2-D Seismic Interpretation of the Tumaco Basin, SW Colombia: Implications for Tectono-Stratigraphic Evolution and Hydrocarbon Exploration
Campino, Luisa F.; Escalona, Alejandro
The Tumaco on and offshore basin is located in the Pacific region of NW corner of South America, southwestern Colombia. It is classified as a forearc basin and it is considered a frontier exploration basin. The basin was formed during Paleogene-Recent convergence of oceanic derived terranes against South America. The stratigraphy consists of a volcano-clastic basement overlie by an Eocene to Recent clastic sedimentary cover. The last exploratory well, drilled in the 80's, showed non-commercial amounts of oil and gas. This study integrates new onshore outcrop data (e.g. biostratigraphy, petrography, geochronology, and organic geochemistry) with more than 3000 Km of 2-D seismic data on- and offshore in order to better understand the main basement terranes, its control on basin evolution and the hydrocarbon potential within the context of the Caribbean plate evolution in the region.
Preliminary results based on seismic interpretation, plate tectonic models and surface geology indicate that the basement high, the Remolinogrande high, is the continuation of the Gorgona large igneous province to the north, which was accreted in the Late Eocene during subduction of the Farallon plate beneath South America. This accretion resulted in the development of the Tumaco onshore basin, located between the Remolinogrande high and the Western Cordillera of Colombia. To the south, the region may correlate with arc and oceanic terranes that outrcrop in the Ecuador region (San Lorenzo and Piñon tarranes), that were accreted during subduction of the Caribbean plate beneath South America in the Paleogene.
The Tumaco offshore basin seems to be the forearc basin that results of the subduction of the Nazca plate beneath South America. The subduction affected the entire region, resulting in continuous uplift of the Remolinogrande high. Eocene-Recent basin infill of the Tumaco onshore basin occurred mostly from the Western Cordillera of Colombia with the development of deep marine to continental deposition, whereas the Tumaco offshore consists of mostly marine sedimentation since Miocene. Source rocks mostly include Eocene marine shales in the Tumaco onshore basin that are buried today to a depth of 8 km. Reservoir rocks include marine and continental sandstones of Paleogene and Miocene age.
Because the Tumaco basin has a sag type basin configuration most of the traps are pinchtouts against the uplifted Remolinogrande high and stratigraphic traps.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013