Fault-creep or Strain-accumulation on Flat Surfaces of Decollement? A GPS Study on the Salt Range and Potwar Plateau of Pakistan

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

The Potwar Plateau in Pakistan is a 5-10 km thick assemblage of rocks all younger than 450 million years that are being driven southward over a salt-rich decollement by tectonic forces at approximately 10 mm/year. The investigations are seeking to establish whether aseismic creep is a significant component of the translation process of this 150 km x150 km province, or whether the Plateau is locked, partly or completely, and slips during earthquakes. Global Positioning (GPS) methods are used to examine the deformation process, both as displacements of colonial trigonometrical points installed in 1850, and as annual motions of newly installed geodetic markers. If the Plateau is currently locked it will have important consequences for earthquake hazards in the region. If it is creeping rapidly this will have important implications for the structural formation and deformation of the Plateau, a region steeped with oil reservoirs. The Potwar Plateau is representative of numerous geologic decollements documented in earth's history, and its present kinematic behavior can place bounds on the types of deformation that have occurred within them.