Geology and petroleum potential of Seychelles
Seychelles archipelago represents a microcontinent in the western Indian Ocean with an exclusive economic zone of over 1.15 million km/sup 2/. Seychelles lies within the Somali plate, which is attached to the African plate along the Mozambique fracture zone and rift valley system on the mainland. Until the Late Jurassic, Seychelles had been associated with the depositional regime of east Africa, Madagascar, and thereafter with the latter until the Late Cretaceous when a portion of the continental crust separated from Madagascar and moved counterclockwise, representing the present-day Seychelles Banks and possibly the western flank of the Mascarene Plateau north of Cargados Carjos. Over 8 km of sediments are expected in the deeper basinal area. The Karroo (possibly pre-Karroo) group of rocks of Permian-Jurassic age are the oldest sediments deposited on the granitic basement. These are overlain by Bajocian transgressive mudstones and limestones followed by rifting. Marine sedimentation in places interrupted by block faulting, tilting, and differential erosion continued thereafter until the outpour of Maestrichtian submarine lavas. Following Late Cretaceous regression and possible erosion of the high structures, transgression again occurred during the Paleocene-lower Eocene, overstepping the earlier sedimentation. After the middle Eocene unconformity, rapid differential shelf carbonate growth continued during the rest of the Tertiary, with development of reefs at places. Three wells drilled on the western shelf indicated hydrocarbon shows of 1.1% (average) organic carbon and maturity (vitrinite reflectance of 0.5 R/sub 0/ at 2430 m), pointing to source potential in the drilled Upper Jurassic-Lower Cretaceous marine clastics, which are expected to be preserved in grabens, depressions, and fault blocks and may be over 1000 m thick.
- Research Organization:
- Seychelles National Oil Co. Ltd., Mahe
- OSTI ID:
- 6186646
- Report Number(s):
- CONF-870606-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:5; Conference: American Association of Petroleum Geologists annual meeting, Los Angeles, CA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrocarbon potential of the Lamu basin of south-east Kenya
Cenozoic transpressional model for the tectonic and basinal development of Venezuela and Trinidad
Related Subjects
INDIAN OCEAN
PETROLEUM DEPOSITS
EXPLORATION
RESOURCE POTENTIAL
CRETACEOUS PERIOD
MATURATION
PERMIAN PERIOD
RESERVOIR ROCK
RIFT ZONES
SOURCE ROCKS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MESOZOIC ERA
MINERAL RESOURCES
PALEOZOIC ERA
RESOURCES
SEAS
SURFACE WATERS
020200* - Petroleum- Reserves
Geology
& Exploration