Bentonite Clay Minerals Mapping Using ASTER and Field Mineralogical Data: A Case Study from the Eastern Rif Belt, Morocco

Remote sensing and mineralogical data have been integrated to map the spatial distribution of bentonite clay minerals in the Zeghanghane area, located in the eastern Rif belt of Morocco. Numerous bentonite deposits of substantial economic potential are recognized in this region and their acceptability is still restricted. These clay minerals are directly derived from different weathering types of Neogene volcanic outcrops. For this purpose, different remote sensing processing techniques have been applied to the Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite data, including Relative absorption band-depth, Minimum noise fraction, Pixel purity index, and ND visualization. The obtained results allowed identifying three clay minerals, namely kaolinite/smectite, illite, and montmorillonite which typically characterize the bentonite clay minerals. They are mainly concentrated in the Neogene volcanic massifs such as Gourougou, Tidiennit and Amjar. Field work, petrographic and X-ray diffraction analyses permitted the verification and validation of the obtained results. A new bentonite alteration zones have been discovered and the majority of pre-existing ore deposits have been confirmed. The established bentonite map will serve as a guide for future mining exploration in the Zeghanghane area.