Figure 2-1. Pre-Cretaceous tectonic framework of study area, Eastern Region of Oriente Basin--map and regional cross-sections in perspective, located by Lines I, II, III, and IV. The half-grabens were developed by a west-northwest extensional episode during pre-Cretaceous. The resulting architecture was controlled by fault geometries, which were heavily influenced by pre-existing basement fabrics. Lines 1, 2, and 3 show locations of seismic lines in Figures 2-2 and 2-3.