Complex Imbricate Systems in the Southern Caribbean Basin, Offshore Northern Colombia: Advanced Structural and Stratigraphic Analysis, and Implications for Regional Exploration of Hydrocarbons

Freddy Corredor¹ and Tomas Villamil^2
1 Harvard University, Cambridge, MA
² Lukoil Overseas Colombia Ltd, Bogota, Colombia

Imbricate thrust structures are common in deep-water environments of active margins worldwide. The imbricate systems in the Southern Caribbean basin, offshore northern Colombia, are part of the accretionary prism that resulted from the transpressional collision between the Caribbean and South American plates during Tertiary times. The Southern Caribbean basin offers an extraordinary opportunity to study imbricate thrust systems in active margins and to assess the potential for petroleum exploration in this region, as these structures are extremely well imaged at deep levels in seismic reflection profiles and because they preserve growth strata that record the tectonic and stratigraphic evolution. Individual fault-related folds within this imbricate system are characterized by long planar backlimbs that dip less than the associated fault ramps, with increasingly shallower dips to growth strata, suggesting a component of progressive limb rotation. Forelimbs are short compared to backlimbs, but growth strata show dips that suggest a component of folding by kink-band migration. Growth sediments are deposited in piggyback basins formed over the backlimbs of individual imbricates and as onlapping sequences against the forelimbs. The growth stratigraphy consists of distal marine, fine-grained sediments; turbidite deposits, and condense sections. Unlike conventional imbricate systems, the southern Caribbean thrust system is characterized by decreasing ramp and dip angles in adjacent thrust sheets toward the hinterland. The decrease in ramp and dip angles, effectively produce an increase in accommodation space for growth sedimentation, and a decrease in structural relief, which might have a strong impact on the petroleum generation and migration in this region.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005