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1.
Amal Saidi Abdelfatah Tahiri Lahcen Ait Brahim Maraim Saidi 《Comptes Rendus Geoscience》2002,334(3):221-226
The fracturing analysis in the Permian basins of Jebilet and Rehamna (Hercynian Morocco) and the underlying terranes allowed us to suggest a model for their opening. Three tectonic episodes are distinguished: a transtensional episode NNE–SSW-trending (Permian I), occurring during the opening along sinistral wrench faults N70–110-trending, associated with synsedimentary normal faults; a transpressive episode ESE–WNW-trending (Permian II), initiating the closure, the normal faults playing back reverse faults and the N70 trending faults dextral wrench faults; a compressional episode NNW–SSE (post-Permian, ante-Triassic), accentuating the closure and the deformation and putting an end to the Tardi-Hercynian compressive movements. To cite this article: A. Saidi et al., C. R. Geoscience 334 (2002) 221–226. 相似文献
2.
Geochemical and isotopic investigation of the aquifer system in the Djerid-Nefzaoua basin, southern Tunisia 总被引：2，自引：0，他引：2
In the Djerid-Nefzaoua region, southern Tunisia, about 80% of agricultural and domestic water supply is provided by the complex terminal (CT) aquifer. However, 20% of this demand is provided by other hydraulically connected aquifers, namely the continental intercalaire (CI) and the Plio-Quaternary (PQ). Overexploitation of the CT aquifer for agricultural practices has contributed to the loss of the artesian condition and the decline of groundwater level which largely increased the downward leakage from the shallow PQ aquifer. Excess irrigation water concentrates at different rates in the irrigation channels and in the PQ aquifer itself. Then, it returns to the CT aquifer and mixes with water from the regional flow system, which contributes to the salinization of the CT groundwater. A geochemical and isotopic study had been undertaken over a 2-years period in order to investigate the origin of waters pumped from the CT aquifer with an emphasis on its hydraulic relationships with the underlying and the overlying CI and PQ aquifers. Geochemistry indicates that groundwater samples collected from different wells show an evolution of the water types from Na-Cl to Ca-SO4-Cl. Dissolution of halite, gypsum and anhydrite-bearing rocks is the main mechanism that leads to the salinization of the groundwater. Isotopic data indicate the old origin of all groundwater in the aquifer system. Mixing and evaporation effects characterizing the CT and the PQ aquifers were identified using δ2H and δ18O relationship and confirmed by the conjunction of δ2H with chloride concentration. 相似文献
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Brahim Abdelkader Ahmed Arab Marwan Sadek Isam Shahrour 《Geotechnical and Geological Engineering》2018,36(4):2077-2085
This paper presents the results of triaxial tests conducted for the investigation of the influence of geotextile on both the stress–strain and volumetric change behavior of reinforced sands. Tests were carried out on loose sand. The experimental program includes drained compression tests on samples reinforced with different values of both geotextile layers (1 ≤ Ng ≤ 3) and confining pressure (\(\upsigma_{\text{c}}^{\prime }\)) varying from 50 to 200 kPa. Tests show that the contribution of geotextile is negligible until an axial strain threshold that range between 2.5% for a confining pressure of 50 kPa to lower than 1% for 100 and 200 kPa confining pressure. At higher values of εa, geotextile induces a quasi-linear increase in the stress deviator (q) and volume contraction in the reinforced sand. Tests show a negligible influence of the number of geotextile layers (Ng) on the contribution of geotextile to both stress–strain and volumetric change, when normalized with Ng. Tests also show that the contribution of geotextile to the stress–strain mobilization augments with the increase in the confining pressure, while its contribution to the volume contraction decreases with the increase in the confining pressure. The reinforced soil becomes contracting in the case of 2 and 3 geotextile layers. 相似文献
5.
Temporal and spatial zonation of macroepiphytes on Posidonia oceanica (L.) Delile leaves in a meadow off Tunisia 
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下载免费PDF全文 The aim of this survey was to study the cover and the composition of macroepiphytic species on the leaves of Posidonia oceanica in the east of Tunisia. Surveys were conducted in December 2009 (winter period), March (spring period) and August 2010 (summer period) in a fringing reef located in Chebba. At each sampling date, 15 adult leaves were randomly collected and divided into basal and apical parts. The inner face of each part was examined with ocular glasses and microscope to estimate species cover by orthogonal projection. PERMANOVA and ANOSIM were used to test for differences of cover between sampling dates and leaf parts. SIMPER, cluster analysis, and PCA were used to ordinate species assemblages. Comparison of epiphytic cover along leaf blades showed significant differences for all groups, except cyanophycea, with high cover of hydrozoans and bryozoans in the basal part and high cover of algae in the apical part. The species composition and cover also vary with sampling date; minimum values were detected in December and the epiphytic community was composed of a few pioneer species, whereas maximum epiphytic cover values were registered in August, with the epiphytic community being composed of a more mature and more diverse community, termed ‘climax’. The main regulatory factors for this distribution are discussed. 相似文献
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The aim of this work is to study the temporal dynamics of rhizome epiphytes and sessile animals living on the rhizomes of the seagrass Posidonia oceanica in the east of Tunisia. Surveys were conducted in October 2009, and in January, April and August 2010 on a fringing reef located in Chebba. Rhizomes were sampled by SCUBA diving at three stations. Samples were examined with a microscope to estimate the cover of macroinvertebrate and macroalgal organisms on the top 10 cm of each rhizome. Results revealed a high diversity of epiphytes on P. oceanica rhizomes with a dominance of red and brown algae, ascidians, and bryozoans. Distinct temporal changes were observed in Oued Lafrann, with a high January cover (winter period) for all groups. These winter increases can be attributed to: (i) the low phenological parameters of P. oceanica in winter that reduce the effects of shading, (ii) life cycles of the epiphytes and invertebrates, (iii) water motion and (iv) grazing. 相似文献
