Apport de la gravimétrie à l\'étude de la structure du...

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ArticleApport de la gravimétrie à l étude de la structure du bassin des Triffa (Maroc nord-oriental) : implications hydrogéologiquesDecember 2004Comptes Rendus Geosciences 336(16):1427-1432DOI: 10.1016/j.crte.2004.09.012Project: Multiscale analysis of Gravity and magnetic lineaments : structural, hydrogeological and mining implicationsAuthors:

Driss KhattachUniversité Mohammed Premier

Pierre KeatingConsultant

El Mostafa Mili

Touria ChennoufShow all 6 authorsHide

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Request full-textDownload citation Copy link Link copied Request full-text Download citation Copy link Link copiedTo read the full-text of this research, you can request a copy directly from the authors.Citations (59)References (9)AbstractVarious techniques (horizontal and vertical derivatives, upward continuation, Euler deconvolution) have been applied to the gravity data from the Triffa s plain and the north flank of the Beni-Snassen massif to delineate various major geological structures such as faults and basins. These results allow the production of a structural map showing the fault systems for the survey area. This map forms the basis for planning future hydrogeological research in this region. To cite this article: D. Khattach et al., C. R. Geoscience 336 (2004).

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Request full-text PDFCitations (59)References (9)... In order to make better use of these data, we used various filtering techniques, Euler deconvolution and a multiscale analysis of the geological contacts based on the horizontal gradient at a series of upward continuation heights [1, 2,12]. The success of these interpretation techniques was shown in many studies [4,5,8,13,14]. ...... Pour la présente étude, nous disposons de données numériques relatives à 5450 stations de mesure, couvrant la partie nord-est du Maroc oriental : Oujda, El Aioun, Berkane et les pays des horsts. Cela permettra, en appliquant des techniques de traitement récentes, telles que l analyse multiéchelle des contacts géologiques basée sur le couplage des techniques du gradient horizontal, le prolongement vers le haut et la déconvolution d Euler [1, [12][13][14], d apporter plus de précisions sur le tracé des principaux accidents qui affectent la région, sur leur extension, leur profondeur et leur degré d importance. ...... Dans le but de mieux exploiter ces données et d extraire le maximum d information des signaux gravimétriques, nous avons utilisé les techniques modernes de filtrage du signal gravimétrique dans le domaine des fréquences, telles que l analyse multiéchelle des contacts géologiques, basée sur la technique du gradient horizontal couplé avec le prolongement vers le haut [1], ainsi que la déconvolution d Euler [12]. Le succès de l application de ces traitements a été démontré par de nombreuses études antérieures [4,5,8,13,14]. ...Principales lignes structurales du Maroc nord-oriental : apport de la gravimétrieArticleMay 2007CR GEOSCITouria Chennouf

Driss KhattachAbdellah Milhi

Pierre KeatingThe present work is based on various filtered maps (horizontal derivative, upward continuation) and Euler deconvolution of the gravity data from northeastern Morocco. These results allow the delineation of many geological structures, such as faults, basins, or diapirs. Some of these structures are hidden totally or partially by the Mesozoic and Cenozoic cover. The results were used to make a structural map of the study area; this map confirms the existence of several faults, localised or inferred, from former geological studies. It complements information on some of them and outlines a great number of deep or near-surface faults that had remained unknown until the present time. The major features show two principal directions: N080°–085° and N055°–065°, with a predominance of the latter, and their depth can reach 4500m. The N080°–085° directions correspond to the Kebdana, Sidi Bouhouria, Naima, and Guefait faults, and the N055°–065° directions correspond to a fault parallel to the Mediterranean coast and the Moulouya, Madagh, Angad, and Zekkara faults.ViewShow abstract... La méthode d analyse multi-échelle basée sur l orientation du gradient horizontal permet d étudier ces discontinuités. Ces méthodes se sont avérées efficaces dans des études similaires aussi bien dans le bassin de Triffa que dans l Anti-Atlas du Maroc (Khattach et al. 2004Vanié et al. 2005Vanié et al. , 2006Chennouf et al., 2007 ;El Gout et al., 2010). ...... Conformément aux études gravimétriques menées par les chercheurs (Cordel et al.1985 ;Blakely et al. 1986 ;Archibald et al. 1999 ;Everaerts Mansy, 2001 ;Khattach et al., 2004Khattach et al., et 2006, le calcul du gradient horizontal est effectué dans l objectif de mettre en évidence sur une carte, les zones de failles, de discontinuités. L analyse du gradient est également souvent employée pour localiser les changements brusques en profondeur des sources magnétiques et/ou des propriétés magnétiques qui peuvent être produites par les failles géologiques (Hansen et de Ridder, 2006). ...... Le calcul du gradient horizontal à partir de l anomalie résiduelle est très utile pour la localisation des contacts géologiques, du fait que la limite entre deux blocs de densités différentes correspond au maxima de ce gradient (Blakely, Chennouf et al., 2004 ;Cordell, Khattach et al., 2004). En effet, audessus d un contact vertical entre des roches de densités différentes, le champ gravimétrique se manifeste par un changement de niveau marqué par le passage des valeurs faibles au-dessus des roches de faible densité, vers des valeurs plus élevées à l aplomb des roches de forte densité. ...Contribution de la gravimétrie à l étude de la partie sud du bassin sédimentaire côtier onshore du BéninArticleFull-text availableJan 2013

Yalo Nicaise

Agnidé LawinD AlmeidaG F DagbaLe bassin sédimentaire côtier onshore du Bénin a fait l objet de plusieurs études qui ont permis d avoir des précisions sur son histoire géologique. Basée sur l analyse et l interprétation de données gravimétriques, la présente étude gravimétrique vise à améliorer la connaissance de la structure de la partie sud du bassin sédimentaire côtier onshore du Bénin. La carte des anomalies gravimétriques résiduelles réalisée par la méthode de la moyenne mobile en utilisant la carte d anomalie de Bouguer, met en évidence aussi bien des zones d anomalies négatives et positives, que des zones à fort gradient. Cette carte fournit des informations sur la variation de la densité du sous-sol. Les anomalies négatives peuvent refléter l existence de bassins, de chenaux ou de l effondrement du socle, tandis que les anomalies positives sont associées à une surrection du socle. Dans la localité de Sèhouè, l anomalie positive orientée N-S à NE-SW a été liée à une remontée du socle alors que l anomalie négative caractériserait le graben d Allada. Le calcul du gradient horizontal a permis d identifier, à l Ouest de l anomalie positive de la localité de Sèhouè, un linéament gravimétrique de direction NNE-SSW. Ce linéament est matérialisé par un contraste de densité et apparait comme la signature gravimétrique de la faille de Sèhouè. L analyse spectrale réalisée sur trois profils choisis transversalement aux anomalies dans la région d étude, a permis d estimer les profondeurs moyennes des sources d anomalies à 1870, 1820 et 2300 m de l ouest vers l est du bassin sédimentaire côtier onshore du Bénin confirmant ainsi l affaissement du socle dans sa partie sud est. Mots clés-gravimétrie, anomalie, bassin sédimentaire côtier du Bénin, onshore, gradient horizontal, analyse spectrale, profondeur. Contribution of gravimetry to the study of the south part of the onshore coastal sedimentary basin of Benin Abstract – The onshore coastal sedimentary basin of Benin has been an object of several studies which provide insights into his geological history. Based on gravimetric data analysis and interpretation, the present gravimetric study aims to improve knowledge of the structure of the southern part of the onshore coastal sedimentary basin of Benin. The map of residual gravimetric anomalies realized by the method of the mobile average using Bouguer anomaly map, highlight as well zones of negative and positive anomalies, as zones of strong gradient. This map provides information of the density variation of the subsurface. The negative anomalies may reflect the existence of basins, channels or basement collapse, while the positive anomalies are associated to basement uplift. In Sèhouè locality, the positive anomaly of N-S to NE-SW direction was linked to basement uplift while the negative anomaly should characterize the Allada graben. The calculation of the horizontal gradient allows the identification in the West of the positive anomaly of Sèhouè locality, a gravimetric lineament of NNE-SSW direction. This lineament is materialized by a contrast of density and seems to be the gravimetric signature of the Sèhouè fault. The spectral analysis carried out on three profiles chosen transversely to the anomalies of the study area permits to evaluate the averages of depths of the sources of anomalies at 1870, 1820 and 2300 m from west towards the east part of the onshore coastal sedimentary basin of Benin confirming thus the profundity of the basement in its southern part.ViewShow abstract... The complete gravity anomaly map (Figure 3) has much information on present discontinuities in the basement, which can be extracted by analyzing pressure gradients between anomalies [48][49][50]. The complete Bouguer gravity anomaly values range from −20 mGals in the southeast to 18 mGals in the northeast. ...... In order to separate shallow sources, the residual ano-maly was obtained by subtracting the regional field to the Bouguer anomaly. For this reason, upward continuation method was used to constrain regional map [50][51][52][53][54]. The upward continuation of the Bouguer anomaly to 20 km of altitude expresses a very smooth gravity pattern, a big positive anomaly in the NE part of the map (Cretaceous series) and negative anomaly in the south (plains with quaternary sediments) (Figure 4). ...... In order to delineate lineaments associated with boundaries of rock units or faults [49,[50][51][52]] the horizontal gradient maxima method is applied on the Bouguer anomaly map. In this case, lineated contacts correspond to faults, while the circular contacts are the limits of diapirs or of intrusive bodies. ...Gravimetric Study of Geological Structures of Teboursouk Area, Northern TunisiaArticleFull-text availableJan 2012IJGAmira Ayed-KhaledGravity data associated with surface geology in the Northern Tunisian Atlas offer better understand to the underlying structures in Teboursouk area and to highlight other deep or unknown structures in surface. The gravity study was based on qualitative and quantitative analysis including the construction of the gravity Bouguer anomaly, upward continuations, residual anomaly, and Horizontal gradient maxima maps. The main results display many positive and negative anomalies as the response of geological structures (J. Cheid Triassic structure, Khalled plain, El Aroussa plain). In addition, the horizontal gradient maxima integrated with geological and structural maps let the identification of major directions of gravimetric lineaments in the study area us NE-SW trending features at the boundaries of J. Cheid structure, NW-SE direction that limit Gaafour plain and Tabet Ech Cherif syncline, and N-S trending that bordered El Aroussa basin. Major results allowed the construction of a new structural map of the study zone.ViewShow abstract... The complete gravity anomaly map (Figure 3) has much information on present discontinuities in the basement, which can be extracted by analyzing pressure gradients between anomalies [48][49][50]. The complete Bouguer gravity anomaly values range from −20 mGals in the southeast to 18 mGals in the northeast. ...... In order to separate shallow sources, the residual ano-maly was obtained by subtracting the regional field to the Bouguer anomaly. For this reason, upward continuation method was used to constrain regional map [50][51][52][53][54]. The upward continuation of the Bouguer anomaly to 20 km of altitude expresses a very smooth gravity pattern, a big positive anomaly in the NE part of the map (Cretaceous series) and negative anomaly in the south (plains with quaternary sediments) (Figure 4). ...... In order to delineate lineaments associated with boundaries of rock units or faults [49,[50][51][52]] the horizontal gradient maxima method is applied on the Bouguer anomaly map. In this case, lineated contacts correspond to faults, while the circular contacts are the limits of diapirs or of intrusive bodies. ...Gravimetric Study of Geological Structures of Teboursouk Area, Northern TunisiaArticleFull-text available

