A reassessment of the human dimension of desertification     

Fouad Ibrahim 《GeoJournal》1993,31(1):5-10

So far, the human dimension of desertification has been confined to some peripheral aspects of desertification. Man is either set at the beginning of the process as a triggerer or at the end as a victim. This paper tries to show the high degree of involvement of human communities in the process of desertification itself and that they undergo degradation just like the vegetation associations and the wildlife communities. A new, more human-orientated definition of desertification is discussed here.  相似文献   

Tectonic analysis of the Central Eastern Desert of Egypt applying aeromagnetic and aeroradiometric survey data     

Ahmed A. Ammar  Magdy L. Meleik  Kadry M. Fouad 《Precambrian Research》1982,16(4):A7

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Lands at risk in the third world: local level perspectives     

Fouad Ibrahim 《GeoJournal》1986,12(2):220-220

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Geochemistry of Triassic Carbonates: Exploration Guide to Pb–Zn Mineralization in North Tunisia          下载免费PDF全文

Nejib Jemmali  Fouad Souissi  Emmanuel John M. Carranza  Mohsen Henchiri 《Resource Geology》2016,66(4):335-350

The Triassic carbonate rocks in Northern Tunisia (Nappes, Domes, Jurassic Mountains zones), consist of massive carbonates, clays and gypsum with authigenic minerals. These are associated with several Pb–Zn deposits and occurrences. At Jebel Ichkeul, Bechateur and Oum Edeboua, these Triassic carbonates exhibit enrichment in Pb (0.32 to 228 ppm), Zn (17 to 261 ppm), Cd (5 to 6 ppm) and Co (0.3 to 89.5 ppm), with respect to their average contents in crustal carbonates. The enrichment is more pronounced at Oum Edeboua (near the ore zone). Permeability is one of the most effective factors of dispersion of metallic trace elements, causing the development of geochemical halos. The genetic relationship of the Triassic carbonate rocks with the ore deposits was controlled by diapirism and tectonic movements, which favored mineralization along the Triassic‐cover contact as well as the remobilization of metals from the mineralized rocks. Analysis of metallic trace elements in Triassic rocks provides clues to the presence of possible mineral deposits. These could be effectively used for both geochemical interpretation and mineral exploration. Carbon and O‐isotope data (– 9.3‰ < δ¹³C < +3‰; +21.9 < δ¹⁸O < +31‰) suggest that the Triassic carbonates of all study areas have marine carbonates as their origin; some of them show significantly lower δ¹⁸O values indicating some exchange with hydrothermal fluids. Calcites associated with mineralization at Oum Edeboua have δ¹³C of –6.2‰ to –8.22‰ and δ¹⁸O of +24.88‰ to +25‰. The C‐isotope compositions of these calcites are ¹³C depleted, indicating an organic origin.  相似文献   

Filtering of the gravimetric anomalies to the study of the geological structures of Oued Zarga (Septentrional Tunisia): structural implications     

Amira Ayed-Khaled  Mohamed Ghanmi  Fouad Zargouni 《Arabian Journal of Geosciences》2012,5(1):169-180

Gravity data were analysed in the Northern Tunisian Atlas (case study of Oued Zarga area) to better understand the organization of its underlying structures. The gravity data analysis included the construction of a gravity anomaly maps and two and a half dimensional gravity model. The qualitative analysis of gravimetric maps served for the foundation of a new structural map of the study region that constitutes a new contribution of the gravimetry in this present work. In addition, the complete Bouguer and residual gravity anomaly maps indicate a negative gravity anomaly over the Triassic evaporitic outcrops of Jebel Guerouaou and prominent NE?CSW-trending features associated with the boundary of the Triassic rocks and surrounded layers. A NW?CSE-trending gravity model that crosses the Triassic evaporitic outcrop at Jebel Guerouaou can be explained by a deep-rooted salt diapir.  相似文献   

Structural context of meso-scale and cartographical duplex structure genesis in thrusting tectonics: role of tear faults. Zaghouan thrust belt. Case of Bir M'Cherga-Ain Asker area     

Sabri Aridhi  Kais Aridhi  Mohamed Ghanmi  Fouad Zargouni  Eric Mercier 《Arabian Journal of Geosciences》2014,7(6):2499-2514

