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Badia Chulli Aysen Davraz Jalila Makni Mourad Bedir Hamed Ben Dhia 《Environmental Earth Sciences》2012,66(1):1-16
The Sfax Basin in eastern Tunisia is bounded to the east by the Mediterranean Sea. Thermal waters of the Sfax area have measured
temperatures of 23–36°C, and electrical conductivities of 3,200 and 14,980 μS/cm. Most of the thermal waters are characterized
as Na–Cl type although there are a few Na–SO4–Cl waters. They issue from Miocene units which are made up sands and sandstones interbedded with clay. The Quaternary sediments
cap the system. The heat source is high geothermal gradient which are determined downhole temperature measurements caused
by graben tectonics of the area. The results of mineral equilibrium modeling indicate that the thermal waters of the Sfax
Basin are undersaturated with respect to gypsum, anhydrite and fluorite, oversaturated with respect to kaolinite, dolomite,
calcite, microcline, quartz, chalcedony, and muscovite. Assessments from various chemical geothermometers, Na–K–Mg ternary
and mineral equilibrium diagrams suggest that the reservoir temperature of the Sfax area can reach up to 120°C. According
to δ18O and δ2H values, all thermal and cold groundwater is of meteoric origin. 相似文献
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A. Jambon J. A. Barrat O. Boudouma M. Fonteilles D. Badia C. Gpel M. Bohn 《Meteoritics & planetary science》2005,40(3):361-375
Abstract— We report on a new angrite, Northwest Africa (NWA) 1296, a fine‐grained rock with a magmatic texture of rapid cooling. Dendritic olivine (?Fo50) crystallized first in association with anorthite microcrysts (An98–100) forming composite chains separated from one another by intergrown Al‐Fe diopside‐hedenbergite pyroxenes. In addition, some olivines with lower Mg# and increased CaO (up to 12%) are found between the chains as equant microphenocrysts. Pyroxenes and olivines are both normally zoned from Mg# = 0.52 to less than 0.01 in the rims. Ca‐rich olivines are surrounded by, intergrown with, or replaced by subcalcic kirschsteinite. They appear after plagioclase crystallization stopped, at the end of the crystallization sequence. Minor phases are pyrrhotite, F‐apatite, and titanomagnetite. Pyroxene is the last silicate phase to grow, interstitial to idiomorphic olivine‐kirschsteinite. Numerous small vesicles and some channels are filled with microcristalline carbonate. The mode (vol%) is about 28% olivine, 3% kirschsteinite, 32% anorthite, 34% pyroxene, and 3% of the minor phases—close to that reported previously for D'Orbigny and Sahara (SAH) 99555. The bulk chemical composition of NWA 1296 is similar to D'Orbigny and SAH 99555; NWA 1296 differs by its texture and mineralogy, which are interpreted as resulting from rapid crystallization—an evidence of impact melting. Angrites cannot be produced by partial melting of a CV source because segregation of a “planetary” core is necessary to explain the low FeO/MgO ratio of magnesian olivines. Neither the odd Ca/Al ratio nor the very low SiO2 content can be explained by conventional partial melting scenarios. We suggest that carbonate is the key to angrite genesis. This is supported by the striking similarities with terrestrial melilitites (low SiO2, superchondritic Ca/Al ratio, presence of carbonate). The lack of alkalies could be the result of either loss after impact melting or absence of alkalies in the source. 相似文献
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Hakim Gabtni Badia Chulli Zenatti Chokri Jallouli Kevin L. Mickus Mourad Bedir 《Arabian Journal of Geosciences》2011,4(3-4):507-516
An analysis of Bouguer gravity anomaly data and geothermal gradient data obtained from bottom hole and drill stem tests temperature is used to determine the crustal structure of the Sahel Basin in eastern Tunisia and its role in the maturation and location of the large number of oil and gas fields in the region. The regional Bouguer gravity anomaly field is dominated by gradual increase in values from the northwest to southeast and is may be caused by crustal thinning as revealed by regional seismic studies. In addition, higher geothermal gradients in the same region as the Bouguer gravity anomaly maximum add an additional constraint for the existence of crustal thinning in the region. A detailed analysis of the Bouguer gravity anomaly data was performed by both upward continuation and horizontal gradients. These two techniques were combined to show that the study area consists of two structural regions: (1) the North–South Axis (NOSA)–Zeramedine region which is characterized by northwest-dipping, northeast-striking faults, thicker crust (30–31 km) and low geothermal gradients, and (2) the Mahres–Kerkennah region which is characterized by vertical, northwest-striking faults, thinner crust (28–29 km) and higher geothermal gradients. The correlation of a variety of features includes mapped and geophysically defined faults, volcanic rocks, a thinned crust and high geothermal gradients within the same location as known oil and gas fields indicate that the faults are a major factor in the location of these petroleum accumulations. 相似文献
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Résumé Des données géologiques, géochimiques et géophysiques ont été analysées dans le but d’évaluer le potentiel en eaux thermales du bassin du Sahel de Sfax (Tunisie orientale). Nous avons étudié le réservoir hydrogéothermique pour déterminer les différents faciès chimiques des eaux thermales et comprendre leurs origines. L'analyse des données existantes et nouvellement acquises montre que l'eau thermale à température plus élevée est d'origine météorique. Elle s'est infiltrée profondément dans des sables et grès du Miocène supérieur (Serravalien-Tortonien) et a atteint une température de 75°C, avant de resurgir par un drainage vertical en suivant les dysharmonies tectoniques. Le gradient géothermique élevé de cette région confirme qu'il s'agit bien d'un réservoir à intérêt géothermal exploitable. Citation Chulli, B., Makni, J., Bedir, M. & Ben Dhia, H. (2011) Une approche multidisciplinaire pour la prospection des bassins hydrogéothermiques: cas du Sahel de Sfax (Tunisie orientale). Hydrol. Sci. J. 56(3), 507–520. 相似文献
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