Investigation of active faults in Morocco using morphometric methods and drainage pattern analysis

A survey has been done of recently active faults in Morocco. In addition to field observations, morphometric methods were applied and an analysis was made of the drainage pattern. In the morphometric analysis, a map of vertical deformation was established from the elevations of summit level surfaces. This enables the recognition of neotectonic discontinuities and lithological contrasts; the actual discrimination of different rock-types can only be achieved by comparison with field observations. The analysis of drainage patterns — including their perturbations and anomalies — can also reveal the presence of features due to neotectonics, structural control or lithological variation. Certain faults can be detected which correspond to structures known from field geology or remote sensing (NE-SW and NW-SE oriented sets). Some new faults are observed which belong to these sets, as well as others which define a new N-S trending set. The present analysis leads to a distinction between ancient faults and currently active faults. The results of this study are shown on a map of recently active faults where the respective vertical displacements are also indicated.

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Zusammenfassung Bei einer Untersuchung der heute aktiven Störungen in Marokko wurden zusätzlich zu Feldbeobachtungen morphometrische Untersuchungen sowie eine Analyse des Entwässerungsnetzes durchgeführt. Bei der morphometrischen Analyse wurde eine Karte der vertikalen Deformationen von Aufragungen aus den Gipfelfluren abgeleitet. Dadurch können neotektonische Diskontinuitäten sowie lithologische Kontraste erkannt werden; die wirkliche Unterscheidung verschiedener Gesteinstypen kann aber nur im Vergleich mit Feldbeobachtungen erreicht werden. Die Analyse des Gewässernetzes — auch seiner Komplikationen und Anomalien — kann gleichfalls Elemente aufdecken, welche neotektonischen Ursprungs bzw. strukturell bedingt oder aber auf lithologische Unterschiede zurückzuführen sind. Bestimmte Störungen korrespondieren mit Strukturen, die aus der Feldgeologie oder der Fernerkundung bekannt sind (NE/ SW- und NW/SE-gerichtete Scharen). Einige neu entdeckte Störungen gehören zu diesen Scharen, während andere ein neues, N/S-streichendes System deutlich machen. Die vorgelegte Analyse erlaubt, zwischen älteren und noch heute aktiven Störungen zu unterscheiden. Unsere Ergebnisse sind in einer Karte der aktiven Störungen zusammengefaßt, in die die vertikalen Versätze gleichfalls eingetragen wurden.

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Résumé Un recensement des failles à jeu récent (néotectonique) a été fait sur l'ensemble du Maroc. Outre les observations de terrain, les méthodes de la morphométrie et celles de l'analyse du réseau hydrographique sont appliquées. En morphométrie, l'établissement d'une carte de la déformation verticale d'après la situation altimétrique de la surface sommitale permet la reconnaisance de structures (discontinuités) néotectoniques et d'alternances lithologiques (la discrimination ne peut être faite que sur le terrain). De même l'analyse du réseau hydrographique, de ses perturbations et de ses anomalies (cf. infra) met en évidence des discontinuités dues à la néotectonique, à la structure des terrains et à la lithologie. Les ensembles morphostructuraux marocains (Meseta, Rif, Atlas), ressortent nettement de la carte de synthèse. On y retrouve les failles connues par la géologie de terrain et par l'analyse des images satellitaires (ensembles de direction NE-SW et NW-SE), de nouvelles failles appartenant à ces deux familles, ainsi qu'un nouvel ensemble de failles de direction N-S. Cette analyse permet de distinguer failles actives et failles anciennes. Les résultats sont portés sur la carte des principales failles à jeu récent avec leurs rejets verticaux respectifs.

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Fluoride contents in groundwaters and the main consumed foods (dates and tea) in Southern Algeria region

In the Algeria South, the dental fluorosis is a “silent” epidemic spreading within the populations. The present study was aimed to determine the fluoride content in water, dates and tea that are widely consumed. The results reveal that 35% of water wells had excessive fluoride levels (>1.5 mg/L). The eastern areas where dental decay is the most widespread pathology present the highest contents. Dates, tea and water are considerable sources of fluoride, with a daily contribution of 10, 20 and up to 70%, respectively. For these three sources, the daily intake of fluoride ingested by an adult exceeds the proposed safe threshold of 0.05–0.07 mg/kg day.     

Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell–Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.     

Seismicity of Morocco for the Period 1987–1994

— A seismic data file of 3,740 earthquakes from January 1987 to December 1994 has been elaborated for Morocco and the border regions, with 10 main events registering magnitudes from 5 to 5.6. Such seismicity is particularly important for Morocco as the released seismic energy constitutes a considerable part of the total energy radiated during the 20th century. Relative seismicity maps confirm the persistence of the major features of the seismicity of Morocco. An important seismic activity is observed in the Alboran region continental crust, which absorbs the maximum deformation resulting from the convergence of the African and Iberian plates. However, in the longitude window 3.5°– 6° W at depths of 25 to 50 km, a seismic gap zone seems to take place. An explanation of this phenomenon may be provided by the slab breakoff model. Even if the seismicity of Morocco remains moderate, heavy damage is observed when the magnitude of earthquakes exceeds 4.5, especially in the case of traditional buildings.     