Taher ZouaghiAmira Ayed-Khaled

Ghanmi Mohamed

Fouad ZargouniGravity data associated with surface geology in the Northern Tunisian Atlas offer better understand to the underlying structures in Teboursouk area and to highlight other deep or unknown structures in surface. The gravity study was based on qualitative and quantitative analysis including the construction of the gravity Bouguer anomaly, upward continua-tions, residual anomaly, and Horizontal gradient maxima maps. The main results display many positive and negative anomalies as the response of geological structures (J. Cheid Triassic structure, Khalled plain, El Aroussa plain). In addi-tion, the horizontal gradient maxima integrated with geological and structural maps let the identification of major direc-tions of gravimetric lineaments in the study area us NE-SW trending features at the boundaries of J. Cheid structure, NW-SE direction that limit Gaafour plain and Tabet Ech Cherif syncline, and N-S trending that bordered El Aroussa basin. Major results allowed the construction of a new structural map of the study zone.ViewShow abstract... Pour l étude de ces discontinuités, nous avons appliqué la méthode de l analyse multi-échelle basée sur le gradient horizontal couplé au prolongement vers le haut, et la déconvolution d Euler. Ces méthodes se sont avérées efficaces dans des études similaires (Khattach et al. 2004, Vanié et al. 2005, Chennouf et al. 2007, El Gout et al. 2010. ...... Dans cette étude, nous avons utilisé trois méthodes de traitement dans le but de déterminer de failles, leur pendage, leur longueur et leur profondeur (Cordel et al. 1985, Blakely et al. 1986, Archibald et al. 1999, Everaerts Mansy 2001, Khattach et al. 2004 : gradient vertical, gradient horizontal couplé au prolongement vers le haut, et déconvolution d Euler. 1) Le gradient vertical permet, en l absence d hétérogénéités intra-sédimentaires, de reconnaître les parties supérieure et inférieure du socle. L intérêt des conversions des cartes du champ gravimétrique en gradient vertical (ou première dérivée verticale) a été reconnu depuis longtemps (Evjen 1936) ; des méthodes de calcul ont été proposées et illustrées par Aynard (1953), Baranov (1957), Le Mouël (1970), Gérard Griveau (1972) et Galdeano (1980. ...... 2) Le gradient horizontal couplé au prolongement vers le haut permet la localisation des failles et la détermination de leur pendage (Archibald Bochetti 1999, Khattach et al. 2004, Vanié et al. 2005. Les contacts linéaires correspondent à des failles alors que les contacts de forme circulaire sont les limites de diapirs ou de corps intrusifs. ...Contribution de la gravimétrie à l étude de la structure des Hauts Plateaux (Maroc oriental)ArticleFull-text available

Jamila Abderbi

Driss KhattachRésumé. La carte gravimétrique des Hauts Plateaux met en évidence des anomalies négatives et des anomalies positives séparées ainsi que des zones à fort gradient. Les hauts gravimétriques sont associés au socle et à ses hétérogénéités, alors que les bas gravimétriques sont la signature de bassins sédimentaires, de granites dans le socle et de dômes de sel. Pour cartographier les contacts géologiques, les failles et leurs caractéristiques spatiales, trois méthodes d interprétation ont été utilisées : gradient vertical, gradient horizontal couplé au prolongement vers le haut et déconvolution d Euler. L application de ces traitements a permis de cartographier un grand nombre de linéaments gravimétriques matérialisant les discontinuités de densité. Les directions obtenues sont NE-SW, E-W et NW-SE, avec une dominance des directions NE-SW. Les solutions d Euler indiquent des profondeurs pouvant atteindre 2400 m. La carte des linéaments établie permet d améliorer la connaissance de la structure profonde des Hauts Plateaux et constitue un guide pour la prospection des ressources du sous-sol (eau et hydrocarbures). Structural setting of the High Plateaus; insights from gravity data analysis (Eastern Morocco). Extended English abstract. The purpose of the present work is to use gravity data to improve the knowledge on the structure of the High Plateaus, located between the Jerada mountains to the north, the eastern High Atlas to the south, the Rekkam to the west, and the Algerian border to the east (Fig. 1). Most part of the High Plateaus is covered by thick Quaternary deposits, outcrops of older rocks are exposed. From the structural point of view, according to the first draft of the northern High Plateaus, the area is affected by faults which led to the development of grabens and horsts (Fig. 2). In order to improve the knowledge on the deep structure of the study area, the gravimetric map was reinterpreted. The isogal curves of the Bouguer anomaly map of the High Plateaus (scale 1/200,000; d=2.5 g/cm 3) were digitized and a regular grid was calculated with a mesh of 250 m (Fig. 3). We used various filtering techniques to delineate the major geological structures such as faults and basins: vertical and horizontal derivatives, upward continuation, and Euler deconvolution (Fig. 4). The residual-gravity anomaly field (Figs. 5-6) map presents (positive/negative) anomalies separated by strong gradient zones. Interpretation makes it possible to associate the negative anomalies with deep basins, domes or granites (Tab. I). The positive anomalies are associated to basement uplift or outcrop. The statistical analysis of the anomalies allows identifying the major structural trends of the region (Fig. 5b). The vertical gradient allowed us to amplify short waves and to reduce interferences between anomalies (Fig. 7). The superimposition of horizontal derivative maxima from the Bouguer anomaly and from its upward continuation at several heights up to 4,000 m by steps of 250 m (Fig. 8) shows alignments outlining the contacts and gives information on their dip (Fig. 9a). The statistical analysis of contacts interpreted as faults shows five main trends: N00; N120; N70; N90 and N45, with a clear predominance of the last trend (Figs. 9b-c). Euler deconvolution was used to determine source depths and their location. Solutions are well grouped and correlate with various contacts previously inferred from horizontal derivative maxima. The values of sources depth can reach 2,338 m (Fig. 10). Superimposition of the interpreted major faults to the geological map, shown in figure 9, indicate that NE-SW and E-W system is well developed and represented by several faults with regional importance; the other fault systems are mainly N-S, NW-SE (Fig. 11).ViewShow abstract... The Moulouya catchment is characterized by a semi-arid to arid Mediterranean climate. Average precipitations range from 150 to 600 mm between the basin lowlands and the Atlas Mountains (Kaemmerer and Revel, 1991). Highest fluctuations of the water discharge occur from October to January; they are generally related to heavy rainfall events, usually very concentrated in time (Snoussi et al., 2002). ...... In the High and Middle Atlas regions, two main processes resulted in rock uplift: thrusting due to tectonic shortening, active since the Paleogene, and long-wavelength surface uplift due to mantle-driven buoyancy since the Late Cenozoic (Babault et al., 2008). In the Ksabi basin (Fig. 1A), the existence of a Quaternary terrace staircase, encompassing up to eight distinct levels, and stacked terraces were recognized (Raynal, 1961;Lef evre, 1989;Kaemmerer and Revel, 1991). The landscape is characterized by a tight inter-fingering between alluvial deposits of the Moulouya and footslope sedimentation landforms (alluvial cones, glacis), the latter usually capping the river sediments (Lef evre, 1989). ...... Both massifs are primarily formed by diverse Mesozoic carbonate rocks, including limestone, dolomite, dolomitic limestone, calcareous marl and sandstone, and marl (Ruellan, 1971). They are secondarily composed of sandstone and slate formations of the Palaeozoic flysh series (Ruellan, 1971;Khattach et al., 2004). Located to the north of the Triffa plain ( Fig. 2A), the up to 10 kmwide and up to 130 m-high Ouled Mansour plateau is mostly formed of Mio-Pliocene marls and partly solidified sands (Ruellan, 1971). ...Contrasting terrace systems of the lower Moulouya river as indicator of crustal deformation in NE MoroccoArticleNov 2016J AFR EARTH SCI

Gilles Rixhon

Melanie Bartz

Meriam El Ouahabi

Helmut BrücknerView... In addition to stratigraphic and structural data, geophysical techniques have proven to be effective indirect methods for geometrical aspects, as for the deep structure identification in major groundwater basins (Khattach et al., 2004Najine et al., 2006;Vani e et al., 2005Vani e et al., , 2006Chennouf et al., 2007;El Gout et al., 2009;Aqil et al., 2010;Farhat et al., 2010;Hssaisoune et al., 2012). At the whole Haouzplain scale, in addition to regional hydrogeological data on the unconfined aquifer (Sinan, 2000;Lyakhloufi, 2001;Razoki, 2001;Abourida, 2007), some investigations recently focused on hydrogeology based on gravimetric approaches (e.g. ...... Evaluation of the directions of the contact dips of linear structures was ensured through the upward continuations of the residual gravity map at different altitudes (100, 200, 500 and 1000 m), followed by the determination of the horizontal gradient maxima for each level. The progressive migration of these maxima while the upward altitude is increased indicates the dip direction (Khattach et al., 2004). The values of the upward continuation altitudes were selected arbitrarily; however two main factors conditioned such a choice, in order to: (1) realize continuations at altitudes sufficiently far apart to show the displacements of the horizontal gradient maxima at different levels for the dip contacts, and (2) to prevent these levels from being so far apart that the effect of the gravity contacts would be attenuated. ...Gravimetry contributions to the study of the complex western Haouz aquifer (Morocco): Structural and hydrogeological implicationsArticleDec 2015J AFR EARTH SCI

Ibtissam Chouikri

Albert Casas

Abdennabi EL MANDOUR El Mandour

Mohammed JaffalThis study provides new elements that illustrate the benefits of combining gravity, structural, stratigraphic and piezometric data for hydrogeological purposes. A combined methodology was applied to the western Haouz aquifer (Morocco), one of the main sources of water for irrigation and human consumption in the Marrakech region. First, a residual anomaly map was calculated from the Bouguer anomaly data. The computed map provided information on the ground density variation, revealing a strong control by a regional gradient. We then used various filtering techniques to delineate the major geological structures such as faults and basins: vertical and horizontal derivatives and upward continuation. This technique highlighted news structures and provided information on their dip. The gravity anomalies perfectly delineated the basement uplifts and the sedimentary thickening in depressions and grabens. The interpretation of gravimetric filtering, geological and hydrogeological data then highlighted two types of groundwater reservoirs, an unconfined aquifer hosted in conglomeratic mio-pliocene and quaternary rocks, covering the entire western Haouz and a deep confined aquifer contained in cenomanian-turonian limestone and eocene dolomitic formations in the south. Combining piezometric and residual anomaly maps revealed that groundwater flow and storage was in perfect agreement with the structures showing a negative anomaly, while structures with positive anomalies corresponded to groundwater divides. The study of gravity gradient zones by contact analysis enhanced the existing structural pattern of the study area and highlighted new structures, mainly oriented N70 and N130. The results of this study present a common framework and provide a notable step forward in the knowledge of the geometry and the groundwater flow pattern of the western Haouz aquifer, and will serve as a solid basis for a better water resource management.ViewShow abstract... du Maroc oriental présente de forts contrastes (gradients) qui seraient le reflet de discontinuités ou interfaces telles que les failles et les flexures. Pour l étude de ces discontinuités, nous avons procédé à une analyse multi-échelle (Archibald Bochetti 1999, Khattach et al. 2004) basée sur le couplage de la méthode du gradient horizontal avec celle du prolongement vers le haut. Cette approche, qui s est avérée efficace dans des études de détail (Khattach et al. 2004), devrait nous permettre de mettre en évidence les structures géologiques majeures et de cartographier les différents accidents tectoniques qui affectent la zone d étude tout en déterminant leur degré d importance et leur pendage. ...... Pour l étude de ces discontinuités, nous avons procédé à une analyse multi-échelle (Archibald Bochetti 1999, Khattach et al. 2004) basée sur le couplage de la méthode du gradient horizontal avec celle du prolongement vers le haut. Cette approche, qui s est avérée efficace dans des études de détail (Khattach et al. 2004), devrait nous permettre de mettre en évidence les structures géologiques majeures et de cartographier les différents accidents tectoniques qui affectent la zone d étude tout en déterminant leur degré d importance et leur pendage. La zone d étude concerne uniquement la région couverte par la feuille gravimétrique d Oujda au 1/500.000, ...Apport des filtrages des anomalies gravimétriques à l étude des structures profondes du Maroc orientalArticleJan 2005L.T.A. Vanié

