Segre River Research Articles

Geochemical Study of Chert Artefacts from Xicotó Rockshelter (NE Iberia) Archaeological Site. New Data on Neolithic and Mesolithic Human Occupations

Xicotó Rockshelter (Alòs de Balaguer, Lleida, Spain) is located in the eastern Pre-Pyrenean range in north-east Iberia, in the middle Segre River Basin. Since 2013, archaeological works have been developed by a team from the Prehistoric Studies and Research Seminar (SERP) at the University of Barcelona and up to three sedimentary levels have been identified. The preserved archaeological remains have allowed determining that the site was occupied during at least two different periods: the Ancient Neolithic and the Middle Mesolithic. The relative chronology given by the archaeological assemblage has been confirmed by several radiocarbon dates that place the occupations of the site to be during the VI and VII millennia cal BC. This paper presents the results obtained after the analysis of lithic raw materials from the entire lithic assemblage. The analysis was performed using the classic petroarchaeological approach, comprising textural and micropalaeontological descriptions, combined with the application of geochemical methods, using energy-dispersive X-ray fluorescence (ED-XRF) and laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICP-MS). The results show that several rock types were selected for confectioning the lithic tools, among which chert was the preferred. Different types and origins have been identified, with similar sourcing strategies that involved local and regional procurement.

Absence of Gradients and Nernstian Equilibrium Stripping (AGNES): An Electroanalytical Technique for Chemical Speciation: A Tutorial Review

Free metal ion concentrations of amalgamating elements such as Zn, Cd, In, or Pb can be determined with absence of gradients and Nernstian equilibrium stripping(AGNES) in a variety of matrices, ranging from seawater to wine or dissolving nanoparticles. In this hands-on paper, we review the fundamental concepts and provide the practical steps to implement AGNES, including ready-to-run files for the software controlling the potentiostat, computation spreadsheets, step-by-step laboratory protocols, etc. Two case studies with a free Zn concentration determination are discussed: (i) a synthetic solution with the ligand oxalate and (ii) a natural sample of the Segre river (Catalonia, Spain). Suggestions for the extension of AGNES to other systems are indicated.

Reconstructing Mousterian landscapes in the southeastern Pyrenees (Roca dels Bous site, Pre-Pyrenees ranges, Spain)

AbstractLandscape evolution studies enable us to understand site formation processes affecting past hunter-gatherer settlements. This work presents a landscape reconstruction of Roca dels Bous site (RB), which is a reference site for the Late Mousterian occupation of the incised valleys of the southeastern Pyrenees. For this purpose, we combined geomorphological studies, stratigraphic descriptions, new single-grain optically stimulated luminescence datasets, statistical methods, and geophysical surveys. RB formed by gravitational processes induced by fluvial undermining of the Segre River during changing late Pleistocene climatic conditions. Geomorphological and chronological data combined with fluvial age-incision models suggest that, during Late Mousterian occupation, RB was located very near the Segre floodplain level and closer to water and raw material natural resources than at present. The accumulation of gravitational deposits associated with the archaeological levels occurred at rates of 0.16–0.44 m ka-1, between 55 and 47 ka, coinciding with Marine Oxygen Isotope Stage 3 (MIS3). More detailed comparison with available climatic curves suggests that the dated RB layers were potentially deposited during cold phases within MIS3. This work provides new landscape-based evidence to examine the paleoenvironmental context of Neanderthal presence in the southeastern Pre-Pyrenees, an important region in the debate regarding Neanderthal demise in Western Europe around 40 ka.

Enantiomeric fraction and isomeric composition to assess sources of DDT residues in soils

Chiral pesticides such as o,p′-DDT can undergo enantioselective microbial degradation in soil. Hence, the enantiomeric fraction (EF) of o,p′-DDT was used as an approach to assess potential recent inputs of DDT in the lower part of the Ebro River basin (NE Spain), a region heavily impacted by agricultural and industrial activities, including a dicofol production and a chloro-alkali plants. The EFs of five out of nineteen soils were not different from the racemic value (0.505±0.010), confirming that the Ebro River and some of its tributaries, Segre and Cinca rivers, transported fresh DDT residues despite its ban in Spain during the 90s. o,p′-DDT/p,p′-DDT ratios in soils suggest that recent use of technical DDT and/or DDT-contaminated dicofol may be responsible for the fresh DDT inputs in the Segre River, while in the Ebro River, they indicate a dominant contribution of technical DDT, likely related to the residues accumulated by the chloro-alkali plant discharges.

