Formation and evolution of the Lower Terrace of the Rhine River in the area of Basel

The response of fluvial systems to tectonic activity and climate change during the Late Pleistocene influenced sedimentary processes and hence the conditions of river terraces formation. The northern Alpine foreland is well adapted for such studies due to the high sediment input and the variety of depositional environments. This study focuses on sediments of a part of the Rhine River in the area of Basel, at the Border between Switzerland, Germany and France. A detailed evolution of the Lower Terrace is inferred from sedimentological, geomorphologic and pedological observations as well as historical documents, and calibrated using different dating methods (optically stimulated luminescence, uranium series disequilibrium, radiocarbon). The Lower Terrace was deposited during two periods (30-15ka and 13-11ka), which correlate with two cold climatic phases, representing the Last Glaciation of the Alps and the Younger Dryas. These ages underline that main incision of the Lower Terrace braidplain in the area of Basel is restricted to post Younger Dryas times, as sediments of that age (13-11ka) are found atop the highest levels. From then on, a flight of cut-terraces were formed with minor re-accumulation due to Holocene flood events. These findings demonstrate that the surface of a terrace does not always represent the age of sediment aggradation, and this should be remembered when using terraces to reconstruct the tectonic history of an are

Revealing the pace of river landscape evolution during the Quaternary: recent developments in numerical dating methods

During the last twenty years, several technical developments have considerably intensified the use of numerical dating methods for the Quaternary. The study of fluvial archives has greatly benefited from these enhancements, opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions. In this contribution, we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context: radiocarbon, Luminescence, Electron Spin Resonance (ESR), 230Th/U and terrestrial cosmogenic nuclides (TCN) dating. We focus on the major recent developments for each technique that are most relevant for new dating applications in diverse fluvial environments and on explaining these for non-specialists. Therefore, essential information and precautions about sampling strategies in the field and/or laboratory procedures are provided. For each method, new and important implications for chronological reconstructions of Quaternary fluvial landscapes are discussed and, where necessary, exemplified by key case studies. A clear statement of the current technical limitations of these methods is included and forthcoming developments, which might possibly open new horizons for dating fluvial archives in the near future, are summarised

Pleistocene terraces in the Hochrhein area : formation, age constraints and neotectonic implications

Pleistocene fluvial gravel terraces appear to be useful to decipher neotectonic movements. To achieve this, however, chronologic and sedimentologic data on the terraces are required. Thus, this thesis represents a multidisciplinary approach. After presenting methodological aspects of U/Th (Uranium-series disequilibrium) dating, compared to OSL (Optically Stimulated Luminescence), the ages obtained are used, together with sedimentological data, to constrain the formation processes and timing of the Late Pleistocene terraces in the Hochrhein area. Finally, the geometry of these terraces is interpreted in terms of neotectonics. Hitherto, dating coarse-grained sediment has proved often impossible due the lack of datable material, and developing new methods in this domain is thus of crucial importance. U/Th is a well established method, often used for speleothems and coral dating, and it is tested here on pedogenetic crusts growing within the Late Pleistocene gravels of the Hochrhein area. These results are compared to OSL ages from the same sampling sites. Our results show that this method has a development potential, but is highly dependant on a sufficient and stable Uranium content of the samples, which is partly controlled by bacterial activity. Comparisons with OSL ages highlight the fact that the event that is dated by mean of U/Th is the precipitation of the crust, not the deposition of the sediment. Sedimentological and morphological data show that the Late Pleistocene gravels (Lower Terrace) were deposited as a braided river, where flood events played a major shaping role. The gravels are arranged into terrace levels, where the highest level is an accumulation level, and the lower levels are erosion level with minor re-accumulation. The flood deposits are mostly conserved on top of the different terrace levels because the general incision regime prevented them from being reworked. OSL ages show that the main gravel accumulation occurred between 27 an 11 ka in the Hochrhein area, but minor re-accumulation occurred until historical times. The accumulation level was thus formed during the Younger Dryas, and the lower levels were formed from the Youger Dryas on, until historical times. These results are confirmed by radiocarbon ages from fossil trees and U/Th ages from speleothems. Terrace longitudinal profiles are used to assess neotectonic activity in the Hochrhein area. Four main groups of Pleistocene terrace exist in this area: the Earliest Pleistocene Higher Deckenschotter, the Early Pleistocene Lower Deckenschotter, the Middle-Late Pleistocene High Terrace and the Late Pleistocene Lower Terrace. The three older terrace groups do not show original surfaces anymore, so outcrop altitudes are used to build the longitudinal profi le. This profi le shows that the gradient of the terraces increases with their age, and each of the terrace groups show an increased gradient at the location where the profi le crosses the eastern main border fault (MBF) of the Upper Rhine Graben (URG). The terraces converge, cross and fi nally continue as basin fi lling. This suggests a relative uplift of the headwater area and extensional activity for the MBF during Pleistocene. The Lower Terrace features still well preserved surfaces and these are analysed with a high precision Digital Terrain Model (DTM). Using a high precision DTM highlights the complex arrangement of sublevels and the irregularities of the surfaces, which are mostly caused by sedimentary and erosive processes. NW of Basel in the URG, fi eld evidences indicate Late Pleistocene activity of NW-SE striking normal faults

Mapping & enhancing substance use treatment for migrants and ethnic minorities

MATREMI DR/84info:eu-repo/semantics/publishe

Migrants et minorités ethniques : recueil sur l’accessibilité et l’interculturalité des services pour usagers de drogues

Ce recueil fournit un aperçu de pratiques que les professionnels peuvent utiliser pour accueillir et accompagner les migrants et les minorités ethniques dans les services de santé et spécialisés en toxicomanie. Ces personnes ont souvent des difficultés d’accès aux soins. Ce recueil souhaite inspirer la mise en place de nouvelles pratiques pour ces publics dans le secteur social santé. Cette publication propose également un aperçu de la situation en Belgique sur base du projet de recherche MATREMI (Belspo). Projet et publication coordonnés et mis en œuvre par l’Université de Gand en étroite collaboration avec l’Université Libre de Bruxelles et les organisations faîtières qui représentent le traitement spécialisé en toxicomanie en Belgique : VAD, FEDITO BXL et FEDITO Wallonne