Mari-Bugti Fold-and-Thrust System and Rotation in the Sulaiman Lobe of Pakistan: Interpretation of the Satellite Data (1:50,000)

Abstract

  The Mari-Bugti fold-and-thrust system in the Sulaiman fold belt is an active tectonic feature of the Himalayan collision zone. Satellite data (LANDSAT and SPOT) combined with surface and subsurface studies show a general EW in the central and NWstructural trends in the western part of the thrust system. The central part is dominated by a series of paired foreland and hinterland vergent reverse faults and related folds. These faults of variable map length show minor displacement ( Ion) and generally sole out at a shallow depth of 4-5 Ion in an upper detachment of the Cretaceous strata above a duplex. Some faults penetrate to a depth of about 9-15 Ion and sole out in lower detachment of the Paleozoic strata. As a result Cretaceous and younger strata is exposed in the cores of tight anticlines as pop-ups, or fault-related anticlines at the tip of a blind or emergent thrust. Variation of structures from tight fault-related anticlines (i.e. Fazal Chal, Kalabuha) to relatively broad folds and synclinal flats (i.e. Sund Thai) is observed due to lateral transfer of displacement and structures. In the western Sulaiman, NW structural trends can be related to drag at the lateral termination of the fold belt. Besides, a series of EW trending anticlines of left-stepping and en-echelon arrangement are interpreted to develop between the dextral Hamai and Khalifat faults. LANDSAT and SPOT data shows a system of EW trending dextral faults with significant strike-slip displacement (as much as 5 Ion). These are recognized to obliterate former structural features and geometries. In conclusion, active deformation of the Mari-Bugti fold-and-thrust system can be explained in tenns of out-of-sequence faulting and anti clockwise rotation due to transpression near the western sinistral boundary of the Indian subcontinent.