Bir M'Cherga-Ain Asker area, situated in the hinterland of Zaghouan thrust (Tunisian dorsal), was the land example treated with metric and cartographic scale in order to identify duplex genesis criteria and to include thrusting tectonics associated with tear faults, which are in fact the directory response generating duplex structures identified in outcrop for the first time through Tunisia in this case. Given its geological location between the "dôme" and the "dorsal" zone of Tunisia, this area was the most exposed to a highly paleostress history expressed by a huge fault system remobilization and reactivation through several tectonic events from NE–SW middle Cretaceous distension to a NW–SE and NNW–SSE Paleogene compression. Regarding fault planes generated analysis, they show numerous streak generation of normal, strike-slip, and reverse faults that go with geodynamic and paleostress evolution of the studied area; we note that each streak generation is perfectly matching with one of the tectonic event (mentioned before) affecting the area. In this paper, we analyze duplex structure elaboration scenarios to assess the involved kinematics and their geometrical recognition criterious. We propose to discuss the causes of duplex structures installation in a thrust belt system and the predictable geometrical styles after its installation on foreland or backland. Using the geometrical criteria acquired through this analysis, we will show that such, however, exceptionable structures exist on the land, and that they record the mechanisms of their genesis linked to the tear faults acting in this case. We describe "tear faults" as the sliding breaks which disunite two compartments during deformation, allowing them to undergo different independent deformations in their drawing and their width (for example more or less stretched folds). These types of faults differ from that of the true stick-slip faults, which slice and shift preformed structures (it's even this shift which makes it possible to highlight them); here, there are no shift but dissimilarity of the structures on both sides of the fault; therefore, deformations are the direct results of displacements; they are expressed in thrust belts by ramp folds, intense internal deformations, and even by complex duplex structures. A duplex feature that is not mainly studied is made up by tilted imbricate sedimentary sequences (or horses), separated by link thrusts and underlined respectively at their tops and bottoms by roof and floor thrusts. Imbrications cause a shortening, a thickening, or a thinning of stratigraphic columns and even its crushing and inverting. In thrust belts, duplexes are usually set up following two or even more deformational events; those structures start typically with decollement and imbricate sedimentary unit ones which are made cover by a roof thrust sometimes visible at outcrop. Through this paper, we suggest to discuss geometrical duplex criteria, and we will try a zooming through different scales, from regional to local one in order to show how the shape (expression) of the deformation differs.  相似文献   

Study of a Neogene basin dynamics: The “Bizerte basin”, northeastern Tunisia: relevance to the global Messinian Salinity Crisis     

Salah Harrab  Beya Mannai-Tayech  Mohsen Rabhi  Fouad Zargouni 《Comptes Rendus Geoscience》2013,345(5-6):251-261

The Messinian sediments of northeastern Tunisia were deposited under an active tectonic setting. They are organized in sequences indicating a transitional deposit from margin – littoral to lacustrine – continental facies. These series unconformably overlie the Serravallian–Tortonian silty clays packages, and are overlain by the transgressive Early Pliocene marl (Zanclean). The presence of evaporitic strata points out to the Messinian Salinity Crisis described in the peripheral basins of the western Mediterranean. The Messinian sedimentation was found to have been closely controlled by transtensive tectonics and differential subsidence at a large spatio-temporal scale. It is organized in sequences typical of a depositional environment controlled by eustatism, tectonic and maybe by climate changes. Despite the existence of some local specific sedimentological characteristics, our results corroborate previous findings that pointed out to the Messinian times as a singular period all around the Mediterranean Basin. Field and subsurface seismic profile data helped reconstructing either the sedimentary or tectonic unconformities existing between the studied Messinian series and older Neogene successions.  相似文献   

Hydrochemistry and bacteriology of western and Saharan spring waters of Algeria     

Hakim Saibi  Fouad Bahri  Ahcène Semar 《Arabian Journal of Geosciences》2013,6(3):665-677

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Book reviews     

Haruhiko Yamaji  Thomas K. Poiker  Fouad Ibrahim  Dieter Richter  G. Kunkel  M. J. Pasqualetti 《GeoJournal》1984,8(2):188-190

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Reply to comment on ‘A geomorphological explanation of the unit hydrograph concept’ by C. Fleurant and P. Boulestreau     

C. Cudennec  Y. Fouad  I. Sumarjo Gatot 《水文研究》2005,19(2):545-547

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