From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, December 3, 2010
Tectonic and subsidence history of the Llanos foreland basin of Colombia
Link to streaming video TBA: available 12.03.2010 at 8:55am
Henry Miguel CamposHenry Campos
UTIG Graduate Student
University of Texas at Austin , Paul Mann
M.S. GeoSci, UTIG
The University of Texas at Austin, 2011
The Llanos foreland basin of eastern Colombia shows a major episode of Middle Miocene subsidence at the onset of the formation of the foreland basin. This subsidence was in response to shallow subduction and collision events along the Pacific margin of northwestern South America. The collision of the Panama arc along the Pacific margin of Colombia has caused east-west shortening that began in the Middle Miocene and continues today. These events created a major thrust salient, the Cordillera Oriental, that overrides the Llanos foreland basin, forming an arcuate thrust front that extends 40km basinward. For this thesis, we interpreted 1200km of 2D-seismic data arranged along 4 regional cross-sections. A sedimentary backstripping technique was applied to the observed structure maps to construct subsidence maps. Also, a 2D flexural modeling was performed to calculate the tectonic and sedimentary subsidence. Subsidence maps show an increase in the tectonic subsidence rate in the salient area from the middle to late Miocene, coeval with the collision of the Panama arc with the northwestern South America plate. The models developed also help predict the position of the basin edge as well as the position, height, and length of the forebulge, indicator parameters for hydrocarbon migration and accumulation through time. Most known hydrocarbons in the thrust belt and foreland basin are located either south of the salient (Cusiana-Cupiagua, Rubiales oilfields) or north of the salient (Guafita-Cano Limon, Arauca oilfields) but surprisingly not within the salient where subsidence, source rock thicknesses, and fracturing may be most favorable according to the model of Macedo and Marshak (1999).