ABSTRACT: Olduvai Gorge, Tanzania, often cited as a textbook example of continental stratigraphic study (as depicted by Hay 1976 and others) is well known for its abundant Plio-Pleistocene fauna, hominin fossils, stone artifacts, and well-dated tephra layers used widely in the calibration of human evolution. However, precise stratigraphic correlation between various sites within Olduvai has been hampered by the rarity of unaltered volcanic glass suitable for geochemical characterization. Geochemical characterization of tephra for stratigraphic correlation purposes is difficult when fresh glass is absent or secondarily altered. A multi-component approach using the major and minor element compositions of phenocrysts and glass (where present) provides successful results at Olduvai and is proposed here as a viable methodology for use elsewhere. Six widespread Bed I (~2.1-1.79 myr) tephra layers of the Olduvai area are geochemically fingerprinted and used here to show the viability of themulti-component method. This method for geochemically fingerprinting tephra successfully provides a means for distinguishing similar looking tephra layers and for correlating fresh and altered tephra layers amongst a variety of depositional and diagenetic environments (freshwater wetlands, saline-alkaline lake, and fluvial plain). Application of this technique at Olduvai is providing high-resolution stratigraphic correlations and should prove applicable to other volcaniclastic sequences where tephra is poorly preserved.
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