Temporal evolution of weathered cataclastic material in gravitational faults of the La Clapiere deep-seated landslide by mechanical approach

After a few years of research, the observation and the analysis of the deep-seated landslides suggest that these are mainly controlled by tectonic structures, which play a dominant role in the deformation of massif slopes. The La Clapière deep-seated landslide (Argentera Mercantour massif) is embedded in a deep-seated gravitational slope deformation affecting the entire slope, and characterized by specific landforms (trenches, scarps??). Onsite, the tangential displacement direction of the trenches and the scarps are controlled by the tectonic structures. The reactivation of the inherited fault in gravitational faults create a gouge material exposed to an additional mechanical and chemical weathering as well as an increased of leaching. The displacement of these reactivated faults gets increasingly important around the area of the La Clapière landslide and this since 3.6?ka BP. In this study, mechanical analysis and grain size distributions were performed and these data were analysed according to their proximity the La Clapiere landslide and times of initiation of the landslide by ¹⁰Be dating. Triaxial test results show that the effective cohesion decreases and the effective angle of internal friction increases from the unweathered area to the weathered area. The whole distribution of the grain size indicates that the further the shear zone is open or developed, the further the residual material loses its finest particles. This paper suggests that the mechanical evolution along the reactivated fault is influenced by the leaching processes. For the first time, we can extract from these data temporal behaviour of the two main mechanical parameters (cohesion and angle of internal friction) from the beginning of the La Clapiere landslide initiation (3.6 ka BP) to now.     

Seismic reflection imaging of active faults and their tectonic behavior in the Northern Moroccan margin. Is the Nekor fault a pure strike-slip fault?

The study of 1000-km seismic reflection profiles, along the Northern Moroccan margin, allowed browsing new imaging in detail about the regional geological structures and their functioning. To achieve this goal, we elaborated a high-resolution depth model and a global tectonic sketch. The influence of recent tectonic activity is manifested by normal and strike-slip faults, trending mainly 70° N and 125° N. In this segment, the Nekor strike-slip fault seems to be connected to a secondary major fault system that changes direction from 30° N to 70° N, and changing behavior to left-lateral strike-slip fault with normal component. Analysis of local seismic activity recorded from 1990 to 2014 with moderate magnitudes activity shows alignments in clear superposition with the detected active faults in seismic reflection lines.     

Seasonal variation of solar irradiance and sunshine duration in Saudi Arabia

Saudi Arabia is a huge area with diverse climatic and topographical features. This diversity in climate is augmented by seasonal weather variations. The study discusses solar irradiance and sunshine duration in terms of seasonal weather systems. Sunshine duration and solar irradiance maps show that the East Mediterranean weather systems (such as Cyprus low) in winter affect the majority of the geographical regions in Saudi Arabia. In spring and autumn, Sudan low becomes more active than Cyprus low, especially in the west and central regions. Sunshine duration in April is 47% compared to 50% in January. Sunshine duration in the southwest region is affected by the rainy and wet summer monsoon which reduces sunshine duration to 33% in summer (July), while it is 43% in winter (January). In addition, the study uses the Angstrom equation to estimate solar irradiance. The absolute relative error between estimated and observed solar irradiance ranges between 2 and 10% in the majority of cases, with a few cases exceeding 13%.     

Geologic hazards assessment of Cairo and vicinity

The greater area from Cairo to west of Suez and a smaller area directly around Cairo are subjected to general and detailed analysis of hazard due to geological fractures. Fracture density contour maps and rose diagrams of the fracture trends are provided. Possible natural geologic hazards which might affect the area are discussed. These include landslides, block failure, earthquakes, maars, fumarolic activity, hot springs, caves and possible rejuvenation of old fault systems.     

Evolution of groundwater salinity in the unconfined aquifer of Bou-Areg, Northeastern Mediterranean coast, Morocco

The Bou-Areg plain in the Mediterranean coast at the North-eastern of Morocco is characterized by a semi-arid climate. The aquifer consists of two sedimentary formations of Plio-quaternary age: the upper formation of fine silts and the lower one of coarse silts with sand and gravels. The aquifer is underlain by marly bedrock of Miocene age that dips toward the coastal lagoon of Bou-Areg. The hydrodynamic characteristics vary between 10⁻⁴ and 10⁻³ m/s; and transmissivities range between 10⁻⁴ and 10⁻¹ m²/s. The general direction of flow is SW to NE, toward the lagoon. The aquifer is crossed by the river Selouane, which also ends in the lagoon. The groundwater is characterized by a high salinity that can reach 7.5 g/l. The highest values are observed in the upstream and in the downstream sectors of the aquifer. The temporal evolution of the physico-chemical parameters depends on the climatic conditions and piezometric variations. The analysis of the spatio-temporal distribution of the physico-chemical parameters suggests different sources of groundwater salinization: the seawater intrusion, the influence of marly gypsum-bearing terrains, and the influence of anthropogenic products as the agricultural fertilizers, which cause great nitrate concentrations that vary between 80 and 140 mg/l.     