Driss Khattach

Mohammed-Rachid HouariView... La gravimétrie permet de mettre en évidence les zones du sous-sol présentant un contraste de densité. Les limites entre ces zones sont décelées par l analyse des gradients gravimétriques (Archibald et al. 1999, Keating et al. 2004, Khattach et al. 2004, 2006. L objectif principal de ce travail est de montrer l apport de l analyse approfondie (analyse des gradients, modélisation) de données gravimétriques à l étude du sous-sol de la plaine de Bou-Houria (Maroc Nord-oriental) qui présente un intérêt hydrogéologique potentiel (Fig. 1). ...... La carte des anomalies de Bouguer renferme des gradients et aussi des anomalies de faibles amplitudes qui sont souvent masquées par les anomalies régionales. Il est donc nécessaire d appliquer à ces cartes les traitements adéquats pour extraire le maximum d information de ces signaux gravimétriques (Nabighian 1984, Blakely et Simpson 1986, Archibald et al. 1999, Asfirane-haddadji et Galdeano 2000, Keating et al. 2004, Khattach et al. 2004, 2006. Afin de mettre en évidence les structures géologiques superficielles, il est nécessaire d atténuer, voire de supprimer la composante régionale qui déforme et parfois masque les relations entre la géologie d un socle peu profond et la forme des anomalies. ...Contribution de la gravimétrie à la reconnaissance de l aquifère profond de la plaine des Angad (Maroc nord-oriental)ArticleOct 2010

Hicham Aqil

Driss Khattach

Radia El Gout

Kaufmann OlivierView... Les cartes gravimétriques renferment des gradients et des anomalies de faible amplitude souvent masquées par les anomalies régionales. Il est donc nécessaire d appliquer à ces cartes des traitements appropriés pour identifier les hauts et les bas gravimétriques et localiser les zones à forts gradients (Nabighian 1984;Moreau et al. 1997;Hornby et al. 1999;Khattach et al. 2004Khattach et al. , 2006Aqil et al. 2010;Keating et Pinet 2011). ...... 6 et 7). Cette analyse est largement appliquée dans l interprétation des cartes gravimétriques et magnétiques (Archibald et Bochetti 1999;Hornby et al. 1999;Everaerts et Mansy 2001;Khattach et al. 2004;Vanié et al. 2005;Chennouf et al. 2007;El Gout et al. 2009;Abderbi et Khattach 2010;Aqil et al. 2010). Elle est basée sur l utilisation conjointe des techniques de prolongement vers le haut et du gradient horizontal. ...Rectificatif to Fonctionnement hydrogéologique du bassin de la bahira (maroc central): Apport de l analyse des données géologiques et gravimétriques (Rev. can. sci. Terre, (2014), 51, (517-526))ArticleFull-text availableJun 2014Nourddine Khalil

Morad Karroum

Abdennabi EL MANDOUR El Mandour

Driss KhattachView... L expérience a prouvé l intérêt des données géophysiques pour la cartographie des linéaments et l identification des structures géologiques (Archibald et Bochetti, 1999;Khattach et al., 2004Khattach et al., , 2006Vanié et al., 2005Vanié et al., , 2006Chennouf et al., 2007;El Gout et al., 2010). Le tracé et l extension des accidents qui affectent la région des Hauts Plateaux, ainsi que la géométrie des bassins qu ils délimitent ne peuvent être approchés uniquement par les données de surface puisqu elle paraît peu tectonisée, mais sa véritable structure est enfouie sous les sédiments plio-quaternaires. ...... Afin d exploiter au mieux ces données, nous avons appliqué une analyse multi-échelle des contacts géologiques, basée sur les techniques du gradient horizontal, du prolongement vers le haut et de la méthode de la déconvolution d Euler. L application de la méthode du gradient horizontal couplé au prolongement vers le haut permet la localisation des contacts géologiques et la détermination du sens de leur pendage (Archibald et Bochetti, 1999;Khattach et al., 2004Khattach et al., et 2006Vanié et al., 2005). Les contacts linéaires correspondent généralement à des failles alors que les contacts de forme circulaire représentent les limites de diapirs ou de corps intrusifs. ...Apport des données aéromagnétiques et gravimétriques à l’étude de la structure géologique des Hauts Plateaux méridionaux (Maroc).ArticleFull-text availableFeb 2012

Jamila Abderbi

Driss KhattachCette étude présente les résultats de l interprétation de la carte des linéaments géophysiques des Hauts Plateaux méridionaux obtenus par le traitement des données aéromagnétiques et gravimétriques. Trois méthodes de filtrage (le gradient horizontal, le prolongement vers le haut et la déconvolution d Euler) ont été appliquées. Le tracé, la direction du pendage et la profondeur des discontinuités magnétiques ou de densité ont été déterminés. Ainsi, quatre directions NE-SW, ENE-WSW à E-W, NW-SE et N-S ont été décelées, avec une nette dominance de la direction NE-SW. Les profondeurs estimées par les solutions d’Euler vont jusqu’à 2000m pour la gravimétrie et dépassent 3000m pour le magnétisme. La carte structurale de la zone d étude, élaborée à partir de celle des linéaments, constitue un document susceptible de rationaliser les futurs travaux d exploration hydrogéologique et/ou pétrolière.Mots clés : Hauts Plateaux méridionaux, Maroc, aéromagnétisme, gravimétrie, filtrage, linéaments, structure géologique.ViewShow abstract... A better exploitation of the gravity data by emphasizing more information is compared to those provided by the residual map. The interest of such transformations was raised a long time ago and several methods of calculation were developed (Gérard and Griveau, 1972) and successfully applied (Everaerts and Mansy, 2001;Khattach et al., 2004;Najine et al., 2006). ...... Evaluation of the directions of the contact dips of linear structures is ensured through the upward continuations of the residual gravity map at different altitudes (500, 1000, 2000 and 3000 m), followed by the determination of the horizontal gradient maxima for each level. The progressive migration of these maxima while the upward altitude is increased indicates the dip direction (Archibald et al., 1999;Khattach et al., 2004). The values of the upward continuation altitudes were selected arbitrarily; however two main factors conditioned such a choice, in order to: (1) realize continuations at altitudes sufficiently far apart to show the displacements of the horizontal gradient maxima at different levels for the dip contacts, and (2) to prevent these levels from being so far apart that the effect of the gravity contacts would be attenuated. ...2010 JAES HAOUZ CENTRALDataFull-text availableFeb 2015

P. Ayarza

Ramon Carbonell

Antonio TeixellMoroccoView... Les maximas du gradient horizontal calculé selon la méthode de Blakley et Simpson (1985) [17], permettent la localisation des contacts géologiques liés à la présence de failles et discontinuités géologiques [16] ; [18]. ...... Le pendage des contacts géologiques peut être déterminé par le prolongement vers le Haut de la carte du gradient horizontal à divers altitude [19] Les niveaux de prolongement les plus élevés correspondent au structures géologiques les plus profondes [18] ; [20]. ...Contribution of Gravimetry to the hydrogeological recognition of the area of Wadi Righ –OuarglaArticleFull-text availableFeb 2017

Oualid Melouah

Zeddouri AziezGravimetry is a geophysical methods often used in oil exploration and mining research but rarely in the hydrogeological field, the aim of this work is to exploit the gravimetric data to develop a structural model of the region of Oued Righ-Ouargla has less than 1,000 m depth and perform a litho-stratigraphic modeling of subsurface formations to assess the ability of a karst formation of the terminal complex water table (Eocene Senonian). Multiple filtrations and signal processing techniques for gravimetric datas were operated such as the Euler Déconvolution, the analytical signal and the horizontal gradient. The results were used to evaluate the potential of karstification in the area and to model the phenomenon; the subsurface structural mapping has also led to the relationship between the well productivity and network of faults and fractures.ViewShow abstract... The Triffa basin, which forms the lowermost reach, is bordered by the Beni Snassen mountains to the south and the Kebdana mountains to the north (Fig. 2a;Ruellan, 1971;Boughriba et al., 2006). Both mainly consist of Mesozoic carbonate rocks, sandstone and slate formations (Ruellan, 1971;Khattach et al., 2004). ...... The model of athermal detrapping first proposed by Huntley (2006) and modified by Kars et al. (2008) was used to estimate sample specific field saturation (n/N) ss (Huntley and Lian, 2006), in which the natural IRSL intensity is governed only by the competing rates of signal accumulation due to environmental radiation and signal loss by anomalous fading (Kars et al., 2008). We used a 15% acceptance threshold of the environmental steady state level (Guralnik et al., 2015;King et al., 2016) in order to account for the uncertainty of interpolating a D e value onto a dose response curve close to saturation (Wintle and Murray, 2006). ...Successful combination of electron spin resonance, luminescence and palaeomagnetic dating methods allows reconstruction of the Pleistocene evolution of the lower Moulouya river (NE Morocco)ArticleApr 2018QUATERNARY SCI REV

Mathieu Duval

Melanie Bartz

Gilles Rixhon

Helmut BrücknerBased on a combination of Electron Spin Resonance (ESR) dating of quartz, luminescence dating of K-feldspar and palaeomagnetism, this study presents the first chronostratigraphic framework for the Pleistocene fluvial deposits of the lower Moulouya river in the Triffa basin (NE Morocco). K-feldspar pIRIR225 and pIRIR290 signals of all samples are saturated, suggesting fluvial deposition at least as early as the Middle Pleistocene (∼0.39–0.80 Ma). Consequently, further chronological information was obtained with ESR dating of quartz grains from the ancient Pleistocene fluvial deposits. As for ESR, the multiple centres approach provides equivalent dose values derived from the Al and Ti centres that mostly agree within 1σ-error, suggesting complete signal resetting from the former during fluvial transport. ESR dating results yield Calabrian deposition ages for all river profiles from ∼1.1 to ∼1.5 Ma. These ages are remarkably consistent with the palaeomagnetic results: the occurrence of mostly reversed polarity in the deposits indicates a Matuyama age ( 0.78 Ma). While low incision rates in the Triffa basin (0.025 ± 0.003 mm/a) related to thrusting activity during the Calabrian could be inferred, the fluvial record points to an acyclic and discontinuous sedimentation pattern over the last ∼1.3 Ma. It thereby probably rules out climate as the main driver for fluvial aggradation in the lowermost sedimentary basin. At a regional scale, several indicators point to transient fluvial response resulting from major Quaternary tectonic activity along the Beni Snassen gorge, located directly upstream of the investigated basin. We suggest that a capture event at the margin of the uplifting Beni Snassen massif occurred between 1.04 and 1.36 Ma at the latest and subsequently led to the creation of the gorge.ViewShow abstract... Thus, different mathematical transformations have been applied, namely the tilt angle ( Fig. 4) (Miller and Singh on 1994), in order to map out the inlier boundaries in the massif Jbel Saghro. Finally, the method of local maxima ( Fig. 6) (Khattach et al. 2004(Khattach et al. , 2006Vanié et al. 2005) was applied on the horizontal gradient ( Fig. 5) (Cordell and Grauch 1985) in order to establish a structural mapping of the geophysics lineaments. ...... The calculation of the local maxima was realized according to the method to develop by Blakely and Simpson (1986). This processing allows the localization of geophysical lineaments and the determination of their dips (Bektas et al. 2013;Buyuksarac 2007;Khattach et al. 2004Khattach et al. , 2006Vanié et al. 2005). The linear contacts correspond to faults while the circular shape contacts are the limits of diapers or intrusive bodies. ...Contribution of the geomagnetism to the region of the massif Jbel Saghro geology, Eastern Anti-Atlas, MoroccoArticleFull-text availableNov 2017

