Bioavailable Strontium from Plants and Diagenesis of Dental Tissues at Olduvai Gorge, Tanzania
Date
2018-07-11
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Abstract
Stable strontium isotope analysis is used to assess the migration and mobility of past populations of people and animals. This study aimed to determine the feasibility of conducting future studies using this method at Olduvai Gorge, Tanzania by determining the variability in biologically-available strontium (87Sr/86Sr) throughout the region from areas with metamorphic and volcanic bedrock, as well as recent unconsolidated lacustrine sediments. This was done by analysing modern plants collected from 33 different localities. As well, the degree to which archaeological animal teeth from Juma’s Korongo, a ~1-million-year-old site at Olduvai Gorge, have been affected by diagenetic alteration was assessed. To do this, the dentine and enamel of the teeth were analysed with and without pre-treatment with weak acetic acid: a protocol used for removing diagenetic strontium from dental specimens. There was no difference in 87Sr/86Sr values of volcanic (n=19) and metamorphic (n=9) sampling localities, but the lacustrine localities (n=5) had significantly higher values. 87Sr/86Sr values tended to decrease moving northeast towards the active volcano Oldoinyo Lengai, a major source of soil constituents for the area. Also, localities where trees were sampled had significantly higher 87Sr/86Sr values than those without them. Despite the homogeneous 87Sr/86Sr values described between metamorphic and volcanic localities, much higher values have been found in the northern extent of Serengeti National Park (Copeland et al., 2012), suggesting that animals who have immigrated into the area from long distances away can be identified as non-local. The animal teeth (n=7), which include zebras, crocodiles, and a hippopotamus, were all from local animals. There was a significant difference between enamel and dentine values after acid washing, suggesting that biogenic 87Sr/86Sr values are preserved in the enamel. These values were consistently higher than the modern bioavailable strontium values, possibly due to environmental differences between the past and present. The results of this study suggest that Olduvai Gorge is a suitable area for future studies using stable strontium isotope analysis, though more work is required to fully understand the inconsistencies between ancient and modern bioavailable strontium.
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Keywords
strontium, isoscape, diagenesis, Olduvai Gorge, fossil, animal teeth
Citation
Tucker, L. L. (2018). Bioavailable Strontium from Plants and Diagenesis of Dental Tissues at Olduvai Gorge, Tanzania (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32357