Abstract Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic d... more Abstract Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic dykes have been studied for their petrofabric using Anisotropy of Magnetic Susceptibility (AMS) technique. Four dykes, namely TF, TD, FF and FE show andesitic compositions and are considered to belong to the same dyke swarm. They are oriented respectively N25E, N40E, N50E, and N10E and have been emplaced during a first tectonic event. The dyke FW, oriented N90E displays a composition of alkali basalt and its emplacement is attributed to a subsequent tectonic event. These rocks are propylitized under greenschist facies conditions forming a secondary paragenesis constituted by calcite, chlorite, epidote and sericite. The dykes TF, TD, FF and FE are sub-volcanic calc-alkaline, typical of post-collisional basalts/andesites, belonging to plate margin andesites. The FW dyke shows a within-plate basalt signature; alkaline affinity reflecting a different petrogenetic process. The thermomagnetic analyses show a dominantly ferromagnetic behaviour in the TF dyke core carried by single domain Ti-poor magnetite, maghemite and pyrrhotite. The dominantly paramagnetic susceptibilities in TF dyke rims and TD, FE, FF and FW dykes are controlled by ilmenite, amphibole, pyroxene and chlorite. The magnetic fabrics of the Imider dykes, determined by our AMS study, allows us to reconstitute the tectonic conditions which prevailed during the emplacement of these two generations of volcanic dykes. The first tectonic event was characterized by a roughly NE-SW compression and the second tectonic event is characterized by an E-W shortening followed by a relaxation recording the end of the Pan-African orogeny in the eastern Anti-Atlas.
Abstract: The West African craton (WAC) was constructed during the Archaean and the c. 2 Ga Palae... more Abstract: The West African craton (WAC) was constructed during the Archaean and the c. 2 Ga Palaeoproterozoic Eburnian orogeny. Mesoproterozoic quiescence at c. 1.7–1.0 Ga allowed cratonization. In the absence of Mesoproterozoic activity, there are no known WAC palaeogeo-graphical positions for that time. At the beginning of the Neoproterozoic, the WAC was affected by several extensional events suggesting that it was subjected to continental breakup. The most important event is the formation of the Gourma aulacogen in Mali, and the Taoudeni cratonic sub-circular basin and deposition of platform sediments in the Anti-Atlas. At the end of the Neopro-terozoic, the WAC was subjected to convergence on all its boundaries, from the north in the Anti-Atlas, to the east along the Trans-Saharan belt, to the south along the Rockelides and the Bassarides and to the east along the Mauritanides. This led to a partial remobilization of its cratonic boundaries giving rise to a metacratonic evolutio...
Morocco presents a varied and globally important geology reflecting its successive continental-sc... more Morocco presents a varied and globally important geology reflecting its successive continental-scale geological settings through geological time. Central, Southern and Western Morocco exhibits a rich geological history of crustal, magmatic, tectonic, metamorphic, sedimentary, and palaeontological features from Archaean to Quaternary, from large- to small-scale and varying in significance from international to local. The geostrategic position of Morocco renders it a land where many civilizations met through time leaving archaeological evidence of outstanding values - as such, its geodiversity is even more attractive as is related to historical, archaeological, architectural, cultural and traditional frames which vary with its geology. In this context, we focus on the central Anti-Atlas that consists of numerous Precambrian inliers amongst a matrix? of Palaeozoic strata, and each inlier has the merit to be transformed into thematic geoparks. Zenaga Inlier is a good example of an ensem...
This study aims to improve knowledge of the hydrogeology of the Haouz Central aquifer and to reco... more This study aims to improve knowledge of the hydrogeology of the Haouz Central aquifer and to record a hydro chemical characterization of groundwater and surface water. The geological map of the area shows a basin deposited on a Paleozoic basement, filled with the dismantling of the upper Atas and Jbillets, and crossed by outcrops of the Paleozoic basement (Exp: Guemassas and Tazakourt). On a hydrogeological level, groundwater circulation is geologically controlled and traces a flow to the northwest. The study area is drained by wadi Rhyghaya, wadi N'fiss and wadi Assif l’mal. The groundwater circulation is geologically controlled and traces a flow to the northwest. The study of groundwater mineralization has shown the strong bond between it and chlorides, sulphates, calcium and sodium. It increases gradually from South to North, recording calcium saturation along the wadi Tensift. The study of strontium and sulphates proves the contribution of evaporitic rocks of Trias.
