MODELLO

The kinematic evolution of the Barinas-Apure Basin and the southern Venezuelan Andes since Lower Miocene to Present is numerically modeled using flexural isostatic theory and geophysical and geological data. Two published regional geological transects were used to build up a reference section, which was used to constrain important parameters (e.g., shortening, sedimentary thicknesses) for the flexural modelling. Seismological data was used to control the location of the main fault system in the final flexural model. The gravity response of the final flexural model was computed and compared with the observed gravity data in the study area and a good fit was obtained between them without major modifications to the flexural model. The estimated elastic thickness during the flexural modelling was of 40 km for the southamerican lithosphere under the Barinas-Apure Basin and Venezuela Andes Range. The value for the final total shortening was of 67 km which is higher than other values published for the study area. The flexural isostatic model shows that Andean uplift has been responsible for south-american lithosphere subsidence and the development of the Barinas-Apure Basin. The predicted morphology in the lower crustal level of the final model favours the hipothesis of a present delamination or Megathrust of Maracaibo crust over the southamerican shield. This process is usually referred to as an incipient A-type subduction.