排序方式： 共有7条查询结果，搜索用时 15 毫秒
1
1.
Jaloul Bejaoui Mohamed Samaali Souad Baccouche Nafaa Regugui Mohamed Fethi Ben Hamouda Zohra Azzouz Adel Trabelsi Salah Bouhlel Boulamia Salim 《Arabian Journal of Geosciences》2013,6(7):2685-2689
In this study we investigate the radiological hazard of naturally occurring radioactive material in Tunisian and Algerian phosphorite deposits. Eight samples of phosphorite were collected from the phosphorite mines. The Tunisian and Algerian phosphorites occur in the Late Paleocene and Lower Eocene (Ypresian-Lutetian) in age (Béji Sassi 1984 and Zaïer 1999). Activity concentrations in all the samples were measured by alpha spectrometry and gamma spectrometry. Alpha spectrometry analyses show that the specific activity values of 238U, 234U and 235U in the samples of Tunisian phosphorite were 327?±?7 (321–327), 326?±?6 (325–331) and 14.50?±?0.72 (13.90–15.57) Bq kg?1, respectively. Specific activity measured by gamma spectrometry in the samples of the Tunisian and Algerian phosphorite shows a small difference. Specific activity levels of 40K, 226Ra, 232Th, 235U and 238U in the phosphorite samples from Tunisia were, respectively, 71.10?±?3.80, 391.54?±?9.39, 60.38?±?3.74, 12.72?±?0.54 and 527.42?±?49.57 Bq kg?1 and Algeria were 15.72?±?1.73, 989.65?±?12.52, 12.08?±?1.20, 47.50?±?1.52 and 1,148.78?±?7.30 Bq kg?1, respectively. The measured value of specific activity of 232Th and 40K in the Tunisian phosphorite samples is relatively higher than that found in the samples of Algerian phosphorite. The measured activity of uranium (238U) in the Tunisian phosphorite (527?±?49) Bq kg?1 is lower than in Algerian phosphorite. The measured activity of 238U in the Tunisian phosphorite samples was (527–1,315?±?65) 238U Bq kg?1 which is higher than its maximum background value of 110 Bq kg?1 in soils of the various countries of the world (Tufail et al. Radiat Meas 41:443–451, 2006). Different geological origins of phosphorites deposits are the main reason for the large spread in worldwide specific activities. The obtained results of uranium concentrations in phosphorites of different types (Algerian and Tunisian) demonstrate that the uranium concentrations are mainly governed by the phosphatic material. The present study reveals that phosphorite deposits contain natural radioactivity higher than background level. 相似文献
2.
Mohammed Jaffal Azzouz Kchikach Jean-Pierre Lefort Lahoucine Hanich 《Comptes Rendus Geoscience》2002,334(4):229-234
A large number of seismic reflection lines and boreholes have been carried out in the Essaouira Basin by the oil industry. The present study concentrates on the reinterpretation of these data in the restricted area of Khemis Meskala, in order to better characterise the structure of the Cretaceous aquiferous system. The reflector corresponding to the bottom of the Vraconian formation has been identified on the different seismic sections. This horizon, which marks the base of the aquiferous system, was first digitised on time migration sections and then converted to depth sections using a suitable linear velocity law. The isobath map of the bottom of the Vraconian resulting from this study images the 3D geometrical structure of this horizon and shows that it is slightly folded in domes and basins. This document will be useful for rationalising the future hydrogeological researches that will be undertaken in the Khemis Meskala area. To cite this article: M. Jaffal et al., C. R. Geoscience 334 (2002) 229–234. 相似文献
3.
Najib El Goumi Mohammed Jaffal Christian Rolf Christoph Grissemann Frank Melcher Azzouz Kchikach Mohammed Hibti Torsten Graupner 《Arabian Journal of Geosciences》2013,6(7):2581-2597
This paper describes a multidisciplinary study approach (petrography and rock magnetism) conducted on samples collected from the study area to characterise the magnetic mineralogy and to determine if the magnetisation of both lithologies were induced or retain a remnant component. Petrophysical, mineralogical and geochemical analyses confirm bimodal aspects, particularly in basic rocks; the two magnetic modes depend essentially on the mineralogical and geochemical characteristics of the samples. The ultramafic rocks comprise a highly altered primary mineralogy with chromite and magnetite as magnetic phases. The second type is of mafic composition with a less altered primary mineralogy and essentially magnetite and/or (hemo-ilmenite) as a carrier of magnetic mineralisation. Sulphides are characterised by high concentrations of Cu, Zn and Pb. The mineralogy is composed mainly of pyrrhotite (85% to 90%), sphalerite, galena, chalcopyrite, arsenopyrite and, occasionally, stannite. Monocline pyrrhotite seems to be the magnetic carrier of magnetisation in both Draa Sfar and Koudiat Aïcha. However, we suspect a different amount of hexagonal pyrrhotite as the cause of different magnetic behaviour. Paleomagnetic and thermomagnetic analyses reveal different. The calculated characteristic direction of natural remnant magnetisation for sulphides was used to model the magnetic anomaly of Draa Sfar. The proposed model match the geological features concluded from geological mapping and boreholes. Results from this work can be very useful for any modelling processes of magnetic anomalies suspected due to a sulphide mineralisation in an area with poor outcrops and no presence of boreholes information or of any geological or geochemical data. 相似文献
4.