Miftah Abdelhalim

Driss El AzzabAhmed Attou

Ahmed ManarOur investigation relates to the interpretation of the magnetic data of Jbel Saghro, by aeromagnetic processing using Geosoft and ArcGis software. The data were obtained from digitizing the preexisting maps. From the magnetic field anomaly maps, different anomalies were identified with differences in intensities, sizes, and shapes and in being isolated or interfered. The directions are in general ENE-WSW, NNW-SSE, W-E, and NW-SE which are in good agreement with the general tectonic structure of the region. In order to correspond the anomalies to their natural sources and their geometrical configuration, it was necessary to calculate the residual polar. This avoids the presence of two lobes for the same source, what makes it possible to delimit the geological sources laterally. Thus, the attribution of each magnetic anomaly to its geological source becomes possible. Indeed, generally magnetic anomaly of strong intensities and big wavelengths is associated to very magnetized structures related to the Precambrian basement, and the negative a.m. is connected to structures of weak magnetization located in general in the cover. The application of the tilt angle filter allowed the localization of the outcrops of the inliers and new geophysical lineaments. On the other hand, the local maxima of the horizontal gradient made it possible to reveal the large structural features concerning the main tectonic events of the area.ViewShow abstract... Les cartes gravimétriques renferment des gradients et des anomalies de faible amplitude souvent masquées par les anomalies régionales. Il est donc nécessaire d appliquer à ces cartes des traitements appropriés pour identifier les hauts et les bas gravimétriques et localiser les zones à forts gradients (Nabighian 1984;Moreau et al. 1997;Hornby et al. 1999;Khattach et al. 2004Khattach et al. , 2006Aqil et al. 2010;Keating et Pinet 2011). ...... 6 et 7). Cette analyse est largement appliquée dans l interprétation des cartes gravimétriques et magnétiques (Archibald et Bochetti 1999;Hornby et al. 1999;Everaerts et Mansy 2001;Khattach et al. 2004;Vanié et al. 2005;Chennouf et al. 2007;El Gout et al. 2009;Abderbi et Khattach 2010;Aqil et al. 2010). Elle est basée sur l utilisation conjointe des techniques de prolongement vers le haut et du gradient horizontal. ...Fonctionnement hydrogéologique du bassin de la Bahira (Maroc central) : apport de l’analyse des données géologiques et gravimétriquesArticleFull-text availableJul 2014CAN J EARTH SCI

Morad Karroum

Abdennabi EL MANDOUR El MandourNoureddine Khalil

Driss KhattachCette étude, basée sur l’analyse des données gravimétriques, a pour but d’améliorer la connaissance des structures géologiques de la plaine de la Bahira (Maroc central) qui contrôlent l’écoulement des eaux souterraines. La carte de l’anomalie résiduelle a d’abord été calculée à partir de la carte de l’anomalie de Bouguer en soustrayant un gradient régional. Elle fournit des informations sur la variation de la densité dans la plaine de la Bahira. Plusieurs hauts et bas gravimétriques qui indiquent la présence des zones soulevées (hauts) et des zones effondrées (bas) ont été mises en évidence. La superposition de la carte piézométrique de la plaine de la Bahira et de la carte de l’anomalie résiduelle a montré que les eaux souterraines s’écoulent des zones de recharges de Ganntour, Jbilet et Rehamna (hauts gravimétriques) vers les dépressions fermées de Sed El Mejnoun et du lac Zima (bas gravimétriques). Afin de localiser les différentes failles qui contribuent à la structuration de la zone d’étude, les techniques du gradient horizontal et du prolongement vers le haut ont été appliquées pour déterminer les linéaments gravimétriques qui représentent l’emplacement des contrastes de densité. Trois familles de fractures ont été mises en évidence. Elles participent au contrôle de l’écoulement souterrain.ViewShow abstract... Cette méthode est particulièrement valable pour l étude des contacts linéaires comme ceux des failles régionales, des grands chevauchements, etc. (Khattach et al. 2004, Chennouf et al. 2004). C est d ailleurs ce genre de discontinuités qui contrôle principalement la structuration géologique de la zone d étude. ...Gravimetry contributions to the study of the collapsed structures in northeast Tunisia: hydrogeological implicationsArticleFull-text availableJan 2013

Sarra Ouerghi

Noamen Rebai

Samir Bouaziz

Hakim GabtniView... On each level, the maxima of the horizontal gradient are localized. The overlay of horizontal derivative maxima at several heights underlines the various contacts and shows their dips (Khattach et al. 2004(Khattach et al. , 2006El Gout et al. 2009, 2010, 2011. In the case of a dipping contact, the maxima move down dip with increasing continuation height. ...Tectonic control of mineralization in the Taourirt–Oujda Corridor–Horst belt (north-eastern Morocco): geophysical evidenceArticleFull-text availableFeb 2014

Radia El Gout

Driss Khattach

Mohammed-Rachid HouariAbstract In this study, we present a magnetic lineaments map of the Horst belt and the Taourirt–Oujda Corridor in the northeastern of Morocco. This map is performed by means of a multi-scale approach for detecting and analysing magnetic sources boundaries and contacts. Two filtering methods horizontalgradient coupled to upward continuation technique and Euler deconvolution have been applied to ground magnetic and aeromagnetic anomalies. The result map is consistent with many faults already recognized or supposed by the traditional structural studies and highlights new ones by specifying their layout and dips. The results show clearly the relationships between the structural setting of the Horst belt and mineralization deposit. The ore deposit is described as mainly associated with shear zones strikes in NE–SW to ENE–WSW and NW–SE direction. This significant result suggests an epigenetic origin of the mineralization.ViewShow abstract... Gravity is an important geophysical method, used to identify deep structures and to reveal fault systems (Blakely and Simpson 1986;Everaerts and Mansy 2001;Khattach et al. 2004;Arfaoui et al. 2011). In our case, gravity data are an important supply to the structural interpretation by the confirmation of geological mapping faults and by the identification of the morphology of Bazina Triassic structure. ...Major faults, salt structures and paleo-ridge at tectonic nodes in Northern Tunisia: contribution of tectonics and gravity analysisArticleFull-text availableNov 2014

Wissem Marzougui

Fetheddine Melki

Mohamed Arfaoui

Fouad ZargouniStructural analysis, fault kinematics, detailed geological mapping and gravity analysis provide a new approach regarding to the tectonic-model of the Bazina–Aouana structure (North–Eastern Tunisia). They show that the Bazina Triassic outcrops, such as several other structures, are related to the NE and E trending major faults junction, controlling its halokinesis, and pouring out to the NW of tectonic nodes in the collapsed compartment. During the Eocene and Tortonian compressive phases, the Triassic materials previously forming a intumescence in the NE and E major faults intersection have acted as a barrier on which collided the Aouana structure. Therefore, this structure is blocked between overthrust nappes and the Bazina paleo-ridge forming an imbricated zone overlapping the Triassic materials. This paper aims to present a new evolutionary geodynamic model for the Bazina–Aouana structure related to the tectonic node easing the Triassic salt mobilization, the paleo-ridge formation and the development of a collapsed zone. By comparing with previous works, this model is likely applicable to the important Triassic outcrops of Northern Tunisia.ViewShow abstract... In order to study these discontinuities, we have conducted an analysis based on the horizontal gradient coupled with upward continuation and Euler deconvolution. These approaches have been successfully used in detailed studies, such as in reference [12] and have led to delineation of the major geological structures and the mapping out of the different tectonic lineaments that affect the study area. ...Delineation of Lineaments in South Cameroon (Central Africa) Using Gravity DataArticleFull-text availableJan 2013OJGOwona Angue Marie Louise ClotildeTabod Charles Tabod

Séverin Nguiya

Alain Pierre TokamView... The vertical and/or horizontal derivatives of gravity fields have been used to obtain source parameters when interpreting gravity data [20] [25]- [27]. Horizontal gradient magnitude of the Bouguer gravity anomaly has been associated to the upward continuation of the field to characterize faults [28]. Nevertheless, an offset in the maximum of the horizontal gradient magnitude from a position directly above the geological contacts can occur; this can be the case when these contacts are not steep or when many of them are close to each other [29]. ...Gravity Model for an Anomalous Body Located in the NW Portion of the Douala Sedimentary Sub-Basin, Cameroon (Central Africa)ArticleFull-text availableJan 2014OJG

Eric N. NdikumCharles T. TabodBernard Z. Essimbi

Constant NoutchogweView... To determine the source parameters in gravity interpretation, the vertical derivatives and/or horizontal derivatives of the gravity field have been used commonly (Cordell, 1979;Cordell and Grauch, 1985;Blakely and Simpson, 1986;Marson and Klingel, 1993). For example, Khattach et al. (2004) associated the horizontal gradient magnitude of the Bouguer gravity anomaly to the upward continuation of the field to characterize faults of the Triffa basin in North Morocco. However, it must be noted that the maxima of the horizontal gradient magnitude can be offset from a position directly above the geologic contacts, especially when contacts are not steep or when several contacts are close together (Grauch and Cordell, 1987). ...A Gravity Model Study for Differentiating Vertical and Dipping Geological Contacts with Application to a Bouguer Gravity Anomaly Over the Foumban Shear Zone, CameroonArticleFull-text availableJan 2011

Constant Noutchogwe

Charles Tabod

Fidèle KoumetioEliezer Manguelle-DicoumThe determination of the type of the contacts from gravity data is an important step in the determination of a model of geological structures. In this paper we present the multi-scale horizontal derivative of the vertical derivative (MSHDVD) method which allows us to efficiently differentiate vertical from dipping geological contacts and to determine the direction of dip. The method determines the locations of the maxima of the horizontal gradient of the vertical derivative of upward continued gravity field at different height levels. The technique to compute the vertical derivative at different levels is also suggested. The MSHDVD method is tested on synthetic data and on the Bouguer gravity anomaly over the Foumban Shear Zone (FSZ) in Cameroon, within an area around Foumbot, where the granite-gneiss basement is widely covered by volcanic rocks of the Cameroon Volcanic Line. The MSHDVD method shows the presence of a deep fault, oriented N68°E and dipping towards southeast.ViewShow abstract... Cette méthode est particulièrement valable pour l étude des contacts linéaires comme ceux des failles régionales, des grands chevauchements, etc. (Khattach et al. 2004, Chennouf et al. 2004). C est d ailleurs ce genre de discontinuités qui contrôle principalement la structuration géologique de la zone d étude. ...Apport de la gravimétrie à l étude des structures effondrées du Nord-Est de la Tunisie: Implications hydrogéologiquesArticleFull-text availableAug 2013HYDROLOG SCI J

Sarra Ouerghi

Riadh Rebai

Hakim Gabtni

Samir BouazizCette étude basée sur l’analyse des données gravimétriques a pour but d’améliorer la connaissance des structures effondrées du Nord-Est de la Tunisie. La carte de l’anomalie résiduelle a d’abord été calculée à partir de la carte de l’anomalie de Bouguer en enlevant un gradient régional. La résiduelle calculée fournit des informations sur la variation de la densité dans les bassins sédimentaires de l’Oued Chafrou-Khlidia, de Mornag et de Grombalia. Afin de mettre en évidence les différentes structures géologiques (failles, bassins, etc.) dans le secteur d’étude, différentes techniques (gradient vertical, gradient horizontal, prolongement vers le haut, déconvolution d’Euler) ont été appliquées à la carte gravimétrique des structures effondrées du Nord-Est de la Tunisie. Les résultats obtenus ont permis de dresser une carte structurale présentant le système de failles responsable de la structuration de la zone d’étude. Cette carte constitue un document très utile pour orienter les recherches hydrogéologiques futures qui seront menées dans ces plaines.Editeur Z.W. KundzewiczCitation Ouerghi, S., Rebai, N., Gabtni, H., Farhat, B., et Bouaziz, S., 2013. Apport de la gravimétrie à l’étude des structures effondrées du Nord-Est de la Tunisie: implications hydrogéologiques. Hydrological Sciences Journal, 58 (6), 1361–1373.ViewShow abstract... Computation of the horizontal derivative maxima of the RTP magnetic anomaly or gravity anomaly has been achieved by the method proposed by Cordell and Grauch (1985), Blakely and Simpson (1986), and Roest and Pilkington (1993) for different values of anomaly upward continuations. This method, which assumes that upward continuation provides a mean to image sources at deeper crustal depths, is a useful tool to assess the dip of magnetic or density (Archibald et al. 1999;Khattach et al. 2004Khattach et al. , 2006. This multiscale analysis method gives the best results for isolated linear anomalies because upward continuation tends to merge adjacent anomalies as the continuation height increases (Pinet et al. 2008). ...Structure and peridotite of Gibraltar arc southern bloc: gravimetric and aeromagnetic evidencesArticleFull-text availableMar 2015

