Rharb Basin Research Articles

Integrated assessment of the Plio-quaternary sedimentary succession and groundwater mineralization forecasting in the Rharb Basin (Northwestern Morocco)

Hydrogeophysical methods have been used in conjunction with new numerical models (statistical and other) in recent years within intricate alluvial aquifers. Understanding aquifer distribution and improving groundwater quality knowledge in the context of huge databases is made feasible by the numerous descriptive statistics approaches (such as Principal Component Analysis (PCA), clustering, and moment calculations) and regression modeling. The study area database includes physicochemical data collected throughout multiple periods and over 2600 vertical electrical sounding (VES). Numerous studies have revealed that the water table is dropping and the quality of the water is declining in this area. To illustrate the spread of mineralization, we used a four-phase technique. The occurrence of four geoelectrical levels, as demonstrated by our results, suggests that the deep deposits are rather homogeneous when compared to the shallow surface data. Additionally, there may be a statistical relationship between the hydrochemical data and the two upper geoelectrical levels. It was, as a consequence, feasible to forecast a distribution map for the mineralization that was consistent with the geological information from earlier work by developing a regression relation between apparent resistivity and electrical conductivity. The acquired results provide new opportunities for understanding large-scale database exploitation, enhancing our understanding of intricate aquifers, and integrating hydrogeophysical and hydrochemical data in predictive modeling.

Geology and stratigraphy of the Neogene section along the Oued Beth between Dar bel Hamri and El Kansera (Rharb Basin, northwestern Morocco) and its otolith-based fish fauna: a faunal inventory for the Early Pliocene remigration into the Mediterranean

The coquina on the banks of the Oued Beth in the Rharb Basin in northwestern Morocco has long been known to be exceptionally rich in fossils. The stratigraphic position ranging from the Late Miocene to the Pliocene has been controversial, however. In the course of my master’s degree field work in 1975/76, I mapped the right bank of the Oued Beth from Dar bel Hamri to El Kansera. Following multiple recent studies in the general region, I here review my results and present an updated comprehensive stratigraphic and geologic frame for the first time. The coquina near Dar bel Hamri is interpreted to be of Early Pliocene age, possibly containing some reworking of Late Miocene fossils. The coquina and other locations along the Oued Beth have yielded a rich otolith assemblage, which is described in this article. It represents the first fossil otolith-based fish fauna described from Northwest Africa and contains 96 species, 16 of which are new. The new species in the order of their description are Diaphus maghrebensis n. sp., Ophidion tuseti n. sp., Centroberyx vonderhochti n. sp., Myripristis ouarredi n. sp., Deltentosteus planus n. sp., Caranx rharbensis n. sp., Trachurus insectus n. sp., Parapristipoma bethensis n. sp., Pomadasys zemmourensis n. sp., Cepola lombartei n. sp., Trachinus maroccanus n. sp., Trachinus wernlii n. sp., Uranoscopus hoedemakersi n. sp., Uranoscopus vanhinsberghi n. sp., Spondyliosoma tingitana n. sp., and Opsodentex mordax n. sp. In addition, a new species is described from the Tortonian and Zanclean of Italy: Rhynchoconger carnevalei n. sp. Some additional otoliths are described from another Northwest Moroccan location of Early Pliocene age near Asilah, 50 km south of the Strait of Gibraltar. The Early Pliocene fish fauna from Dar bel Hamri in the Rharb Basin is also of interest, because it constitutes the nearest Atlantic fauna of the time of the reconnection of the Mediterranean with the Atlantic and may have acted as a hosting area for the remigration of fishes into the Mediterranean. Indeed, the correlation is high between the Northwest Moroccan and the well-known time-equivalent Mediterranean fish fauna, but the Moroccan fauna also contains a good proportion of putative endemic taxa and taxa with tropical West African affinities that apparently did not migrate into the Mediterranean. Thus, the Early Pliocene fish fauna from the Rharb Basin represents a unique assemblage for which I propose the biogeographic term “Maghrebian bioprovince.”

