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Three microbialite forms are recognized in the Lower-Cambrian succession of Irherm area in the western Anti-Atlas (Morocco). Stromatolites, which correspond to non-calcified shallow marine laminated microbialites, are well developed in the basal Lower-Cambrian succession. Occurrence of calcified microbial thrombolites, in the middle part of this succession, reflects an increasing sea level from the peritidal zone to the subtidal environment. In the upper part of this succession, a second increasing water depth event and the development of branching archaeocyathan reefal framework lead to dendritic microbialite emergence. To cite this article: M. Benssaou, N. Hamoumi, C. R. Geoscience 336 (2004). [Copyright &y& Elsevier]

In the Moroccan western Anti-Atlas, the combined extensive tectonic events with a long-term sea-level rise is the main factor on building vertical stacking transgressive–regressive sequences. In the Ait Abdallah-Boussafene axis, the subsidence processes, relayed by a brutal platform tilting generated an elongated NE–SW graben. This is an evidence of the persistence of the Anti-Atlasic rifting process during the last part of the Lower-Cambrian succession. [Copyright &y& Elsevier]

• Ironstones of Morocco are economically attractive because of low P and high Fe. • Found at points in sequence stratigraphic cycle where clastic supply is minimum. • Favored at top of the highstand and on ravinement surfaces. • Fe sourced from older BIF, carried in rivers as particles, deposited at coast. • Solid Fe3+ converted to soluble Fe2+ in sediment, waves reworked into Fe3+ ooliths. In Morocco, iron deposits of sedimentary origin are mainly developed in the Ordovician where they are interbedded at different levels of the stratigraphic column. A detailed analysis of the sedimentary facies shows that the iron ores are not randomly distributed but are concentrated at omission surfaces of the sequences thus raising the question of their sedimentological significance within the sequences that shelter them. This study determines three morphological types of ore, which provide a possible avenue for economic exploitation. These morphological types are: firstly, from metric to decametric bodies of regional extension (examples are "Caid Rami" and "Tachilla"), consisting of a set of detrital facies organized in two stratigraphic stages that cyclically recur to form genetic sequences. Within each sequence, the maximum mineralization is at the top of the prograding basal stage and is expressed by diagenetic iron cement and at the base of the regressive stage in the form of strata of iron oolites, or in massive beds. Secondly, lenses with a thickness up to 30 m over a kilometer width (example of "Imi n'Tourza" field), corresponding to incisions cut along the ravinement surfaces. The maximum mineralization of this second type is within the median sandstone stage in connection with a large transgressive event. Thirdly, there is a type of reworked material consisting of discontinuous layers of ferruginous conglomerates and bioclastics lining the ravinement surface that separates the higher order sequences. It is this third type that has generated the most economic interest. The iron-bearing mineral phases identified are: magnetite, hematite, iron chlorite, maghemite, iron hydroxides (goethite, lepidocrocite) and siderite. The ultimate source of iron would probably be the large reserves of banded iron formation of the West Africa Craton (Mauritania in particular). Intense tropical weathering would have leached the silica and left a highly enriched iron residuum that was carried as particulate iron to shallow marine shelf environments where Fe3+ was converted to Fe2+ during early diagenesis. This reduced iron was recycled into the water column by tidal currents or storm waves where it precipitated as ferric oxide or ferrous silicate ooliths. This depositional mechanism accounts for the positioning of ironstone beds at times of stasis and reworking. [ABSTRACT FROM AUTHOR]

The open areas in the Western Moroccan Anti Atlas Mountains constitute a diversified natural potential. However, this wealth is doomed to disappearance under the growing impact of natural and anthropogenic hazards - an example being the changes introduced on the agricultural production system. Hence, the importance of having a look at these territories in terms of participative sustainable development is great. This paper provides the first elements of a work-in-progress research, which aims at setting up a geographical information system integrating the components of geo-bio-diversity, the local know-how, the heritage, and the risks that are associated with them. It is to present the results of the study of the flora throughout the Tafraoute Ida Ouzdoute Valley (Ighrem, Taroudant). The exploration, sampling, and the semi-structured interviews are the main methodological tools adopted. The inventory and analysis of the data on the local flora confirm the diversity of plants, their importance in the development of agriculture and the enrichment of the ecosystem services of the mountains. In addition, a great need has been detected in terms of communication on the enhancement and preservation of this component of biodiversity. [ABSTRACT FROM AUTHOR]

