Project Description
We have samples from sediment cores from Pleistocene paleolake Olduvai in Tanzania, East Africa. We are analyzing these for their mineral assemblages using X-ray Diffraction (XRD), to obtain a record of lake mineralogical changes over the last 1.5 million years. This closed-basin, saline-alkaline lake shows changes in mineralogy that can be linked to changes in lake level and lake chemistry, which are tied to regional climate. In particular, changes in clay minerals, zeolites, carbonates, sulfates, and sulfides can help document changes in salinity, pH, oxidation, and lake level. Changes in feldspar, quartz, and augite can help document changes in sediment source. These changes can be identified using XRD, and linked to other proxies we have for the same cores (for example, elemental abundances derived from core scan X-ray Fluorescence (XRF)). Since Olduvai Gorge also has a well-known hominid fossil and archaeological record, these results can help us constrain the conditions under which hominids evolved.
Tasks and Responsibilites
The student will prepare core sediment samples for XRD analysis. They will be provided with an agate mortar and pestle, and they will grind ~10 samples into a fine powder each week (from home, under the current COVID restrictions). The student will be provided with a new set of samples each week, depending on her rate of progress. Samples will be mounted and run by XRD each week by McHenry, and the raw data will be supplied to the student for plotting, interpretation, and analysis. The student will also have access to geochemical data (core scan XRF) for the same intervals, and can try to link changes in the mineralogy (taken at 32 cm intervals) to changes in the elemental abundances (taken at 1-cm intervals) to reconstruct a high-resolution record of mineralogical changes for a portion of one of the cores.
Desired Qualifications
None Listed.