Imaging of hydrothermal altered zones in Wadi Al-Bana, in southern Yemen, using remote sensing techniques and very low frequency–electromagnetic data

© 2019, Saudi Society for Geosciences. Economic mineralization and hydrothermally altered zones are areas of great economic interests. This study focusses on hydrothermal altered zones of high mineralization potentials in Wadi Al-Bana, in southern Yemen. An azimuthal very low frequency–electromagnetic (AVLF-EM) data acquisition was conducted in search for mineralization in the study area. The study integrated observations from geophysical field data with others extracted from object-oriented principal component analysis (PCA) to better map and understand mineralization in the investigated area. This technique was applied to two data sets, ASTER and Landsat 8 Operational Land Imager (OLI) imagery. The results of PCA revealed high accuracy in detecting alteration minerals and for mapping zones of high concentration of these minerals. The PCA-based distribution of selected alteration zones correlated spatially with high conductivity anomalies in the subsurface that were detected by VLF measurements. Finally, a GIS model was built and successfully utilized to categorize the resulted altered zones, into three levels. [Figure not available: see fulltext.]

Enquete ethnobotanique sur les plantes antipaludiques utilisees dans la lutte anti vectorielle au Togo

La nouvelle méthode d’enquête ethnobotanique ATRM (Achat en Triplet de Recette Médicinale) couplée avec celle d’enquête par interview semi structurée, ont été utilisées pour recenser entre 2007 et 2011, les plantes utilisées au Togo pour soigner le paludisme et les pathologies associées. Parmi les plantes collectées, seules 7 espèces ont été citées pour leurs propriétés anti vectorielles utilisées contre les moustiques (Anopheles sp), agents vecteurs du paludisme. Ces plantes dont les unes sont à activités insecticides et les autres répulsives, appartiennent à 6 familles dont les Lamiaceae, représentées par deux espèces, sont les plus citées. Cymbopogon citratus (DC.) Stapf, Azadirachta indica L. et Hyptis sauveolens Poit sont les espèces les plus fréquentes. C’est la première qu’une enquête ethnobotanique recense les plantes antipaludiques aux propriétés anti-vectorielles au Togo. Des études seront entreprises pour la vérification des propriétés larvicides et insecticides d’extraits de ces plantes sur les moustiques.Mots clés: Enquête ethnobotanique, plantes antipaludiques anti- vectorielles, Anopheles sp, TogoEnglish Title: Ethnobotanical survey of mosquito repellent medicinal plants of TogoEnglish AbstractThe new ethnobotanical method named ATRM (Purchase in Triplet of Medicinal Recipes, in English) coupled with the semi structured interview, was used to collect from 2007 to 2011, medicinal plants used in Togo for the management of malaria and its associated pathologies. Among the recorded plants, only 7 species were quoted for their mosquitoes repellent properties, used against Anopheles sp, the vector agents of the malaria. These plants among which some are potential of insecticidal activities and the others are repulsive, belong to 6 botanical families. Lamiaceae represented by two species, is most cited. Cymbopogon citratus (DC). Stapf, Azadirachta indica L. and Hyptis sauveolens Poit were the most frequent species. It is the first time that an ethnobotanical investigation lists the antimalarial plants with mosquito repellent properties in Togo. Studies will be undertaken for the evaluation of the larvicidal and insecticidal activities of extracts from these plants on mosquitoes.Keywords: ethnobotanical survey, mosquito repellent plants, Anopheles sp, Tog