Faults,
Critical Taper, and the Mechanics of Foreland Basement-cored Uplifts
Bump, Alexander P.1 (1) BP
Exploration and Production Technology Group,
Foreland basement-cored uplift (FBCU)
systems, such as the Laramide and Sierras Pampeanas, are the products of compressional
deformation within continental interiors. They are composed of discrete,
fault-bounded uplifts that are separated by low-lying, undeformed
basins. They may be produced either by tectonic edge-load, as in continental
collision, or by basal traction, as in flat-slab subduction.
This paper presents a simple, two-dimensional analytical model for the
mechanical evolution of these systems based on the explicit consideration of
fault strength and the application of tectonic force. Fault strength is modeled
as the sum of four components describing fault propagation, frictional and
viscous drag on the fault plane, internal deformation of the hangingwall and gravity. Fault slip builds topography,
increasing the weight of the hangingwall and
effectively strengthening the fault. The model is based on the premise that
faults build topography, gaining strength until they are in equilibrium with
the applied tectonic force. The system of uplifts thus evolves toward a tapered
envelope that is defined by the peaks of the high uplifts. The model offers
predictions for gross topography, patterns of seismic activity and relative
timing of uplift growth. The Sierras Pampeanas and
central
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California