Najib Amar

Ali Azdimousa

Mounir Amar

Driss KhattachThe southern Gibraltar Arc’s bloc (Rif’s belt) has a complex geological setting including peridotites outcropping in the Rif and Betic. They are among the largest infracontinental mantle rock outcrops worldwide. In spite of several geological studies, the deep structure of this area remains poorly defined. The aim of this work is giving a reliable geometry of the major geological structures of the Rif, especially the peridotite bodies and faults or geological contacts. The results obtained from a multiscale analysis of geological contacts applied to gravity and aeromagnetic data were used to generate a structural map of the studied area. This method in association with the Euler method allowed estimating the strike direction, shape, dip, and depth of contacts. The map gives a model of the region and confirms the existence of several faults, localized or inferred, from former geological studies. This study suggests a large extension of the Beni Bousera peridotites on the offshore from Jebha to Ceuta, and highlights an extended anomaly related to deeper crops probably ophiolite remnant of the suture zone.ViewShow abstract... For each upward continuation of the Bouguer anomaly map, the HGMs maxima were calculated and located. Superposing the maxima of various upward continuations makes it possible to determine the direction of dip for the different lineaments (faults), expressed by the change of the positions of these maxima according to the altitudes of the upward continuations (Archibald et al., 1999;Khattach et al., 2004). ...ArticleZaghdoudi Nov2020ArticleOct 2020

Sabrine Zaghdoudi

Mouna Ben Alayet

Ali Kadri

Mohamed GasmiThe Oued Gueniche plain is located in the northeastern Tunisia. It is a part of the Bizerte Neogene molassic basin, developed at the front of the Alpine chain (The Maghrebides). The subsurface structure of this area is not enough explored and was subject of controversial interpretations. Gravity and seismic data acquired in the northeast of Tunisia were used to specify the subsurface structural configuration and the formation mechanism of the OuedGueniche plain, as well as, its relationship with the surrounding folds. A total number of 664 gravity measurements were used to define the density distributions below the surface in the study area. The complete Bouguer gravity anomaly was performed with a reduction density of 2.4 g/cm3. Bouguer anomalies range from 9.5 to 34.8 mGal, high anomalies coincide with the Oued Gueniche plain in the northwest while weak anomalies are located on the southern part of the study area. The main NE-SW anomalies are superposed to the geologicalstructures.The power spectrum of gravity data shows that the calculated average depth to the top of regional gravity sources is approximately 4 km while that of local (or residual) sources is approximately 0.6 km. The techniques for locating the limits of anomalous structures and estimating their depths (tilt derivative (TDR), Euler deconvolution (ED) and analytical signal (AS)) were applied to the Bouguer anomaly map to further specify the undergroundgeological characteristics. The maxima of the horizontal gradient magnitudes (MGH) of Bouguer anomalies, upward continuated at different altitudes, revealed several NE-SW and E-W trending lineaments. A three-dimensional (3D) inversion model of gravity data has been developed for the Oued Gueniche plain in order to follow the distribution of densities.In addition, the interpretation of seismic profiles indicates that the central part of this plain is marked by the diapirism of Triassic rocks.The combination of these results with those of the surface (geological map and shallow hydrogeological boreholes) has led us to propose a kinematic model of the Bizerte region since the Middle Miocene and to update the structural scheme. Then, the NE-SW major faults (e.g. the newly defined Sfaia-Metline fault) and the NW-SE secondary ones have controlled the paleogeography and the structuration of the study area.ViewShow abstract... The acquired data include the responses of deep structures and enable calculations of a residual gravity anomaly, which should be distinguished from a regional background gravity anomaly. The horizontal gradient techniques coupled with the upward continued maps [e.g., Everaerts and Mansy 2001, Khattach et al. 2004, Vanié et al. 2005, Ayed et al. 2006, Ayed-Khaled et al. 2012 show density contrasts and provide information allowing to delineate geological units [Cordell andGrauch 1982, Blakely andSimpson 1986]. The effects of high wave lengths were assessed from upward continued maps at altitudes of 3 km, 5 km, 10 km, and 20 km. ...Amira et al.2015DataFull-text availableNov 2015

Mohamed AtawaAmira Ayed-Khaled

Taher Zouaghi

Ghanmi MohamedView... At the Tunisian scale, this study is primarily a geophysical application for the characterization of metamorphic aquifers. In terms of methodology, the innovation of the present study consists of the application of two geophysical methods having different investigation depth and generally used separately in hydrogeological studies, namely: vertical electrical soundings (e.g., Gasmi 2002;Zouhri et al. 2004;Asfahani 2006;Gouasmia et al. 2006;Ben Lasmar et al. 2013, 2014 and gravity survey (e.g., Khattach et al. 2004;Najine et al. 2006). The aim of the combined application of these two geophysical methods in this study is to characterize two types of aquifers (alluvial and metamorphic) in order to determine favorable areas for exploitation of groundwater for irrigation. ...Geophysical Contributions to Hydrogeological Study in the Chemtou–Sidi Miskine Agricultural Sector (Northwestern Tunisia)ArticleFull-text availableFeb 2017Nat Resour Res

A. AmiriMohamed Ben Youssef

Rihab Guellala

R. Ben LasmarThis study presents an example of the use of geophysics for agricultural water management. Borehole data, gravity measurements and vertical electrical soundings were used to reconstruct a precise hydrogeological scheme of the Chemtou–Sidi Meskine area (Northwest of Tunisia) in order to assist exploitation and judicious management of the underground water resources for irrigation. The Chemtou–Sidi Meskine area belongs to Mejerda basin, the most important agricultural sector in Tunisia. It is characterized by the coexistence of alluvial and basement aquifers, which are very scare in this country. The computed gravity maps emphasize an E–W lineament separating Hairech metamorphic formations and Mejerda alluvial deposits. The apparent resistivity maps confirm the presence of this lineament. The interpreted vertical electrical soundings are correlated with lithological columns to give more accurate structural patterns. The resulting geoelectrical cross sections highlight a normal fault network that collapsed metamorphic aquifers, controlled the Quaternary alluvial aquifers thickness and created closed areas with high water salinity that is unfavorable for exploitation.ViewShow abstract... The aim of this study is to enhance knowledge and understanding of the Zaghouan aquifer system by: (1) analysis of existing borehole data, such as well logs, to identify the various water reservoirs and follow their lateral evolution through lithostratigraphic correlations; (2) application of geophysics and remote sensing to construct a complete structural map including both surface fractures and deep tectonic features that control the aquifer systemÕs geometry and behavior; and (3) analysis by application of two exploration methods, each suited to a different investigation depth, namely gravity for subsurface investigation (Khattach et al. 2004;Farhat et al. 2010;Hamed Ferjani et al. 2018) and satellite imagery for surface investigation (Youan Ta et al. 2008;Gnamba et al. 2014;Gannouni and Hamzaoui 2015). (1) Zaghouan geological map (after Bajanik et al. 1977). ...Enhanced Characterization of Water Resource Potential in Zaghouan Region, Northeast TunisiaArticleMar 2020Nat Resour ResA. Hamed Ferjani

Sonia Gannouni

Rihab Guellala

mohamed hedi InoubliThis study presents a range of approaches to achieve enhanced characterization of the Zaghouan aquifer system (northeastern Tunisia). Existing water borehole data were analyzed to identify the different reservoir formations, while satellite imagery is analyzed to determinate the superficial lineaments affecting these formations. To define the deep structures determining the geometry of the Zaghouan aquifer system, lithostratigraphic correlations were constructed and analyzed supported by both quantitative and qualitative assessment of gravity measurements. The available lithological columns and their corresponding well logs reveal different carbonate and detritic reservoirs. The carbonate reservoirs consist of Jurassic, Cretaceous and Eocene limestones, whereas the detritic ones are composed of Oligo–Miocene sandstones and Plio-Quaternary to Quaternary sands and gravels. The structural map obtained from processing the satellite imagery confirms several lineaments drawn on the geological map, such as the Zaghouan fault, but also reveals new ones hitherto unrecognized. The intersections of the detected lineaments explain the occurrence of many springs in the area offering potentially favorable opportunities for accessing water resources in fractured aquifers. Analysis of lithostratigraphic correlations shows notable variations in the thickness, depth and composition of reservoir formations. Gravity data interpretation gives more precision by highlighting buried structures and discontinuities with different directions and depths. The delineated tectonic features demonstrate an aquifer system compartmentalized in raised and subsided blocks. The raised compartments may constitute continental divide areas and preferential aquifer recharge zones, while the sunken ones contain a multilayer aquifer composed of Quaternary and Pliocene reservoirs overlying multiple permeable layers, Tertiary and/or Mesozoic in age.ViewShow abstract... Euler deconvolution was calculated for different altitude upward continued magnetic anomalies. This analysis was done under the assumption that upward continuation provides a mean to image sources at deeper crustal depths, allowing obtaining information about the dip of magnetic structures (Archibald et al., 1999;Khattach et al., 2004Khattach et al., , 2006Fedi and Pilkington, 2012). However, interpretations in regions affected by interference between sources were conducted with caution due to possible ambiguities (Fedi and Pilkington, 2012;Pinet et al., 2008;Amar et al., 2015). ...Aeromagnetic patterns in Southern Uruguay: Precambrian-Mesozoic dyke swarms and Mesozoic rifting structural and tectonic evolutionArticleFeb 2020TECTONOPHYSICS

Pablo Núñez Demarco

Henri Masquelin

C. Prezzi

Leda Sanchez BettucciNew high-resolution airborne magnetic data of Uruguay allowed constructing new maps concerning the spatial distribution of dyke swarms, main faults and other magnetic bodies, which compose the Uruguayan Shield. We combined geophysical analyses (vertical derivatives, upward continuation, Euler deconvolution), structural analyses of the magnetic maps and previous geological data in order to discriminate the main structural features of the Uruguayan Shield and contribute to a better understanding of its tectonic evolution.The magnetic maps revealed several outstanding features in the Uruguayan Shield. The Paleoproterozoic dyke swarm is larger, denser, more widespread and complex than originally thought, suggesting a possible plume origin. In addition, a new Mesozoic dyke swarm, as complex as the previous one, was identified crosscutting the Paleoproterozoic dyke swarm and the Neoproterozoic orogenic structures. Moreover, this swarm is connected to volcanic calderas in the Merín basin, and shows displacements along Neoproterozoic shear zones, in the magnetic maps, revealing its brittle reactivation during Mesozoic times.The new observations clarify how Proterozoic basement structures controlled the development of the Mesozoic rift. Paleoproterozoic dyke swarms were reactivated as normal faults and Neoproterozoic structures hindered the rift growth, deflecting the deformation in transcurrent movements. Meanwhile, the Mesozoic dyke swarm was developed in a perpendicular direction to the Neoproterozoic structures. Moreover, these findings contradict the current rift model for Uruguay and rise a new model in which the Mesozoic rift developed as two rift basins connected by a central transfer zone, generated by the reactivation of Dom Feliciano Belt structures, between the Sierra Ballena and Sarandí del Yí Shear Zones.ViewShow abstract... Map. The horizontal gradient is the best way to localize geological contacts in the basement, especially faults by determining their track, dip and their degree of importance [47,48]. Indeed, the limit between two blocks characterized by different susceptibilities is underlined by the line representing the local maxima value of this gradient. ...Evidence of Major Structural Features over the Pan-African Domain in the Bertoua-Mbangue Area (East Cameroon) from a Multiscale Approach of Modeling and Interpretation of Aeromagnetic DataArticleFull-text availableMar 2019Yandjimain Justine

