Seismic sequence stratigraphy and depositional modelling of the Cambro-Permian Succession in the Potwar Sub-basin, Pakistan: an integrated interpretation of seismic and well data

Abstract Seismic sequence stratigraphy has fundamentally transformed the discipline of stratigraphy by providing a robust framework for correlating and mapping the spatial distribution of sedimentary successions. This study presents an integrated tectono-seismic sequence stratigraphic framework for the Cambrian and Permian successions of the Missa Keswal Oilfield, located in the southeastern part of the Upper Indus Basin, Pakistan. The investigation employs a multidisciplinary approach, integrating 2D seismic with well log data from five exploration wells to elucidate the spatial and temporal evolution of basin infill and delineate stratigraphic architecture. Well log analysis utilized composite suites of gamma-ray and sonic logs to delineate litho and sequence stratigraphic boundaries, which were translated to seismic profiles to identify key stratigraphic surfaces and bounding discontinuities. Tectono-stratigraphic modeling revealed differential subsidence patterns and lateral facies shifts corresponding to major second-order depositional sequences. Both Cambrian and Permian formations were classified within a second-order cyclicity framework, based on depositional Model 3 and a genetic stratigraphic approach. Stratigraphic thinning was observed towards the eastern margin of the Salt Range, indicating variant subsidence or sediment supply. Two Type-1 sequence boundaries were identified along with the depositional environments. Identification of sequence surfaces and associated systems tracts (LST, TST, HST) helped in understanding the basin evolution model and enhanced the predictive understanding of reservoir distribution. The final stratigraphic framework was validated against existing published literature for consistency and reliability. This work contributed to refining the tectono-stratigraphic model of the eastern Salt Range, advancing the regional exploration strategy by delineating sedimentary responses to Paleozoic tectonic regimes and stratigraphic discontinuities.