Northeastern Morocco is made up of several units belonging to the Alpine belt and its foreland. Miocene to plio-quaternary volcanic rocks with variable mineralogy and geochemistry dominate the geology of this region. ...Northeastern Morocco is made up of several units belonging to the Alpine belt and its foreland. Miocene to plio-quaternary volcanic rocks with variable mineralogy and geochemistry dominate the geology of this region. The presence of active faults in different directions explains the high tectonic instability and the high frequency of earthquakes. This study contributes to the effort of understanding the geothermal potential of the Northeast of Morocco. Heat source and permeability are both key factors in the geothermal process. Indeed, lineaments analysis constrains the structures and their directions and indicates severely faulted zones, which are the most promising areas for geothermal exploration. For this purpose, we used Landsat data combined with geological and structural maps available in this region. Different image processing techniques were applied including band ratio (6/2) and directional filters. To validate the results, we conducted a comparative study between linear structures, available geological data, and previous studies. Results of the automatic extraction method of lineaments from Landsat 8 OLI/TIRS indicate three main lineament systems: 1) a NE-SW system ranging from N40 to N70;2) an N-S system ranging from N10 to N45;3) an EW to WNW-ESE systems ranging from N80 to N120. Most of lineaments extracted are localized in Kebdana, Amejjaou, Nador and Melilla regions. Compared to previous studies, the NE-SW system is consistent with an extensive period (Tortonian to Pliocene);the NW-SE system is consistent with the last compressive episode (Pliocene);the N-S system is consistent with the first compressive period (Late/End Tortonian).展开更多
Cenozoic volcanic activity in Morocco started in the Miocene and proceeded, after a short break, during Pliocene and Quaternary. Calc-alkaline magmatic activity occurred first and was accompanied by the eruption of tr...Cenozoic volcanic activity in Morocco started in the Miocene and proceeded, after a short break, during Pliocene and Quaternary. Calc-alkaline magmatic activity occurred first and was accompanied by the eruption of transitional lavas, followed by Plio-Quaternary alkali basaltic activity, which was emplaced within Neogene sedimentary basins of the Rif belt and its foreland. From calc-alkaline to alkaline magmatism, passing through a transitional term, volcanic activities in Morocco formed magnificent outcrops, very diversified in their affinities, their mineral compositions and their geochemistry. The petrographic study and geochemistry of Plio-quaternary volcanic rocks in the areas with high geothermal potential in northeast of Morocco show a dominance of Na-rich basaltic rocks (basanites, basalts, tephrites and basaltic trachy-andesites), followed by trachy-andesites. Most of the samples exhibit an enrichment of large-ion lithophile elements (LILEs) over high-field-strength elements (HFSEs). These results were used to test the global model of Circum-Mediterranean Anorogenic Cenozoic Igneous Province (CiMACI) and the regional model of [1].展开更多
The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retriev...The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retrieved from the Oualidia lagoon and analyzed using neutron activation analysis. The results indicated that heavy rare earth elements are slightly enriched the sediment cores over light rare earth elements. The highest values of REEs were recorded in the top layers of the cores and depleted with depth, suggesting a possible change in factors controlling their accumulation, including mechanical, chemical, and environmental parameters such as weathering intensity, grain size, and Fe-Mn oxides. The sediments display positive Ce anomalies, which are probably related to the submarine weathering process and detrital input. Noting also the variation of hydrodynamics conditions and confinement of the upstream part of the lagoon played a key role in changing the sediment origins.Thus, further investigation of REEs origin in the Oualidia lagoon sediment is required to identify their sources,provenances, and the factors controlling their spatial and vertical distributions. However, these results provide baseline data of occurring changes in REEs geochemical composition and constitute a typical study case to understand the link between sedimentary and geochemistry processes in a lagoonal ecosystem.展开更多
