Paleolakes of Eastern Africa: Zeolites, Clay Minerals, and Climate

The eastern branch of the East African Rift System hosts many shallow modern lakes and paleolakes, which can be sensitive recorders of changing climate conditions (complicated by tectonics) during the past few million years. However, many of such lakes are saline-alkaline (salty and high pH), and these conditions do not easily preserve pollen and other biologi-cally derived paleoclimate indicators. Fortunately, some preserved minerals that formed in these extreme environments reflect subtle shifts in lake water chemistry (controlled by changes in climate conditions) and therefore provide a continuous record of local and regional climate change. We present two different mineral proxies (zeolites and clays) from two different paleolake basins (Olduvai Gorge, Tanzania, and Chew Bahir, Ethiopia) as examples.