Tectonic division of the Offshore Indus Basin by integrated gravity and magnetic study

The Offshore Indus Basin (OIB) is an important oil and gas exploration target area in Pakistan sea area. The exploration of the basin, limited by the quantity and quality of exploration data, is still in the early stage, which restricts the oil and gas investigation in this area. Based on the new generation of satellite altimetry gravity anomaly data (V29.1) and magnetic data from the Earth Magnetic Anomaly Grid (EMAG2-V2), the integrated gravity and magnetic field technique was applied to study the tectonic framework of the OIB, with which the integrated gravity and magnetic field was established and the structure of the OIB was interpreted. Results show that the areas of low-value magnetic and low-value gravity correspond to the sedimentary depressions, while those of high-value magnetic and low-value gravity correspond to the depressions with magma intrusions, whereas the areas of high-value magnetic and high-value gravity correspond to the uplift areas of the basin, and the areas of low-value magnetic and high-value gravity correspond to the carbonate platforms. Combined with the ocean drilling and 2D seismic profile data, three depressions and two uplifts in E-W in the OIB were inferred. Based on the previous tectonic division, the western depression and the western uplift in the southwestern corner of the basin were re-defined, the scope of the southern depression was expanded, and the southern edge of the basin was extended to near the Palatina ridge. This study provided evidence for basic geological and oil-gas exploration in the OIB and its adjacent areas.