Copper mineralization in the Lower Paleozoic sedimentary cover of the Anti-Atlas (Morocco) is continually being revised not only to improve its mining capacity, but also to determine its origin, which remains a matter of debate. As evidenced by the various models proposed, the related research is fragmented, localized, and confusing. The origin of the Anti-Atlas Lower Paleozoic copper mineralization is shared between synergistic and epigenetic processes or a superposition of the two processes. Based on new tectono-magmatic data and a reinterpretation of the ore structural arrangement, we propose a link between the last concentration of copper deposits and the Late Triassic–Early Liassic CAMP (Central Atlantic Magmatic Province) tectono-thermal event, as evidenced by the significant concentration of copper mineralization in the three NE–SW corridors affected by extensional faults, some of which are filled with dolerite CAMP magma. The heat flow generated by the mafic dykes within these reactivated corridors causes mineralized fluids to up well into the sedimentary layers, depositing material rich in juvenile or leached copper, or even a mixture of the two. In some cases, these fluids are trapped by fracture systems that accompany passive folds initiated on normal faults. In other cases, these fluids can infiltrate bedding planes, and even karst caves, formed during carbonate exhumation. Notably, extensive NE–SW faults systematically cover the early Hercynian structures, suggesting that they belong to a post-Hercynian extensional episode. During the Late Triassic, the global fragmentation of the Pangaea supercontinent was manifested by the stretching of the continental crust at the margin of northwest Africa, with the simultaneous opening of the Central Atlantic Ocean and emplacement of CAMP magmatism. This last and often overlooked tectonothermal event must be considered in the remobilization and reconcentration of copper mineralization and other mineralization in Morocco. [ABSTRACT FROM AUTHOR]

The Cretaceous marine transgression proceeded through successive steps from the Albian to the Turonian (dated with ammonites). The onlapping wedge begins with coastal transgressive–regressive short-term sequences on massive, probably fluvial sandstones to be correlated with the very thick continental Lower Cretaceous succession found in the Puerto Cansado well in the Tarfaya sub-basin to the north. A second step, of probable Cenomanian age, reached the Palaeozoic basement. A third, more pronounced step occurred during the earliest Turonian with platy laminated limestone overlain by marlstone bearing pyritized ammonites. At early Turonian peak transgression, a marine connection was possibly established between the Atlantic and the Tethyan margins, between the Anti-Atlas and the Reguibat Shield. From large-scale correlation integrating what occurred along the southwestern shoulder of the Atlas rift, the South Moroccan Atlantic margin may have undergone a short-lived tectonic uplift around the Cenomanian–Turonian boundary. [ABSTRACT FROM AUTHOR]

The Nile Delta has become an economically important region of Egypt, because of large-scale natural gas and oil discoveries in recent decades. The offshore Baltim East field is one of the Nile Delta's major gas producers from the upper Miocene clastic reservoirs, but detailed lithofacies and petrophysical analyses of the Abu Madi gas reservoir have not been conducted to date. This study investigates the petrographical and petrophysical properties of the upper Miocene Abu Madi Formation from the Nile Delta to infer the lithofacies distribution, depositional environments, and reservoir qualities of the Level 3 Main and Lower sands. In this work, we used a variety of data sets, including core samples, petrophysical measurements, and well logs, to identify the most important characteristics of these sandstone reservoirs. Both reservoirs are hydrostatically pressured and exhibit a gas gradient of ∼2.26 MPa/km. We have identified six different lithofacies from the two reservoirs. SEM and thin section analyses indicate that trough cross-bedded (F-1), parallel laminated (F-2), and massive sandstones (F-6) are the primary reservoir lithofacies composed of texturally immature subfeldspathic quartz arenites. These sandstones have sharp bases and exhibit fining-upward trends with ripple laminated siltstone (F-3), heterolithic silt and clay (F-4), and laminated claystone (F-5) facies lying on top. We inferred the reservoir depositional environment as fluvial channels and sequence stratigraphically these incised valley-fills represent low stand systems tract. The reservoir sandstone facies show good porosity (10–28%), mostly interparticle. Chlorite coatings around quartz grains are abundant, while pore-filling kaolinite is the dominant porosity-destroying clay phase. Grain dissolution introduced secondary intergranular porosity along the potassium feldspar cleavage planes within the F-1 lithofacies. Porosity, permeability, and reservoir quality parameters (RQI, NPI, and FZI) calculated from routine core analysis indicate that the F-1 and F-6 lithofacies have excellent hydraulic flow properties with >100 mD permeability, RQI>1 μm and FZI >5 μm, while the fine-to very fine-grained F-2 offers poor to fair reservoir quality defined by a wide permeability range of 0.1–2150 mD. The clay and silt-dominated lithofacies (F-3, F-4, and F-5), due to their impervious nature, act as intra-reservoir vertical permeability barriers. The differences in rock composition and facies control diagenesis and physical properties of the reservoir. The results presented, provide further insight into the exploration of the fluvial channel deposits and regional reservoir quality of the upper Miocene Abu Madi Formation of the Nile Delta. • An integrated sedimentary facies analysis and a core-based petrophysical assessment for Abu Madi gas reservoirs are introduced. • High energy channel sandstones deposited in lowstand system tracts are mineralogically mature but texturally immature. • The depositional environments, sequence stratigraphy, and their influences on reservoir quality are discussed. • Overload compaction, cementation, and secondary mineralization (i.e. chlorite and kaolinite) are the main reservoir quality-reducing diagenetic features. • F-1 and F-6 lithofacies have the best reservoir qualities, while F-2 lithofacies offer variable reservoir storage and hydraulic flow capabilities. [ABSTRACT FROM AUTHOR]