Loess and soils in the eastern Ebro Basin

Wind-blown sandy and silty deposits were formed during the late Quaternary in the NE Iberian Peninsula. They are the most significant in the West Mediterranean region, together with those described in the Tagus River basin (Iberian South Subplateau), forming small scattered patches across parts of the SE Ebro Depression and SW Catalan Mediterranean Range. Two major depositional environments are distinguished. The first (largest) outcrop covers the lower Ebro reaches on the SE border of the Ebro Depression, the Prelitoral Coastal Range and the Móra d'Ebre Basin. A second outcrop, to the north, consists of a few patches scattered over a wide amphitheatre surrounding the western tributaries of the Segre River, from the wind-exposed Segrià platforms to the Almenara Range in its northernmost part. They consist of highly sorted fine sands and silts, 1–12 m thick (though most typically 3–4 m thick), and coarser than typical loess. They are highly uniform, lack any sedimentary structures and are pale ochre. The deposits are calcareous (30–45% CaCO3), basic to alkaline and with some soluble salts.Five selected sequences of primary loess (namely Mas de l'Alerany, Tivissa, Guiamets, Batea and Almenara) were studied to ascertain deposit characteristics and soil development. All sections show a consistent vertical granulometric variability that may be attributed to wind intensity changes, and hinders the recognition of spatial particle size distribution. Pedogenesis is mostly related to calcium carbonate redistribution, which accumulates as nodules, large rhizocretions or biogenic calcite. Secondary gypsum (Batea and Almenara sequences) is probably related to primary gypsum blown from the source areas that was redistributed by leaching and precipitation at the bottom of the profiles. In a few places (Mas de l'Alerany outcrop) a fersialitic, rubefacted-recalcified soil indicates the presence of an older generation of loess. While the dominant WNW winds and particle coarseness suggest that the loess originates from nearby alluvial fans and fluvial plains, the presence of gypsum and Mg anomalies may be evidence of more distant sources of the Central Ebro Depression and Ondara-Corb alluvial fans.Optical Stimulated Luminiscence (OSL) ages for the more recent deposits (Guiamets, Batea, Almenara) are between 18 and 34 ka, while the old Mas de l'Alerany sequence is more than 115 ka. These ages indicate loess deposition during the last cold phases of the Quaternary and with pedogenesis occuring during warm interglacial periods.

Benchmark soils on alluvial, fluvial and fluvio-glacial formations of the upper-Segre valley .

The upper reaches of the Segre river, flowing through the Pyrenees, offers a variety of geomorphic surfaces that allow us to study soil chronosequences. The objective of this work is to widen the knowledge about the main characteristics and formation processes of some benchmark soils developed on fluvio-glacial, alluvial-fan and terrace materials of Pleistocene and Holocene age related to the Segre river, either siliceous or carbonatic. This knowledge will allow us to identify soil forming processes, commonly found in Mediterranean environments such as carbonate redistribution, clay formation and mobilization and rubefaction, all as functions of parent material and age. Five profiles, ranging from the Lower Pleistocene to the Holocene were classified according to Soil Taxonomy/WRB. The Montferrer profile (Calcic Palexeralf /Calcic Cutanic Luvisol (Chromic) is a deep, partly decarbonated soil, with calcium carbonate accumulation in depth covering glacial features. The Torre del Remei profile (Typic Paleustalf /Cutanic Luvisol) developed on silicic moraines and shows an extreme clay formation and illuviation. The Alp (Typic Haplustalf /Cutanic Luvisol) and Tartera (Petric Calciustept /Petric Calcisol) soils are developed on alluvial fans with calcium carbonate sources. The former is partly decarbonated, whilst the latter is rubefacted on top and shows speleothem-like carbonate pendants with superposition of clay illuviation. The youngest profile, Abellerols, (Typic Calciustept /Typic Calcisol) shows only a partial decarbonation and calcite accumulation at depth. The results show that soil development is determined by the age of the surface and the source of calcite, either in the parent rock or brought by subsurface flow: clay illuviation is extreme in absence of it. Special morphologies of carbonate pendants are indicators of environmental conditions. The coexistence of clay coatings and secondary calcite can be explained by recarbonatation or by spatial differentiation of soil environments in the profile. One of the implications of this research is the inconsistence of using soil development indices based on morphological indicators when soils are formed on different parent materials and are subjected to different geomorphic dynamics.

