Structural Interpretation And Source Rock Maturation Modeling Along Two Distinct Transects In The Upper / Middle Magdalena Basin, Colombia

The tectonic and stratigraphic evolution of the Magdalena Valley and adjacent areas of Colombia took place in a number of episodes. The original Jurassic back-arc extensional basin in the area has been modified during several periods of compression, oblique-slip and elevation through the late Cretaceous, and Cenozoic. A complex finite geometry has been developed, and maturation and migration histories are significantly different in different sub-areas. On two distinct geologic transverses, the structural interpretation has been studied using forward kinematic reconstruction approach allowing a depth extrapolation of the major structural blocks to be consistent with the surface geology and thermal and paleo-temperature indicators. The area of specific interest is the neighborhood of the Ibague Fault zone, a structure which almost certainly initiated during the initial back-arc rifting and which is usually taken to be the line separating the Upper Magdalena and Middle Magdalena basins. Significant Eocene elevation has occurred south of the fault; north of it a thick Cretaceous shale section reached its peak of hydrocarbon generation in the Paleogene. It was not possible to model the evolution of the local area without extending the scope of the investigation to include a couple of transects from the Llanos across the whole Eastern Cordillera. The Eastern Cordillera seems to have remained a positive area through the Cenozoic, hence its relative immaturity.