Sedimentologic and structural research at the hinge between the High and the Middle Atlas Mountains, and the High Moulouya, Morocco

The northeast border of the central Atlas Mountains lies at the hinge between three structural units: the High Atlas, the Middle Atlas and the inter-mountainous plateau of the High Moulouya. Situated along the northwest border of the African continental plate, the region’s sedimentological and geodynamic evolution was strongly influenced by both the Mediterranean (or Tethysian) mobile zone to the east and the Atlantic Ocean to the west. The other major factor influencing the area's evolution during the Mesozoic and Cenozoic eras was the intersection of the adjoining African and Iberian tectonic plates. Due to the dislocation and break-up of the supercontinent Pangaea and the resulting reactivation of the older Hercynian tectonic structures, a typical intracontinental rift system developed during the Upper Triassic period. From the Lower Jurassic to the Eocene, a remarkable diversity of facies zones developed in the depositional areas, ranging from deep platform environments to continental settings. The relatively rigid overlying strata were fractured and faulted during the initiation of the main compressive phase in the Upper Cretaceous period under the influence of the predetermined underlying faulting structure. Therefore, normal faults and thrust faults with a certain lateral extension were established over the resulting hydrogenetic and highly ductile Triassic sediments. Because of the complexity regarding the tectonic relations between the three structural units, there is a high level of interest in their junction zone, located in the research area. Therefore, the study area is divided into two different regions: the Ouaouizarth region in the southwest border of the contact zone of the High and Middle Atlas, and the Aghbala region to the northeast (the latter comprising the High Moulouya plateau and the convergence of the Atlas ranges). One of the main focuses of the present work is the establishment of a Geographic Information System (GIS) for the northern border of the High Atlas system. In order to insure subsequent use of the system, a high level of exchangeability has been implemented. As of now, there is no similar system for the entire Atlas mountain range, despite a clear and present need. Such an “AtlasGIS“ system would prove indispensable not only in the fields of ground water provisioning and natural hazard management, but in the implementing sustainable tourism model (in the framework of the UNESCO geopark concept) as well. With regard to contents, data resulting from new geological investigations conducted during this project was integrated with previously existing and readily available data (primarily geological maps, aerial photographs and satellite images). As a direct result of the AtlasGIS project, two new geological maps of the investigation area have been generated. The sedimentological and structural results of the present work fit well within the paleogeographical context of the bordering regions of the western Tethys. In particular, answers to the following questions have been outlined: • Timeframe and character of the differentiation of the High and Middle Atlas and the High Moulouya; • Dating of the Jurassic and Cretaceous Redbeds, formerly considered as free of fossils; • Influence of the deformation on the classification of the Jurassic and Cretaceous Redbed sediments; • Relationships between the post-Triassic sedimentary cover and the hercynian basement; • Chronological setting of the development of the deformation structures; • Sedimentary, paleogeographical and structural relation between the Middle and the High Atlas; Detailed lithological investigations of the geological history of the Atlas system have focused on the redbed sediments from the Dogger, Malm and the Lower Cretaceous. During these periods, important changes in environmental conditions have been noted and the first compressional structures had been detected. A geodynamic model consisting of five evolutionary phases has been developed. Furthermore, a change of polarity of the sedimentary accumulation area has been identified: although previously controlled only by the Tethys, during the Lower Cretaceous (Barremian) period the area also came under the influence of the Atlantic Ocean. Though the Turonian period, occurrences of both oceans are clearly visible. The Middle Atlas could be regarded as an estuary of the High Atlas, which shares similar sedimentary and structural developments. They do not, however, reflect the evolution of two separated basins, despite local compressions during the Dogger. The differentiation of the two mountain chains did not occur earlier than during the first compressive main phase at the uppermost Cretaceous, most likely during Tertiary.La bordure nord-est du système atlasique assure l’articulation entre trois unités structurales différentes : le Haut Atlas au sud, le Moyen Atlas au nord ouest et la Haute Moulouya, plateau intra-montagneux au nord est. L’évolution sédimentologique et géodynamique de cette région a été influencée à la fois par les deux océans voisins, la Téthys à l’est et la marge atlantique à l’ouest, et par les deux plaques continentales adjacentes, la plaque africaine au sud et l’Ibérie au nord. A la suite de la dislocation du supercontinent Pangée, les structures tectoniques hercyniennes ont été réactivées en transtension et un bassin de type rift intracontinental typique s’est créé à partir du Trias inférieur. Entre le Jurassique inférieur et l’Eocène, périodes de sédimentation résultantes ont été enregistrées des variations notables de faciès et de milieux de dépôt, allant d’un environnement de plate-forme plus ou moins profonde jusqu’au domaine continental émergé. Avec le début de la phase compressive du Crétacé supérieur, la couverture relativement souple a été faillée et plissée sous l’influence du dispositif structural hercynien hérité, un socle plus rigide. De grands accidents profonds et des chevauchements latéraux en sont le résultat, entraînant le décollement de la couverture post-hercynienne sur les séries du Trias, souvent évaporitiques et plastiques. En raison des relations tectoniques complexes entre les trois unités atlasiques concernées, une attention particulière à été portée à leur zone d’articulation. Le terrain d’étude est ainsi reparti en deux régions distinctes : la région de Ouaouizarth à la limite sud-ouest de la zone de contact entre Haut et Moyen Atlas, et la région d’Aghbala en position nord orientale. Cette dernière implique également la Haute Moulouya, qui assure ici la jonction entre le Haut et le Moyen Atlas. Le corps de l’ouvrage est tout d’abord consacré à la réalisation d’un Système d’Information Géographique (SIG) sur le domaine du Haut Atlas central. Ce système est construit en gardant une grande possibilité de modifications et d’adaptations afin d’assurer des utilisations et perfectionnements ultérieurs. Jusqu’à présent, un tel système était inexistant, en dépit d’un besoin très réel, notamment en matière de gestion des ressources en eau, de la prévention des risques naturels, ou du tourisme. Pour ce dernier, un « Atlas SIG » est indispensable. La base de données contient les résultats de la recherche ici présentés, mais aussi les données déjà existantes et disponibles, surtout celles qui sont consignées dans les anciennes cartes géologiques. Dans le cadre de « l’Atlas SIG », deux cartes ont été générées (feuille de Ouaouizarth et feuille d’Aghbala). Concernant la recherche fondamentale, les résultats obtenus s’intègrent bien à l’échelle atlasique, tant dans les cadres stratigraphique, sédimentologique, paléogéographique que géodynamique, déjà connus pour la marge ouest de la Téthys. Les questions essentielles suivantes ont été traitées: • datation des « couches rouges » auparavant considérées comme azoïques. • style de déformation en fonction de l’organisation de la sédimentation des couches rouges du Crétacé ; • relations entre couverture post-triasique décollée et socle hercynien ; • première étape de déformation compressive ; • importance et fonctionnement des chevauchements nord-atlasiques frontaux; • relations sédimentaires, paléogéographiques et structurales entre Haut Atlas, Moyen Atlas et Haute Moulouya; L’étude détaillée des formations lithologiques s’appuie sur les couches rouges du Dogger, du Malm et du Crétacé inférieur. C’est ici que les changements importants de l’évolution géodynamique régionale se sont enregistrés, comprenant aussi les premières phases compressives locales. Les analyses sédimentologiques conduisent à proposer un schéma d’évolution géodynamique, qui comporte cinq stades. C’est d’abord le changement de la polarité des aires de dépôt à partir du Crétacé inférieur (Barrémien) : la sédimentation, auparavant influencée par la Téthys, est désormais soumise à l’influence du rift atlantique juvénile. A partir du Turonien, on remarque une influence mixte de deux océans sur la bordure nord du système atlasique. Le Moyen Atlas peut être considéré comme « branche » du Haut Atlas, qui a plus ou moins subi les mêmes évolutions sédimentaire et structurale, de sorte qu’on ne peut pas parler de deux bassins atlasiques distincts. Malgré des compressions locales durant le Dogger, la différentiation du Haut et du Moyen Atlas est tardive et ne se fait pas avant la phase compressive majeure, à partir du Crétacé sommital, mais plus vraisemblablement au cours du Tertiaire