Boldness is related to the development of the cephalic crest in the male of the river blenny Salaria fluviatilis (Asso, 1801)

Abstract Boldness is defined as the tendency of an individual to take risks when exposed to novel objects or situations. The main aim of this work was to dilucidate if boldness was related to the development of the secondary sexual traits (SSTs) in the male of the river blenny Salaria fluviatilis, a freshwater fish which takes care of eggs. As a second objective SSTs effect on parental status adoption was also be explored. Wild young fish were caught in the Segre River (Ebro basin) in November 2010. Fish were kept in five aquaria in groups of eight males and eight females with artificial nests. Boldness (boldness score and hesitancy) of males (initially with little SSTs development) was tested as the time required to exit a refuge when exposed to a new environment. Fish were mantained in the same aquaria for several months, and males’ SSTs development and reproductive behaviour were monitored. Boldness score was negatively associated to cephalic crest development. Hesitancy was negatively related to male length and was also influenced by the interaction between male length and cephalic crest. Parental status acquisition was positively related to the male’s length, marginally related to anal gland development, and non-related to cephalic crest. These results suggest an intrasexual role of the crest as an informative trait of boldness (honest signal) which might not necessarily be chosen by the females. It is also discussed that correlational selection could be responsible for linking boldness and growth rate in this species. Sexual selection, in addition to having directed the evolution of secondary sexual traits, might have favored certain personality traits (e.g. boldness) associated with the achievement of a larger body length.

Reintegración de un territorio entre fronteras: el Alto Segre, Pirineos

Los valles de la cuenca alta del río Segre tienen elementos deidentidad comunes. Entre los siglos XIII y XVII se produce la división político-administrativa de este territorio, repartido actualmente en tres estadosdiferentes (España, Francia y Andorra). La región comprende cuatro áreasdiferenciadas; Alt Urgell y Baixa Cerdanya (comarcas catalanas en España),Alta Cerdanya (comarca natural en Francia) y el Principado de Andorra.Las cuatro áreas han desarrollado distintas especializaciones económicas,afectadas por la actual crisis de la burbuja inmobiliaria. La cooperación entreestos territorios se refleja principalmente en los flujos transfronterizos porrazones de trabajo, de compras y acceso a los servicios, adquisición de viviendaspermanentes y estacionales y en actividades culturales. Ante el nue -vo escenario, son deseables modelos de desarrollo sostenibles con serviciospúblico-privados mancomunados que pueden ser recogidos por las políticasde cooperación territorial de la UE en un plan común.

Annually-resolved lake record of extreme hydro-meteorological events since AD 1347 in NE Iberian Peninsula

We present an annual reconstruction of extreme rainfall events interpreted from detrital layers and turbidites interbedded within a varved sediment record since the 14th century in Montcortés Lake (NE Spain, 1027 m a.s.l.). Clastic microfacies intercalated within the biochemical calcite varves were characterized and their depositional dynamics interpreted using high-resolution geochemical and sedimentological analyses. Annual number of detrital layers was compared against instrumental records of extreme daily rainfalls providing minimum rainfall thresholds and return periods associated to the identified types of clastic microfacies. Non-continuous detrital layers were deposited during rainfall events higher than 80 mm (>2-year return period) while graded detrital layers and turbidites were associated with higher magnitude rainfall events (>90 mm and >4-year return period). The frequency distribution of extreme hydro-meteorological events is not stationary and its pattern coincides with historical floods from the nearby Segre River. High frequency of heavy rainfalls occurred during the periods AD 1347–1400 and AD 1844–1894. A lower frequency of heavy rainfall was found during the periods AD 1441–1508, 1547–1592, 1656–1712, 1765–1822 and 1917–2012. The 20th century stands out as the longest interval within the studied period of very low number of extreme rainfall events. Variability in extreme rainfall events prior to the 20th century is in phase with solar activity, suggesting a mechanistic link in mid-latitude atmospheric circulation patterns that ceased during the 20th century.

Terrace staircase development in the Southern Pyrenees Foreland: Inferences from 10Be terrace exposure ages at the Segre River

