Authigenic clays are potential proxies for paleoclimate change when formed under saline conditions. Between 1.9 -1.7 mya, Olduvai was a closed-hydrologic basin into which Al- and Fe- rich detrital clays were transported from surrounding soils. Authigenic Mg-rich smectite formed within the basin due to chemical alteration in alkaline and saline conditions. 40 samples were chosen from a stratigraphic section in the center of the paleolake and analyzed to characterize the geochemical facies of the material using XRD, EMPA, and FTIR. ~70% of samples were Mg-rich with clay d060 XRD peaks between 1.506-1.523Å. EMPA indicated (Al2O3 + Fe2O3)/MgO ratios ranged from 0.2-4.8, 21 had ratios >1.0, indicating higher (Al2O3 + Fe2O3) content. These clay data correlated with bulk XRF data, indicating diagenetic controls on bulk composition. Therefore, bulk geochemistry can potentially indicate paleoclimate change when influenced by Mg-rich phyllosilicate formation.
| Identifer | oai:union.ndltd.org:GEORGIA/oai:scholarworks.gsu.edu:geosciences_theses-1094 |
| Date | 07 May 2016 |
| Creators | Simpson, Alexandra M |
| Publisher | ScholarWorks @ Georgia State University |
| Source Sets | Georgia State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Geosciences Theses |
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