Risikomanagement: Wildfeuer im Nordwesten Tunesiens Risk Management: Wildfires in the Northwest of Tunisia

The issue of wildfi res is being considered with a focus on northwest of Tunisia in the context of an extensive literature research. Various statistics on the problem are analyzed and possible trends are identifi ed. On the basis of the knowledge gained, a risk analysis will be carried out, including vulnerability and hazard analysis. The vulnerability analysis is carried out using the Multi Criteria Evaluation (MCE) with Analytic Hierarchy Process (AHP). The concept of fuzzy quantities is extended in order to cover the whole risk analysis. For the area of investigation, a spatial distribution of the risk caused by wild fires is calculated and the impact of diff erent membership functions on criteria (interpreted as fuzzy quantities) is presented

Field data and the gas hydrate markup language

Data and information exchange are crucial for any kind of scientific research activities and are becoming more and more important. The comparison between different data sets and different disciplines creates new data, adds value, and finally accumulates knowledge. Also the distribution and accessibility of research results is an important factor for international work. The gas hydrate research community is dispersed across the globe and therefore, a common technical communication language or format is strongly demanded. The CODATA Gas Hydrate Data Task Group is creating the Gas Hydrate Markup Language (GHML), a standard based on the Extensible Markup Language (XML) to enable the transport, modeling, and storage of all manner of objects related to gas hydrate research. GHML initially offers an easily deducible content because of the text-based encoding of information, which does not use binary data. The result of these investigations is a custom-designed application schema, which describes the features, elements, and their properties, defining all aspects of Gas Hydrates. One of the components of GHML is the "Field Data" module, which is used for all data and information coming from the field. It considers international standards, particularly the standards defined by the W3C (World Wide Web Consortium) and the OGC (Open Geospatial Consortium). Various related standards were analyzed and compared with our requirements (in particular the Geographic Markup Language (ISO19136, GML) and the whole ISO19000 series). However, the requirements demanded a quick solution and an XML application schema readable for any scientist without a background in information technology. Therefore, ideas, concepts and definitions have been used to build up the modules of GHML without importing any of these Markup languages. This enables a comprehensive schema and simple use