Balanced Structural Cross-section of the Sulaiman Lobe, Pakistan: Evolution, Geometry, Shortening and Hydrocarbon Prospects of a Thrust System at the Western Terminus of the Indian Plate

Abstract

 Surface and subsurface data from the Sulaiman Fold-belt thrust belt are integrated to evaluate geometry Of a thrust system and tectonic shortening across the Western margin of the Indian subcontinent. A balanced Strutured cross-section suggests 4 to 10 km uplift of crataceous and younger strata from foreland to hinderd of the Sulaiman lobe of Pakistan. This strutural uplift is due to a thin-skinned, passive-roof duplex style of deformation. The duplex sequence Is hundred between a decollement on the crystalline basement and a passive-roof thrust in the Cretaceous shales the passive-roof sequence is preserved for about 15Okm In the Sulalman thrust system. Structural cross-section shows ophiolites, a triangle lone, out of sequence structures (secondary faults and related pop-ups), fault-related, and concentric buckle fold from hinterland to foreland respectively. A balanced structural cross-section 349 km long From the Sulaiman fold belt restores to an original Length of 727 km, suggesting a maximum of 378 km of shortening in the cover strata of the Indian subcontinent. The shortening in the roof sequence is accommodated along emergent passive-roof thrust and backthrusts. Calculation of displacement rates over the sulaiman lobe (18 mmjyr) added to the resolved rate of the Chaman fault vector for the component parallel to the plate convergence direction (15 mmjyr) are close to the current India-Asia plate convergence rate (37mm/yr).
Total shortening of about 378 km and transitional Crust underneath the Sulaiman lobe compared to full thickness crust ln northern Pakistan suggests an early stage of collision along the western margin of the Indian plate.