CHEMOSTRATIGRAPHIC RECORDS OF HYDROCLIMATE AND LIMNOLOGICAL CHANGE OVER THE COMMON ERA IN LAKE TANGANYIKA (EASTERN AFRICA)

Lake Tanganyika provides a world-class example of how sediments from ancient tectonic lakes can generate high-fidelity records of tropical hydroclimate and limnological change over a range of timescales. Laminated deepwater sediments from Lake Tanganyika provide a glimpse of environmental variability at seasonal-annual resolution. However, few high-resolution records of environmental change have appeared for the Common Era from Lake Tanganyika. Here, we present a high-resolution chemostratigraphy derived from mXRF scanning of a well-dated sediment core from Lake Tanganyika’s southern basin that spans the last two millennia. We used elemental abundances to probe diatom productivity (via Si/Ti) and runoff from the landscape (using Ti, Al, K, and Fe as proxies of detrital inputs). Peaks in Si/Ti, coupled with characteristics of laminae, suggest pulses of intense diatom productivity that likely relate to strong upwelling and nutrient availability under the influence of strong seasonal winds. Peaks in detrital proxies, which occur when Si/Ti is low, suggest periods of weak seasonality and greater runoff likewise occurred in the Common Era, perhaps linked to changes in climate such as the El Niño Southern Oscillation and/or solar forcing.