A 300 Million Years History of Rift Lakes in Central and East Africa: An Updated Broad Review

Abstract

Over the past 300 Ma, the complex geological history of the African continental plate has been marked by an important development of lacustrine domains of various size. We present in this paper an updated broad review of major Central and East African lakes initiation, development or extinction during this 300 Ma-long period of time before present. Today, more than 35 wide/deep and narrow/shallow lakes occupy a wide surface area in Eastern and Central Africa between longitudes 30° E and 40° E. They belong to the 3000-km long East African Rift System (EARS) which goes from the Afar Depression to the north down to Lake Malawi in the south. These lakes have been formed as the result of a combination of interacting forcing factors such as major rifting processes (faulting and volcanic activities), that started to develop from about 40 Ma ago in Southwest Ethiopia and Northern and Central Kenya, and regional or global climate changes. The largest and deepest lakes, not necessarily the oldest, have been formed during the last 10 Ma along the Western Branch of EARS, while the smallest lakes of the Eastern Branch and Main Ethiopian Rift are the remnants of lakes developed during Pliocene-Pleistocene times. The rifting phase that is affecting today the Central and Eastern regions of Africa has been preceded by two other major rifting phases that started during Upper Palaeozoic times at about 280 Ma, and during Mesozoic times at about 160 Ma, respectively, as well as several more local events. Their duration have been at least two times longer than the duration of the present East African Rift System formation. Tens of lakes developed during these two oldest phases of rifting in Central and Southeastern Africa, displaying limnogeological characteristics similar to some of the modern lakes of the EARS.