Geology and hydrocarbon potential of the offshore Indus Basin, Pakistan

The offshore Indus Basin is a rift and passive margin basin offshore Pakistan and northwest India. Rifting associated with break up of the India/Madagascar/Seychelles plates began during the Late Cretaceous and was accompanied by a major period of volcanism associated with the Deccan volcanic event. A major volcanic centre was located along the south of the basin adjacent to the Saurashtra Arch transform fault and resulted in the deposition of up to 7 km of extrusive basalts interbedded with Late Cretaceous–Paleocene marine sediments. The basalts show stacked prograding reflection patterns on seismic data. A chain of northeast–southwest-trending volcanic seamounts in the central part of the deep-water basin formed topographic highs for the development of shallow-water carbonates during the Eocene post-rift phase. The passive margin stratigraphy includes up to 9 km of Oligocene–Recent age clastic sediments from the Indus River system. The proximal part of the Indus Fan contains spectacular large-scale channel-levees in the Miocene and Plio-Pleistocene intervals. Fourteen major channel-levee systems have been identified in the Plio-Pleistocene and represent potential reservoir targets. Trap types include extensional rollover anticlines at the shelf edge, drape structures over the Eocene carbonate highs, stratigraphic traps along the Murray Ridge and folds associated with strike-slip faults along the Murray Ridge. A key challenge for future exploration is to determine whether source rocks are present in sufficient quality for commercial discoveries.