Crustal structure of the southwestern colombian caribbean margin : Geological interpretation of geophysical data

The active Colombian Caribbean margin has evolved since the late Cretaceous time, resulting in a complex deformation history involving oblique subduction, accretion, extension and tectonic inversion during the Cenozoic period. The combined interpretation of 2D seismic reflection, gravity and magnetic data provides new insights into the margin configuration (Morrosquillo Gulf area) and the architecture and types of crust present. The margin displays the morphological and tectonic characteristics of a typical accretion-dominated subduction complex. The 3D gravity modelling suggests that the Caribbean Plate is subducting beneath NW Colombia at a low angle of about 5° in an E to SE direction. The major tectonic domains forming the margin include, from west to east: trench, active accretionary prism, outer high and forearc basins. The trench axis coincides with the toe of the active accretionary prism. The active prism corresponds to the deformation front of the Sinu-Colombia Accretionary Wedge. The outer high domain includes the major structural complex formed by the easternmost part of the Sinu-Colombia Accretionary Wedge and the San Jacinto Fold Belt. It represents the fossil part of the accretionary prism which today acts as a dynamic backstop to the active accretionary prism.