The fluvial network of the Southern Pyrenees is an example of transverse drainage systems in young (alpine) mountain belts and it features well preserved fluvial terrace records. Some of the major Southern Pyrenees tributary rivers have been studied previously and have some age controls on their fluvial terrace levels. We extend these records to one of the largest streams in the Southern Pyrenees, the Segre River.In this paper, we present new GIS data, field observations and exposure ages obtained from in situ produced terrestrial cosmogenic nuclides (10Be). The focus of this paper is set to unravel the relative impact of climatic controls on the formation of the Segre terrace staircase in the Southern Pyrenees foreland (Ebro Basin).The Pleistocene terrace staircase of the Segre River is built up by seven major terrace levels, which range from 112 to 3m above the present-day active channel. The prominent upper and middle terraces TQ1, TQ2, TQ3 and TQ4 have been sampled for 10Be exposure dating. Exposure ages have been calculated using Monte Carlo parameter simulations. Additionally, we applied a Profile Rejuvenation method accounting for variable 10Be inheritance in the samples, and which yielded comparable results. The Monte Carlo results show Middle to Late Pleistocene exposure ages for TQ1: 202ka (MIS 7), TQ2: 139ka (MIS 6), TQ3: 100ka (MIS 5), and TQ4: 62ka (MIS 4), involving denudation rates of 3–8mmka−1. The results indicate that the abandonment of Segre paleo-floodplains and the change from aggradation to predominant incision is related with Middle to Late Pleistocene cold-warm climate transitions (or early stages of interglacial periods). Major floodplain aggradation appears to be linked with intense deglaciation at the end of MIS 8, MIS 6, and MIS 4. The exposure of terrace TQ3 (MIS 5) indicates that terrace formation might also occur during relatively warm isotope stages with sufficient climate instability.On a regional scale, the staircase morphology at the Segre River shows similarities with adjacent fluvial systems in the Southern Pyrenees. In addition, previously published chronologies for these systems are consistent with the timing of aggradation and terrace abandonment. Both, staircase morphology and chronology point to regionally synchronous phases of floodplain aggradation and river incision, which seem to be triggered by climate variability and Pleistocene glaciations in the Pyrenees since the Mid Pleistocene Climatic Revolution.

External controls on Quaternary fluvial incision and terrace formation at the Segre River, Southern Pyrenees

Focusing on climatic- and structural (tectonic) controls, we aim to determine their relative importance for the (Pliocene to Quaternary) fluvial landscape evolution in the Southern Pyrenees foreland. We investigate the Segre River, which is one of the major streams of the Southern Pyrenees that drains the elevated chain towards the Ebro foreland basin. Along its course, the Segre River has a flight of fluvial cut-and-fill (and strath-type) terraces preserved that have been mapped based on DEM's and geomorphological fieldwork. This paper presents the first results of our study and reports on the Segre terrace staircase, which is characterized by seven major Quaternary terrace levels with elevations up to more than 110 m above the modern floodplain. At the upper and middle reaches, the semi-parallel terraces of the Segre River occasionally show anomalies featuring extensive gravel thickness and deformation caused by faulting, folding and local subsidence. The longitudinal correlations of terrace levels reveal increased vertical terrace spacing in the foreland, which could originate from enhanced fluvial erosion after the Mid-Pleistocene climate transition in combination with base level lowering controlled by the progressive downcutting of the Catalan Coastal Range. Since the Ebro Basin opening (Late Miocene), the Catalan Coastal Range, which borders the Ebro foreland basin to the Mediterranean Sea, was progressively cut down and the exorheic drainage system gradually adjusted to sea level. The Segre longitudinal terrace profiles and the Ebro gorge morphology at the Catalan Coastal Range indicate a base-level of about 200 m.s.l. at the beginning of (Pleistocene) terrace formation, which implies that the Catalan Coastal Range might have functioned as a local base-level upstream of the sea outlet, presumably until the Late Pleistocene. Alternatively, a yet unknown tectonic process might have caused base level lowering and the preservation of terrace staircases at the Ebro drainage system.

The Magdalenian in Catalonia (northeast Iberia)

The Magdalenian is the first Upper Palaeolithic period to show a widespread human occupation throughout the northeastern territories of Iberia. Several sites have been located in both the plains and mountains extending from the Pyrenean valleys of the Segre River to the mouth of the Ebro River. The oldest dates (in the XIXth millennium cal BP) were obtained at the open-air site of Montlleó, in the Pyrenean valley of Cerdanya. Most of the Magdalenian sites have yielded information about short or seasonal occupations related with the exploitation of natural resources. Parco cave preserves a good stratigraphic sequence ranging from Middle to Upper and Late Upper Magdalenian (from XVIIth to XIVth millennium cal BP). In this site, various human activities were organized around a significant number of hearths. They were related with animal and mineral processing. The data obtained at Parco and Montlleó sites have enabled the reconstruction of the Late Upper Pleistocene palaeoenvironment for the southeastern Pyrenees area. However, other sites from the southern part of the country are also providing very interesting information about climate, as well as faunal and floral elements, with more recent radiocarbon dates (XVth to XIVth millennium cal BP). Some malacological remains found in Montlleó come from the Mediterranean coast, but others come from the Cantabrian area, thus indicating a route of connection between the two seas during the Magdalenian. There is also limited artistic evidence in Taverna cave, Molí del Salt, l’Hort de la Boquera, Sant Gregori, and Parellada IV sites. One of the most significant findings of the research is the archaeological confirmation of the existence of human movements across the Pyrenees during the Magdalenian. Some raw materials found in Montlleó are of French origin, others come from the southern slopes of the Pyrenees, and still others could come from either side. The site is near the westernmost route opened during the last glaciation for crossing the Pyrenees. Thus, people and materials may well have circulated across the Pyrenees through this corridor.

