Mapping of Hydrothermal Alteration Zones in the Kelâat M’Gouna Region Using Airborne Gamma-Ray Spectrometry and Remote Sensing Data: Mining Implications (Eastern Anti-Atlas, Morocco)

Younes Mamouch,Mohammed Ouchchen,Yassine Et-Tayea,Abdelhamid Allaoui,Giovanni Randazzo,Lahsen Achkouch,Bouchra Dadi,Stefania Lanza,Mustapha Boualoul,Abdelhalim Miftah,Ahmed Attou,Anselme Muzirafuti

doi:10.3390/app12030957

Abstract

The mapping of hydrothermal alteration zones associated with mineralization is of paramount importance in searching for metal deposits. For this purpose, targeting alteration zones by analyzing airborne geophysical and satellite imagery provides accurate and reliable results. In the Kelâat M’Gouna inlier, located in the Saghro Massif of the Moroccan Anti Atlas, natural gamma-ray spectrometry and ASTER satellite data were used to map hydrothermal alteration zones. Natural gamma-ray spectrometry data were processed to produce maps of Potassium (K in %), Uranium (eU in ppm), Thorium (eTh in ppm) and ratios of K/eTh and K/eU. In addition, four-band ratios were computed, on ASTER data, to map the distribution of clay minerals, phyllitic minerals, propylitic minerals, and iron oxides. The combined results obtained from geophysical and satellite data were further exploited by fuzzy logic modelling using the Geographic Information System (GIS) to generate a mineral prospectivity map. Seven hydrothermal alteration zones likely to be favorable for mineralization have been identified. They show a spatial correlation with (i) known surface prospects and mineral occurrences, (ii) the granite-encasing contact zone, and (iii) the fault zones (Sidi Flah and Tagmout faults). This research therefore provides important information on the prospecting of mineral potential in the study area.

Highlights

The mapping of hydrothermal alteration zones associated with mineralized systems is of great importance in mineral exploration, especially in the early stages of metal deposit exploration [1,2,3,4,5,6,7,8,9,10,11]
The study demonstrates the importance of combining natural gamma-ray spectrometry and ASTER data in the early stages of mineral exploration. This combination was applied to target areas with high mining potential in the Kelâat M’Gouna inlier
The results obtained allowed detailed mapping of hydrothermal alteration zones related to mineralization

Summary

Introduction

The mapping of hydrothermal alteration zones associated with mineralized systems is of great importance in mineral exploration, especially in the early stages of metal deposit exploration [1,2,3,4,5,6,7,8,9,10,11]. The method of processing multispectral satellite images, especially those of the ASTER sensor, is qualified among the most used approaches [4,6,7,8,10,11,13,14,15,16,17,18]. Apart from remote sensing data, processing of geophysical data contributes assuredly to minerals exploration through their different geophysical components (gravimetric, magnetometric, electrical, electromagnetic and natural gamma spectrometric methods) [19,20,21,22,23,24]. The natural gamma-ray spectrometric method has been widely and successfully used in mineral exploration and identification of alteration zones [20,21,25,26,27,28,29,30]. Few studies have been tested the application of this method in conjunction with the open accessible free satellite images

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Conclusion