Hydrochemical and geophysical characterization of the Mnasra coastal aquifers (Rharb basin NW Morocco)

Hydrochemical and geophysical characterization of the Mnasra coastal aquifers (Rharb basin NW Morocco)

Plio-quaternary deposits in the Eastern Rharb (Nw Morocco): Electrosequential characterization

The Rharb basin, of which our study area is part, is located at the western extremity of the south Rif corridor. It corresponds to a subsiding zone that appeared in the Upper Miocene, between two major structural domains: the Rif to the north and east and the Meseta domain to the south. The eastern part of this basin is characterized by a Plio-Quaternary continental fill. Its geographical position and its structural and paleo-environmental contexts are reflected by a great facies heterogeneity.This work aims to image the subsurface structure and to characterize the distribution mode of Plio-Quaternary deposits of the eastern Rharb. The use of a database consisting of geo-electrical cross sections, hydrogeological drilling and wireline logging integrated in a Geographic Information System (GIS) allowed us to establish a new three-dimensional model of the top of the Mio-Pliocene substratum, new geo-electrical cross sections, as well as the isopach maps of lower, intermediate, upper and superficial geo-electric interval.This approach allowed us to characterize the Plio-Quaternary deposits of the study area and to highlight the effects of the tectonic regime and the relative sea level fluctuations on the sequential organization of these deposits. Our new model shows the development of prograding, aggrading and retrograding parasequences denoting the existence of autogenic mechanisms in the organization of plio-quaternary deposits of the eastern part of the Rharb basin. Therefore, it opens new perspectives for the exploration of water resources and monitoring their quality throughout the basin.

Electrical and well log study of the Plio-Quaternary deposits of the southern part of the Rharb Basin, northern Morocco

The Rharb Basin is located in the NW of Morocco. It is the onshore extension of a lager offshore basin between Kenitra and Moulay Bousselham. The Rharb plain (properly called) extends over an area of 4200 Km2 between two very different structural entities: the unstable Rif domain in the NE and the East and the ''relatively stable'' Meseta domain in the south. The distribution of Pliocene-Quaternary deposits under this plain is complex and was controlled by both tectonics and climatic factors. The main objective of the present work is to define the spatiotemporal evolution of these deposits in the onshore part of the basin and to make a comparison with a sequence analysis defined, for equivalent deposits in the offshore basin, by a previous work. The proposed model allows thus to characterize the geometry of these deposits in the extension of continental shelf under the present day onshore basin, and to explain there is genesis in terms of interactions between eustatic sea level fluctuations, tectonics and sedimentary rates at the mouths of paleo-rivers that had drained the Rharb plain during Pliocene to Quaternary Times.

Geoelectrical structure and hydrogeological investigations of the southern Rif Cordillera (Morocco)

AbstractAn electrical prospecting survey is conducted in the Rharb basin, a semi‐arid region in the southern part of the Rifean Cordillera (Morocco) to delineate characteristics of the aquifer and the groundwater affected by the marine intrusion related to Atlantic Ocean. Analysis and interpretations of electrical soundings, bi‐logarithmic diagrams and the geoelectrical sections highlight a monolayer aquifer in the southern part, a multilayer system in the northern part of the Rharb basin and lenticular semi‐permeable formations. Several electrical layers have been deduced from the analysis of bi‐logarithmic diagrams: resistant superficial level (R0), conducting superficial level (C0), resistant level (R), intermediary resistant level (R′), conducting level (Cp) and intermediary layer of resistivity (AT). Spatial distribution of the resistivity deduced from the interpretation of apparent resistivity maps (AB = 400 and 1000 m) and the decreasing of resistivity values (35–10 Ωm), in particular in the coastal zone show that this heterogeneity is related to several anomalies identified in the coastal area, which result from hydraulic and geological processes: (i) heterogeneous hydraulic conductivity in particular in the southern part of the Rharb; (ii) lateral facies and synsedimentary faulting and (iii) the relationship between the electrical conductivity and chloride concentration of groundwater shows that salinity is the most important factor controlling resistivity. The distribution of fresh/salt‐water zones and their variations in space along geoelectrical sections are established through converting subsurface depth‐resistivity models. Copyright © 2010 John Wiley & Sons, Ltd.

FA2BOUG—A FORTRAN 90 code to compute Bouguer gravity anomalies from gridded free-air anomalies: Application to the Atlantic-Mediterranean transition zone