Effects of prospective landscape changes on species viability in Segre River valley, NE Spain

Traditional land use in Mediterranean region resulted in complex landscape structures characterized by great ecological and cultural diversity. Recent changes such as intensification of agriculture, infrastructure development, rural depopulation and abandonment of the less productive regions led to landscape simplification and loss of biodiversity. In this project, we used a multispecies modelling approach to explore the possibility to develop landscape management plans that combine urbanization and infrastructure development with maintenance of traditional land-use to prevent further loss of biodiversity. For this purpose we studied the effect of progressing land use changes on the abundance and viability of fauna in the Spanish Pyrenees landscape. We compared the present land use situation in Cerdanya and Alt Urgell with foreseen changes in a near future grouped in two management scenarios. The assessment of the population size and viability of indicator species was conducted with the landscape model LARCH. Our results indicate that most of the selected species maintained viable populations in the present situation. Conservation of traditional land use would strongly improve the viability of the species characteristic for the habitats of higher conservation value like riparian forest. In contrast, the abandonment of traditional land use would lead to a decline of numbers and loss of viability of all species, with the strongest negative impact for specialist species. Based on these results we developed specific land use recommendations, both at local and regional level, that allow combining conservation efforts with economic and demographic developments in Mediterranean regions.

Soil evolution over the Quaternary period in a semiarid climate (Segre river terraces, northeast Spain)

Abstract A macro- and micromorphologic study was done on the soils from a stepped sequence of seven dated fluvial terraces in the lower Segre river valley (Lleida, northeast Spain) under a present-day semiarid Mediterranean climate. The soils have evolved from the Holocene through the early Pleistocene, providing an excellent morphostratigraphic framework for evaluating time-dependent factors influencing soil formation in a dry and calcareous environment. Throughout the chronosequence, some properties are regularly age-related specially carbonatation in subsurface horizons. The carbonates occur mainly as micrite, and although microsparite and sparite also appear in the oldest soils, they are replaced by fine-grained calcite by dissolution–reprecipitation processes (micritization process), which is active at present. Some pedological paleofeatures as the presence of sparite and recarbonated argillans in oldest terrace can be interpreted as the reflex of climatic changes during the Quaternary. In spite of this climate variability, the soils display progressive and systematic patterns of carbonate accumulation: on the lowest terraces, the soils do not yet have secondary carbonates but in the beginning Late Pleistocene calcic horizons, with carbonate pendents, are developed; these pendents increase its thickness with age although pendent growth rates decreases from Late Pleistocene to Middle Pleistocene. In the middle of the Late Pleistocene, calcic horizons evolved to petrocalcic horizons, which increase its thickness in the Middle and specially in Early Pleistocene. The presence of calcic and petrocalcic horizons is the primary basis for soil classification. This criterion is applicable not only to the soils of the lower Segre river basin, but also to many soils throughout the semiarid Mediterranean region.

Genetic refuges for a self‐sustained fishery: experience in wild brown trout populations in the eastern Pyrenees

Abstract – Management policies balancing harvest and conservation of natural populations of fish are difficult to establish, both scientifically and politically. This issue is particularly difficult when those populations represent native genetic resources. Since 1997, several brown trout populations in the eastern Pyrenees Mountains (Spain) were designated as ‘genetic refuges’ under varying fishing regulations, where releases of hatchery‐origin fish are not permitted. We analysed genetic variation in samples of brown trout from six of those refuge populations and four non‐refuge populations within the same region. Each population was sampled in four separate years: 1993, 1999, 2004 and 2006. Our analyses were based on a diagnostic allele (LDH‐C*90) that distinguishes native and exogenous hatchery populations. Comparisons were based on stocking histories before and after refuge designations and on three management strategies: fished, unfished and catch‐and‐release. Overall, we detected significant genetic introgression resulting from past stocking practices despite the current restriction of hatchery releases imposed by the recent genetic refuge policy. However, this new policy has prevented detectable introgression from increasing throughout the region and together with additional measures on length and number of captured fish is contributing to self‐sustained fisheries that are achieving conservation goals. Quick acceptance of ‘genetic refuges’ by anglers in one particular river, the Ter River basin, has been a key factor in protecting native gene pools compared with the Segre River basins where refuges were not readily accepted.