Multichannel seismic profiles, potential fields and surface and subsurface data from the North Colombia fold belt reveal the cross-sectional geometry and the structural style of the Sinu-San Jacinto accretionary prism. A balanced cross section shows an overall shortening of about 50% that has been accommodated by folding and thrusting. The folds have been formed by the process of fault-bend folding related to thrusts that ramp up section from a decollement near the top of the Cretaceous(?) with fundamental cutoff angles of about 18^o to 28^o. The structural interpretation indicates that the Sinu-San Jacinto prism is a two-sided wedge that developed in response to the compressional stresses at the convergent margin. A blind east-verging backthrust near the sediment-basement interface is proposed to account for the slip on the west-verging thrusts near the Romeral fault zone. The timing of the deformation appears to be pre-Oligocene to middle Miocene in the San Jacinto belt and Quaternary to Pliocene in the Sinu belt.

Gravity and magnetic modeling suggests a north-west dipping crystalline basement beneath the San Jacinto and the continental margin. The magnetic modeling suggests a south-east dipping oceanic slab in the basement beneath the Romeral fault zone.

Application of the critically tapered wedge model of Davis et al. to the observed prism geometry suggests that high pore pressures occur in the prism.

The burial and thermal history of the Oligocene has been reconstructed. Tirne-temperature modeling indicates hydrocarbon maturation for strata older than the Miocene east of the Romeral. West of the Romeral, hydrocarbon maturation is expected to occur in strata older than the Oligocene.