Mapping from remote sensing has become more effective in the field of geology, mainly in lithological discrimination and identification of hydrothermal alteration zones. The use of this technique consists in obtaining...Mapping from remote sensing has become more effective in the field of geology, mainly in lithological discrimination and identification of hydrothermal alteration zones. The use of this technique consists in obtaining information about the rock mass and the main ones existing in the inaccessible areas. Satellite data from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor represent a favorable potential for detecting the spectral signatures of mineral zones and identifying their nature. These data are more reliable in places where the climate is arid with less abundant vegetation, as at the Oumjrane-Boukerzia mining district. This region which is part of the Eastern Anti-Atlas, is composed of several mineralized veins which still require detailed studies and exploration by the technique of remote sensing. In this work we applied several processing techniques on ASTER imagery such as Colored Composition, Principal Component Analysis and Ratio Bands. The use of the reports of the specialized Bands makes it possible to identify some hydrothermal alteration minerals within the mining district of Oumjrane Boukerzia. These minerals are represented mainly by iron oxides and hydroxides (Hematite, jarosite, limonite and goethite), carbonate minerals (dolomite, calcite), clay minerals (Illite, kaolinite and chlorite) and quartz minerals. This work allows us to produce a map of hydrothermal alteration zones which can be used as a valuable reference in the strategy of mining exploration for the base metals (Cu, Pb, Zn and Ba), in the mining district of Oumjrane-Boukerzia and in the entire Eastern Anti-Atlas.展开更多
The Oulad Dlim Massif,adjacent to the Reguibat Shield in South Morocco was considered up to now as part of the Variscan belt(Mauritanides)with a polyphase geologic history and a complex geodynamic evolution implicatin...The Oulad Dlim Massif,adjacent to the Reguibat Shield in South Morocco was considered up to now as part of the Variscan belt(Mauritanides)with a polyphase geologic history and a complex geodynamic evolution implicating oceans closures and accretion of exotic terranes(Avalonian and Meguman)during the Variscan-Alleghanian orogeny.The use of modern technology to characterize the petrology,the geochemistry and the geochronology of the lithological units forming this region,combined to field surveys has led to an updated geological architecture and different geological history.The Oulad Dlim Massif is mainly a deformed Archean terrane,as recorded by its eastern and western sectors,dominated in its central part by a bimodal felsic-mafic magmatism forming the Ediacaran sector.The study of these magmatic complexes supports strongly the intracontinental origin of this bimodal magmatism vs.the oceanic origin published before in literature.The exploration of this massif conducted also to the identification of a Silurian-Devonian sector in the western part.Therefore,up to date,different magmatic events lasting from the Meso-Archean to the Cretaceous are recorded in the Oulad Dlim Massif rocks,among them different generations of granitoids are reported.New data on granitoids from the Ediacaran sector are presented in this paper.This recent data demonstrates that Oulad Dlim Massif has been affected by the main Ediacaran–Cambrian extensional event widely documented in other structural domains of Morocco and other parts of North Gondwana.Additionally,the study of the Silurian-Devonian sector rocks highlighted the presence of a Caledonian tectonic event challenging the ideas about the paleogeography of this part of northwestern Africa and its geological evolution during the Paleozoic.However,despite the significant contribution of this extensive survey and the abundance of data on the Oulad Dlim Massif,more studies are required to reconstruct the puzzle at plate tectonic scale.展开更多
The Moroccan Anti-Atlas is a vast geological region composed of a Precambrian basement covered by a late-Neoproterozoic to Paleozoic sedimentary sequences. More than 200 copper occurrences are listed in these sequence...The Moroccan Anti-Atlas is a vast geological region composed of a Precambrian basement covered by a late-Neoproterozoic to Paleozoic sedimentary sequences. More than 200 copper occurrences are listed in these sequences. The copper mineralization of the Jbel N’Zourk (Central Anti-Atlas) is observed into the lower Limestones of the lower Cambrian (Adoudou formation), just above the volcanic formations of the Jbel Boho between Bou Azzer El Graara and Zenaga inliers. The region is by an E-W shortening resulting in an overlapping structure with vergence associated with folds. Generally, the mineralization is hosted along the principal fault of Jbel N’Zourk and sometimes in the anticlines hinges. The petrographic study showed that the mineralization can be observed in several aspects, either in the fractures and veins, in small karsts or rarely disseminated in calcite and dolomite minerals. These observations host new arguments who contribute to a later reconcentration of the copper mineralization of Jbel N’Zourk, trapped on faulted and folded structures attributed to Variscan deformation.展开更多
