Contribution of Landsat 9 OLI-2/TIRS-2 Imagery to the Mapping of Dolerites in Aboutelfan (Central Chad Massif): Structural Implications

Abstract

This study focuses on the structural and lithological characterization of dolerite dykes in the Aboutelfan Massif, central Chad, using an integrated remote sensing and field-based approach. Landsat 9 OLI-2/TIRS-2 multispectral imagery was processed through radiometric calibration, spectral band combinations, and principal component analysis to discriminate doleritic bodies from surrounding lithologies. Field observations and petrographic analyses provided ground verification and detailed mineralogical descriptions. The dolerite dykes, generally post-tectonic, intrude the granitic basement with sharp contacts and exhibit variable thicknesses ranging from 3 to 25 m. Rose diagrams reveal dominant structural orientations along N 30° E, N 65° E, N 135°E, and N 153° E, reflecting the regional Pan-African tectonic control on dyke emplacement. The integration of satellite imagery and structural data led to the production of a high-resolution lithological and structural map of the Aboutelfan region. The results highlight the efficiency of Landsat 9 OLI-2/TIRS-2 imagery for identifying mafic intrusions and deciphering tectonic patterns in arid environments. This work provides new insights into the structural evolution of central Chad and establishes a methodological framework for future studies combining hyperspectral imagery and geochemical analyses to better constrain the petrogenesis and geochronology of doleritic intrusions.