Rodent paleofaunas as indicators of climatic change in Europe during the last 125,000 years

This paper presents a quantitative reconstruction of the European late Pleistocene paleoclimate based on 72 rodent assemblages of five sequences from France, Germany and Bulgaria, covering the last interglacial-glacial cycle. They show a pattern of severe changes in temperature, with reduced precipitation during the coldest periods. A tentative correlation between the isotopic and palynological records and the paleotemperature changes is shown. These changes are consistent with variations in atmospheric circulation patterns in response to an expanding-retracting Fennoscandian ice-sheet. They can be attributed to the enhancement-weakening of the Scandinavian-Polar anticyclone and its associated dry winds, the south-north shifting of the North Atlantic Polar Front, and the varying supply of moist air from the Atlantic. Qualitative paleoenvironmental analysis shows broadleaved-deciduous forests in France and Bulgaria during most of the studied period. Taiga and tundra appeared in eastern France during the lower Würm. The German sequence indicates the presence of coniferous forests. These results are broadly consistent with other paleobiological records (mammalian, avian and insect faunas, isotopic record in dental tissue, palynology). The main discrepancies with the paleoclimate inferred from the palynological record are found during the coldest periods and are probably due to the interaction between vegetation, climate, and atmospheric CO₂ levels.     

Interpretation and modelling of regional gravity data of the Aveiro Basin (Northwest Portugal)

The gravity map of the Aveiro Basin, North West Portugal was produced in 2000/2001 and some limited two dimensional (2D) interpretation was carried out. It is intended in this article to advance the interpretation and modelling of the original Aveiro basin gravity data. Thus, the data were processed and the horizontal gradient, the second vertical derivative and downward continued field computed. The corresponding maps have been processed and a new interpretation of the basin tectonic features has been proposed. This is compared with the previous geological and tectonic information obtained from former surveys and local boreholes. As the next step a more detailed modelling of the Aveiro Basin took place. Bearing the interpretation of the basin tectonic features in mind, several north–south and east–west gravity profiles were established and modelled. The proposed models were presented and discussed. As a result, a comprehensive mass distribution model for the basin was proposed. Finally, comparison was made between the new gravity model and the previously published tectonic features map. This modelling is particularly useful for groundwater protection, exploration and exploitation and also for the dimensioning of drilling operations. Bearing in mind the geomorphology of the basin the gravity method is a very economical tool for the investigation of basin structures.     

Progressive failure leading to the 3 December 2013 rockfall at Puigcercós scarp (Catalonia,Spain)

A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m³) occurred on Puigcercós pilot study area (Catalonia, Spain) is presented. The exact date of failure was obtained based on a photographic monitoring performed every 4 h. The long-term monitoring (2,217 days) of the rock slope carried out by a Terrestrial LiDAR allowed the early detection of both pre-failure deformation and precursory rockfalls preceding the final failure. By means of the analysis of the pre-failure deformation, four different deformed areas were detected and the tertiary creep phase was observed in three of them. An attempt to predict the time to failure was performed using the Fukuzono’s (1985) method. Furthermore, the temporal evolution of the precursory rockfalls occurred in those four areas during the progressive failure showed a close resemblance with the exponential pattern of the cumulated displacements at tertiary creep stage. Finally, the study of the meteorological conditions did not show any single triggering factor associated with the final failure. Reversely, the increase in the occurrence of precursory rockfalls on several areas of the slope together with the observed acceleration on the deformation pattern reinforce the role of a progressive degradation of the stability conditions, which ultimately leaded to the 3 December rockfall event.     

Generalized plasticity state parameter‐based model for saturated and unsaturated soils. Part II: Unsaturated soil modeling

The aim of this paper is to extend the generalized plasticity state parameter‐based model presented in part 1 to reproduce the hydro‐mechanical behavior of unsaturated soils. The proposed model is based on two pairs of stress–strain variables and a suitable hardening law taking into account the bonding—debonding effect of suction and degree of saturation. A generalized state parameter for unsaturated state is proposed to reproduce soil behavior using a single set of material parameters. Generalized plasticity gives a suitable framework to reproduce not only monotonic stress path but also cyclic behavior. The hydraulic hysteresis during a drying—wetting cycle and the void ratio effect on the hydraulic behavior is introduced. Comparison between model simulations and a series of experimental data available, both cohesive and granular, are given to illustrate the accuracy of the enhanced generalized plasticity equation. Copyright © 2010 John Wiley & Sons, Ltd.     

Superposition of tectonic structures leading elongated intramontane basin: the Alhabia basin (Internal Zones,Betic Cordillera)

International Journal of Earth Sciences - The relief of the Betic Cordillera was formed since the late Serravallian inducing the development of intramontane basins. The Alhabia basin, situated in...     

Geotechnical Properties of Sandy Seafloors and the Consequences for Dynamic Penetrometer Interpretations: Quartz Sand Versus Carbonate Sand

The societal usage of coastal zones (including offshore wind energy plants, waterway deepening, beach conservation and restoration) is of emerging importance. Sediment dynamics in these areas result in sandy deposits due to strong tidal and wave action, which is difficult to simulate in laboratory geotechnical tests. Here, we present data from in situ penetrometer tests using the lightweight, free-fall Nimrod penetrometer and complementary laboratory experiments to characterize the key physical properties of sandy seafloors in areas dominated by quartzose (North Sea, Germany) and calcareous (Hawaii, USA) mineralogy. The carbonate sands have higher friction angles (carbonate: 31–37°; quartz: 31–32°) and higher void ratios (carbonate: 1.10–1.40; quartz: 0.81–0.93) than their siliceous counterparts, which have partly been attributed to the higher angularity of the coral-derived particles. During the in situ tests, we consistently found higher sediment strength (expressed in deceleration as well as in estimated quasi-static bearing capacity) in the carbonate sand (carbonate: 68–210 g; quartz: 25–85 g), which also showed a greater compressibility. Values were additionally affected by seafloor inclination (e.g., along a sub-aqueous dune or a channel), or layering in areas of sediment mobilization (by tides, shorebreak or currents). The study shows that the differences in in situ measured penetration profiles between carbonate sands and quartz sands are supported by the laboratory results and provide crucial information on mobile layers overlying sands of various physical properties.     

The impact of hydrological changes on travertine deposits related to thermal springs in the Pamukkale area (SW Turkey)

Pamukkale thermal waters (35 °C), exhibiting calcium-bicarbonate-sulfate composition and high carbon dioxide concentration, are of a predominantly meteoric origin. The meteoric fluid, circulating through faults and fractures, is heated by magmatic intrusions at great depth, and ascends from deep reservoirs to the surface. Mixing with relatively cold groundwater in the near surface zone promotes different saturation conditions with respect to calcium carbonate that later precipitates at depth and/or the surface. Dissolution-deposition processes of calcium carbonate both at surface and depth environments may help to reconstruct past climate direction in the field. During wet climate conditions a high-rate of calcium carbonate accumulation would be expected to occur at the surface because thermal fluid would be under-saturated with respect to calcium carbonate at depth because of a relatively higher mixing ratio with cold groundwater. During dry climate conditions the thermal fluid would be super-saturated at depth because of the highly acidic environment. Hydrometeorological studies reveal that the annual precipitation at the Pamukkale hydrothermal field tends to decrease with time. This climatic change in the area was also detected from geological records. While humid climate conditions prevailed during the late Quaternary, the area has recently been affected by arid/semi-arid climate conditions, followed by some episodic transitions. This study has shown how the system has possibly reacted to different climate conditions since antiquity.