文摘Northeastern Morocco is made up of several units belonging to the Alpine belt and its foreland. Miocene to plio-quaternary volcanic rocks with variable mineralogy and geochemistry dominate the geology of this region. The presence of active faults in different directions explains the high tectonic instability and the high frequency of earthquakes. This study contributes to the effort of understanding the geothermal potential of the Northeast of Morocco. Heat source and permeability are both key factors in the geothermal process. Indeed, lineaments analysis constrains the structures and their directions and indicates severely faulted zones, which are the most promising areas for geothermal exploration. For this purpose, we used Landsat data combined with geological and structural maps available in this region. Different image processing techniques were applied including band ratio (6/2) and directional filters. To validate the results, we conducted a comparative study between linear structures, available geological data, and previous studies. Results of the automatic extraction method of lineaments from Landsat 8 OLI/TIRS indicate three main lineament systems: 1) a NE-SW system ranging from N40 to N70;2) an N-S system ranging from N10 to N45;3) an EW to WNW-ESE systems ranging from N80 to N120. Most of lineaments extracted are localized in Kebdana, Amejjaou, Nador and Melilla regions. Compared to previous studies, the NE-SW system is consistent with an extensive period (Tortonian to Pliocene);the NW-SE system is consistent with the last compressive episode (Pliocene);the N-S system is consistent with the first compressive period (Late/End Tortonian).
文摘Cenozoic volcanic activity in Morocco started in the Miocene and proceeded, after a short break, during Pliocene and Quaternary. Calc-alkaline magmatic activity occurred first and was accompanied by the eruption of transitional lavas, followed by Plio-Quaternary alkali basaltic activity, which was emplaced within Neogene sedimentary basins of the Rif belt and its foreland. From calc-alkaline to alkaline magmatism, passing through a transitional term, volcanic activities in Morocco formed magnificent outcrops, very diversified in their affinities, their mineral compositions and their geochemistry. The petrographic study and geochemistry of Plio-quaternary volcanic rocks in the areas with high geothermal potential in northeast of Morocco show a dominance of Na-rich basaltic rocks (basanites, basalts, tephrites and basaltic trachy-andesites), followed by trachy-andesites. Most of the samples exhibit an enrichment of large-ion lithophile elements (LILEs) over high-field-strength elements (HFSEs). These results were used to test the global model of Circum-Mediterranean Anorogenic Cenozoic Igneous Province (CiMACI) and the regional model of [1].
文摘The present work assesses the temporal distribution pattern and geochemical changes of rare earth elements and Yttrium, Scandium, Thorium, and Uranium delivery into the Oualidia lagoon. Two sediment cores were retrieved from the Oualidia lagoon and analyzed using neutron activation analysis. The results indicated that heavy rare earth elements are slightly enriched the sediment cores over light rare earth elements. The highest values of REEs were recorded in the top layers of the cores and depleted with depth, suggesting a possible change in factors controlling their accumulation, including mechanical, chemical, and environmental parameters such as weathering intensity, grain size, and Fe-Mn oxides. The sediments display positive Ce anomalies, which are probably related to the submarine weathering process and detrital input. Noting also the variation of hydrodynamics conditions and confinement of the upstream part of the lagoon played a key role in changing the sediment origins.Thus, further investigation of REEs origin in the Oualidia lagoon sediment is required to identify their sources,provenances, and the factors controlling their spatial and vertical distributions. However, these results provide baseline data of occurring changes in REEs geochemical composition and constitute a typical study case to understand the link between sedimentary and geochemistry processes in a lagoonal ecosystem.
