Mineralogy and Geochemistry of the Guenfouda Clay Deposit, Jerada Province, Northeastern Morocco

peer reviewedThe Guenfouda clay deposit is located at about 36km to the southwest of Oujda city and 6km to the south of Guenfouda village. It belongs to the Jerada Province of the northeastern Morocco and hosted within the Upper Visean calc-alkaline dacite lava interbedded within a schisto-volcanic complex. This deposit is mined for more than 15 years and the product being mainly used for refractories and industrial ceramics. This clay deposit is funnel or trough-like in form, narrowing downwards and display a E–W trend, which follows the major dextral strike-slip fault that passes through the south of the deposit. Based on mineral assemblages, four lateral alteration zones were defined from the north to south parts of the deposit: the Illite zone, the Pyrophyllite-illite zone, the Pyrophyllite zone and the Quartz zone. The presence of high-temperature minerals such as pyrophyllite, diaspore, the alteration zonation pattern and the chemical characteristics are diagnostic of hypogene origin. However, the variation diagrams, Zr vs TiO2 and P2O5 vs SO3 as well as the values of the chemical Index of Weathering (CIW) and the Alteration Index (AI) revealed a mixed type. It seems that the genesis of Guenfouda clay deposit was first controlled by the eastwest strike-slip faults, which brought ascending hydrothermal solutions that led to clay formation and finally, the weathering processes have continued and extended the argillization

L’histoire éruptive du volcan monogénique quaternaire de Timahdite (Moyen Atlas, Maroc)

Le volcan de Timahdite fait partie de la province volcanique alcaline quaternaire du Moyen Atlas et se compose d’un maar à cratère grossièrement elliptique entouré d’un anneau de tufs, au sein duquel se niche un cône strombolien. Les travaux de cartographie, pétrographie, morphoscopie et granulométrie réalisés sur les dépôts volcaniques de cet appareil montrent que son édification s’est déroulée en quatre phases éruptives qui se relayent dans le temps : (I) une phase phréatomagmatique, (II) une première phase effusive à l’origine du lac de lave, (III) une phase strombolienne et (IV) la phase effusive terminale. La phase phréatomagmatique, engendrée par l’interaction magma-eau, est constituée par des déferlantes basales de plus en plus sèches et entrecoupées de niveaux de retombées. La première phase effusive est représentée par un lac de lave basaltique qui colmate le cratère du maar et déborde vers l’est pour se canaliser dans le lit de l’Oued Guigou. La phase strombolienne se met en place à la suite d’une courte pause représentée par une discordance angulaire synchrone de la mise en place du lac de lave. Cette troisième phase est matérialisée par un cône de scories avec une séquence pyroclastique dominée par des retombées stromboliennes auxquels sont associées des bombes fusiformes et en bouse de vache. La phase effusive terminale correspond à la mise en place de la coulée basaltique terminale et sa brèche qui nappent le sommet et le flanc sud-est du cône. Outre les causes volcanologiques et tectoniques, la variabilité du bilan hydrique de l’Oued Guigou a pu jouer un rôle majeur dans la dynamique de construction du volcan de Timahdite, influençant largement les dynamismes éruptifs et les modalités de dépôts.The Timahdite volcano is part of the Middle Atlas quaternary alkaline volcanic province and consists of a roughly elliptical crater maar surrounded by a tuff ring within which is edified a Strombolian cone. The cartography, petrography, morphoscopy and granulometry work carried out on the volcanic deposits of this edifice show that its construction took place in four eruptive phases which are relayed in time: (I) a phreatomagmatic phase, (II) a first effusive phase at the origin of the lava lake, (III) a Strombolian phase and (IV) the second effusive phase. The phreatomagmatic phase, generated by the magma-water interaction, consists of increasingly dry base surge interstratified with fallout levels. The first effusive phase is represented by a basalt lava lake which overflows the crater of the maar and pours out to the east and channeled into the Oued Guigou valley. The Strombolian phase is set up following a short pause represented by an angular unconformity. This third phase is materialized by a scoria cone with a pyroclastic sequence dominated by Strombolian fallout with ellipsoidal and cow pie bombs. The second effusive phase corresponds to the setup of the second basalt flow and its breccia which cover the top and the south-east flank of the cone. Besides the volcanological and tectonic causes, the variability of the water balance of Oued Guigou could play a major role in the dynamics of construction of the Timahdite volcano, largely influencing the eruptive dynamics and the deposits modalities

The Frequency of Human Papillomaviruses and Epstein-Barr Virus in Colorectal Cancer Samples in Algeria

Background: Environmental factors may play a role in colon cancer. In this view, several studies investigated tumor samples for the presence of various viral DNA with conflicting results. The purpose of this study is to investigate the prevalence of Human papillomaviruses (HPVs) and Epstein-Barr virus (EBV) in patients with colorectal carcinomas. Materials and Methods: In this study, we collected 74 tumorous paraffin-embedded tissues (Mean±SD age: 66.3±14.98) from the Pathology Department of a hospital in AinTemouchent and laboratories of pathological anatomy in western Algeria. DNA from each tissue was extracted and the presence of HPV and EBV was investigated using PCR. Results: None of our samples were HPV or EBV positive, and we failed to find an obvious correlation between EBV and HPV infections and this type of cancer. Conclusion: The results suggested that EBV and HPV infection is not common in patients with colorectal cancer in our population. However, the findings merit more investigations on a large number of cases