Olivier Ulrich Owono

Theophile Ndougsa Mbarga

Arsene MeyingThe aim of this study is to investigate crustal structures from East Cameroon, using aeromagnetic data. The modeling of aeromagnetic data is conducted using the Oasis Montaj 8.0 software. The total magnetic intensity map reduced to the equator (RTE-TMI) shows important anomalies features, namely, the Northern East magnetic anomalies of high amplitude, the Southwest where very low values of the magnetic intensity were observed, and a corridor with negative values relatively high, separating the anomalies. The horizontal gradient map shows on the one hand brittle and folded structures carried out in the area of study and on the other hand various rectilinear, narrow, and short-wave anomalies that can be classified as a family of little faults. The maxima observed on the RTE-TMI maps are correlated to intrabasement contacts; and the map derived from Euler’s solutions permitted to evaluate the depth of the geological accidents observed from the other filters. This map also reveals new faults with a depth greater than 5000 m. The lineaments identified in the Southwestern part could be linked to the Pan-African orogeny and seem to correspond to deep-seated basement structures, which are referred to the tectonic boundary between Congo Craton and the Pan-African orogeny belt. A 2 3/4 -D modeling confirmed the observations derived from the RTE-TMI and HGM maps analyses. It shows intrusive bodies composed of gneiss and porphyroid granite and some domes with their roof situated at various depths not exceeding 1800 m from the surface. The structural map of the study area shows the trending of the structural features observed, namely, NE-SW, NW-SE, ENE-WSW, and WNW-ESE, respectively, while the E-W and N-S are secondary orientation of the observed tectonic evidence. Moreover, circular anomalies observed over the area are assimilated to intrusions of high magnetic materials or to granitic domes.ViewShow abstract... The acquired data include the responses of deep structures and enable calculations of a residual gravity anomaly, which should be distinguished from a regional background gravity anomaly. The horizontal gradient techniques coupled with the upward continued maps [e.g., Everaerts and Mansy 2001, Khattach et al. 2004, Vanié et al. 2005, Ayed et al. 2006, Ayed-Khaled et al. 2012 show density contrasts and provide information allowing to delineate geological units [Cordell andGrauch 1982, Blakely andSimpson 1986]. The effects of high wave lengths were assessed from upward continued maps at altitudes of 3 km, 5 km, 10 km, and 20 km. ...New evidence on the geologic setting of Medjerda Valley plain (northern Tunisia) from integrated geophysical study of Triassic evaporite bodiesResearchFull-text availableNov 2015

Taher ZouaghiAmira Ayed-Khaled

Mohamed Atawa

Ghanmi MohamedNew evidence on the geologic setting of Medjerda Valley plain(northern Tunisia) from integrated geophysical studyof Triassic evaporite bodiesViewShow abstract... The interest of this method has been mentioned for a long time [51]. The success of this method s application has been demonstrated by numerous previous studies [51,52,53,54,55,56,57]. The principle of this technique is to compute the horizontal gradient of the residual anomaly and its upwards continuations at different altitudes. ...Contribution of gravity data and Sentinel-1 image for structural mapping. Case of Beni Mellal Atlas and Beni Moussa plain (Morocco).ArticleFull-text availableJan 2018Ikram Boutirame

A. BoukdirAhmed AkhssasBrahim AghzzafThe present work is a combined study of gravity and Sentine-1 data for fracture mapping in the karstic massif of Beni Mellal Atlas and the adjacent plain of Beni Moussa. In order to locate the various faults that contribute to the study area structuring, the gravimetric contacts analysis method, based on the joint use of the horizontal gradient and the upward continuation at different altitudes, has been applied to the gravity data. To optimize the structural mapping in the study area, the gravimetric lineaments obtained were completed and correlated with the lineaments got from Sentinel-1 image. Four faults families of NE-SW; E-O; N-S and NWSE directions have been highlighted. There fault families are perfectly combined with the studied area’s surface water network, moreover, they corroborate with the previous geological and structural studies.ViewShow abstract... Gravity anomaly over a vertical contact is realized by a curve having a minimum for a weak density rocks and a maximum for a high density rocks (Briggs 1974;Khattach et al. 2004). The inflection point of the curve is in the equilibrium of this contact showing the maximum of the horizontal gradient. ...Preliminary structural configuration of the Goubellat Upper Cretaceous carbonate aquifers using gravity method (Northwestern Tunisia)ArticleFull-text availableJun 2018

Aymen NefziChokri Jlidi

Mohamed Dhaoui

Hakim GabtniGravity method can help locate hidden structural blocks bounded by faults related to the Upper Cretaceous carbonate aquifers of Goubellat region (Northwestern Tunisia). The Quaternary deposits are present over the majority of the Goubellat plain basin and cover the Upper Cretaceous carbonate. The produced residual gravity map supported by vertical and tilt angle derivatives was used to reveal the subsurface structural framework of the study area shaped by uplifted (high gravity anomalies) and downlifted areas (low gravity anomalies). The horizontal gravity gradient and Euler deconvolution maps were elaborated in order to locate major faults. These faults are primordial for the subsurface water recharge pathways. Finally, the presented lineament/structural map is very useful for large-scale structures and lineaments mapping giving the principal keys of the preliminary structural configuration of the Goubellat Upper Cretaceous carbonate aquifers.ViewShow abstract... At the Tunisian scale, this study is primarily a geophysical application for the characterization of metamorphic aquifers. In terms of methodology, the innovation of the present study consists of the application of two geophysical methods having different investigation depth and generally used separately in hydrogeological studies, namely: vertical electrical soundings (e.g., Gasmi 2002;Zouhri et al. 2004;Asfahani 2006;Gouasmia et al. 2006;Ben Lasmar et al. 2013, 2014 and gravity survey (e.g., Khattach et al. 2004;Najine et al. 2006). The aim of the combined application of these two geophysical methods in this study is to characterize two types of aquifers (alluvial and metamorphic) in order to determine favorable areas for exploitation of groundwater for irrigation. ...Une approche multidisciplinaire pour la recherche des ressources en eau dans un secteur touristique. Cas de la région de Tabarka (Nord‑Ouest de la Tunisie)ArticleFull-text availableFeb 2017HOUILLE BLANCHE

Rihab GuellalaRÉSUMÉ. – L’imagerie satellitaire, les sondages électriques verticaux, les diagraphies et les données de forages sontconjointement utilisés pour caractériser les aquifères de la région de Tabarka (Nord‑Ouest de la Tunisie) et déterminer leszones favorables à leur exploitation.Le traitement et le filtrage suivant différentes directions d’une image satellitaire Landsat TM 5 ont apporté des précisionsau schéma structural de la région en décelant des nouveaux linéaments tectoniques.Les enregistrements diagraphiques ont permis une précise restitution des colonnes lithologiques des forages préexistantset par conséquent l’étalonnage des sondages électriques, interprétés par abaques et logiciel.Les modèles géoélectriques résultants ont confirmé la présence des linéaments extraits de l’image satellitaire et ontdévoilé d’autres déformations cassantes et souples qui affectent les dépôts quaternaires.Les mécanismes de sédimentation dans les plaines alluviales et les traits tectoniques mis en évidence dans cette étude ontcontrôlé la distribution de l’aquifère alluvionnaire et ses caractéristiques.La zone méridionale de la plaine qui correspond à une structure soulevée ainsi qu’à la partie amont des principaux ouedsexpose pour cet aquifère les valeurs les plus fortes de résistivité, d’épaisseur, de débit et de perméabilité et les plusfaibles valeurs de profondeur et de salinité de l’eau. Elle s’avère très favorable à son exploitation.Mots‑clés : imagerie satellitaire, sondages électriques, diagraphies, forages, aquifères, Tabarka, Tunisie.ViewShow abstract... The acquired data include the responses of deep structures and enable calculations of a residual gravity anomaly, which should be distinguished from a regional background gravity anomaly. The horizontal gradient techniques coupled with the upward continued maps [e.g., Everaerts and Mansy 2001, Khattach et al. 2004, Vanié et al. 2005, Ayed et al. 2006, Ayed-Khaled et al. 2012 show density contrasts and provide information allowing to delineate geological units [Cordell andGrauch 1982, Blakely andSimpson 1986]. The effects of high wave lengths were assessed from upward continued maps at altitudes of 3 km, 5 km, 10 km, and 20 km. ...New evidence on the geologic setting of Medjerda Valley plain (northern Tunisia) from integrated geophysical study of Triassic evaporite bodiesArticleFull-text availableDec 2015ANN GEOPHYS-ITALYAmira Ayed-Khaled

Taher Zouaghi

Mohamed Atawa

Ghanmi MohamedIntegrated gravity, two dimensional (2D) seismic and field data (lithostratigraphy and tectonic deformations) help to understand the structural setting of the Triassic evaporites in the Atlas Mountains of northern Tunisia. In the Medjerda Valley plain, Triassic outcrops are bounded by NE-, ENE-, and NW-trending faults. These faults have been reactivated and have controlled the basin framework. The gravity analysis included the construction of a gravity anomaly maps, and 2D gravity model. Corresponding gravity responses of the complete Bouguer anomaly, the residual gravity anomaly, and upward continued maps reveal that the Triassic evaporites do not have a neat gravity signature. 2D seismic profiles show rising structures of Triassic strata associated with Mesozoic and Cenozoic tectonic edifices. The seismic horizons, calibrated to outcrop and well data, reveal paleohighs and diapirs of Triassic strata that were existed during the Jurassic and Early Cretaceous. These structural features induced a lateral outpouring of evaporitic strata within Late Cretaceous strata. A NW–SE-trending gravity model, which crosses the Medjerda Valley plain, highlights geometry identified on seismic lines. In the Medjerda plain, Mesozoic extensional and transtensional movements were associated with rising of Triassic evaporites, thus resulting in diapiric structures. The Late Cretaceous-Eocene structural setting was marked by outpouring of locally extruded Triassic evaporites. The Tertiary and Quaternary times are marked by major contractional events, causing inversion of pre-existing tectonic edifices. This integrated geophysical study provides a greater understanding of the Thibar deep structure, and a new geometry model of the Triassic evaporite bodies in the North Tunisia. © 2015 by the Istituto Nazionale di Geofisica e Vulcanologia. All rights reserved.ViewShow abstract... If they are superimposed, the 299 corresponding lineament is vertical. However, if there is a displacement of the maxima with 300 the various prolongations, the lineament shows a dip with the same movement direction 301(Archibald et al., 1999;Khattach et al., 2004). Generally, the lineament can be a fault or a 302 ...Subsurface structure of Teboursouk and El Krib plains (dome zone, northern Tunisia) by gravity analysisArticleFull-text availableMar 2016J AFR EARTH SCI

Hadhemi Balti

Fatma Hachani

Ali Kadri

Mohamed GasmiGravity data was used to investigate sub-surface structure of the Teboursouk and El Krib plains belonging to the dome zone in the Northwest of Tunisia. Analysis of the gravity data included the computation of the Bouguer anomaly, the horizontal and vertical gravity gradients, the upward continuations, Euler deconvolution and analytic signal of high-resolution. The Bouguer anomaly map (d = 2.4 g cm−3) has provided information on the variation of the underground density and shown contrasting anomalous zones. The treatments applied to the Bouguer anomaly map have detected new deep faults and provided details on their dips and depths (exceeding 1500 m per places).ViewShow abstractContribution of Geophysics to the Management of Water Resources: Case of the Ariana Agricultural Sector (Eastern Mejerda Basin, Tunisia)ArticleFull-text availableDec 2014Nat Resour Res

R. Ben Lasmar

Rihab Guellala

Benen Sarsar

mohamed hedi InoubliIn Tunisia, the Mejerda basin is the most important agricultural sector. Identification of additional water sources and good management of current and new resources is required to maintain and increase its productivity. The present study concerns the Ariana region (north-east of Tunisia) covering the eastern part of Mejerda basin. Lithological columns, well logs, vertical electrical soundings, and gravity data were analyzed and interpreted to give more precise information for exploitation of the water resources of the Ariana region. Lithological columns, well logs, and geoelectrical models reveal that the permeable Quaternary alluvial deposits, the Upper Campanian–Lower Maestrichtian, Albian and Barremian limestones, and Valanginian–Hauterivian sandstones are the main aquifers in Ariana. Comparison of geoelectrical cross sections to the Bouguer anomaly map of the Ariana region reveals tectonic influence on the geometry of the aquifers. The folded structures attributed to the Tortonian compressive stress and the tectonic movements in N–S, E–W, NW–SE, and NE–SW directions have resulted in the compartmentalization of Ariana’s aquifers into subsided and raised blocks. This reconstituted geometry of the region influenced the depth of burial of permeable lithologies and inhibited groundwater circulation in some localities.ViewShow abstractGeometry, Recharge and hydrogeological functioning of reservoirs of the Western Haouz FIELD middle congress GUIDConference PaperFull-text availableSep 2014

