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41.
The Alboran Ridge is an anticlinorium structure trending N65°E bounded by two main right lateral strikeslip fault systems, one north and one south. These transpressional features connect westward to a pull-apart zone where massive diapirism occurs. The orientation of the diapiric zone is N150°E. That orientation and the right lateral motion along the Alboran Ridge fit a N150°E convergent motion between African and Iberian plates. We suggest that the southern Alboran Basin evolved as an extensional stage from Burdigalian to Langhian and as a transpressional stage during Tortonian to present time.  相似文献   
42.
Toxic organic compounds in wastewater are serious threats for both human and environment healthy states. This study investigates the potential sources of surface water, sediment and groundwater pollution by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) as discharged by wastewater into the River of Oued El bey in northeastern Tunisia. Analysis indicates that the concentration of PAHs and PCBs are high in wastewater and vary from 0.37 to 0.83 mg/L and from 0.28 and 1.18 mg/L, respectively. The spatial distribution of PAHs and PCB in surface water showed a variation between 0.37 to 9.91 mg/L and between 0.1 to 0.47 mg/L, respectively. However, the quality of surface water is changed after wastewater evacuation at Oued Tahouna. The determination of PAH and PCB pollutants in groundwater shows a great interest in the development of water resources. The Concentration of these pollutants varying from 0.0204 to 1.93 mg/L and from 0.0052 to 0.196 mg/L, respectively. For PAH, analysis reveals also that naphtelene, fluorene, anthracene and chrysene are the most detected PAHs compounds in water and sediment samples while benzo[b]fluoranthene and benzo[a]pyrene are less present and in trace level. Higher concentrations of PAHs and PCBs are found in samples taken close to industrial areas of Bouargoub and Soliman, and wastewater discharge locations in Soliman. Analysis of the spatial distribution of PAHs and PCBs clearly link their higher concentration in water and sediments to wastewater and manufacturing discharges in the study area. In surface sediment, the organic pollutants are present. The cluster analysis for organic pollutants in different state and different matrix highlight a relationship between the wastewater evacuation and the water qualities which confirmed the direct response of the pollution sources on the surface water and groundwater organic pollution quality.  相似文献   
43.
Geotechnical and Geological Engineering - Adopting a low spatial resolution remote sensing imagery to get an accurate estimation of Land Use Land Cover is a difficult task to perform. Image fusion...  相似文献   
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45.
Two significant airborne gamma ray spectrometic (AGRS) statistical parameters, i.e., the arithmetic mean and the standard deviation, were computed for all lithologic units and formations of the Bahariya Oases area, Northern Western Desert, Egypt. The results ascertain that the maximum AGRS values are associated with sabkha sediments, Bahariya Formation, basalt flows and sand dunes. The intermediate values are correlated with El-Heiz, El-Hefhuf, Qazzun and Naqb formations. The minimum values are connected with Khoman Chalk and El-Hamra formations. The AGRS records were found to vary from one type of rock to another and to some extent between units of the same rock type too. On the aerial total-count (TC) radiometric maps, the records change from 6.2 to 69.36 μR/h. On the potassium map, the values range from 0.05% to 4.35%. On the equivalent uranium (eU) and equivalent thorium (eTh) maps, the records oscillate from 0.12 to 7.4 ppm and from 0.28 to 8.4 ppm, respectively. Concerning the Bahariya Oases area, the calculated arithmetic mean natural dose rate values originating from the terrestrial gamma radiation were found to range from 0.14 to 0.26 mSv/year and where the maximum value attains 0.62 mSv/year. These values remain on the safe side and within the maximum permissible safe radiation dose without harm to individuals, with continuous external irradiation of the whole body.  相似文献   
46.
We constructed an analytical theory of satellite motion up to the third order relative to the oblateness parameter of the Earth (J 2). Equations of secular variations was developed for the first three orbital elements (a, e, i) of an artificial satellite. The secular variations are solved in a closed form.  相似文献   
47.
