Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8868524 | Palaeogeography, Palaeoclimatology, Palaeoecology | 2017 | 12 Pages |
Abstract
We have analyzed the phytolith content of 37 samples from the paleosol capped by Tuff IC dated 1.84Â Ma within Middle Bed I at Olduvai Gorge, Tanzania. Samples were obtained from different trenches sampling an area of about 25Â ha to document the paleovegetation associated with the abundant faunal remains and hominin artifacts in FLK, AMK, PTK and DS sites. The analysis reveals the abundance of globular granulate and forest indicator phytoliths (from 3% to 86% relative to the total number of phytoliths in the assemblages) attributed to woody plants, and of short cell grass phytoliths (up to 22%). The presence of palm phytoliths (up to 57%) attests for meso-haline soils in the area in agreement with the presence of the saline/alkaline Olduvai paleolake and one (or more) groundwater discharge areas (freshwater springs and/or wetland). Phytoliths provide botanical evidence for a mixed paleovegetation dominated by forest and woodland with patches of open-spaces occupied by grasses, prior to the deposition of Tuff IC. The presence of fern phytoliths in some assemblages suggest shaded and humid habitat, which supports the presence of freshwater (watercourses or springs) that might have attracted hominins and other animals. Yet, we have found that our phytolith extractions (residues) also include micrometric zeolites (chabazite, clinoptilolite, phillipsite), which attest that the phytolith signal in the Zinj paleosols is certainly affected by dissolution. This study completes the spatial analysis of the area and reveals that the wooded area extends north, south, and west of FLK Zinj, with palm trees preferentially located in the periphery, like the Zinj, AMK, and DS sites. The phytolith-inferred distribution of plants does not support the hypothesis that topography was influential in the location of these sites, particularly given that trees and/or shrubs were dominant all over. Rather, it is the presence of freshwater ponds that seem to have been the attractive factor for hominins at this particular place and time.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth-Surface Processes
Authors
H. Arráiz, D. Barboni, G.M. Ashley, A. Mabulla, E. Baquedano, M. DomÃnguez-Rodrigo,