文摘Mapping from remote sensing has become more effective in the field of geology, mainly in lithological discrimination and identification of hydrothermal alteration zones. The use of this technique consists in obtaining information about the rock mass and the main ones existing in the inaccessible areas. Satellite data from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor represent a favorable potential for detecting the spectral signatures of mineral zones and identifying their nature. These data are more reliable in places where the climate is arid with less abundant vegetation, as at the Oumjrane-Boukerzia mining district. This region which is part of the Eastern Anti-Atlas, is composed of several mineralized veins which still require detailed studies and exploration by the technique of remote sensing. In this work we applied several processing techniques on ASTER imagery such as Colored Composition, Principal Component Analysis and Ratio Bands. The use of the reports of the specialized Bands makes it possible to identify some hydrothermal alteration minerals within the mining district of Oumjrane Boukerzia. These minerals are represented mainly by iron oxides and hydroxides (Hematite, jarosite, limonite and goethite), carbonate minerals (dolomite, calcite), clay minerals (Illite, kaolinite and chlorite) and quartz minerals. This work allows us to produce a map of hydrothermal alteration zones which can be used as a valuable reference in the strategy of mining exploration for the base metals (Cu, Pb, Zn and Ba), in the mining district of Oumjrane-Boukerzia and in the entire Eastern Anti-Atlas.
基金International Geoscience Program Project 683(No.igcp683.org)。
文摘The Oulad Dlim Massif,adjacent to the Reguibat Shield in South Morocco was considered up to now as part of the Variscan belt(Mauritanides)with a polyphase geologic history and a complex geodynamic evolution implicating oceans closures and accretion of exotic terranes(Avalonian and Meguman)during the Variscan-Alleghanian orogeny.The use of modern technology to characterize the petrology,the geochemistry and the geochronology of the lithological units forming this region,combined to field surveys has led to an updated geological architecture and different geological history.The Oulad Dlim Massif is mainly a deformed Archean terrane,as recorded by its eastern and western sectors,dominated in its central part by a bimodal felsic-mafic magmatism forming the Ediacaran sector.The study of these magmatic complexes supports strongly the intracontinental origin of this bimodal magmatism vs.the oceanic origin published before in literature.The exploration of this massif conducted also to the identification of a Silurian-Devonian sector in the western part.Therefore,up to date,different magmatic events lasting from the Meso-Archean to the Cretaceous are recorded in the Oulad Dlim Massif rocks,among them different generations of granitoids are reported.New data on granitoids from the Ediacaran sector are presented in this paper.This recent data demonstrates that Oulad Dlim Massif has been affected by the main Ediacaran–Cambrian extensional event widely documented in other structural domains of Morocco and other parts of North Gondwana.Additionally,the study of the Silurian-Devonian sector rocks highlighted the presence of a Caledonian tectonic event challenging the ideas about the paleogeography of this part of northwestern Africa and its geological evolution during the Paleozoic.However,despite the significant contribution of this extensive survey and the abundance of data on the Oulad Dlim Massif,more studies are required to reconstruct the puzzle at plate tectonic scale.
文摘The Moroccan Anti-Atlas is a vast geological region composed of a Precambrian basement covered by a late-Neoproterozoic to Paleozoic sedimentary sequences. More than 200 copper occurrences are listed in these sequences. The copper mineralization of the Jbel N’Zourk (Central Anti-Atlas) is observed into the lower Limestones of the lower Cambrian (Adoudou formation), just above the volcanic formations of the Jbel Boho between Bou Azzer El Graara and Zenaga inliers. The region is by an E-W shortening resulting in an overlapping structure with vergence associated with folds. Generally, the mineralization is hosted along the principal fault of Jbel N’Zourk and sometimes in the anticlines hinges. The petrographic study showed that the mineralization can be observed in several aspects, either in the fractures and veins, in small karsts or rarely disseminated in calcite and dolomite minerals. These observations host new arguments who contribute to a later reconcentration of the copper mineralization of Jbel N’Zourk, trapped on faulted and folded structures attributed to Variscan deformation.
