Analysis of gravity field to reconstruct the structure of Omo basin in SW Ethiopia and implications for hydrocarbon potential

摘要

The Omo basin in south western Ethiopia at the Kenyan boundary is a northern extension of the trans-boundary Turkana rift It is an Early Pliocene north-south trending depression bounded on either side by normal faulting. The Omo river flows in the middle of the basin and empties itself at its southern end into Lake Turkana. The structural pattern of the Omo basin is determined from 2D and 3D analyses of the gravity field. The basin is an asymmetric half-graben formed by and localized within the NS/NNE trending Early Pliocene normal faults. It is built up on the older NW trending structures that were reactivated and affected the recent NS faults. Automatic depth determination techniques and 3D inversion are used to estimate depth to the basement and determine the sedimentary thickness. The results indicate over 4 km thick sediments were deposited over the graben. The Omo basin lies within the East African Rift system and appears to connect the generally NW trending oil-rich Muglad-Melut basins of south Sudan and the highly prospective and similarly trending Anza graben of Kenya. The Omo basin contains thick sequence of sediments and appears to be a promising future site of intensive hydrocarbon exploration.