HR: 1340h
AN: T13D-0508    [Abstracts]
TI: Complications in The Identification and Mapping of the Foot of the Slope on the Indus Submarine Fan
AU: * Inam, A
EM: asif.inam@gmail.com
AU: Rabbani, M M
EM: niopk@cubexs.net.pk
AF: National Institute of Oceanography, ST. 47 Clifton Block 1, Karachi, 76300 Pakistan
AU: Tabrez, A R
AB: Offshore geology of Pakistan is indicative that the country has a broad continental margin and therefore, may very likely extend its legal continental shelf beyond the 200 nautical mile limit in the Indus offshore region, if the UNCLOS Article 76 criteria in this regard are satisfied. If the entitlement is proved scientifically, it is expected that a substantial seabed area may possibly be added to the national maritime jurisdiction, in addition to the already existing EEZ area of about 240,000 sq. km. The potential area for continental extension is considered extremely important from the point of view of natural resources and other seabed related activities. The new developments and innovations in the offshore technology and ever-growing interests of the petroleum industry in the exploration and exploitation of the deeper ocean waters are making the areas like Indus deep offshore of great economical importance. The basement underlying the sedimentary cover in the upper/middle Indus fan region, generally has a variable relief. The area of continental shelf establishment it, in particular, consists of ridges/topographic highs and lows as well as faulted structures produced by the rift/tectonic processes during its evolution and subsequent phases of development as shown by Droz and Bellaiche (1991). The nature of the crust is arguable. Miles et al. (1998) consider the location of Continent-Ocean Boundary (COB) at the southern edge of the Laxmi ridge. Kolla & Coumes (1990) infer that the Eastern Arabian sea north and east of the Laxmi ridge has rifted transitional crust, whereas the region south and west of the ridge has oceanic crust. On the other hand Clift et al. (2003) suggest that the Continent-Ocean Transition (COT) is located close to the present shelf break, rather than more than 350 km to the south. The possible subsurface extension of the Laxmi ridge, `jagged' basement configuration, seaward dipping reflectors (SDRs) etc. have also been reported in the scientific literature. The investigation and identification of the COB/COT/SDRs might be one of the most critical element in determining the FoS using geological/geophysical evidence, when invoking the `evidence to the contrary' provision of the Art.76 for the establishment of the continental shelf. The seafloor spreading, basement topography and the SW Monsoon have influenced the sediment deposition in the geological past, resulting in variable sediment thicknesses in the area. This will be one of the most critical factor when pursuing the `sediment thickness rule' for the proposed establishment of the continental shelf. The rugged bottom topography and variations in the sediment thicknesses over the Indus submarine fan has made the delimitation of marine boundary a very challenging task for the scientists involved in the application of Article 76 in this part of the world.
UR: http://www.niopk.gov.pk
DE: 8100 TECTONOPHYSICS
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8105 Continental margins: divergent (1212, 8124)
SC: Tectonophysics [T]
MN: Fall Meeting 2005