Print this pageRegional Structural Evolution of the North Colombia Accretionary Wedge
Steven J. Ings1, Mark Deptuck2, Scott Sumner2, and Chris Beaumont1
1 Dalhousie University, Halifax, NS
2 Shell international E&P Inc, Houston, TX
The North Colombia (NC) accretionary wedge results from the subduction of the Caribbean plate beneath the South American plate beginning in the Late Cretaceous. The NC wedge lies between a northeast trending offshore deformation front and a broad belt of northeast trending fore-arc basins in onshore northwest Colombia. Along strike, the accretionary wedge defines a deformed belt extending from the Isthmus of Panama to the Venezuela border and encompasses an area of ~200,000 km2.
The structural style of the offshore component of the NC accretionary wedge, the focus of this talk, varies significantly along strike. The southwest segment of the wedge is characterised by well-developed northwest verging folds and thrusts and an actively accreting front that forms a prominent seafloor escarpment. In contrast, no actively accreting front or seafloor escarpment is observed along the central segment of the wedge. Instead, the margin is characterised by a broad trench filled with thick sediments of the Miocene-recent Magdalena Fan. The northeast segment of the wedge is characterised by an actively accreting front with north-northwest verging folds and thrusts and a margin-parallel supra-wedge basin 150 km long and up to 60 km wide.
The structural segmentation of the NC accretionary wedge will be described using regional seismic interpretations and 2D (cross section) finite element numerical modeling results. The numerical models reproduce critical wedge, subcritical wedge, and wedge-top basin architectures, and provide useful insight into the role of focused sedimentation on the structural segmentation of the North Colombia margin.