Basin neotectonics of Lakes Edward and George, East African Rift
Abstract The Edward and George lake basins are located in the western branch of the East African Rift System (EARS). Both basins occupy half grabens with the main boundary fault located in the west and are separated by a high relief accommodation zone. This structural high formed where the NNE–SSW trend of the Miocene rifting and NW–SE oriented basement lineaments interfere. The Kazinga Channel, connecting Lake George to Lake Edward, cuts across this uplifted area. The course of the channel has been affected by syn- and antithetic faulting. Volcanism in this part of the EARS is related to high relief accommodation zones, and volcanic craters are either parallel to the NW–SE oriented Precambrian lineaments or the NNE–SSW oriented Miocene rift. Volcanism that initiated during the early stages of rifting commonly parallels the NW–SE oriented accommodation zones and basement lineaments, while craters that formed during the later stages of rifting tend to parallel the large border faults of the NNE–SSW oriented rift. Rifting processes in the Edward and George basins have been disturbed by uplift mechanisms related to the Rwenzori horst block formation. The Kasindi Fault Zone located in the central part of the Edward Basin is related to a low relief accommodation zone formed between two opposite dipping border faults. The Edward–George basin is tectonically active; the large boundary faults, the syn- and antithetic faults of the rift basin, and the accommodation zones all show signs of recent movement. Faulting related to the Kasindi Fault Zone suggests a >12 m fault movement during the Holocene, possibly related to periods of extensive volcanism within the Toro Ankole volcanic province.