In this paper we present a computer program written in FORTRAN 90 specifically designed to determine the Bouguer anomaly from publicly available global gridded free-air anomaly and elevation database sets. FA2BOUG computes the complete Bouguer correction (i.e. Bullard A, B and C corrections) for both land and sea points in several spatial domains according to the distance between the topography and the calculation point. In each zone a different algorithm is used. In a distant zone we consider the harmonic spherical expansion of the potential of each right rectangular prism representing an elevation grid point. In an intermediate zone we compute the gravitational attraction produced by each prism using the analytic formula. Finally, an inner zone contribution is divided into two parts: a flat-topped prism with a height equal to the elevation of the calculation point, and four quadrants of a conic prism sloping continuously from each square of the inner zone to the calculation point. The program has been applied to the Atlantic-Mediterranean transition zone to obtain a complete Bouguer anomaly map of the area, integrating available onshore Bouguer anomaly with satellite-derived free-air anomaly data. Positive Bouguer anomalies are found in the Atlantic oceanic domain (240–300 mGal), central and eastern Alboran Basin (40–160 mGal) and SW Iberian Peninsula (>40 mGal). Major negative Bouguer anomalies are located beneath the west Alboran Basin (<−40 mGal), the Rif, the Rharb Basin and the Atlas Mountains (<−120 mGal). An isostatic residual anomaly map of the study area has been computed and compared with the crustal and lithospheric structure inferred from previous work.

New evidence for Hercynian faulting in the southernmost margin of the Rharb Basin (Morocco)

The Miocene-Pliocene Rharb Basin has important groundwater and hydrocarbon potential in western Morocco. The Pliocene-Quaternary reservoir rests upon the Miocene-Pliocene marly units. The paleogeographic limits are based on planktonic foraminifera biozones. They contributed to the geometric reconstruction of this basin. The goal of the present study is to establish the paleogeographic evolution of the Rharb Basin and the Hercynian structures deduced from seismic and gravity data interpretation. The Pliocene-Quaternary deposits exhibit thickness and lateral facies variations. The Pliocene bathyal gulf showed several tectonic phases, marked by the westward migration of the paleogeographic limit in its eastern part, and a southward migration from its northern one. During Miocene-Pliocene times, the tectonic activity within the study area is characterized by extensional and compressional structures. The faults affecting the Paleozoic units were reactivated several times. The comparison between the paleogeographic limits and identified Hercynian structures constitutes fresh evidence for reactivation of pre-existing Hercynian faults.

Total variation diminishing schemes for pollutant transport in porous media

AbstractA bidimensional numerical model has been used in order to simulate the contaminant transport in the coastal groundwater area (Atlantic margin of the Rharb basin, Morocco). This groundwater is materialized by means of the salt contamination derived from several factors: evapotranspiration, lithological series formations, marine intrusion, and processes of interaction between water and rocks. In order to reduce the numerical diffusion and limit the numerical dispersion, we use the Superbee flux limiter as a total variation diminishing scheme to discretize the convective operator. This kind of discretization was applied to the coastal groundwater of the Rharb basin (Morocco). The results show that the Superbee flux limiter is efficient at drawing the path of the contaminant front with high accuracy. Consequently, this scheme could constitute an approach in water management and allows one to prevent the risks of pollution and to manage the groundwater resource from a durable development perspective. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Flux-limiting techniques for simulation of pollutant transport in porous media: Application to groundwater management

The objective of this work is to present a numerical study of contaminant migration in saturated porous media. For this purpose, the advection–diffusion equation describing the evolution of contaminant plumes in a 2D horizontal aquifer (Atlantic margin, Rharb Basin of Morocco) is discretized employing a Total Variation Diminishing method (TVD), which provides an efficient way to eliminate spurious numerical oscillations. The stationary velocity field is computed by the ModFlow code using the finite difference method discretization. The initial concentration needed to determine the solution was specified using data from well samples. Numerical examples showing the implementation of the algorithm to describe groundwater contamination by the chloride in the aquifer are presented. This high accuracy method (TVD) constitutes an approach in the water management and allows us to envisage risks of pollution and to manage the groundwater resource from the durable development perspective.

A rapid method to map the crustal and lithospheric thickness using elevation, geoid anomaly and thermal analysis. Application to the Gibraltar Arc System, Atlas Mountains and adjacent zones

We present a method based on the combination of elevation and geoid anomaly data together with thermal field to map crustal and lithospheric thickness. The main assumptions are local isostasy and a four-layered model composed of crust, lithospheric mantle, sea water and the asthenosphere. We consider a linear density gradient for the crust and a temperature dependent density for the lithospheric mantle. We perform sensitivity tests to evaluate the effect of the variation of the model parameters and the influence of RMS error of elevation and geoid anomaly databases. The application of this method to the Gibraltar Arc System, Atlas Mountains and adjacent zones reveals the presence of a lithospheric thinning zone, SW–NE oriented. This zone affects the High and Middle Atlas and extends from the Canary Islands to the eastern Alboran Basin and is probably linked with a similarly trending zone of thick lithosphere constituting the western Betics, eastern Rif, Rharb Basin, and Gulf of Cadiz. A number of different, even mutually opposite, geodynamic models have been proposed to explain the origin and evolution of the study area. Our results suggest that a plausible slab-retreating model should incorporate tear and asymmetric roll-back of the subducting slab to fit the present-day observed lithosphere geometry. In this context, the lithospheric thinning would be caused by lateral asthenospheric flow. An alternative mechanism responsible for lithospheric thinning is the presence of a hot magmatic reservoir derived from a deep ancient plume centred in the Canary Island, and extending as far as Central Europe.

