Ramon Julià

Paleobiology and comparative morphology of a late Neandertal sample from El Sidrón, Asturias, Spain

Fossil evidence from the Iberian Peninsula is essential for understanding Neandertal evolution and history. Since 2000, a new sample ≈43,000 years old has been systematically recovered at the El Sidrón cave site (Asturias, Spain). Human remains almost exclusively compose the bone assemblage. All of the skeletal parts are preserved, and there is a moderate occurrence of Middle Paleolithic stone tools. A minimum number of eight individuals are represented, and ancient mtDNA has been extracted from dental and osteological remains. Paleobiology of the El Sidrón archaic humans fits the pattern found in other Neandertal samples: a high incidence of dental hypoplasia and interproximal grooves, yet no traumatic lesions are present. Moreover, unambiguous evidence of human-induced modifications has been found on the human remains. Morphologically, the El Sidrón humans show a large number of Neandertal lineage-derived features even though certain traits place the sample at the limits of Neandertal variation. Integrating the El Sidrón human mandibles into the larger Neandertal sample reveals a north–south geographic patterning, with southern Neandertals showing broader faces with increased lower facial heights. The large El Sidrón sample therefore augments the European evolutionary lineage fossil record and supports ecogeographical variability across Neandertal populations.

Mid-Holocene vegetation and climatic history of the Iberian Peninsula

The aim of this research is to study the climate and vegetation history in the western Mediterranean, in the Iberian Peninsula, during the middle Holocene through pollen analysis. The origin of the deposits varied from the most xeric to more mesic Mediterranean environments. The timing, extent, and progress of the establishment of the Mediterranean climate have a degree of variability depending on the biogeographical region. Analyses of several pollen sequences reveal climatic transformations in the flora and vegetation between 7000 and 4000 cal. yr BP. Pollen concentrations have been used in some sequences to evaluate the order of magnitude in biomass changes through time. Three main spatial and taxonomic responses could be assumed: (1) in littoral regions, deciduous broadleaf trees were frequently dominant and then replaced by sclerophyllous and evergreen forests; (2) in continental regions and sub-Mediterranean mountains, the dominance of pine throughout the whole Holocene signals a change of less magnitude; and (3) in southeastern semiarid Mediterranean regions, the main changes are reflected by alternation between steppe and shrub communities. The emplacement of the Mediterranean climate is reflected in an aridification process. A temporal first approach of Holocene climatic changes is proposed: a humid phase (12 000—7000 cal. yr BP), a transition phase (7000—5500 cal. yr BP) and an aridification phase (5500 cal. yr BP—Present). According to archaeological data, natural changes in the forests favoured the environments suitable for human settlements, farming and sheepherding.

Karstification without carbonic acid: Bedrock dissolution by gypsum-driven dedolomitization

Aggressive karstification can take place where dolomite and gypsum are in contact with the same aquifer. Gypsum dissolution drives the precipitation of calcite, thus consuming carbonate ions released by dolomite. Lake Banyoles, in northeastern Spain, is a karst lake supplied by sublacustrine springs, and karstic collapse is occurring in the immediate vicinity of the lake. Lake water is dominated by Mg-Ca and SO 4 -HCO 3 , and is supersaturated with calcite that is actively accumulating in lake sediments. Water chemistry, sulfur isotope composition, local stratigraphy, and mass-balance modelling suggest that the primary karst-forming process at at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. Gypsum-driven dedolomitization may be responsible for other karstic systems heretofore attributed to soil-generated carbonic acid.

Sedimentary patterns in perched spring travertines near Granada (Spain) as indicators of the paleohydrological and paleoclimatological evolution of a karst massif