Groundwater is the most important source of water supply in southern Tunisia. Previous hydrogeologic and isotopic studies carried out in this region revealed the existence of two major aquifer systems: the “Complex Terminal” (CT) and the “Continental Intercalaire” (CI). Turonian carbonates constitute one of the major aquifer levels of the CT multilayered aquifer. It extends over most of southern Tunisia, and its hydrodynamic regime is largely influenced by tectonics, lithology and recharge conditions. Forty-eight groundwater samples from the CI and Turonian aquifers were collected between January and April 2004 for chemical and isotopic analyses. Hydrochemistry and isotopic tools were combined to get an insight into the processes controlling chemical composition of groundwater and wide-scale interaction of these two aquifer systems. Analysis of the dissolved constituents revealed that several processes control the observed chemical composition: (i) incongruent dissolution of carbonate minerals, (ii) dissolution of evaporitic minerals, and (iii) cation exchange. Dissolution alone cannot account for the observed high supersaturation states of groundwater with respect to calcite and dolomite. The observed supersaturation is most probably linked to geogenic CO2 entering water-bearing horizons of the CT and CI aquifers via deep tectonic faults and discontinuities and subsequent degassing in the exploitation wells. Presence of geogenic CO2 in the investigated region was confirmed by C isotope data of the DIC reservoir. The radiocarbon content of the Turonian samples varied between 9.5 and 43 pmc. For CI samples generally lower values were recorded, between 3.8 and 22.5 pmc. Stable isotope composition of Turonian groundwater samples varied from −8.3 to −5.3‰ for δ18O and from −60 to −25‰ for δ2H. The corresponding ranges of δ values for the Continental Intercalaire samples were from −8.9‰ to −6.9‰ for δ18O and from −68.2‰ to −45.7‰ for δ2H. Stable isotope composition of groundwater representing CT and CI aquifers provide strong evidence for regional interaction between both systems.  相似文献   
48.
ABSTRACT

The Sebkhet El Behira–Garaat El Majdoul multilayer aquifer system is composed of Mio-Plio-Quaternary and Oligocene groundwater exploited in Sidi Bouzid and Kairouan governorates. Annual withdrawal volumes from El Behira Oligocene groundwater were about 0.37 hm3 in 2005 and 0.36 hm3 in 2008. The present study of the Oligocene reservoir in the Sebkhet El Behira–Garaat El Majdoul basin is based on various data including 2D seismic sections, petroleum wells, field geological cross-sections and geochemical analysis. The gathered data allowed us to establish the tectonic framework and to define its influence on the structure of the aquifers seated in the deep Oligocene sandstone reservoirs. Three Oligocene sub-basin aquifers are defined showing different depth, thickness and petrophysical characteristics: lower salinity (<1.5 g/L) and higher porosity (30%). Two field sections in the northern and in the southern parts of Cherahil anticline exhibit the presence of four to five sandstone levels. The anticlines limit the Sebkhet El Behira–Garaat El Majdoul basin. In addition, the morphostructural configuration controls the piezometry of underground flows in the Oligocene and Mio-Plio-Quaternary unconfined aquifers.
Editor D. Koutsoyiannis; Associate editor M. Besbes  相似文献   
49.
The geodynamic processes in the western Mediterranean are driven by both deep (mantle) processes such as slab‐rollback or delamination, oblique plate convergence and inherited structures. The present‐day deformation of the Alboran Sea and in particular the Nekor basin area is linked to these coeval effects. The seismically active Nekor basin is an extensional basin formed in a convergent setting at the eastern part of the Rif Chain whose boundaries extend both onshore and offshore Morocco. We propose a new structural model of the Nekor basin based on high‐resolution offshore data compiled from recent seismic reflection profiles, swath bathymetry acquisitions and industrial seismic reflection profiles. The new data set shows that the northern limit of the basin is oriented N49° with right‐stepping faults from the Bousekkour–Aghbal fault to the sinistral Bokkoya fault zone. This pattern indicates the presence of an inherited left‐lateral basement fault parallel to the major inherited Nekor fault. This fault has been interpreted as a Quaternary active left‐lateral transfer fault localized on weak structural discontinuities inherited from the orogenic period. Onshore and offshore active faults enclose a rhombohedral tectonic Nekor Basin. Normal faults oriented N155° offset the most recent Quaternary deposits in the Nekor basin, and indicate the transtensional behaviour of this basin. The geometry of these faults suggests a likely rollover structure and the presence at depth of a crustal detachment. Inactive Plio‐Quaternary normal faults to the east of the Ras Tarf promontory and geometries of depocentres seem to indicate the migration of deformation from east to west. The local orientations of horizontal stress directions deduced from normal fault orientations are compatible with the extrusion of the Rifian units and coherent with the westward rollback of the Tethyan slab and the localization of the present‐day slab detachment or delamination.  相似文献   
50.
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