De nouveaux éléments structuraux du complexe aquifère profond du bassin du Rharb (Maroc) : implications hydrogéologiques

The Rharb basin is located in northwestern Morocco. It is a part of one of the most important hydrogeological basins of Morocco, and extends over some 4000 km 2. The nature of its Plio-Quaternary sedimentary fill and its structural and palaeoenvironmental contexts are reflected by great variations in aerial and temporal facies distribution. This distribution, in turn, is a direct cause of the observed complexity in the geometry of potentially water-bearing beds. In the present work, we present an image of potential new hydrogeological reservoirs and define new structures that partially explain their architecture. To cite this article: M. Kili et al., C. R. Geoscience 338 (2006).

The Hydrodynamism of the Coastal Aquifer System Belonging to the Southern Border of the Rharb Basin (Morocco)

The Hydrodynamism of the Coastal Aquifer System Belonging to the Southern Border of the Rharb Basin (Morocco)

Spatial distribution of resistivity in the hydrogeological systems, and identification of the catchment area in the Rharb basin, Morocco / Répartition spatiale de la résistivité dans les systèmes hydrogéologiques et détection des zones de captages dans le bassin du Rharb, Maroc

Geophysical results obtained in the Rharb basin, Morocco are reported. Correlations between hydrogeological well logs reveal several water-bearing Plio-Quaternary units resting on a substrate of blue marls. Geo-electrical borehole analyses were interpreted using bi-logarithmic diagrams which indicate the permeable layers of the aquifer and also its basement. Resistivity data from NE–SW and NW–SE electrical sections allow definition of the permeable/impermeable levels, and identification of ȁditchesȁ that may be favourable sectors for hydrogeological exploitation. Resistivity anomalies were investigated by analysing maps of resistivity at 400 and 1000 m AB. Anomalies identified in the Rharb basin are related to the thickening of the permeable bodies (sand, limestone, sandstone deposits). In the coastal zone (AB = 1000 m), there is a strong decrease of the resistivity gradient (35–10 Ω m), which is probably linked to marine intrusion. Electrical anomalies allow detection of the water-bearing zones notably in the western and southwestern parts of the Rharb basin.

Evidence of flexural extension of the Rif foreland: The Rharb-Mamora basin (northern Morocco)

Abstract The Rharb-Mamora basin is the foreland of the Rif Cordillera (orogenic belt). The Mamora area (northern Morocco) is located at the southern border of the Rharb basin and intercalated between the Alpine Rif Mountains to the north and the Hercynian Moroccan Meseta domain to the south. Analysis and interpretation of seismic lines, hydrogeological and oil wells, have allowed to precise the major structural elements of the Mamora area, which is covered by late Neogene sediments. The structure of the area is controlled by faults that also affect the Paleozoic basement. The NE-SW and NW-SE trending faults induce the palaeogeographical evolution and control, the facies distribution and the thickness variations. The most important or relevant structural feature of the Mamora area is the Kenitra-Sidi-Slimane fault (K2SF) [Zouhri et al., 2001]. This fault N110oE trending is south of the Rif Alpine thrust front and is marked by a progressive deepening of its northern compartment, at least since Cretaceous time. Thus the Mamora appears as a hinge between the Rharb Basin and the Moroccan Meseta from Cretaceous to Neogene time.

