Discovery of Mesozoic Strata in the Eastern Offshore Pakistan and Its Significance for Mesozoic Timescale Calibration and Hydrocarbon Potential

The presence and distribution of Mesozoic strata in the offshore region of Pakistan have historically been obscured by widespread Late Cretaceous volcanic successions, resulting in poorly constrained tectonic evolution, stratigraphic architecture, and chronostratigraphic framework. Long-term hydrocarbon exploration in this area has focused predominantly on Cenozoic deposits, leaving Mesozoic intervals under-investigated and their resource potential unassessed. The eastern offshore Pakistan, characterized by complex Neogene tectono-sedimentary evolution and substantial terrigenous input associated with Himalayan uplift, represents a key area for Mesozoic stratigraphic correlation and geological timescale calibration along the northern Arabian Sea margin. High-quality 2D seismic data were employed to mitigate volcanic shielding effects through integrated seismic reflector interpretation, seismic wave group characterization, and interval velocity inversion. Systematic seismic-stratigraphic analysis revealed the widespread occurrence of Mesozoic strata across the study area. These successions were formed under syn-sedimentary extensional faulting, which partitioned the basin into numerous secondary depressions and generated an alternating uplift-and-depression paleogeographic pattern. Total stratal thickness ranges from 800 m to 10,000 m, exhibiting a pronounced southeastward thickening and northwestward thinning geometry, with prominent onlaps toward the north and west. Major depocenters were identified in the southeastern and northwestern parts of the study area. Stratigraphic correlation with well-established onshore successions in the Lower Indus Basin confirms that these offshore Mesozoic units correspond to critical hydrocarbon source rock intervals. This study establishes a refined seismic-stratigraphic framework for eastern offshore Pakistan, provides robust constraints for regional Mesozoic chronostratigraphic correlation and timescale calibration, and improves the understanding of Mesozoic basin dynamics along the western Indian passive margin. The delineation of extensive and thick Mesozoic successions significantly expands the hydrocarbon exploration potential and offers new stratigraphic targets for future offshore petroleum exploration.