Abdennabi EL MANDOUR El MandourThe Western Haouz plain and the Mejjate plain constitute a vast alluvial plain of about 2800 km2. The area is located between 30 and 80 km south-west of Marrakech city and it is characterized by a semi-arid climate. The morphology of the plain is known by a flat topography, monotone and it is drained by three rivers; Nfis river, Assif El Mal river and Chichaoua river.The compilation of Geological, Geophysical and hydrogeological data shows that the Western Haouz plain is divided into two parts, it is a synclinal form separated by Marmouta horst and Guemmassa horst. In the southern part, the Mejjate syncline is subsiding and shows a several formations from the shales of the Paleozoic to the alluvium of the quaternary. In the northern part, the syncline is less developed and it is formed by the conglomerates of the Mio-Pliocene and the alluvium of the Quaternary. The gravity map established shows positive anomalies due to the outcrop of the basement, and negative anomalies in the subsiding basins.Hydrogeologically, the geometry of the reservoirs and the groundwater circulation are controlled by geology (Rifts, flexure, anticline and syncline). The southern part of the plain between the Marmouta anticline and the piedmont of the High Atlas Mountains shows two aquifers; the unconfined aquifer housed in thick formations of Quaternary and Mio-Pliocene; and the confined aquifer housed in dolomitic limestones of the Cenomanian-Turonian. The confined aquifer is fed at the northern flank of the High Atlas showing karts morphology and high cliff of limestone slab of the Turonian (Station 2). The outlet of the deep confined aquifer is shown by Abainou source with a variation between 300 and 600 l/s (Station 3) south of the Marmouta anticline and constitutes a barrier for the deep waters flow circulations.Isotopic dating of groundwater analysis of C14 shows a significant age difference between the groundwater of the Western Haouz; the ancient waters appear at forty Khettaras elongated along the Assoufid fault (Station 1), the Abainou water source and the borehole No 397/52 water capturing the Cenomanian-Turonian confined aquifer have an age of about 5000 years and finally the waters of the unconfined aquifer are the younger.ViewShow abstract2.5D Modelling of Aeromagnetic Data and their Mining Implications over the Ngaoundere Area (Adamawa Province, Cameroon)ArticleFull-text availableJan 2019IJG

Arsene Meying

Gouet Daniel

Theophile Ndougsa Mbarga

Olivier Ulrich OwonoViewApport des filtrages des anomalies gravimétriques dans la détermination des accidents tectoniques majeurs de l’Anti-Atlas (Maroc)Conference PaperSep 2006Vanie L. T. A.

Mohammed-Rachid Houari

Victor Corchete

Driss KhattachThe Anti-Atlas (Morocco) gravimetric map shows significant gravimetric anomalies bordered by high gradients due to density contrast of anomalies sources. Using the horizontal gradient method associated to upward continuation of this map permit to outline several gravimetric lineaments associated with. A structural map showing the spatial organization of the major faults affecting the Anti-Atlas domain has been established. Mots clés : Gravimetry; anomalies, horizontal gradient, upward continuation, faults, Anti-Atlas ; MoroccoViewShow abstractGravity Data from the Teboursouk Area (“Diapirs Zone”, Northern Tunisia): Characterization of Deep Structures and Updated Tectonic PatternArticleFull-text availableApr 2016

Fatma Hachani

Hadhemi Balti

Ali Kadri

Mohamed GasmiLocated between eastern segments of the Atlas and Tell-Rif orogenic belts, the “Dome zone” of northern Tunisia is characterized by the juxtaposition of various structures that mainly controlled the long geodynamic history of this part of the south-Tethyan Margin. To better understand the organization and deep extension of these structures, gravity data from the Teboursouk key area are proposed. These data include the plotting of Bouguer anomaly map and related parameters such as vertical and horizontal gradients, upward continuation and Euler solution. Compared to geological and structural maps available, they allow the identification of new deep structures and greater precision regarding the characteristics and organization of known ones; consequently, an updated structural pattern is proposed.ViewShow abstractContribution de la gravimétrie à l’étude de la structure profonde du Bassin de Bou-Houria (Maroc Nord-Oriental): Implications hydrogéologiquesArticleDec 2014HYDROLOG SCI J

Hicham Aqil

Kaufmann Olivier

Driss Khattach

Radia El GoutCette étude vise à améliorer la connaissance de la structure du bassin de Bou-Houria en se basant sur l’analyse et l’interprétation de données gravimétriques. Des cartes de l’anomalie résiduelle, du gradient vertical et du gradient horizontal ont été calculées à partir de la carte de l’anomalie de Bouguer. Ces cartes fournissent des informations sur la variation de la densité dans le sous-sol et permettent de mieux cerner la structure de la zone d’étude en mettant en évidence les principales unités et accidents tectoniques généralement masqués par les dépôts quaternaires. L’ensemble des résultats obtenus conduit à l’amélioration de la carte structurale de la zone d’étude, qui pourrait constituer un document de base pour orienter les futurs travaux d’exploration des eaux souterraines dans le bassin.ViewShow abstractNew insights into the structure of Om Ali-Thelepte basin, central Tunisia, inferred from gravity data; Hydrogeological implicationsArticleMay 2016J AFR EARTH SCIMongi Harchi

Hatem El Mejri

Hakim Gabtni

Abdallah Ben MammouThis work presents new results from gravity data analyses and interpretation within the Om Ali-Thelepte (OAT) basin, central Tunisia. It focuses on the hydrogeological implication, using several qualitative and quantitative techniques such as horizontal gradient, upward continuation and Euler deconvolution on boreholes log data, seismic reflection data and electrical conductivity measurements. The structures highlighted using the filtering techniques suggest that the Miocene aquifer of OAT basin is cut by four major fault systems that trend E-W, NE-SW, NW-SE and NNE-SSW. In addition, a NW-SE gravity model established shows the geometry of the Miocene sandstone reservoir and the Upper Cretaceous limestone rocks. Moreover, the superimposition of the electrical conductivity and the structural maps indicates that the low grade mineralisation of sampled water from boreholes is located around main faults.ViewShow abstractJoint evaluation of gravity, electrical and magnetotelluric methods for geothermal potential of fractured Aptian reefal carbonates in the Hmaima–El Gara area (Oued Serrat basin, Central–Western Tunisia)ArticleFull-text availableMay 2011

Mouez Gouasmia

Hakim GabtniHmaima–El Gara area is located in Central–Western Tunisia and is known as an important geothermal province. In this study, we attempt to delineate the subsurface structures of the area using integrated interpretation of gravity, electrical and magnetotelluric data. The Hmaima thermal aquifer, associated with fractured Aptian reefal limestones, is characterized by high gravity and high resistivity. Horizontal gradient and Euler deconvolution method has been applied to the gravity data and provided fast information about both the depth and trends of the shallower subsurface structures in the area. As several of the mapped lineaments correlate with published geological fault trends, the other lineaments may be indicators of new insights for hydrothermal exploitation in the Hmaima–El Gara area (economical potential favorite zones).ViewShow abstractFault pattern delineation and structural interpretation of the Gafsa trough (onshore central Tunisia) using gravity dataArticleMay 2011

Mohamed Dhaoui

Hakim GabtniThe purpose of this investigation was to identify subsurface lineaments in Gafsa trough (onshore central Tunisia) after gravity data analysis. The Bouguer and residual gravity maps show a gravity values decrease from west to east associated with subsidence variation and confirmed by a regional seismic reflection profile. The deep structural map of the study area is elaborated after the application of two methods: (1) the automatic lineament tracing after horizontal gravity gradient and (2) 3D Euler method. The dominant trends show approximately NW–SE, E–W, and NE–SW directions. Some of these trends are well correlated with the major faults systems. We can qualify the deep structuration model as a mosaic of quadratic blocks bounded by significant deep flower fault corridors. The elaborated structural map of the study area constitutes also a useful document for rationalizing the future petroleum exploration in the Gafsa trough.ViewShow abstractStructural and hydrogeological features of a Lias carbonate aquifer in the Triffa Plain, NE MoroccoArticleSep 2012J AFR EARTH SCIJ. SardinhaJúlio Carneiro

Yassine ZarhlouleBoubker El HouadiThe rising demand for water and the contamination of shallow water table aquifers has led authorities in NE Morocco to look for deeper groundwater resources in the Triffa Plain, namely in Lower Jurassic (Lias) dolomitic limestones. The liassic aquifer is of strategic importance for the development of the region, however, its hydrodynamic behaviour is poorly understood due to lack of hydrogeological data and block structure.This article presents a first effort towards understanding the structure and hydraulic behaviour of the aquifer. Exploration borehole data and results from geophysical campaigns were integrated into a GIS environment to build a preliminary model of the aquifer structure. The aquifer behaves as an unconfined aquifer in the northern part of the Béni Snassen Mountains (the recharge area), but as it dips to the north, it becomes confined by marls and shales of the Middle/Upper Jurassic. Even though piezometric level data are scarce, a tentative piezometric map was produced. Three blocks separated by NW–SE trending faults in a horst and graben structure, with distinct flow behaviours were identified: Berkane, Fezouane and Sidi Rahmoun blocks. Those blocks also show differences in hydraulic conductivity distribution. As a result of the reaction with the dolomitic limestones, the groundwater is of calcium-magnesium bicarbonate type. Groundwater temperature as measured in springs ranges from 29 °C to 37 °C in springs and constitutes a potential low enthalpy geothermal resource.ViewShow abstractContribution de la gravimétrie à l étude de la structure de la plaine de Mornag (nord est de la Tunisie): implications hydrogéologiquesArticleNov 2010HYDROLOG SCI JBoutheina Farhat

Ramdhane Benassi

Chokri Jallouli

Abdallah Ben MammouCette étude est basée sur l analyse des données gravimétriques; elle a pour but d améliorer la connaissance de la structure de la plaine de Mornag. La carte de l anomalie résiduelle a d abord été calculée à partir de la carte de l anomalie de Bouguer en enlevant un gradient régional. La résiduelle calculée fournit des informations sur la variation de la densité dans le bassin de Mornag. Afin de mettre en évidence les différentes structures dans le bassin, nous avons calculé la magnitude du gradient horizontal (MGH). Cette technique a permis de déterminer des linéaments gravimétriques représentant l emplacement des contrastes de densité, et de déduire une carte structurale de la zone d étude. Cette carte constitue un document très utile pour orienter l exploration des ressources en eau dans la plaine de Mornag.Citation Farhat, B., Benassi, R., Jallouli, C. Ben Mammou, A. (2010) Contribution de la gravimétrie à l étude de la structure de la plaine de Mornag (nord est de la Tunisie): implications hydrogéologiques. Hydrol. Sci. J.55(8), 1396–1404.ViewShow abstractStructural features of South-Adamawa (Cameroon) inferred from magnetic anomalies: Hydrogeological implicationsArticleJun 2010CR GEOSCI

Constant Noutchogwe

Fidèle KoumetioEliezer Manguelle-DicoumStructural directions of the southern part of the Adamawa plateau in Cameroon are highlighted by filters applied on the magnetic anomaly map. Determination of the magnitude maxima of (1) the horizontal gradient of the field reduced to the pole, and (2) the analytic signal, allowed a map to be produced showing various lineaments interpreted as the fault system of the studied area. In particular, the faults on the shaded relief map of the horizontal gradient magnitude suggest a slide to the left of the Foumban shear zone in the studied area. Interpretation of the observed anomaly along a profile directed SSE-NNW shows the presence of a magnetized body considered as an intrusion into the granitic basement of probably basaltic volcanic rocks, put in place during the reactivation of the Foumban shear zone. In addition, the observed correlation between the mapped structural directions, the sites of thermo-mineral springs and the hydrographical network shows that the results of this study will be helpful for further hydrogeological research in the studied area.ViewShow abstractA new emergent alpine front chain in central Tunisia (Maktar area): Filtering gravimetric data contributionArticleSep 2012

