Tropical East African climate change and its relation to global climate: A record from Lake Tanganyika, Tropical East Africa, over the past 90+ kyr

Forcing mechanisms of tropical climate in continental areas remain poorly understood, due in large part to a lack of continuous, long-term, high-fidelity records. Sediment core T97-52V from Lake Tanganyika provides new insight into the timing and mechanisms behind East African climate change over the past 90+ kyr. This record is particularly important, because, other than a recently recovered scientific drill core from Lake Malawi, there are no other continuous, well-dated records from East Africa prior to 60 ka. The high resolution age model presented here provides a large degree of age certainty for the past 45+ kyr, and our suite of proxies allows a thorough examination of Lake Tanganyikaʹs dynamics. From core stratigraphy and chemical analyses, we present evidence of a lake level drop greater than 400 m sometime prior to ∼ 90 ka, much greater than that inferred for the LGM, suggesting a period of intense aridity sometime around 100 ka. Additionally, core T97-52 V preserves evidence of worm burrows detected by X-radiographic imagery as indicated by burrow-shaped deposits of iron oxide, indicating a shallow lake at the time of deposition of that material. Intermittently high lake levels between ∼ 78 ka and ∼ 72 ka developed at the same time as a weakened Asian monsoon and a pluvial phase in Northeast Brazil, suggesting a global reorganization of climate, possibly forced by a reduction in orbital eccentricity. Over the past 60 ka this core preserves the same events recorded in a core collected ∼ 100 km away in the southern basin of Lake Tanganyika, including an unexplained increase in biogenic silica at ∼ 37 ka, suggesting that this vast lake is responding coherently across both major bathymetric basins to regional and global climate forcing.