Author ORCID Identifier
0009-0008-6946-3253
Date of Award
12-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Daniel Gebregiorgis
Second Advisor
Crawford W. Elliott
Third Advisor
Nadine Kabengi
Fourth Advisor
Richard Potts
Abstract
This study examined the geochemistry and mineralogy of the Koora Drill core ODP-OLO12-3A and compared the results to other paleoenvironmental data. The core spans ~190 kyr (~400-211 kyr) and was recovered in 2012 alongside another core (ODP-OLO12-1A). Core 1A covers a longer period and has been extensively studied, forming an excellent scale from which core 3A was examined. The Olorgesailie Drilling Project aimed at retrieving a continuous stratigraphic section to enable a high-resolution analysis of the paleoenvironment, including sections not seen within the Olorgesailie Basin due to hiatuses. The Koora Basin is a sediment depocenter downstream, and adjacent to the Olorgesailie Basin, making it a convenient place to drill and retrieve the missing strata at the Olorgesailie Basin. The mineralogy and geochemistry of the Koora drill core sediments were determined and used as past environmental indicators. This study employed carbon and nitrogen chemistry from the NC analyzer, clay, and bulk minerals by the XRD and potassium concentration using the XRF. Smectite charge was proposed and investigated as a potential proxy for environmental reconstruction. Despite the challenges in determining smectite charge, this approach can be a good proxy for paleoenvironmental studies.
Environmental records were studied alongside the archeological and paleontological records from the Olorgesailie Basin to establish possible links between paleoenvironments and the evolution of species and technology. From ~400 to 211 kyr, the Koora Basin experienced dry, moderately wet, and wet periods. The paleoenvironments were very variable during the initial stages of this period while the later stages had a more stable drying trend. The comparison of the two ODP cores shows that the mineralogy of the two cores agreed most of the time, albeit for some observed differences in the beginning and ending intervals of mineral precipitation. There were similar trends between the Koora drill cores’ data and the regional published data, but no clear influence by global insolation cycles on the geochemistry and mineralogy of core 3A. The highly variable environmental conditions of southern Kenya’s Rift at ~400 to 320 kyr might have caused vertebrate turnover and technological transitions at the Olorgesailie Basin during this time.
Recommended Citation
Muchemi, Francis N., "Environmental Variability and its Effects in the Southern Kenyan Rift Valley from ~400-211 kyr: Insight from Geochemistry and Mineralogy." Dissertation, Georgia State University, 2024.
https://scholarworks.gsu.edu/chemistry_diss/247
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