Projects
Investigation of the sediments of Lake Rukwa (Tanzania): a clue for reconstruction the South equatorial climate during the last 133,000 years
The lakes of the East African rift are well known for being amongst the oldest in the world, but also to contain in thier underlying sediments a unique record of climatic change based mostly on lake level fluctuations. They provides continuous records of continental environmental variations in the tropics, paralleling those from other environments in different latitudes. They could .provide the first detailed palaeoclimatic records of the last 130,000 years in the intertropical area (fig.1). As the sedimentation rates in the lakes range between 0.2 and 5 mm/year, the paleoclimatic records are resolvable to decades, locally even to years. Furthermore, the rift lakes are extremely sensitive to climatic abrupt change (Roberts, Taieb et al, 1993). Their chemical and biological composition respond strongly to variations in their hydrological budget.
The aim of this project is to reconstruct with high-resolution the environmental and climatic changes which occurred during the last climatic cycle (120 ka) in the Equatorial East Africa. Special attention will be focused on short duration changes. Accurate sampling and coring technologies linked with modern methods of data acquisition and analyses will be employed in order 1) to study the surface rocks and the structure of the lake Rukwa basin; 2) to analyse the biological, mineralogical, chemical and physical response of the sediments to climate and environmental changes. The sedimentary material will be collected over a widespread area with short corers (6 m) and on four adequately chosen sites with a powerful mechanical corer (100 m).
The scientific programme is designed to study a time window covering the last climatic cycle (130,000 years) by obtaining and analysing cores of Lake Rukwa and crater lake. The sedimentary archive with a litho-chrono and bio-stratigraphic framework is constrained by 14C, U/Th, K/Ar, Ar/Ar, 210Pb, 137Cs dating, magnetic stratigraphy, sedimentology, micropaleontology and geochemistry. Various methodological approaches will be used for determining the paleohydrological and the paleoclimatical signal. It will be a multidisciplinary quantitative study of the physical, chemical and biological parameters in response of the lake level fluctuations.
The MRAC contributed for the satellite image interpretation, field structural geology in order to determine the geological framework of the basin.
Principal investigator:
Dates:
1994 1996Museum staff:
External collaborators:
M. Taieb (project Coordinator, Laboratoire de Géologie du Quaternaire, Marseille, France)J. Klerkx (Royal Museum for Central Africa, Tervuren, Belgium),
E. Vittori (ANPA, Roma)
R. Kajara (MADINI, Tanzania)
M. De Batist (University of Gent)
E. Kilembe (TPDC, Tanzania).