Dynamics of Sargodha High and its impact on Late Phanerozoic sequence including petroleum system, Indus Basin, Pakistan

The Sargodha High divides Upper and Middle Indus Basin of Pakistan. The flanks of the Sargodha High are covered with thick molasse sediments. The isolated outcrops of the Middle-Late Proterozoic metasedimentary and extensive volcanic are well exposed in the Kirana Hills. Several wells are testified dry in the vicinity of Sargodha high, suggesting absence or immaturities of source kitchen. This study is the first attempt to explain the possible dynamics of tectonic events in association with Sargodha High and its impact on the petroleum system based on seismic and wells data. Sequences, erosional unconformities, and regional truncation lines were analyzed via subsurface geometry of the Sargodha High. An extensive volcanic activity was recorded during 90 and 84 Ma uplifted Sargodha High in conjunction with the northern Indian plate, resulted emergence of regional unconformity at the base of the Palaeocene. Furthermore, during the Oligocene, the Sargodha High was continued uplifted due to the Indian plate collision in the north, the fore bulging unconformity developed. Our interpretation suggests that the thick sedimentary sequence is well preserved on the distal parts of Sargodha High. However, the Pre-Tertiary sequence was eroded from the proximal area. Most of the Pre-Cenozoic sedimentary sequence eroded during the Late Cretaceous to the Early Miocene and perhaps was not deposited during the Oligocene. Seismic data also indicates that Cenozoic sediments are onlapping the older strata, which might be due to local sea-level fluctuations in combination with tectonics. Overall, the geothermal gradient is low over the Sargodha High due to erosion of the overburdened sediments, which may have halted the maturation of potential source rock in the proximity of High. The present study suggests that the Sargodha High originated because of uplifting, which resulted in a tectonic feature-oriented northwest-southeast, affecting sediment erosion and deposition during the Mesozoic and Cenozoic eras, as well as the petroleum system of the area.