Although only part of the TBP (about 25 km across) is shown in this Landsat 7 image, the view is generally representative of the entire province, which attains a maximum width of about 35 km northward. The basement is of Pan-African age and, as such, is clearly younger than that of Al'Oweinat. The northeasterly trend of the metamorphic belt is evident and so is its mega-folding, which can be seen in the upper left part of the satellite image. The largest intrusions shown partly in the upper right side of the view. Several stages of intrusion are deciphered, and it appears that the oval shapes to the southeast and northwest mark sites whereby either much of the intruded igneous rock mass was removed or that the sites point to subsidence whereby much of the intruded rocks have subsequently sunken into their pool. In the latter case, the rims would be marking the boundaries of the roots of the calderas. Ground mapping was not carried out in these two sub-areas, and thus substantiation of either process awaits careful field work.

Tibesti Basement Province (TBP) is the largest areally and occupies the central southernmost part of Libya. Exposures are plentiful and so are wadis, especially on the Chadian side of the border. The general fabric of TBP is shown best in its metamorphic part as a northeasterly trend that is either cut across by round oval or rounded intrusions of varying size or deflecting around them. TBP has long been recognized as comprising two distinctive belts separated by a fault zone: an eastern belt of relatively high grade metamorphites and a host of granite and related rocks, and an areally more expansive western belt of lower grade metamorphites dominated by igneous rocks tending toward granodiorite and diorite. Field work in the province suggests that each of the afore-mentioned belts is further divisible into two sub-belts of diffuse contacts. From east to west, these are: Ayzri, Sanaker-Gazendou, Aouzou, and Ben Ghnema. In the eastern belt, known best as the Jabal Eghei area, a brief field study documents a high grade staurolite schist zone and garnet-rich calc-silicate assemblage. Folding in the schist is tight to moderate, symmetrical to slightly asymmetrical exhibiting sub-vertical axial planes. In the garnetiferous calc-silicate, folding is of many styles and geometries ranging from similar to parallel, open to tight, upright to inclined. Some folds might have thickened hinges. The granites and related rocks are massive, spheroidal to blocky, generally light grey to reddish in color, coarse-grained, and are locally cut by quartz veins and other granites and micro-granite.

In the western belt, metagreywackes dominate the metamorphic suite whereas granodiorite and diorite dominate the igneous suite. Along Wadi Aouzou (within the Aouzou sub-belt), the basement in several places is made up of greenish, brecciated chlorite schist and is overlain by Cambrian to Carboniferous sandstone. Westward in the Ben Ghnema sub-belt, granodioite and diorite of batholithic dimensions abound.