Geological mapping of carbonatites and related ores from the Oulad Dlim massif (Dakhla Province, Morocco) using remote sensing, portable X-ray fluorescence, and mineralogical data

Abstract and Poste

An Integrated Approach for Rapid Delineation of K-Rich Syenites Suitable as Unconventional Potash Resources

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An Integrated Approach for Rapid Delineation of K-Rich Syenites Suitable as Unconventional Potash Resources

Potassium (K)-rich igneous rocks include a variety of silica-undersaturated and alkaline rocks, which distinguished by their elevated KO contents. These rocks have attracted attention for decades and motivated various studies focused either on geodynamic implications or on their association with mineral resources. Recently, further studies of K-rich igneous suites were dedicated to assessing their potential as unconventional potash resource for agricultural K fertilization. These works led many countries to reassess their geological resources in K by including suitable igneous suites, hence promoting detailed geological survey and lithological/geochemical mapping of key areas. In this study, we present an integrated approach coupling remote sensing, GIS, and field data to identify and map K-rich igneous rocks over wide areas. Based on the thermal infrared (TIR) spectral properties of silicate K-bearing minerals commonly found in igneous rocks (e.g., syenites and trachytes), the ASTER TIR emissivity band ratio (B10/B11) was selected to identify potential areas of K-rich rocks. Then, a supervised mapping-based classification was applied to high potential areas using field data (field observations and portable X-ray fluorescence analyses) and petrographic characterization as training data. This approach was applied successfully at a large scale in two different areas in Morocco where potential areas of K-rich syenites have been reported. The accuracy and detail of preliminary band ratio mapping were enhanced, and several K-rich lithologies were differentiated using the spectral angle mapper algorithm. This approach for integrating easily accessible data has proven to be relatively rapid and cost-effective

An integrated ASTER-based approach for mapping carbonatite and iron oxide-apatite deposits

Mapping of carbonatites and related mineral deposits has occupied prominent place in mineral resource exploration programs given their potential to host valuable concentrations of critical metals such as rare earth elements and niobium. Based on spectral characteristics of most indicative minerals for these rocks, a mapping approach was developed using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. The combination of band rationing outcomes with components from the principal component analysis and minimum noise fraction techniques highlighted the targeted rocks, with the excellent prospective zone representing ∼0.2% of the total investigated area. This approach was successfully applied to the Gleibat Lafhouda complex to rapidly delineate carbonatites and iron oxide-apatite ore outcrops. Results were validated through field observations and in-situ geochemical analysis using a portable X-ray fluorescence analyzer. Field data have also served as training data to perform a supervised classification, allowing further improvement of the mapping results