R?le du brassage et du stockage magmatique dans l’homogénéisation des granito?des calco-alcalins: Cas du pluton composite de Za?r (Maroc central)     

Jamila Ha?meur et Iz-Eddine El Amrani El Hassani 《Eclogae Geologicae Helvetiae》2005,98(2):219-236

Resume.  Le pluton calco-alcalin de Za?r est composé de trois principaux faciès pétrographiques répartis en deux unités granitiques imbriquées. Ces faciès, de différents degrés d’hybridation et de différenciation, résultent de mélanges magmatiques entre des magmas basiques mantelliques de type ?HAB? (basalte hyperalumineux) et un magma anatectique issu de la fusion partielle de matériaux crustaux (métapélites ou métagrauwackes). La répartition des faciès granitiques de Za?r peut s’expliquer selon un modèle pétrogénétique de type ?MASH? (melting-assimilation-storage-homogenization) où des magmas hybrides seraient formés suivant différentes proportions de mélanges magmatiques acide-basique. Ces magmas auraient subides conditions d’ascension spécifiques et seraient mis en place sous forme de 3 grandes injections successives:

1)	Une injection précoce de magma fortement hybride donne la granodiorite-tonalite du SW, assez faiblement homogénéisée et à grands xénolites et enclaves microgrenues mafiques (EMM) dont les compositions pétrographiques, chimiques et isotopiques initiales sont bien préservées
2)	Une injection, plus tardive et sur une longue distance, de magma relativement plus différencié, donne le monzogranite-granodiorite du NE, assez bien homogénéisé et riche en petites EMM dont les compositions ont été rééquilibrées avec celles du granite h?te
3)	Une injection très tardive après un stockage de quelques millions d’années et un important brassage magmatique ayant permis un mélange magmatique complet (mixing) des deux composants acide et basique. Cela donne le leucogranite central, très différencié et parfaitement homogène

Manuscrit re?u le 12 décembre 2003 Révision acceptée le 9 mai 2005  相似文献   

Caractérisation géochimique des fluides associés aux minéralisations PbZn de Bou-Dahar (Maroc)     

Samira Adil  Mohammed Bouabdellah  Fidel Grandia  Esteve Cardellach  Àngel Canals 《Comptes Rendus Geoscience》2004,336(14):1265-1272

The Bou-Dahar PbZn Mississippi Valley deposits located in the eastern part of the High Atlas Range (Morocco) are hosted by a Liassic reefal complex. Fluid inclusion and ‘crush-leach’ data show that two distinct fluids were involved in the mineralisation deposition: a warmer, more saline fluid (180?°C, $>25\text{wt\%}$ NaCl equivalent) and a cooler, less saline fluid (70?°C, 16 wt% equivalent NaCl). Mixing of these two fluids resulted in the precipitation of the ore. The solute composition of the ore-forming brine suggests that the MVT mineralising fluids were probably a mixture of halite-dissolution fluids and evaporated seawater. To cite this article: S. Adil et al., C. R. Geoscience 336 (2004).  相似文献   

Groundwater nitrate pollution in the Essaouira Basin (Morocco)     

Nour-Eddine Laftouhi  Marnik Vanclooster  Mohammed Jalal  Omar Witam  Mohamed Aboufirassi  Mohamed Bahir  Étienne Persoons 《Comptes Rendus Geoscience》2003,335(3):307-317