Intelligent methods for predicting nuclear magnetic resonance of porosity and permeability by conventional well-logs: a case study of Saharan field

In the well-log data processing, the principal advantage of the nuclear magnetic resonance (NMR) method is the measurement of fluid volume and pore size distribution without resorting to parameters such as rock resistivity. Preliminary processing of the well-log data allowed first to have the petrophysical parameters and then to evaluate the performances of the transverse relaxation time T ₂ NMR. Petrophysical parameters such as the porosity of the formation as well as the effective permeability can be estimated without having recourse the fluid type. The well-log data of five wells were completed during the construction of intelligent models in the Saharan oil field Oued Mya Basin in order to assess the reliability of the developed models. Data processing of NMR combined with conventional well data was performed by artificial intelligence. First, the support vector regression method was applied to a sandy clay reservoir with a model based on the prediction of porosity and permeability. NMR parameters estimated using intelligent systems, i.e., fuzzy logic (FL) model, back propagation neural network (BP-NN), and support vector machine, with conventional well-log data are combined with those of NMR, resulting in a good estimation of porosity and permeability. The results obtained during the processing are then compared to the FL and NN regression models performed by the regression method during the validation stage. They show that the correlation coefficients R ² estimated vary between 0.959 and 0.964, corresponding to the root mean square error values of 0.20 and 0.15.     

A new biostratigraphic correlation for Late Cretaceous–Paleocene strata of the Gulf of Guinea: Evidence from dinoflagellate cysts

A new biostratigraphic correlation for Late Cretaceous and Palaeocene strata of the Côte d’Ivoire–Ghana continental margin has been developed from the identification of significant dinoflagellate cyst events in ODP Hole 959D. The Late Cretaceous stage boundaries are mostly consistent with previous studies. However, the Maastrichtian/Danian boundary is placed much lower than previously recognized on the basis of the first occurrences of Carpatella cornuta and Damassadinium californicum. The base of the Selandian is recognized from the last occurrence of Cerodinium diebelii and the first occurrence of Adnatosphaeridium multispinosum. The base of the Thanetian is recognized from the first occurrence of Areoligera gippingensis. The rarity of the age-marker taxa is the main reason for different age determinations among studies of the same section.     

Extracts of the seaweed Bifurcaria bifurcata display antifungal activity against human dermatophyte fungi

Bifurcaria bifurcata is a seaweed of the Order Fucales(Ochrophyta, Phaeophyceae) that can be found all year round along the Portuguese Atlantic shore. Although it is considered edible in some countries,its biotechnological potential has not yet been assessed in detail and here we report its antimicrobial potential against human dermatophyte fungi. Three samples were harvested from Baleal Island(Peniche, Portugal)harvested in winter(BbPe); from Aguda Beach(Arcozelo, Vila Nova de Gaia, Portugal), harvested in autumn(BbAg) and a sample obtained by culturing the Aguda sample under laboratory conditions(BbLC).A broth macrodilution assay was applied to determine the MIC(minimum inhibitory concentration) and MLC(minimum lethal concentration) of the B. bifurcata extracts. Results show that the BbPe MeOH extracts were the most effective and had higher antifungal activity against all the tested dermatophyte strains than the BbLC and BaAg extracts [Epidermophyton floccosum FF9(100-200 μg/mL MIC; 200 μg/mL MLC), Microsporum canis FF1(400 μg/mL MIC; 400 μg/mL MLC), Trichophyton mentagrophytes FF7(100 μg/mL MIC; 800 μg/mL MLC), M. gypseum CECT 2908(800 μg/mL MIC; 800 μg/mL MLC), T.mentagrophytes var. interdigitale CECT 2958(800 μg/mL MIC; 800 μg/mL MLC), T. rubrum CECT 2794(200 μg/mL MIC; 400 μg/mL MLC)]. In fact, only E. floccosum FF9 was sensitive to BbAg and BbLC MeOH extracts. To our knowledge, this is the first report of antifungal activity of B. bifurcata against human dermatophyte fungi.     

Results of UHF radar observation of the nocturnal low-level jet for wind energy applications

We use two series of eight-month UHF radar observations collected during the dry and wet seasons of AMMA field campaign. The ultimate goal is to do preliminary work to know whether the lowest layers are suitable for wind energy applications. Surface wind is usually weak in West Africa, but the regular occurrence of a nocturnal low level jet (NLLJ) could provide interesting conditions for wind energy. This work is two-fold: it first aims at improving our knowledge about the NLLJ in West Africa regarding its structure and its variability during the year. Then, special attention is paid to the first 200 m agl, to study the possibility to use the sub-jet wind as a source of energy. A set of enhanced radio-soundings is taken to help to understand the dynamics and thermodynamics and to find a way to extrapolate the wind at low level, where the UHF radars do not provide data.