FIELD OBSERVATIONS FROM THE SOCOTRAN PLATFORM - THEIR INTERPRETATION AND CORRELATION TO SOUTHERN OMAN

Recent fieldwork on Socotra and adjacent islands, located along the so uthern margin of the Gulf of Aden, coupled with extensive biostratigra phic studies, has led to the identification of a number of distinct se dimentary successions in the area. Triassic strata have been identifie d in a fault-bounded area of easternmost Socotra and Jurassic rocks, p reviously unrecognised on the island, are preserved unconformably over lying the Triassic in south-east Socotra. In other parts of the Socotr an Platform, Cretaceous sedimentary rocks lie unconformably above base ment. The oldest and thickest successions are of Barremian to Aptian a ge and occur on the western islands. A marine transgression is recorde d by a transition from estuarine to mixed shallow-marine carbonate and siliciclastic sedimentation. Thin sedimentary sequences of Campanian and Maastrichtian age have been identified in two separate areas of So cotra. Tertiary deposition commenced in latest Palaeocene times and a gentle angular unconformity with the underlying Cretaceous deposits is apparent. Simultaneous with the onset of Gulf of Aden rifting, a new phase of deposition began in the late Oligocene. A wide range of facie s reflect strong tectonic controls on deposition. Plate tectonic recon structions indicate that prior to the Gulf of Aden rifting, Socotra wa s located adjacent to the Dhofar region of Southern Oman. This interpr etation is well-supported by comparisons of the Mesozoic and Tertiary successions in these two areas. (C) 1997 Elsevier Science Ltd.