La Mamora, charnière entre la Meseta et le Rif: son importance dans l'évolution géodynamique postpaléozoïque du Maroc / The Mamora Plain, a hinge between the Meseta and the Rif. Its importance in the post-Paleozoic geodynamic evolution of Morocco

The Mamora area (Morocco) is located in the northern part of the Meseta and the southern part of Rharb. The recent formations (Mesozoic to Quaternary) lie unconformably on a Paleozoic basement. This study based on hydrogeological, sedimentological, drilling data and seismic reflection profiles interpretation, proposes new interpretations of geodynamical evolution of this area particularly in terms of tectonic patterns. The most ancient formations recognized in this region are Paleozoic schists and quartzites in the Tifíete sector. They represent the basement of the basin on which Triassic conglomerates and red mudstones associated with basalts lie unconformably. Jurassic and Cretaceous sediments are limestones and marls. The Mio-pliocene formations are open marine blue marls. Plio-quaternary sediments are limestones and sands containing gravel and pebbles. Miocene to Pliocene blue marls facies corresponds to deep marine marls (bathyal as indicated by planctonic foraminifers) with an attributed age from upper Miocene [9] to middle Pliocene [7]. A facies distribution map of the top of the blue marls has been realized where four main facies—conglomerate, shelly sandstone, limestone and marls—indicate a major regression in the Mamora basin. The datation of the formations was mostly realized by Wernli [22, 23, 24, 25], and Cirac [10], In the Mamora area, Hercynian faults show two main structural directions, N020°E-N040°E (Agadir-Rabat), N120°E (Rabat- Tiflète) [5], and a new major Hercynian fault (K2S). The seismic profiles have been studied between Sidi Slimane and Sidi Yahia area, to illustrate the structure of the Mamora, and to replace it, in the geodynamical evolution. The seismic reflection lines and drilling data show that the eastern Mamora was subdivided into two sectors: i) the southern sector is affected by Hercynian faults which create horsts and grabens in the Paleozoic. Mio-Pliocene formations infill these depressions and are covered by Quaternary sediments; ii) the northern sector is constituted by various formations: 1. Paleozoic formation as basement covered by autochthonous Mesozoic to Miocene, 2. Prerifain nappes (marls and evaporites), 3. Mio-Plio-Pleistocene formations as subautochthonous to autochthonous. These two sectors are separated by a major fault (K2S). On the other hand, in the occidental Mamora, the facies distribution and the Plio-Pleistocene thickening seem to be induced by faults with a NE-SW and NW-SE trends which affect the Paleozoic basement. Then, between the Meseta domain and the septentrional Rharb basin, two major Hercynian initially dextral shear zones, Rabat- Tiflete and K2S, have been recognised. During the Atlantic Ocean opening, they are probably senestral shear zones. At the same time the subsidence in Rharb basin is active, major action of these faults is normal. Therefore, Mamora represents a real hinge between stable Meseta and unstable septentrional Rharb basin. © 2001 Éditions scientifiques et médicales Elsevier SAS

La Mamora, charnière entre la Meseta et le Rif : son importance dans l’évolution géodynamique post-paléozoïque du Maroc

The Mamora area (Morocco) is located in the northern part of the Meseta and the southern part of Rharb. The recent formations (Mesozoic to Quaternary) lie unconformably on a Paleozoic basement. This study based on hydrogeological, sedimentological, drilling data and seismic reflection profiles interpretation, proposes new interpretations of geodynamical evolution of this area particularly in terms of tectonic patterns. The most ancient formations recognized in this region are Paleozoic schists and quartzites in the Tiflete sector. They represent the basement of the basin on which Triassic conglomerates and red mudstones associated with basalts lie unconformably. Jurassic and Cretaceous sediments are limestones and marls. The Mio-pliocene formations are open marine blue marls. Plio-quaternary sediments are limestones and sands containing gravel and pebbles. Miocene to Pliocene blue marls facies corresponds to deep marine marls (bathyal as indicated by planctonic foraminifers) with an attributed age from upper Miocene 〚9〛 to middle Pliocene 〚7〛. A facies distribution map of the top of the blue marls has been realized where four main facies - conglomerate, shelly sandstone, limestone and marls - indicate a major regression in the Mamora basin. The datation of the formations was mostly realized by Wernli 〚22, 23, 24, 25〛, and Cirac 〚10〛. In the Mamora area, Hercynian faults show two main structural directions, N020°E-N040°E (Agadir-Rabat), N120°E (Rabat-Tiflète) 〚5〛, and a new major Hercynian fault (K2S). The seismic profiles have been studied between Sidi Slimane and Sidi Yahia area, to illustrate the structure of the Mamora, and to replace it, in the geodynamical evolution. The seismic reflection lines and drilling data show that the eastern Mamora was subdivided into two sectors : i) the southern sector is affected by Hercynian faults which create horsts and grabens in the Paleozoic. Mio-Pliocene formations infill these depressions and are covered by Quaternary sediments ; ii) the northern sector is constituted by various formations : 1. Paleozoic formation as basement covered by autochthonous Mesozoic to Miocene, 2. Prerifain nappes (marls and evaporites), 3. Mio-Plio-Pleistocene formations as subautochthonous to autochthonous. These two sectors are separated by a major fault (K2S). On the other hand, in the occidental Mamora, the facies distribution and the Plio-Pleistocene thickening seem to be induced by faults with a NE-SW and NW-SE trends which affect the Paleozoic basement. Then, between the Meseta domain and the septentrional Rharb basin, two major Hercynian initially dextral shear zones, Rabat-Tiflete and K2S, have been recognised. During the Atlantic Ocean opening, they are probably senestral shear zones. At the same time the subsidence in Rharb basin is active, major action of these faults is normal. Therefore, Mamora represents a real hinge between stable Meseta and unstable septentrional Rharb basin.