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Al Yacoubi Latifa Bouchaou Lhoussaine Jaillard Etienne Masrour Moussa Ait Brahim Yassine El Mouden Ahmed Schneider Jana Reichert Barbara 《Arabian Journal of Geosciences》2017,10(7):169
The Agadir-Essaouira area in the occidental High Atlas Mountains of Morocco is characterized by a semi-arid climate. The scarcity and quality of water resources, exacerbated by long drought periods, constitute a major problem for a sustainable development of this region. Groundwater resources of carbonate units within Jurassic and Cretaceous aquifers are requested for drinking and irrigation purposes. In this study, we collected 84 samples from wells, boreholes, springs, and rivers. Hydrochemical and isotopic data were used to examine the mineralization and origin of water, which control groundwater quality. The chemical composition of water seems to be controlled by water-rock interactions, such as dissolution of carbonates (calcite and dolomite), weathering of gypsum, as well as ion exchange processes, which explain the observed variability. Stable isotopes results show that groundwater from the mainly marly Cretaceous aquifer are submitted to an evaporation effect, while samples from the chiefly calcareous Jurassic aquifer indicate a meteoric origin, due to a rapid infiltration of recharge runoff through the karstic outcrops. The low values of δ18O and δ2H suggest a local recharge from areas with elevations ranging from 400 to 1200 m for the Cretaceous aquifer and from 800 to 1500 m for the Jurassic units. 相似文献
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Nejib Abidi Joëlle Duplay Amane Jada Raymonde Baltenweck Emna Errais Khadija Semhi Malika Trabelsi-Ayadi 《Arabian Journal of Geosciences》2017,10(16):373
Clays, particularly kaolinite, are promising adsorbents for the treatment of textile effluents, but there is a need of better understanding the mechanisms of adsorption, especially in the case of anionic dyes. Thus, the removal of RR120 anionic dye was investigated using Tunisian raw clay (TBK) composed of kaolinite and illite, and a standard kaolinite (KGa-2), and conducting batch experiments by varying different parameters (contact time, ionic strength, concentration, temperature). We investigated the clays’ surface charges by electrophoretic mobility measures and the dye-clay interactions during adsorption, by the streaming-induced potentials (SIP). The results showed that KGa-2 has higher adsorption capacity for RR120 dye than TBK clay, moreover enhanced by increasing the ionic strength and/or lowering the pH of the aqueous. The SIP results showed an increase of negative charges for both clays, reflecting the adsorption of the anionic dye on the positive charges of the amphoteric surfaces of the clays. The SIP magnitudes indicated a higher adsorption rate for KGa-2 in accordance with the kinetic study. The Sips model that described the best adsorption isotherms indicates lateral interactions of the dye molecules, stronger in the case of KGa-2 than TBK. Also, the dye molecules form a thinner layer on KGa-2 surfaces. In addition, the dye molecule’s structure was not altered, as verified by mass spectrometry. The adsorption process was feasible and spontaneous and favored at ambient temperature. Thus, kaolinite-rich clays are effective in the removal of anionic dyes in aqueous solution and potential good adsorbents in wastewater treatment. 相似文献
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The purpose of this paper is to bring into light the landscape change and natural resources management in the Moroccan Middle
Atlas across centuries. The pastoral way of life prevailed for many centuries. However, following the results of this research,
evidence of important socioeconomic changes and resources use is found. Ancient agricultural activities, as well as the exploitation
of the forest and even mineral resources have been growing activities over time. The survey shows that the agricultural activity
has existed for several centuries as indicated by terraces and encrusted travertine channels used for irrigation. The landscapes
and the ways of resources use are therefore in continuous change. The increasing needs in water and agriculture for demographic
and climatic reasons (the dry periods in summer or periodic droughts) generated because of intensive over-exploitation of
resources. The vegetation degraded facing human pressure (the pastoral activities, the coal of wood making, the lime manufacturing,
etc.). Field observations show that irrigation has been used in this domain, for several centuries. Travertine channels, encrusted
in the valleys of Jnane Mas and Arougou, illustrate these ancient uses of water resources for agriculture irrigation. 相似文献
10.
Mohamed Dass Amiour Hamid Mezghache Brahim Elouadi 《Arabian Journal of Geosciences》2013,6(2):309-319
The study of the organic matter (OM) associated with the phosphate ore of Kef Essennoun deposit (Djebel Onk mining basin, Algeria) was with a view to determine the decomposition degree of the OM within the pellets and the matrix, and the conditions of diagenesis. The sedimentary phosphates of this deposit are constituted of sub-rounded, phosphate-rich grains (pellets) dispersed in a surrounding, much poorer than pellets in P, matrix (or gangue). The survey of the OM associated with both pellets and matrix used several types of analyses: scanning electron microscopy (SEM), scanning electron microscope with energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results show the OM, dispersed approximately homogeneously, in the form of large flat particles, within the gangue and within the phosphatic pellets in the form of small particles. The O/C ratio showed that the OM is more oxidised in the matrix than within the pellets. The oxidation increased with the phosphatisation rate of the pellets and more with the carbonation rate of the matrix, but it decreased with the silicification degree in the siliceous carbonated matrix. Two major functional classes were distinguished within pellets: aliphatic and oxygenated ones, the latter being fundamentally present in humic OM. The presence and abundance of these humic compounds in pelletal phosphorites are known from the 1980s and considered as witnessing a formation of apatite in a strictly closed environment, inside the pellet. 相似文献