Perched spring travertines of the Granada basin (South Spain) constitute a perched system with four well-defined steps, which are formed by several facies associations deposited in different sub-environments (travertine pools, dams and cascades). These perched travertines are considered as a freshwater reef system with a facies zonation and stratigraphic architecture closely resembling that of marine reef terraces and prograding carbonate platforms. The travertine deposits have been dated by 230 Th/ 234 U and 14 C methods. As in other Mediterranean areas, the travertine deposition occurred episodically during warm and wet interglacial periods coinciding with isotopic stages 9, 7 and 5, and with the transition between isotopic stages 2/1. During these periods, underground dissolution, large outflow in the springs and subsequent calcium carbonate precipitation occurred. In the same way that evolution of reef systems indicates sea level changes, the geomorphology, age and architecture of perched spring travertine systems may be used to interpret former climatically controlled changes in outflow, in base level marked by the altitude of springs and in the chemistry of spring waters. Thus, aggradation or climbing progradation may indicate an increase of outflow at the spring, progradation with toplap is due to a stable base level and, conversely, dowlapping progradation may signify that the base level was gradually dropping. Therefore, the travertines can be considered semiquantitative indicators of the paleohydrological evolution of karstic massifs and used as an important terrestrial proxy climate record. D 2003 Elsevier Science B.V. All rights reserved.

Palaeoenvironmental reconstruction of a Pleistocene lacustrine sequence from faunal assemblages and ostracode shell geochemistry, Baza Basin, SE Spain

Abstract We have reconstructed the Early Pleistocene palaeoenvironmental record for a shallow lacustrine sequence from the Baza Basin (Southern Spain), using faunal assemblages and the shell chemistry of two ostracode species (Candona sp. and Cyprideis torosa). In the NE basin sector (Orce area), a Lower Pleistocene lacustrine sequence, up to 10 m thick, contains alternating phases of two fossil assemblages which differ in their salinity requirements. The faunal assemblages record phases of (1) slightly saline, Ca+bicarbonate-rich water, when freshwater organisms predominated, and (2) saline, NaCl-dominant water in which marine-like organisms lived. The ostracode shells from intervals with a saline fauna have higher δ18O values than those from intervals with a freshwater fauna. This feature corresponds to a parallel alternation of positive and negative hydrologic balances. δ18O and δ13C values from ostracode calcite display a covariant trend which indicates that the ostracodes lived in a closed lacustrine system. The isotopic data show a better agreement with the inferences from faunal assemblages than with trace element trends. The trace element data, although locally fitting well with the isotope and faunal interpretations, suggest overall that trace element contents in ostracodes are not consistent indicators of salinity and/or temperature variations, but depend on a set of complex factors, which may not be easily deciphered. The alternation of concentration/dilution phases recorded in the studied section can be correlated with climatic cycles described from synchronous ocean basin records from the Late Matuyama chron.

Late Glacial to Early Holocene environmental adjustment in the Mediterranean semi-arid zone of the Salines playa-lake (Alacant, Spain)

The transition from the Late Glacial to the Early Holocene in the endorheic Salines sequence, which is characterized cyclical sedimentation, occurs between 5.50 and 2.85 m depth. From 5.50-3.50 m depth the cycles are composed of a centimetre alternation of layers of dolomitic marls and gypsarenites and from 3.50-2.85 m depth by the alternation of calcitic marls and calcarenites.Pollen, biotic assemblages and geochemistry provide evidence of a gap with respect to the new hydrological conditions that characterized the beginning of the Holocene. Mesic pollen taxa increased their percentages at the beginning of the Holocene, indicating climate improvement, which coincides with the 14C radiocarbon age of 10,000 years BP. The first biotic remains (gastropods, ostracods and foraminifers) found in this sequence appeared later, at 3.80 m depth, which corresponds to 9,500 years BP, whereas the mineralogical change occurred at 3.50 m depth, which corresponds to 9,000 years BP. The advanced adaptation of the vegetation and biotic aquatic assemblages with respect to the mineralogical response corresponds to a process of a gradual increase in water availability into the lacustrine system. During the Boreal, the calcitic cycles reached their maximum thickness, suggesting a more continuous water input. This assumption has also been corroborated by the expansion of the mesic pollen taxa and the occurrence of biota taxa which depend on a permanent water body for their development.The multiproxy approach in paleoclimate scenarios is an essential tool for understanding the ecosystem adjustment during climate changes. Our results demonstrate an interval of 1000 years between the vegetal and the mineralogical reaction.