Abstract: New Exploration Concept and Petroleum Systems in the Tertiary Rharb Basin, Northern Morocco

Abstract: New Exploration Concept and Petroleum Systems in the Tertiary Rharb Basin, Northern Morocco

An overview of the petroleum systems of Morocco

Abstract Magoon &amp; Dow’s petroleum system concept is utilized in this paper to evaluate the origin of the proven hydrocarbon resources of Morocco, which lie chiefly in the Essaouria, Prerif and Rharb Basins. Several systems are interpreted, in which the confidence in the source-petroleum tie varies from ‘known’ to ‘speculative’, involving charge from Silurian (eastern Essaouira), Lias (Prerif), Oxfordian (western Essaouira), Cretaceous (Ain Hamra) and an intra-Miocene biogenic system in the Rharb Basin. The origin of the Cap Juby heavy oil accumulation in the offshore Tarfaya basin is uncertain, with a Jurassic carbonate source currently the favoured interpretation. The petroleum system concept is extended in this paper to predict further, currently undrilled and unproven systems. These include areas where the proven source systems referred to above are likely to extend, plus additional systems predicted on the basis of analogues to surrounding regions. An example of the latter is a series of postulated Triassic systems developed in lacustrine deposits in offshore half-grabens. Palaeozoic source rocks may be regionally developed and may still be in the oil and gas windows over wide, generally unexplored, regions. Lower to Middle Jurassic source rocks are predicted in lagoonal settings in platform sags and in outer shelf environments, whereas Cretaceous source beds occur in continental rift complexes and passive margins, with maturity likely to be reached in depocentres and below thrusts. Biogenic gas potential is probably confined to Neogene deposits in foreland and divergent margin basins. Further application of the petroleum system concept should help to significantly reduce geological risk, particularly in frontier exploration areas.

OIL AND GAS POTENTIAL OF THE PRERIF FORELAND BASIN, ONSHORE NORTHERN MOROCCO

The PreRif Basin in northern onshore Morocco may contain major oil and gas reserves. This foreland basin is located between the Tertiary‐Recent Rif Orogen to the north and the stable Moroccan Meseta to the south; for the purposes of this paper, it includes the Rharb Basin, an area of strong Neogene subsidence which extends offshore to the west.Prospective sandstone and carbonate reservoirs are present at a number of stratigraphic levels, ranging in age from Triassic and Jurassic to Miocene and Pliocene. Lower and Middle Jurassic shales and carbonates constitute potential source beds for “thermal” oil and gas; biogenic gas is generated within Miocene/Pliocene shales. Potential source beds are expected to have reached thermal maturity in the deepest portions of the present basinal area since the Late Miocene. Seals are provided by intraformational shales, transgressive shales of Tertiary age, Triassic evaporites, and by a thick, complex glidemass (or “olistostrome”) of late Miocene (Tortonian) age. Multiple traps can be expected; they will include anticlines, fault closures, salt‐tectonic features, and structural‐stratigraphic traps.Gravity‐defined low areas in the northern portion of the basin are probably the main generative depocentres. Lateral oil and gas migration has occurred on a regional scale since the Late Miocene, and has continued to the present day.A Jurassic Petroleum System includes the surface oil seeps and shut‐in oilfields of the Sidi Cacem area along the basin's southern flank. A Miocene Petroleum System supplies gas production in the Rharb Basin.The prospective area covers some 15,000 sq. km. Available reconnaissance data include published gravity, magnetic, seismic, and surface‐geological surveys. Modern airborne surveys of prospective areas should be followed by detailed exploration, including 3‐D seismic surveys.New recoverable field reserves may lie in the range of 50 to 150 million barrels oil‐equivalent per discovery; several new discoveries can be expected, leading to new total reserves possibly totalling 0.5 billion barrels oil‐equivalent.