RESEARCH OPPORTUNITIES IN NEOTECTONICS OF INCIPIENT CONTINENTAL RIFT ZONES FOR US UNDERGRADUATE AND GRADUATE GEOSCIENCES STUDENTS IN BOTSWANA AND ZAMBIA

A recently funded NSF project at Oklahoma State University provides international research experience for US students in Botswana and Zambia. During this project, US students will partner with peers from the University of Botswana and University of Zambia to conduct field-based research within a multi-disciplinary framework focused on investigating the interplay between neotectonics and surficial processes due to rifting. Botswana and Zambia hosts the youngest rift basins in the East African Rift System. Therefore, the field sites chosen for the proposed student activities provide a unique opportunity to study the early stages of continental extension and represent a natural laboratory found nowhere else on earth for investigating early rifting processes. We have just completed our first field season in Botswana. Four students from US institutions and two students from the University of Botswana participated in a field based geophysical and paleoenvironmental project in the Okavango Rift Zone in NW Botswana. Near surface geophysical surveys including magnetic gradient, controlled source audiomagnetotelluric (CSAMT), electrical resistivity, and gravity measurements were conducted to investigate detailed fault development and fault scarp morphology of the main faults bounding the rift basin. We acquired more than 160 km of geophysical data across the rift basin. Concurrently, sediment sampling was completed from a 6 m deep trench within the rift basin to investigate environmental change related to rifting as preserved in the sedimentary record. The results will contribute to the over arching goal of our research which seeks to bridge the knowledge gaps between our understanding of rift kinematics during the earliest stages of rifting and that of more evolved continental rifts, while providing students with hands-on experience in international research. Preliminary one-dimensional inverse modeling of the CSAMT suggest that the study area is characterized by conductive sediments (<10-50 ohm-m) overlying a more resistive (>1000 ohm-m) basement of Precambrian units. Within the rift graben, the sediments are very conductive (<20 ohm-m) with little indication of basement features. Our preliminary results suggest a wide zone of extension ~ 150 km but with active subsidence occurring within a zone 50-60 km wide.