An overview of the book “Dams and Reservoirs in Evaporites” is presented. Actual and potential audience and expected impact are analyzed in the context of current research, as well as in the view of global climate and technological changes, and social transformations. A major purpose of authors of this book is to summarize and present the large amount of experience accumulated during the study of dams affected by gypsum and salt dissolution problems in a concise form. Organization, structure, style and presentation of the book were analyzed and found fully corresponding to content and author’s purposes. In this book, the global distribution, properties and types of evaporates are described in the book; geohazards linked with the construction of reservoirs and dams in regions with karst are analyzed; set of geoengineering techniques required to control the rock mass of evaporites is proposed; the design monitoring after construction is discussed; most interesting case studies are presented. Some limitations of this book were also analyzed. It was concluded that this book is important as it provides insight into number of major problems associated with the construction of dams in evaporites, and can be addressed to a wide range of worldwide practical and management issues. [ABSTRACT FROM AUTHOR]

• Petrophysical attributes of the Alamein dolomite reservoir are characterized. • Machine learning approach by Random Forest Regression delivered better permeability prediction than conventional methods. • A new petrofacies zonation scheme is proposed in the heterogenous reservoir. • Inferences are drawn on oil production and optimum drilling-completion strategy. Capturing the petrophysical heterogeneities within a reservoir has a critical influence on reservoir deliverability as well as field development programs. In this study, we report a comprehensive petrophysical evaluation of the oil-producing Aptian Alamein dolomite reservoir from the North Razzak field, Western Desert of Egypt. Integration of wireline logs and routine core analysis indicates that the Alamein reservoir has an extremely wide range of porosity (1–23%) and permeability (0.01–7000 mD), contributed by the early diagenetic dolomitization history and complex distribution of vugs. Petrophysical assessment by reservoir quality index (RQI) and flow zone indicator (FZI) infers that the megaporous rock types offer very good to excellent reservoir qualities and macroporosity dominated intervals are of fair to good quality. Further, we developed a permeability prediction model in this challenging carbonate rock based on Random Forest (RF) regression, and tested its efficacy and generalizability by well-defined performance metrics. The RF-based algorithm provided a more confident permeability prediction (R2 = 0.937) compared to conventional methods. Based on the petrophysical attributes; six distinct petrofacies (PF) associations are identified. PF-1, PF-3, and PF-5 provide excellent reservoir qualities with superlative storage capacity and hydraulic flow potential contributed by connected vugs, while the microporosity-dominated impervious PF-2 and PF-4 intervals act as intra-reservoir permeability barriers. We suggest that the higher initial oil production rate was mainly contributed by the larger connected pores and vuggy spaces. As reservoir pressure drops, hydrocarbon flows restrict to the smaller pores causing accelerated production weakening. Based on this comprehensive analysis, a suitable drilling and completion strategy is recommended for the future reservoir development program. [ABSTRACT FROM AUTHOR]