MINERALOGY AND GEOCHEMISTRY OF AN ANTHROPOCENE (~350 YR) SEDIMENT CORE FROM LAKE BARINGO, KENYA

A mineralogical and geochemical study of a 330-cm deep core of Lake Baringo, Kenya, shows the sedimentary record of environmental change in East Africa. Experimental evidence was obtained by bulk mineralogy by XRD analysis of randomly oriented powders, clay mineralogy by XRD of oriented slides of <1µm size fractions separated by centrifugation, and energy-dispersive X-ray fluorescence spectroscopy of powders using a portable ED-XRF. The bulk mineralogy throughout the core is uniform and dominated by quartz, anorthoclase feldspar, and clay minerals. The clay mineralogy shows that a smectite, montmorillonite, is present along with minor illite and kaolinite. There is also an unidentified phase that is a minor component throughout the core, possibly a zeolite. The peak position of the unidentified phase is 13.49 degrees 2-theta and a d-spacing of 6.57Å.

The stable mineralogy and geochemistry throughout the core provided evidence of a dry East African climate since AD 1650. This evidence is consistent with the previous results obtained by Kiage and Liu (2009). Bulk and clay mineralogical indicators suggest landscape stability, although geochemical indicators show some environmental changes that may be related to the wet and dry episodes previously identified. Past climate change patterns can be identified by the variety of minerals, clays, and bulk materials found in various sediment cores. Knowledge of past climate can lead to understanding of environmental changes, increasing insight into present and future climate change.