Tectonostratigraphy of the northern Okavango Delta and Rift Zone, Botswana

1 The Okavango Rift Zone (ORZ) and Okavango Delta in Northwest Botswana are Earth’s 2 youngest continental rift system and largest inland delta. The delta and its underlying sediments 3 record the effects of incipient rifting on the geomorphology and stratigraphy within the 4 (incipient) southwestern arm of the East African Rift System in Botswana. Three open questions 5 that we use river-borne seismic-reflection profile analyses to answer are (1) whether the Gumare 6 fault extends across the delta, (2) whether the Gumare fault zone is a part of the ORZ, and (3) 7 how wide is the ORZ. Our results suggest that the Gumare fault extends across the delta and is a 8 part of the ORZ. Integration of our and pre-existing geophysical data also suggests that the 9 southern section of the ORZ is more active than the northern section that we imaged, and at least 10 150 km of fault-related extension has occurred within the Okavango Rift Zone. These findings 11 provide constraints on the present-day structural and stratigraphic configuration of the ORZ and 12 OD, which is a fundamental first step towards reconstructing sedimentation and extensional 13 patterns during the earliest stages of continental rifting. 14