IMPACT ANTHROPIQUE SUR LA QUALITE DES EAUX SOUTERRAINES DU BASSIN VERSANT DE L’OUED TAZA (MAROC) ANTHROPOGENIC IMPACT ON GROUNDWATER QUALITY IN THE WATERSHED OF OUED TAZA (MOROCCO)

The main objective of this work is to determine the status of the groundwater quality in the watershed of Taza river, based primarily on physico-chemical and bacteriological parameters of groundwater. The Oued Taza is a small mountain river, 13.44 Km long, which drains a watershed of 40.07 km ². The outlet located at an altitude of 420 m corresponds to the confluence with the Oued Iarbaa. The average annual rainfall varies between 352 mm and 719mm while the annual average temperature is 18.1 ° C. Very high concentrations of nitrates, nitrites, heavy metals and bacterial load in some points near urban areas, illustrate the effect of human activities on degradation of water quality. This contamination could have several causes, the most important are related to household and industrial discharges (especially waters) spilled without any treatment in the rivers, and the use of fertilizers in agricultural areas. These results will enrich the database on water quality in the basin, and help policy makers to better decide on the management of water resources for a better sustainable development of the regio

Nouvelles observations dans le dépocentre volcano-sédimentaire carbonifère du Massif du Tazekka, Moyen-Atlas, Maroc : implications sur l'évolution géodynamique de la chaîne Hercynienne

A análise integrada das estruturas tectónicas e das fácies do Complexo Vulcano Sedimentar do Maciço de Tazekka sugere que este, à escala da grande bacia carbonífera de ante país da Meseta Oriental marroquina, corresponde a um depocentro ou sub bacia em compressão controlada pela propagação, para NW, de dobras de amortecimento do cavalgamento de Hajra Sbaa el Caid. As sequências tectono sedimentares, detrito conglomeráticas e/ou tufíticas, estão associadas a um magmatismo extrusivo com basaltos, andesitos, dacitos, riodacitos e riólitos homogéneos ou piroclásticos com blocos re sedimentados. Estes vulcanitos correspondem a uma sequência sub alcalina equivalente. As sequências calco alcalinas orogénicas características de ambientes de subducção. Estes resultados, assim como a comparação das idades de contracção regional na Meseta marroquina, permitem integrar o Maciço de Tazekka num contexto de wedge top deepzone dum sistema de bacias de ante país flexural, em compressão comandada pela progressão de duas sequências de cavalgamentos prógrados, de NW, desde o Fameno Tournaisiano ao Viseano sup. Terminal Westfaliano inf., da Meseta Oriental para a Meseta Ocidental, em Marrocos setentrional

Low intra-crystalline closure temperatures of Cr-bearing spinels from the mantle xenoliths of the Middle Atlas Neogene-Quaternary Volcanic Field (Morocco): A mineralogical evidence of a cooler mantle beneath the West African Craton

The crystal chemistry of nine Cr-spinels from lherzolite and harzburgite xenoliths from the Middle Atlas Neogene-Quaternary Volcanic Field of Morocco have been studied by means of X-ray single crystal diffraction and electron microprobe analyses. Cell edges are usually within the range 8.13-8.14 \uc5, but there are three samples with longer a value, so that the whole analyzed series is within the range 8.1334 (4) \u2013 8.2021 (2) \uc5, while the oxygen positional parameter values are very similar ranging between 0.2626 (1) and 0.2629 (2) for all of them. The cation distribution shows that the crystal structure is ordered with almost all divalent cations in the tetrahedral site and trivalent cations in the octahedral site. The determined intracrystalline temperatures are in the range 550-750\ub0C, that are the lowest values ever found for Cr-spinels from mantle xenoliths as these are usually higher than 730\ub0C. If we consider the behavior of some geotherms from literature, the determined temperatures are confined in a depth range of about 20-40 Km. Lithospheric models for the studied area indicate that the lower crust reaches its deepest value in a range between 30 and 40 Km. Consequently, we can assume that the studied xenoliths were emplaced at a \u201cshallow\u201d depth of about 20-30 Km, just beneath the lower crust, where they were disrupted and brought to the surface from the ascending alkaline lavas. This assumption is consistent with the concomitant presence of some crustal xenolith