Kinematic and Thermal Modelling of Contractional Belts: An Example From the Colombian Eastern Foothill Belt

Abstract

The evolution of the shape and geometry of geological structures through time has rarely been considered in detail in areas where growth strata are absent. This is a long-standing problem because in such cases kinematic restorations have been mostly schematic in nature, and changes in shape and geometry were not realistically considered. As a result, vectors of movement for individual particles during deformation have been only carefully analyzed during analogue modeling. No real examples of the movement of most of the points in a cross section have been documented. In this context actual rock properties cannot be tracked with confidence through geological time and petroleum systems modeling is therefore very speculative in many aspects. In this work we show examples in the Colombian eastern foothill belt, of the application of a new tool (Fetkin-prep) which allows tracking of the position of individual points in the different steps of a kinematic restoration. In our examples this procedure allows subsequent thermal modeling with Fetkin, where the kinematic restoration is calibrated with respect to thermochronometric data. There are many unexpected findings in this pilot study. The first is the fact that it is highly unlikely that the generation of structural relief and topography in the Colombian Eastern Cordillera is only related with brittle faulting. Instead for most of the duration of the deformation in the Cenozoic we find evidence of homogeneous flattening. This means potentially that this mechanism must be considered during deformation in many other orogenic belts, wherever deformation happens at low rates. The second is that oil generation and migration could be as fast as trap formation, if deformation rates are fast. In such a context prospectivity is reduced in those traps where homogeneous flattening was significant and in contrast risk is reduced in those areas where structures appear to be very young.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015