Collaborative Research: Interactions Between Incipient Continental Rifting, Fluvial Systems, and Regional Climate in Southern Africa: The Okavango-Makgadikgadi Complex, Botswana

The Okavango Rift Zone (ORZ) and Delta (OD), and the Makgadikgadi Paleo-Megalake (MPL) form a

dynamic system in northern Botswana, southern Africa, where tectonic activity, climate change,

sedimentation, vegetation, fauna, and human influences interact with each other at various spatial and

temporal scales. This award provides support for a multidisciplinary study of the interactions and feedbacks between incipient continental rifting, drainage patterns, and Neogene/Quaternary regional climate in the ORZ-OD-MPL complex. The objectives are to develop: (i) a structural and tectonic model of the ORZ-OD; (ii) chronologies for the evolution of the OD and infilling phases of the MPL; and (iii) histories of drainage basin expansions and contractions of the complex climate/vegetation in the OD-MPL, and the links, or lack thereof, between the ORZ, OD, and MPL. The overarching scientific question is: to what degree tectonics interacted with surface processes and climate in the ORZ-MPL system, and what feedback loops were involved in this interaction to control the environmental evolution of central southern Africa since the Miocene?

The PIs will use a combination of seismology and sediment cores to look at the geometry of the rift faults and sediment fill. The material from the cores will additionally be used to establish provenance of the sediment and build climate records. These two datasets from the cores will be used to assess the relative importance of climate (via variable erosion) versus tectonic control (river migration/capture, etc.) on sediment supply. A 2D numerical model will integrate these data to explore the effect of basin asymmetry and sediment loading and how these feedback into basin development via loading and strain localization.