International Journal of Economic and Environment Geology (Dec 2015)
Structural Architecturing of the Western Khisor Range, North of Saiyiduwali: Implications for Hydrocarbon Prospects, KPK, Pakistan
Abstract
Western Khisor Range segment of the Trans-Indus ranges is a south-vergent, east-west trending foldthrust belt that protrudes southward into Himalayan foreland deep. The frontal flanks of range are characterized by east-west trending parallel to enechelon, plunging local anticlines and synclines structures. General structural style of folds was observed asymmetric to overturn and dominantly south vergent. The frontal outskirts of the study area is demarcated by a youngest partly emergent thrust fault named as Khisor Thrust. Outcrops projection to subsurface of the structural features suggests a thin-skinned tectonic mechanism for growth of the western Khisor Range where gliding surface for the frontal thrust sheet being located within the Cambrian rocks of Jhelum Group at a maximum depth of 4km. The structural evolution of the western Khisor Range is generally ascribed to southward directed thrust transferral system along the basal décollement being observed at base of the Cambrian Khewra Sandstone. Along this detachment horizon the Khewra Sandstone emplaced over the Recent alluvium and boulder bed deposits. The Khisor Thrust fault bulldozed the fore limb of the Saiyiduwali Anticline and demarcates the north-western proximity of the Punjab Foredeep. The Khisor Thrust sheet is predominantly comprised of the shallow marine rocks of Paleozoic to Mesozoic, laterally extended along the range. The stratigraphic framework of the western Khisor Range is considerably related and correlative to the eastern Trans-Indus and Salt ranges. Cambrian strata of the western Khisor Range comprise of Jhelum Group where its apex is underlain by the Permian Nilawahan and Zaluch groups rocks, consists of the Sardhai and Amb formations. The Sardhai Formation was observed 50m thick and consists of dark gray to blackish gray and black carbonaceous shale while the lower constituents of the Amb Formation contains dark gray carbonaceous and calcareous shale up to 30m thick, which is favorable setting for hydrocarbon potential of the area. Blending of structural style and stratigraphic framework of the western Khisor Range urges that the south-western foredeep in proximity of Saiyiduwali is significantly associated for the hydrocarbon research, as thick carbonaceous lithofacies of both formations are viable potential source rocks.
