by James Michael Russell, Philip A. Barker, Andrew S. Cohen, Sarah J. Ivory, Jens Kallmeyer, Ismael Aaron Kimirei, Christine S. Lane, Melanie J. Leng

Lake Tanganyika (East Africa) is the one of the oldest, largest, and deepest lakes on Earth and provides a truly outstanding opportunity to transform our understanding of processes controlling tropical climate, biological diversification, Earth surface (source-to-sink) processes in rift basins. Lake Tanganyika contains the only known sedimentary sequence in the tropics that continuously spans the last ~8-10 Ma at drillable depths and its sediments are an established world-class archive of records of precipitation, temperature, and atmospheric dynamics. Drill-cores will allow us to test the response of African climate to fundamentally important reorganizations of the Earth System during the Neogene, such as the response of tropical climates to Miocene-present changes in atmospheric greenhouse gas concentration, the onset and intensification of Northern Hemisphere Glaciation, and the history of tropical African climate spanning the entire time interval of the evolution of the hominins (~7 Ma to present). The lake contains textbook examples of aquatic biodiversity and endemism, with deeply rooted patterns of diversification across multiple taxonomic groups. Drill-cores will allow unique assessments of the environmental controls on diversification, stasis, and extinction using both fossil morphology and preserved DNA. The lake is situated within the Miombo woodlands, one of the largest tropical dry forests on Earth. Drill-cores will afford new insight into the long-term effects of climate, fire, and disturbance on the ecology and biogeography of tropical dry forests, in the environment in which our early ancestors evolved. Lake Tanganyika is a spectacular natural laboratory to study the rates and processes of extensional deformation, volcanism and coupled surface processes, and patterns of weathering and erosion that may serve as a positive feedback on geodynamics. Drill cores will provide a critical constraint on the rates of these processes over long timescales. Furthermore, drill cores from Tanganyika will allow us to explore the geomicrobiology of microbial communities isolated deep in the sediments of one of the most ancient lakes on Earth. In the last four years we have convened a series of workshops attended by ~90 scientists from 11 countries to gauge interest in drilling Lake Tanganyika. These communities have developed a strong consensus that scientific drilling on Lake Tanganyika will transform our understanding of fundamental climate, environmental, and geological processes in the African tropics. Here we propose a drilling program to drill Africa’s oldest and deepest lake to meet the scientific goals of this community.

• Our overarching goal is to obtain the first nearly continuous tropical continental drill-core records spanning the late Miocene-present to understand the coupled climatic, geological, environmental, and biologic evolution of tropical East Africa. Specific research goals include:
• Understanding the dynamics of late Miocene-present African climate change as a consequence of late Miocene global cooling and atmospheric greenhouse gas concentrations changes, the onset and intensification of Northern Hemisphere glaciation, and the development of and interactions with East African rift topography Determining the timing of diversification and extinction events in the highly biodiverse Lake Tanganyika ecosystem, and how they relate to past climatic and paleolimnological events in this important and productive fishery.
• Document the development of the Miombo woodlands and Guineo-Congolian vegetation in the context of late Miocene-present climate changes in this region.
• Study the rates and mechanisms of rifting and fault movement in the Tanganyika basin, and how they relate to sediment pathways and fluxes and the structural evolution of adjacent rift systems.
• To meet these and other goals in geomicrobiology, paleoclimatology, paleoecology, paleobiology, and rift tectonics, we propose to drill ~4100 meters of core from 7 boreholes that will provide a complete stratigraphic record of the lake and its evolution. Drilling will be carried out using a modular barge system designed for the project, with modified tools that will expedite drilling operations. The project will produce a ‘master record’ to contextualize existing ICDP records from elsewhere in Africa and the tropics.

Evolutionary Biology, Neogene, Paleoclimate, Paleoecology, Rift Tectonics, Tropical Africa

Latitude: -8.36361, Longitude: 30.85683