of the collaborative program between the LRC and the IPE.

Sites: In the Iberian Peninsula, we have investigated the climatic evolution since the Last Glacial Maximum in several lacustrine records from the Pyrenees, eastern Spain, and the Ebro Basin. In Banyoles, the correlation of periods of rapid environmental and climatic changes reconstructed from isotopic and sedimentological records with Heinrich events has shown the strong linkage between Iberian and north Atlantic climate. The lake level changes detected in saline lakes from the Ebro Basin suggest that large effective moisture fluctuations affected this semi-arid region during the Lateglacial. The numerous arid phases documented on Iberian lacustrine records indicate that ot her factors besides orbital forcing have controlled the Iberian climates during the Holocene. Environmental, cultural and anthropogenic changes since Neolithic have also been documented in several lacustrine records and archaeological sites from the Pyrenees and Ebro Basin.

Pyrenees: Portalet, Tramacastilla, and Arguisal  (Gállego valley) y  Linás de Broto (Ara valley).

Banyoles

Ebro Basin: Mediana, Chiprana, La Salineta

General Bibliography

Valero-Garcés, B.L. & González-Sampériz, P., (Eds) 1999. Records of environmental and climate change in the Mediterranean region. The lacustrine contribution. 1st workshop of the Southern Europe Working group. European Lake Drilling Programme. Abstract Book. Instituto Pirenaico de Ecología, Zaragoza, pp. 78.

Ibañez, J.J.; Valero-Garcés, B.L. & Machado, C., (Eds.)(1997). Mediterranean landscape through space and time. Implications for desertificacion ( in Spanish). CSIC, Geoforma Ediciones, Logroño, Spain. 478 pp.

The book "Mediterranean landscape through space and time. Implications for desertificacion" has been published by the Spanish Scientific Council (CSIC) and it contains 17 papers dealing with different aspects of erosion and desertification in the Iberian Peninsula. Blas ValeroGarcés was responsible editor for the papers dealing with the paleorecords of environmental change and desertificacion in Spain. The book contains ten papers describing the main paleoenvironmental tecniques and the results in the Iberian regions of different techniques and proxies: palynology, stable isotopes, historical records, meteorological data, dendrochonology, glaciology, paleofloods and lake records.

Glacial Geomorphology

Tramacastilla

Montserrat Marti, J. 1992. Evolucion glaciar y postglaciar del clima y la vegetacion en la vertiente sur del Pirineo. Ph.D. Thesis, Univ. of Barcelona, Geoforma Ediciones, Logroño, 115 p

García-Ruiz, J.M. and Valero-Garcés, B.L., 1998. Historical geomorphic processes and human activities in the central Spanish Pyrenees. Mountain Research and Development., 18 (4): 309-320.

Figure. The last 4000 years of the Tramacastilla record.

Valero Garcés, B.L., Martí Bono, C. & Kelts, K., 1998. El Holoceno Superior en el valle del Tena (Pirineos Occidentales españoles (Late Holocene in the Tena valley, western Spanish Pyrenees, in Spanish). In: Investigaciones recientes de la Geomorfología española (A. Gómez Ortiz y F. Salvador Franch, eds), Barcelona, Geoforma Ediciones, Logroño, p: 463-470

Arguisal

Portalet

González-Sampériz, P.; Valero-Garcés, B.; Lorente, A.; Martí-Bono, C.E.;Beguería, S. y García-Ruiz, J.M. (2000) Primeros resultados del análisis polínico de la turbera del Portalet (Alto Valle del Gállego, Pirineo Central Español). XIII Simposio de la APLE, Cartagena, Spain, September, 2000.

Linás de Broto

Serrat, D., Vilaplana, J.M. & Martí, C. 1983. Some depositional models in glaciolacustrine environments (southern Pyrenees). In: Evenson E.B. et al (ed.) Tills & related deposits. A.A. Balkena, Rotterdam, p. 231-244.

Martí, C. 1996. El glaciarismo cuaternario en el Alto Aragón Occidental. Ph.D. Dissertation, Universidad de Barcelona, 254 p.

Martí-Bono, C., González-Sampériz, P., Valero-Garcés, B. & García-Ruiz, J.M., 2000. Caracterización palinológica de los depósitos glaciolacustres de Linás de Broto (Pirineo aragonés). Meeting of the Sociedad Española de Geomorfología, Madrid.

Banyoles

Valero-Garcés, B.L., Zeroual, E., & Kelts, K., 1998. Arid phases in the western Mediterranean region during the Last Glacial Cycle reconstructed from lacustrine records. En: G. Benito, V.R. Baker and K.J. Gregory, (eds.), Paleohydrology and Environmental Change, pp. 67-80, Wiley & Sons. London.