Modification of thermal and oxidative properties of biodiesel produced from vegetable oils

Trans esterification of three vegetable oils, sunflower oil, linseed oil and mixed oils as; sunflower-soyabean and olein were carried out using methanol, and potasium hydroxide as catalyst. The methyl esters of the corresponding oils were separated from the crude glycerol and characterized by physical-chemical methods to evaluate their thermal properties. This methods are determination of densities, cloud points, pour points, flash points, kinematic viscosities, hydrogen/carbon ratios, sulfur contents, ash contents and triglycerides. The physico-chemical characteristic of biodiesel treated with ozone showed improvement of pour point and flash point indicating higher degree of safety for fuel. Methyl esters mixed with their corresponding ozonated oil were subjected to comparison and evaluation for their thermal properties by the thermo gravimetric analysis differential thermal analysis from which the calculated heat of enthalpy and comparison with the heat of conventional diesel. The results showed that the oxygen content of biodiesel samples treated with ozone increased weight % and resulted in more extensive chemical reaction, promoted combustion characteristics and less carbon residue was produced. Gas chromatography appeared more suitable to address the problem of determining/verifying biodiesel methyl ester and showed that methyl ester content was impurity free. Ultra violet-detection was used for rapid quantization of triglycerols. From the analyses performed biodiesel treated with ozone modified the thermal and oxidative stability shown by the high combustion efficiency indicated by the high heat of enthalpy and reducing the emission of particulate matter.     

Geoelectrical and hydrogeochemical studies for delineating seawater intrusion in the outlet of Wadi Ham, UAE

The Quaternary aquifer of Wadi Ham, UAE has been overexploited during the last two decades to meet the increasing water demands. As a result, the dynamic balance between freshwater and seawater has been disturbed and the quality of the groundwater has deteriorated. In this paper, a 2D earth resistivity survey was conducted in Wadi Ham in the area between Fujairah and Kalba to delineate the seawater intrusion. Existing monitoring wells were used to measure the horizontal and vertical variations in water salinity and thus to improve the interpretation of earth resistivity imaging data. Results of vertical electrical soundings and chemical analyses of collected water samples were used to obtain an empirical relationship between the inferred earth resistivity and the amount of total dissolved solids. This relationship was used along with the true resistivity sections resulting from the inversion of 2D resistivity data to identify three zones of water-bearing formation (fresh, brackish, and salt-water zones). Along the four 2D resistivity profiles, the depth to the fresh-brackish interface exceeded 50 m at the western part of the area and was in the order of 10 m or less in the eastern side near the shoreline. Depth to the brackish-saline water interface reached about 70 m in the western side and was in the order of 20 m in the eastern side. The thickness of the fresh water zone decreases considerably in the farming areas toward Kalba and thus the degree of seawater intrusion increases.     

地球深部碱性元素地球化学行为:来自陨石高压矿物的证据

近年来在球粒陨石冲击脉体中陆续发现了一些天然高压新矿物和矿物组合，这些发现为地球深部碱性元素的地球化学行为的研究提供了重要依据。在地幔过渡带温度和压力条件下，钠和钙离子优先结合到镁铁－镁铝榴石固溶体和长石高压多形之中，钾离子则选择性地进入到长石高压多形中，副矿物涂氏磷钙石是Na、Ba、Sr和轻稀土等元素的潜在载体相。天然冲击变质球粒陨石为我们提供了探索过渡带和下地幔温度、压力条件下碱性元素载体相特征的重要自然界样品。     

Compositional homogeneity in low-temperature chlorites

Electron microprobe analyses of small chlorite grains (10–20 μm width) in diagenetically altered rocks from three deep wells and a series of outcrop samples ranging in maximum age from 4 to 1300 Ma show an increasingly smaller range in grain-to-grain composition as a function of the average age of the specimens in a series. The scatter of composition in a sample in each series changes little with depth despite present day, or estimated maximum temperature differences of 70° C to 100° C from top to bottom. Comparison of these chlorite compositions with those published for geothermal and metamorphic rocks formed under conditions of 300–450° C indicates that the homogeneity of chlorite composition is a function of both the temperature of equilibration and its duration. Apparently total homogenization of Fe/(Fe+Mg), Al/(Al+Mg+Fe) content will occur after 10¹⁰ years at low temperatures. Simple calculations indicate that a slow process such as solid state diffusion could be responsible for the eventual homogenization of mineral grain composition to reach chemical equilibrium after phase equilibrium has been reached.