DIGITAL GEOLOGIC MAPPING USED FOR ANALYSIS OF GEOLOGIC STRUCTURES AND VOLCANISM, TIBESTI VOLCANIC PROVINCE, CHAD

The Tibesti volcanic province (TVP) in northern Chad is one of the largest and least studied intracontinental volcanic regions of the world. Digital mapping of the Tibesti volcanic province (TVP) using satellite remote sensing seems a perfect match for an environment unfriendly to field expeditions due to Saharan climate and political instability. We will present digital maps and profiles developed using satellite remote sensing data. Specifically, we compiled a digital elevation model (DEM) for the entire TVP based on a mosaic of 42 individual 60 X 60 km Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes. Structural and geomorphic features such as faults and rock joint patterns are discernible from the shaded relief map produced from the mosaiced DEM. Digital geologic mapping of the central TVP using ASTER thermal infrared spectra complements structural interpretation. One of the advantages of digital maps is the ability to produce 3-D topographic profiles, with or without geologic map units superimposed, from a variety of perspectives. Based on our observations it appears that the most recent volcanism is closely associated with the intersection of a youthful escarpment and a structurally-controlled drainage which is perpendicular to it. Older volcanism appears to be concentrated in a half-graben. Relative age of volcanism is apparent based on the frequency of rock joints and drainage patterns. The results have the potential to be used as a platform for further exploration of the tectonics governing volcanism in this important volcanic region.