Differing Structural Trends of Oligocene and Miocene Tectonic Events, Northern Putumayo Basin, Colombia: Implications for Petroleum Exploration
Villamil Tomas, Vásquez César, Alix Bolaños, 2007. "Differing Structural Trends of Oligocene and Miocene Tectonic Events, Northern Putumayo Basin, Colombia: Implications for Petroleum Exploration", The Paleogene of the Gulf of Mexico and Caribbean Basins: Processes, Events and Petroleum Systems, Lorcan Kennan, James Pindell, Norman C. Rosen
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3D seismic data acquired in 2007 in the northern Putumayo foothills, along the transition zone between the leading edge of the thrust belt and the basin, allows evaluation of the structural configuration and tectonic transport directions of the Oligocene and Miocene deformation events, and of the clear obliquity between them. Oligocene tectonic transport was towards the east, having an azimuth between 90° and 95°, and faults were oriented north-south (0° to 5° azimuth). The Oligocene deformation front was a thrust belt of multiple stacks, faults are relatively high-angle (30°-35° dip), and they involve the basement. The tectonic transport of the Miocene Andean Orogeny in this region was towards the southeast (azimuth of 130° to 140°); faults are of higher angle and may detach deeper within the basement. There was stratigraphic evidence suggesting that some of these faults might be reactivated extensional features. Miocene deformation was characterized by forward-breaking reverse faults and monoclinal tilting of the foredeep as in a triangle zone. The cause of this tilting could not be seen on seismic data but could be related to propagation of the tip of a triangle zone wedging somewhere within the basement. Most Andean Orogeny traps were breached and 1D basin modeling suggested that they were not charged because of timing of migration was younger than timing of Miocene trap formation. Some Oligocene traps were breached by the Miocene orogeny but some were not; these constitute the primary targets for petroleum exploration in the area.