The Moroccan Anti-Atlas orogenic belt encloses several Precambrian inliers comprising two major N... more The Moroccan Anti-Atlas orogenic belt encloses several Precambrian inliers comprising two major Neoproterozoic ophiolitic complexes: the Sirwa and Bou Azzer ophiolites. These ophiolites expose crustal and mantle units, thrusting over fragments of a long-lived intra-oceanic arc system. We present a detailed geochronological and petrogeochemical study of three mafic/ultramafic units of these two ophiolites: the Khzama sequence (Sirwa ophiolite) and the Northern and Southern Aït Ahmane sequences (Bou Azzer ophiolite). The crystallization of layered metagabbros from the Bou Azzer ophiolite (North Aït Ahmane sequence) has been dated here at 759 ± 2 Ma (U-Pb on zircons). This new age for the Bou Azzer ophiolite is similar to the formation of the Sirwa ophiolite (762 Ma) and suggests that both units formed during the same spreading event. Metabasalts of the three units show tholeiitic signature but with variable subduction-related imprints marked by LILE enrichments, HFSE depletions and variable Ti contents, similar to modern back-arc basin basalts (BABB). Their back-arc origin is also supported by the geochemical signature of ultramafic units showing very low contents in major and trace incompatible elements (Al 2 O 3 : 0.12-1.53 wt%, Ti: 3.5-64.2 ppm and Nb: 0.004-0.10 ppm), attesting of a highly refractory protolith. This is in agreement with the high Cr# (0.44-0.81) and low to intermediate Mg# (0.25-0.73) of their constitutive Cr-spinels. Dynamic melting models suggest that these serpentinites experienced intense and polyphased hydrous melting events, strongly influenced by supra-subduction zone SSZ-fluid influx and subduction-related melt percolation. Being particularly affected by these SSZ-melt/rock interactions and closer to arc units to the south, the Sirwa ophiolite and the South Aït Ahmane unit of the Bou Azzer ophiolite likely represent an early stage of the arc-back-arc system, which has been more influenced by the magmatic products of the arc activity compared to the North Aït Ahmane unit of the Bou Azzer ophiolite.
A significant fraction of the global population is currently without access to sufficient clean a... more A significant fraction of the global population is currently without access to sufficient clean and healthy drinking water. Although it was recently claimed that the Millennium Development Goal of reducing the number of people without access to sufficient potable water by half has been reached (WHO, 2012), it is also acknowledged that this progress was mainly due to improvements in China, while in other regions such as most of Africa, the situation remains severe or is worsening. Considering the impact of climate change and unsustainable water resource management, it is likely that the number of people without sufficient water will increase dramatically
Unusual massive magnetite veins and highly altered Cr-spinels as relics of a Cl-rich acidic hydro... more Unusual massive magnetite veins and highly altered Cr-spinels as relics of a Cl-rich acidic hydrothermal event in Neoproterozoic serpentinites (Bou Azzer ophiolite, Anti-Atlas, Morocco),
Abstract Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic d... more Abstract Located in the Imiter Inlier (Eastern Saghro, Anti-Atlas, Morocco), Ediacaran volcanic dykes have been studied for their petrofabric using Anisotropy of Magnetic Susceptibility (AMS) technique. Four dykes, namely TF, TD, FF and FE show andesitic compositions and are considered to belong to the same dyke swarm. They are oriented respectively N25E, N40E, N50E, and N10E and have been emplaced during a first tectonic event. The dyke FW, oriented N90E displays a composition of alkali basalt and its emplacement is attributed to a subsequent tectonic event. These rocks are propylitized under greenschist facies conditions forming a secondary paragenesis constituted by calcite, chlorite, epidote and sericite. The dykes TF, TD, FF and FE are sub-volcanic calc-alkaline, typical of post-collisional basalts/andesites, belonging to plate margin andesites. The FW dyke shows a within-plate basalt signature; alkaline affinity reflecting a different petrogenetic process. The thermomagnetic analyses show a dominantly ferromagnetic behaviour in the TF dyke core carried by single domain Ti-poor magnetite, maghemite and pyrrhotite. The dominantly paramagnetic susceptibilities in TF dyke rims and TD, FE, FF and FW dykes are controlled by ilmenite, amphibole, pyroxene and chlorite. The magnetic fabrics of the Imider dykes, determined by our AMS study, allows us to reconstitute the tectonic conditions which prevailed during the emplacement of these two generations of volcanic dykes. The first tectonic event was characterized by a roughly NE-SW compression and the second tectonic event is characterized by an E-W shortening followed by a relaxation recording the end of the Pan-African orogeny in the eastern Anti-Atlas.
Abstract: The West African craton (WAC) was constructed during the Archaean and the c. 2 Ga Palae... more Abstract: The West African craton (WAC) was constructed during the Archaean and the c. 2 Ga Palaeoproterozoic Eburnian orogeny. Mesoproterozoic quiescence at c. 1.7–1.0 Ga allowed cratonization. In the absence of Mesoproterozoic activity, there are no known WAC palaeogeo-graphical positions for that time. At the beginning of the Neoproterozoic, the WAC was affected by several extensional events suggesting that it was subjected to continental breakup. The most important event is the formation of the Gourma aulacogen in Mali, and the Taoudeni cratonic sub-circular basin and deposition of platform sediments in the Anti-Atlas. At the end of the Neopro-terozoic, the WAC was subjected to convergence on all its boundaries, from the north in the Anti-Atlas, to the east along the Trans-Saharan belt, to the south along the Rockelides and the Bassarides and to the east along the Mauritanides. This led to a partial remobilization of its cratonic boundaries giving rise to a metacratonic evolutio...