The Kuhmo greenstone belt (Eastern Finland) is mainly formed by mafic volcanic rocks and metasediments. Although the geological observations indicate that this belt appears as a supracrustal synform overlying a gneissic basement, its deep structures are actually unknown. The present gravity study intends to provide a better understanding of these structures. Interpretation of gravity anomalies of the Kuhmo belt, using two-dimensional modelling suggests that the structures of the belt are controlled by granitoids diapirs. Most of the calculated models show that the belt displays in section pocket-like shapes (purses) terminated by a gully-shape close to the surface. This particular geometry corroborates the hypothesis of a gravitational formation with the heavy volcanic material sinking in a light sialic crust. To cite this article: M. Jaffal et al., C. R. Geoscience 335 (2003). 相似文献
5.
Abderrahmane Soulaimani Mohammed Jaffal Lhou Maacha Azzouz Kchikach Abdessamad Najine Abdellatif Saidi 《Comptes Rendus Geoscience》2006,338(3):153-160
Aeromagnetic data of the Anti-Atlas Mountains show an important magnetic anomaly along the ‘Major Anti-Atlas Fault’, produced by different mafic and ultramafic rocks of a Neoproterozoic ophiolite complex. The magnetic modelling of Bou Azzer–El Graara ophiolitic suture shows a deep-seated anomaly through the upper continental crust corresponding to a north-dipping subduction. The polarity of the Pan-African subduction in the Anti-Atlas is therefore compatible with the contemporaneous Pan-African orogenic belts, where polarity of subduction dipped away from the West African Craton during the amalgamation of Western Gondwana. To cite this article: A. Soulaimani et al., C. R. Geoscience 338 (2006). 相似文献
6.
Azzouz Kchikach Mohammed Jaffal Tahar Aı̈fa Lahcen Bahi 《Comptes Rendus Geoscience》2002,334(6):379-386
In the Ouled Abdoun sedimentary basin (Morocco), the phosphatic series is composed of regular interbedded phosphatic and marly limestone layers. Some phosphatic deposits in this basin show sterile bodies causing two kinds of problems: (1) as they are hard, compact and masked by a Quaternary cover, they disturb the exploitation in some yards and give bad reserve calculations; (2) even the use of wells and mechanical boreholes did not evidence their delimitation. Therefore, electric prospecting method has been used to evidence their geometrical shape. Petrographical and geometrical studies on these sterile bodies allowed us to choose the appropriate geophysical method to map them. The electrical resistivity survey that we used in the Sidi Chennane area shows that this technique is a good tool to contour these sterile bodies. This method is now considered as useful to the mining engineers to get round them during the exploitation. To cite this article: A. Kchikach et al., C. R. Geoscience 334 (2002) 379–386. 相似文献
7.
Azzouz Kchikach Pierre Andrieux Mohammed Jaffal Mostafa Amrhar Mohammed Mchichi Baadi Boya Mbarek Amaghzaz Thierry Veyrieras Khadija Iqizou 《Comptes Rendus Geoscience》2006,338(5):289-296
Exploitation of the phosphatic layers in Sidi Chennane deposit (Morocco) collides frequently with problems bound to the existence, in the phosphatic series, of sterile bodies qualified as derangements. Our study shows that these bodies, masked by the Quaternary cover can be mapped using the Time-Domain ElectroMagnetic Soundings method (TDEM). It is based on the acquisition and the interpretation of a series of tests carried out above a visible derangement in an old trench of exploitation and on 2500 TDEM soundings carried out in a virgin area of the deposit. The article concerns to the analysis of the results and of the proceeding for a possible large geophysics survey. To cite this article: A. Kchikach et al., C. R. Geoscience 338 (2006). 相似文献
1