Climate, Surface and Tectonic Controls on the Asymmetry of an Orogenic Wedge:Characterizing Topography Steady-State in the Eastern Cordillera of the Northern Andes

I. Camilo Higuera-Diaz
Northern Illinois University, Department of Geology and Environmental Geosciences DeKalb, IL 60115; [email protected]

The location of mountain ranges around the world is directly related to the position and type of plate boundaries. The highest and most rugged relief of the present world topography corresponds to mountain ranges developing near active plate boundaries. Evolution of orogens not only depends on tectonic forces but also on the result of the feedbacks between tectonics, surface, and atmospheric processes. Variable erosion across orogenic belts resulting from precipitation gradients can play an important role in focusing exhumation and deformation consequently affecting the morpho-tectonic geometry of a mountain range.

I studied the Eastern Cordillera of the Northern Andes a symmetrical, doubly-verging tectonic wedge with an asymmetrical topographic profile. This area provides an excellent case study to quantify the influence of a strong precipitation gradient in the surface and tectonic processes across an orogen, and give insights in determining whether the present state geometry of the wedge is climate- or tectonic-driven. I used geomorphic indices, geological mapping and structural cross sections for a swath profile across the cordillera to analyze these feedbacks. My analyses indicate that there is a strong coupling between geomorphic and structural elements in the east flank and a weak coupling in the west flank. The dichotomy in the coupling between east and west suggest a contrasting kinematics across this tectonic wedge. I suggest that in the west flank of the cordillera deformation concentrates along the frontal fault whereas in the east flank of the cordillera slip is partitioned among several faults from hinterland to foreland.

AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid