Abstract:
During the past ten years the Makran offshore area has attracted considerable attention of
national and international scientists, exploration, and petroleum companies to have a better
understanding of the peculiar geological and oceanographic setting and to considerably
broaden the geological knowledge about Pakistan's EEZ off the Makran margin and its
resource potential.
The morphological structure of the Makran, which is strongly influenced by deformation
during the subduction processes, is very complex. On the continent and on the upper part of
the slope, there are five to seven E-W striking, folded, and elevated accretionary ridges which
have been thrust northward, these ridges are separated by ponded slope basins filled with
turbidites and hemipelagic se'diments, which are horizontal or dip downslope. The large part
of the accretionary wedge is well exposed on the continent. A morphologically characteristic
deep-sea trench associated with active convergent margins does not exist in Makran.
The Makran continental margin is in an area of high biological productivity in the surface
water controlled by monsoonal upwelling. This is one of the causes for the formation of an
oxygen minimum zone resulting in a high accumulation rate of predominantly marine organic
matter in the marine sediments. Seismic data collected recently from the Makran offshore
area provided preliminary identification of some hydrate deposits both at and underneath the
sea floor. A bottom-simulating reflector (BSR), caused by the impedance contrast at the base
of the gas hydrate zone was observed off Makran at about 400 m below the sea floor in the
single channel seismic profiles. The presence of the hydrate indicates that large volumes of
methane are being generated at depth in these regions. Offshore, gas expulsions and turbid waters are reported to occur in places along the Makran continental shelf and slope area.
Localized presence of small gas seeps/vents has been noted at the seabed, which perhaps is
related to the presence of mud diapir or mud volcano structures in the Makran upper slope
sediments. Mud charged with methane gas and traces of heavier hydrocarbon oozes through
active mud volcanoes along the Makran Coast, which is of special interest in relation to
probable oil deposits. Geological, geophysical, and geochemical studies of the Makran zone
may eventually lead to delineating the potential resources of the area including petroleum
deposits.
