Upper Cretaceous to Recent plate tectonics, basin formation and tectono-stratigraphy of the Lower Magdalena valley and San Jacinto fold belt of Northwestern Colombia: implications for hydrocarbon systems

In this thesis I used a regional geological and geophysical dataset to reconstruct the Late Cretaceous to Recent evolution of the Lower Magdalena Valley basin and San Jacinto fold belt of NW Colombia. My detailed interpretations of reflection seismic data and new geochronology analyses reveal that the Lower Magdalena basement is the northward continuation of the basement terranes of the northern Central Cordillera, consisting of Permo-Triassic metasediments, which were intruded by Late Cretaceous granitoids. Structural analyses suggest that the NE-SW trend of basement faults in the northeastern Lower Magdalena is inherited from a Jurassic rifting event, while the ESE-WNW trend in the western part is inherited from a Late Cretaceous to Eocene strike-slip and extension episode. The Upper Cretaceous to lower Eocene sediments preserved in the present day San Jacinto fold belt were deposited in a forearc marine basin formed by the oblique convergence between the Caribbean and the South American plates. A lower to middle Eocene angular unconformity at the top of the San Cayetano sequence, the termination of the activity of the Romeral Fault system and the cessation of arc magmatism are interpreted to indicate the onset of low-angle subduction of the Caribbean plateau beneath South America, which occurred between 56 and 43 Ma. Flat subduction of the plateau has continued to the present and would be the main cause of amagmatic post-Eocene deposition and formation of the Lower Magdalena Valley basin. After the collapse of a pre-Oligocene magmatic arc, late Oligocene to early Miocene fault-controlled subsidence allowed initial infill of the Lower Magdalena with relatively low sedimentation rates. Extensional reactivation of inherited, pre-Oligocene basement faults was crucial for the tectonic segmentation of the basin with the formation of its two depocenters (Plato and San Jorge). Oligocene to early Miocene uplift of Andean terranes made possible the connection of the Lower and Middle Magdalena valleys, and the formation ...