Morocco presents a varied and globally important geology reflecting its successive continental-sc... more Morocco presents a varied and globally important geology reflecting its successive continental-scale geological settings through geological time. Central, Southern and Western Morocco exhibits a rich geological history of crustal, magmatic, tectonic, metamorphic, sedimentary, and palaeontological features from Archaean to Quaternary, from large- to small-scale and varying in significance from international to local. The geostrategic position of Morocco renders it a land where many civilizations met through time leaving archaeological evidence of outstanding values - as such, its geodiversity is even more attractive as is related to historical, archaeological, architectural, cultural and traditional frames which vary with its geology. In this context, we focus on the central Anti-Atlas that consists of numerous Precambrian inliers amongst a matrix? of Palaeozoic strata, and each inlier has the merit to be transformed into thematic geoparks. Zenaga Inlier is a good example of an ensem...
This study aims to improve knowledge of the hydrogeology of the Haouz Central aquifer and to reco... more This study aims to improve knowledge of the hydrogeology of the Haouz Central aquifer and to record a hydro chemical characterization of groundwater and surface water. The geological map of the area shows a basin deposited on a Paleozoic basement, filled with the dismantling of the upper Atas and Jbillets, and crossed by outcrops of the Paleozoic basement (Exp: Guemassas and Tazakourt). On a hydrogeological level, groundwater circulation is geologically controlled and traces a flow to the northwest. The study area is drained by wadi Rhyghaya, wadi N'fiss and wadi Assif l’mal. The groundwater circulation is geologically controlled and traces a flow to the northwest. The study of groundwater mineralization has shown the strong bond between it and chlorides, sulphates, calcium and sodium. It increases gradually from South to North, recording calcium saturation along the wadi Tensift. The study of strontium and sulphates proves the contribution of evaporitic rocks of Trias.
The Moroccan Anti-Atlas orogenic belt encloses several Precambrian inliers comprising two major N... more The Moroccan Anti-Atlas orogenic belt encloses several Precambrian inliers comprising two major Neoproterozoic ophiolitic complexes: the Sirwa and Bou Azzer ophiolites. These ophiolites expose crustal and mantle units, thrusting over fragments of a long-lived intra-oceanic arc system. We present a detailed geochronological and petrogeochemical study of three mafic/ultramafic units of these two ophiolites: the Khzama sequence (Sirwa ophiolite) and the Northern and Southern Aït Ahmane sequences (Bou Azzer ophiolite). The crystallization of layered metagabbros from the Bou Azzer ophiolite (North Aït Ahmane sequence) has been dated here at 759 ± 2 Ma (U-Pb on zircons). This new age for the Bou Azzer ophiolite is similar to the formation of the Sirwa ophiolite (762 Ma) and suggests that both units formed during the same spreading event. Metabasalts of the three units show tholeiitic signature but with variable subduction-related imprints marked by LILE enrichments, HFSE depletions and variable Ti contents, similar to modern back-arc basin basalts (BABB). Their back-arc origin is also supported by the geochemical signature of ultramafic units showing very low contents in major and trace incompatible elements (Al 2 O 3 : 0.12-1.53 wt%, Ti: 3.5-64.2 ppm and Nb: 0.004-0.10 ppm), attesting of a highly refractory protolith. This is in agreement with the high Cr# (0.44-0.81) and low to intermediate Mg# (0.25-0.73) of their constitutive Cr-spinels. Dynamic melting models suggest that these serpentinites experienced intense and polyphased hydrous melting events, strongly influenced by supra-subduction zone SSZ-fluid influx and subduction-related melt percolation. Being particularly affected by these SSZ-melt/rock interactions and closer to arc units to the south, the Sirwa ophiolite and the South Aït Ahmane unit of the Bou Azzer ophiolite likely represent an early stage of the arc-back-arc system, which has been more influenced by the magmatic products of the arc activity compared to the North Aït Ahmane unit of the Bou Azzer ophiolite.
A significant fraction of the global population is currently without access to sufficient clean a... more A significant fraction of the global population is currently without access to sufficient clean and healthy drinking water. Although it was recently claimed that the Millennium Development Goal of reducing the number of people without access to sufficient potable water by half has been reached (WHO, 2012), it is also acknowledged that this progress was mainly due to improvements in China, while in other regions such as most of Africa, the situation remains severe or is worsening. Considering the impact of climate change and unsustainable water resource management, it is likely that the number of people without sufficient water will increase dramatically
Unusual massive magnetite veins and highly altered Cr-spinels as relics of a Cl-rich acidic hydro... more Unusual massive magnetite veins and highly altered Cr-spinels as relics of a Cl-rich acidic hydrothermal event in Neoproterozoic serpentinites (Bou Azzer ophiolite, Anti-Atlas, Morocco),
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