The Essaouira Basin (Morocco) contains a multi-layered aquifer situated in fractured and karstic materials from the Middle and Upper Cretaceous (the Cenomanian, Turonian and Senonian). Water percolates through the limestone and dolomite formations of the Turonian stage either through the marls and calcareous marls of the Cenomanian or through the calcareous marly materials of the Senonian. The aquifer system may be interconnected since the marl layer separating the Turonian, Cenomanian and Senonian aquifers is thin or intensively fractured. In that case, the water is transported through a network of fractures and stratification joints. This paper describes the extent of the nitrate pollution in the area and its origin. Most of the wells and drillholes located in the Kourimat perimeter are contaminated by nitrates with some concentrations over $\text{400 }\text{mg}\text{l}{}^{\mathrm{?1}}$. Nitrate contamination is also observed in the surface water of the Qsob River, which constitutes the natural outlet of the multi-layered complex aquifer system. In this area, agriculture is more developed than in the rest of the Essaouira Basin. Diffuse pollution of the karstic groundwater body by agricultural fertiliser residues may therefore partially explain the observed nitrate pollution. However, point pollution around the wells, springs and drillholes from human wastewater, livestock faeces and the mineralisation of organic debris close to the Muslim cemeteries cannot be excluded.  相似文献   

Modèle de formation du gisement d'argent d'Imiter (Anti-Atlas oriental,Maroc). Nouveaux apports de l'analyse structurale et minéralogique     

Johann Tuduri  Alain Chauvet  Aomar Ennaciri  Luc Barbanson 《Comptes Rendus Geoscience》2006,338(4):253-261

Based on a combined geometrical and mineralogical analysis, a three-stage model of formation of the mineralized veins of the giant Imiter silver deposit (Anti-Atlas, Morocco) is herein proposed. A first episode is characterized by the development of quartz, pink dolomite and Ag-rich minerals veins formed during a dextral transpressive event. The second episode is associated with a normal left-lateral motion that re-opens previous structures, filled by pink dolomite gangue. Alteration stages contribute to a local Ag enrichment. To cite this article: J. Tuduri et al., C. R. Geoscience 338 (2005).  相似文献   

Les sondages électromagnétiques temporels comme outil de reconnaissance du gisement phosphaté de Sidi Chennane (Maroc) : apport à la résolution d'un problème d'exploitation     

Azzouz Kchikach  Pierre Andrieux  Mohammed Jaffal  Mostafa Amrhar  Mohammed Mchichi  Baadi Boya  Mbarek Amaghzaz  Thierry Veyrieras  Khadija Iqizou 《Comptes Rendus Geoscience》2006,338(5):289-296

Exploitation of the phosphatic layers in Sidi Chennane deposit (Morocco) collides frequently with problems bound to the existence, in the phosphatic series, of sterile bodies qualified as derangements. Our study shows that these bodies, masked by the Quaternary cover can be mapped using the Time-Domain ElectroMagnetic Soundings method (TDEM). It is based on the acquisition and the interpretation of a series of tests carried out above a visible derangement in an old trench of exploitation and on 2500 TDEM soundings carried out in a virgin area of the deposit. The article concerns to the analysis of the results and of the proceeding for a possible large geophysics survey. To cite this article: A. Kchikach et al., C. R. Geoscience 338 (2006).  相似文献   

Potentialité d'utilisation d'argiles marocaines de Jbel Kharrou dans l'industrie céramique     

Nadia El Yakoubi  M&#x;hamed Aberkan  Mohamed Ouadia 《Comptes Rendus Geoscience》2006,338(10):693-702

The Ordovician clays of Jbel Kharrou (Rehamna, Morocco) have been studied for their use in ceramic industry. The realised studies were carried out on two samples B1 and B2, the most representative, taken from a clay dominated formation that outcrops 25 km east of the Skhour Rehamna city. The chemical analyses, mineralogical studies and advanced technological tests undertaken on the two samples indicate that these clays can be considered as non-refractory material, so they can be used to the manufacturing of ceramic products: soil and wall tiles, sanitary, pottery, etc. The tested briquettes, cooked at 1040?°C, remain flat, without deformation or defects; they are of cream white dye. These briquettes show a high mechanical resistance to the flexion, the loss in weight remains tolerable with cooking, lightly elevated (12% ); it can be corrected by the addition of a grease-remover. To cite this article: N. El Yakoubi et al., C. R. Geoscience 338 (2006).  相似文献