Angelo Ricco, “Paleolake Mineralogy and Tephrostratigraphy of Paleolake Olbalbal, Tanzania”
Mentor: Lindsay McHenry, Geosciences, Letters & Science (College of)
Poster #145
The Olduvai Basin of Tanzania is well-known for being a Pleistocene archeological site in a paleoanthropological setting of inter-fingering paleolake and volcanic fan deposits. This site has been subject to many studies over the years and provides copious opportunities to reconstruct the paleoenvironments of the paleolake and its depositional patterns. The objective of this research is to examine the resulting diffraction patterns and identify the minerals present as well as their relative abundances, then use this data to establish the depositional patterns of the mineral abundance over time. Thus reflecting the changes in lake conditions. The section this study will focus on is roughly the top 50-75 meters below the surface of core 6A, with an estimated age of ~2 Ma. Samples were collected from core 6A in 32 cm intervals (from 16-18cm, 48-50cm, 80-83 cm, 112-114 cm, and 144-146 cm in each 1.5 m core segment where possible). Approximately 16 samples were analyzed and interpreted using a Bruker D8 XRD, EVA pattern matching software, the ICDD PDF-2 database, and the core 6A stratigraphic outline. Within the core samples that were tested, analcime as well as illite was found in almost every sample. This indicates a highly saline-alkaline environment, consistent with the published results for the underlying sediments. Diopside, anorthoclase, as well as orthoclase, were also found in multiple samples. These volcanic ash/fluvial sediments indicate deposition from the nearby Ngorongoro volcanic outcrops. Quartz as well as albite among other detrital minerals were also found in a few samples likely deposited from the Precambrian metamorphic quartzites and gneisses. The data collected from this project will be used to further study the overall trends and changes within the paleolake over the last 2 million years.