Ines Ezzine

Mohammed Jaffal

Fouad Zargouni

Ghanmi MohamedA residual anomaly gravity map of the Maktar area has been processed via several methods including horizontal gradient, upwardcontinuation, and Euler deconvolution to highlight structures hidden by sedimentary cover. These methods reinforce the existenceof several faults inferred from geologic studies. This work outlines deep or near-surface faults that had remained hiddenuntil now. The most important set of these faults is NE–SW trending, with depths in excess of 3,000 m. These faults limitthe Northwestern limb of Balouta massif and restrain the Northwestern side of Oued Ousafa syncline. This last fault presentsa thrust front which constituted the western continuity of a southern Tunisian thetys margin and a western Zaghouan scar prolongation.E–W striking faults refer to an arched beam of faults limiting Kessera plateau and others situated in the northern part ofthe Maktar plateau. N–S and NW–SE directions correspond to branches of less-apparent importance. Superposition of local maximaspecifies dipping vergence of different proven structures. Results from this work show the importance of gravimetric dataanalysis in Maktar area and provide new insight into Central Atlas Tunisia structure such as new emergent segment front Alpinechain. The proposed map could be a basis for planning future hydrogeological and petroleum research in this region.ViewShow abstractEtude géophysique par gravimétrie du Jebel Ech Cheid et de ses environs (Tunisie Septentrionale) : Implications structuralesConference PaperFull-text availableSep 2020

Fatma Hachani

Mohamed Gasmi

Ali Kadri

Jamila AbderbiEn vue de comprendre l agencement des différentes structures en profondeur de la zone du Jebel Ech Cheid et environs (Tunisie septentrionale), différentes techniques (gradient horizontal, prolongement vers le haut et déconvolution d Euler) ont été appliquées à la carte gravimétrique réalisée avec une densité de correction de 2.4. Les résultats obtenus ont permis de dresser une carte structurale synthétique complétant les données géologiques. Geophysical study by gravimetry of J. Ech Cheid and its surroundings (Northern Tunisia): Structural implications. Abstract: To understand the arrangement of deep different structures in the J. Ech Cheid and its surroundings area (Northern Tunisia), various techniques (horizontal derivative, upward continuation and Euler deconvolution) have been applied to the gravity data corrected with density equal to 2.4. From These results allow the production of a synthetic structural map making up the geological data.ViewShow abstractShow moreMultiscale edge analysis of potential field dataArticleFull-text availableMar 1999EXPLOR GEOPHYSNick Archibald

Paul Gow

Fabio BoschettiABSTRACT Mapping the three-dimensional distribution of rock properties from potential field data is a difficult and arduous task, with inherent ambiguity remaining a major problem. We apply a combination of automated interpretation procedures, based on multiscale wavelet analysis and three-dimensional visualisation methods, in an attempt to extract geometrical information from potential field datasets, and display this information in an easily understandable and intuitive way. The resulting visualisations are similar to ‘worm’ maps commonly produced by interpretation of aeromagnetic data, but are defined in three dimensions. The techniques are tested on a series of synthetic and observed datasets, of varying complexity and geographical scale. The tests show both the effectiveness of the technique as an aid to the geological interpretation of potential field maps and in its use for providing constraints on the three-dimensional geology . The results of the testing on synthetic datasets show that for certain geometries there is an intuitive relationship between 3D edge location and shape, and subsurface geometries. Such relationships prove particularly robust even under ‘noisy’ conditions where surface features (e.g. the response of laterites in magnetic datasets) mask the coarser scale features that characterise the broader geological picture.ViewShow abstractMagnetic interpretation in three dimensions using Euler deconvolutionArticleJun 1988

Alan Barry ReidJ. M. Allsop

Harald GranserI. W. SomertonMagnetic interpretation in three dimensions using Euler deconvolutionA. B. Reid*, J. M. Allsop*, H. Granser*,A. J. Millet and I. W. Somerton*ABSTRACTMagnetic-survey data in grid form may be interpretedrapidly for source positions and depths bydeconvolution using Euler’s homogeneity relation.The method employs gradients, either measured orcalculated. Data need not be pole-reduced, so thatremanence is not an interfering factor. Geologic constraintsare imposed by use of a structural index.Model studies show that the method can locate oroutline confined sources, vertical pipes, dikes, andcontacts with remarkable accuracy. A field exampleusing data from an intensively studied area of onshoreBritain shows that the method works well on real datafrom structurally complex areas and provides a seriesof depth-labeled Euler trends which mark magneticedges, notably faults, with good precisionViewShow abstractRessources en eau du Maroc, domaine du Rif et du Maroc orientalArticleJan 1971J.P. ThauvinViewMagnetic interpretation in 3-D using Euler DeconvolutionArticleJan 1990GEOPHYSICS

Alan Barry ReidJ. M. Allsop

Harald GranserI. W. SomertonMagnetic-survey data in grid form may be interpreted rapidly for source positions and depths by deconvolution using Euler s homogeneity relation. The method employs gradients, either measured or calculated. Data need not be pole-reduced, so that remanence is not an interfering factor. Geologic constraints are imposed by use of a structural index. Model studies show that the method can locate or outline confined sources, vertical pipes, dikes, and contacts with remarkable accuracy. A field example using data from an intensively studied area of onshore Britain shows that the method works well on real data from structurally complex areas and provides a series of depth-lavelled Euler trends which mark magnetic edges, notably faults, with good precision. -AuthorsViewShow abstractLocating edges of source bodies for magnetic or gravity anomaliesArticleJul 1986GEOPHYSICSRichard J. BlakelyRobert W. SimpsonCordell and Grauch (1982, 1985) discussed a technique to estimate the location of abrupt lateral changes in magnetization or mass density of upper crustal rocks. The final step of their procedure is to identify maxima on a contoured map of horizontal gradient magnitudes. Attempts to automate their final step. The method begins with gridded magnetic or gravity anomaly data and produces a plan view of inferred boundaries of magnetic or gravity sources. The method applies to both local surveys and to continent-wide compilations of magnetic and gravity data.-from AuthorsViewShow abstract16. Mapping Basement Magnetization Zones from Aeromagnetic Data in the San Juan Basin, New MexicoArticleJan 1982Lindrith CordellViewApport des données à la cartographie des structures géologiques du Maroc nord-oriental. Tectonique cassante, cinématique et contexte géodynamique du Trias à l Actuel, thèseJan 2000H TabyaouiH. Tabyaoui, Apport des données à la cartographie des structures géologiques du Maroc nord-oriental. Tectonique cassante, cinématique et contexte géodynamique du Trias à l Actuel, thèse, université Mohamed-V, Rabat, 2000, 306 p.Jan 1998179-182A El MandourM BoughribaD KhattachR SadkiA. El Mandour, M. Boughriba, D. Khattach, R. Sadki, Identification et structures des aquifères superficiels et profonds de la plaine des Triffa (Nord-Est du Maroc), Mines. Géologie Energie, Rabat 57 (1998) 179-182.Jan 19911P CarlierP. Carlier, Ressources en eau du Maroc, tome 1 : Domaine du Rif et du Maroc oriental, Notes Mém. Serv. Géol. Maroc 231 (1991) 1.RecommendationsDiscover moreProjectThe Trans Alboran Shear Zone continuity on the northern Morocco from the aeromagnetic data processing

Najib Amar

Driss KhattachThe Trans Alboran Shear Zone is one of the largest shearing structure characterizing the Alboran see and neighboring area. Numerous deep fractures detected using the aeromagnetic data allowed to de fine the TASZ continuity on the continent. This may help to highlight the shearing models on the northern Morocco. ... [more]View projectProjectdoctoral thesis

Hicham Nasri

Said Bengamra

Ali Azdimousa[...]

Mounir AmarView projectProjectMultiscale analysis of Gravity and magnetic lineaments : structural, hydrogeological and mining implications

Driss Khattach

Najib Amar

Radia El Gout[...]Tahar Aifa-Identification of geological contacts from rock density/magnetism contrast-Characterization of these lineaments : direction, sens of dip and deep View projectProjectEvaluation de la contamination métallique des eaux des nappes du Jurassique du haut bassin de Ziz (Haut Atlas central, Maroc) Assessment of metal contamination in Jurassic water tables of Ziz high basin (Central High Atlas, Morocco)

Nordine Nouayti

Driss KhattachManal Hilali[...]

Said. BakiView projectArticleCalculation and analysis of 2 × 2 gravity anomalies over the South China Sea based on Cryosat-2 sat...June 2015 · Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science)J. WanJ. LiS. LiuJ. YangThe gravity anomaly of the South China Sea was calculated with high spatial resolution and precision using the Cryosat-2 data. The tracks and crossover points of the Cryosat-2 satellite altimetry level 2 SIR_GDR_2A data were analyzed. The component of grid residual vertical deflection was calculated with the weighted minimum least squares solution method using the cycle1-cycle4 data, then the ... [Show full abstract] gravity anomalies in 2 × 2 grid over the South China Sea between 4°-24° latitude and 105°-120° longitude were determined. The results show that the Cryosat-2 data have a high track density, and are distributed regularly and uniformly with a 15.9 cm RMS value of crossover point differences, which is slightly higher than the synchronous Jason-2 GDR data. Compared with the post-processed shipboard gravimetry, the root mean square value of the gravity anomaly in 2 × 2 grid over the South China Sea is 4.5×10-5 m·s-2. ©, 2015, Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science). All right reserved.Read moreArticleFull-text availableTrends in gravity changes from 2009 to 2013 derived from ground-based gravimetry and GRACE data in N...November 2015 · Geodesy and Geodynamics

Shen Chongyang

Songbai XuanZhengbo Zou

Guiju WuNorth China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment (GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change rate (GCR) using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji (Beijing-Tianjin-Hebei Province), and Bohai Bay Basin (BBB) ... [Show full abstract] regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be “negative-positive-negative” from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.View full-textConference PaperFull-text availableA Review of Py (Roo) Stream Cipher and its VariantsMarch 2011

Shadab AlamTo overcome the deficiencies and non-standardization, and in search of a standard stream cipher that can provide more security and better performance than AES, ECRYPT (a consortium of European Research organizations) issued a call for stream cipher submission in the form of a project eSTREAM. The submissions were sought in two categories; Profile 1 (software based ciphers) and Profile 2 ... [Show full abstract] (hardware based ciphers). Py (Roo) was submitted by Eli Biham and Jeniffer Seberry in 2005 in software based cipher category was one of the candidates among total 34 submitted candidates. Py was very impressive in terms of efficiency and it was 2.5 times faster than RC4. But unfortunately it was found to be susceptible to some cryptanalytic attacks. An improved version of Py was submitted in form of Pypy but it was also not able to withstand the cryptanalytic attacks due to some errors in the design. To overcome the deficiencies in the previous versions of Py family, the designers of these ciphers proposed the tweaked versions of these ciphers in form of TPy, TPy6 and TPypy. Some attacks were also reported against these ciphers and possible solutions were also proposed in form of its variants RCR-32 and RCR-64 by Sekar, Paul Preneel in 2007. Our aim of this paper is to analyze various stream ciphers of Py (Roo) family, attacks against each of the ciphers and claims of the security of these ciphers for coming to a conclusion regarding security of these ciphers and future improvementsView full-textConference PaperRelated-Key Differential-Linear Attacks on Reduced AES-192December 2007

Wentao Zhang

Lei Zhang

Wenling WuDengguo FengIn this paper, we study the security of AES-192 against related-key differential-linear cryptanalysis, which is the firstattempt using this technique. Among our results, we present two variant attacks on 7-round AES-192 and one attack on 8 roundsusing a 5-round related-key differential-linear distinguisher. One key point of the construction of the distinguisher is thespecial property of MC ... [Show full abstract] operation of AES. Compared with the best known results of related-key impossible differential attacks and related-key rectangleattacks on AES-192, the results presented in this paper are not better than them, but the work is a new attempt, and we hopefurther work may be done to derive better results in the future.Read moreLast Updated: 11 Oct 2020Looking for the full-text?

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