Lake sediment response to land-use and climate change during the last 1000 years in the oligotrophic Lake Sanabria (northwest of Iberian Peninsula)

Abstract High-resolution sequential analysis of the upper 380 mm of a sediment core from Lake Sanabria, an oligotrophic freshwater lake in the granitic zone of the NW Iberian Peninsula, shows four lacustrine sedimentary episodes, some of which have been interpreted as the Little Ice Age (LIA). Radiometric dating of the core (C-14 Accelerator Mass Spectrometry (AMS)) gives an age of 875 AD for the oldest sedimentary episode. Subsequent variations are attributed to human influence on the catchment of Lake Sanabria: agricultural activity of the San Martin de Castaneda monastery during the Middle Ages, the breached Vega de Tera dam in January 1959, or the designation of Lake Sanabria as a natural park in 1978.

Late-glacial and Holocene lacustrine evolution based on ostracode assemblages in Southeastern Spain

Abstract Ostracode fossil analyses of the upper 6.6 m of the Salines core (SE-Spain), and six 14C AMS dates provide an outline of the Late-Glacial and Holocene ecological evolution of an arid Mediterranean environment. Lake Salines has undergone significant changes in its hydrological regime and chemistry, which are highly dependent on climate. After a long hypersaline phase, which corresponds to the Upper Pleniglacial and Late-glacial periods, the lake records climate oscillations of the entire Holocene. During the last 10,000 years two major dry crises occurred, one at 8,500 yr BP and another between 7,000 and about 3,000 yr BP.

Tracing the history of highland human management in the eastern Pre-Pyrenees: an interdisciplinary palaeoenvironmental study at the Pradell fen, Spain

Although high mountain areas have traditionally been viewed as predominantly grazing areas, with low population and a high degree of land-use stasis, recent research suggest that land-use complexity and change over time has been underestimated. This interdisciplinary palaeoenvironmental analysis has been carried out on the Pradell calcareous fen, located in the eastern Pre-Pyrenees (Spain) at 1975 m a.s.l., and it comprises different environmental indicators: pollen, stomata, non-pollen palynomorphs, macrocharcoal particles, lithostratigraphy, sedimentology and geochemistry. The results of this high temporal resolution study are integrated with archaeological data, and together provide strong evidence for the complexity of the high-mountain land-use system over the last 1500 years. Archaeological fieldwork has shown the rise of highland mining activities during the Roman period. Later, frequent fires resulted from the farming and settlement that followed the Christian conquest. Geochemical analysis of sediment cores records late-Mediaeval metal production, while the expansion of feudal cropping and the advent of several Mediaeval crises are clearly recorded in both the pollen and the historical data. Finally, the rise of a mixed economy system based on transhumance, farming, metallurgy and woodland exploitation was established during Modern and Contemporary times. The high correlation between the palaeoenvironmental, archaeological and historical data at the Pradell fen stresses the value of calcareous fens for palaeoenvironmental reconstructions of historical landscapes. Results obtained also depict high mountain landscapes as the result of the long-term interaction of many human practices, including mining and smelting, grazing, cropping and tree exploitation for the production of wood, charcoal and resin.

High-resolution saline lake sediments as enhanced tools for relating proxy paleolake records to recent climatic data series

Abstract Lake level in an endorheic saline lake in Southern Europe has been inferred for the last 105 years (1889–1994) at an annual level of resolution using two independent methods. First, ordination analyses (factor analysis (FA), correspondence analysis (CA) and detrended correspondence analysis (DCA)) have been used to point out the mineral successions of the sedimentary record. These successions are evidenced by the arch disposition of both samples and mineral phases in the plane defined by the first two eigenvectors calculated by these analyses. These temporal evolutions are the same as those obtained during the drying and refilling phases of saline lakes. Relay indices (RI) were obtained from distances to the first two eigenvectors, which accurately reconstructed the lake-level evolution during this period. Second, an inferred lake-level series was obtained using a multivariate time series model from the average maximum temperatures and total rainfall. Six main drought periods were found, which coincided with known droughts in the area. A high level of agreement was found between the two reconstructions, which offered the possibility of directly extending the instrumental record back into the past. Therefore, climatic changes could be reconstructed from saline lakes provided that an accurate chronological control of sedimentary processes is available.