Kinematics of eastern Salt Range and South Potwar Basin (Pakistan): a new scenario

摘要

The Salt Range of northern Pakistan represents an emergent thrust front along which the Potwar Plateau has been translated southward. Based on the analysis of subsurface data, we have constructed a balanced cross-section exhibiting a frontal fault-bend fold and a set of detachment folds below the Potwar Plateau. From the restored section, we are able to propose a forward kinematic modelling using the THRUSTPACK software. The main characteristics of the model are the alternation of periods during which deformation was concentrated on the frontal thrust (between 10 and 5 Ma and since 1.9 Ma) and an intervening episode during which deformation was distributed along the whole section (between 5 and 1.9 Ma). The latter phase is marked by development of out-of-sequence structures. The episodes of frontal thrust activation are characterised by high denudation rates. On the contrary, out-of-sequence folding occurred during periods of important sedimentary accumulation. The consequences for petroleum exploration are also discussed. However, timing of the petroleum system is strongly dependent on hypoteheses made on basal heat flow.