Paleoenvironmental interpretation of lake-margin deposits using δ13C and δ18O results from early Pleistocene carbonate rhizoliths, Olduvai Gorge, Tanzania

AbstractThe phytolith content of 10 samples collected immediately under Tuff IF (~ 1.785 Ma) at FLK N and other surrounding localities (~ 2 km²) provides a direct botanical evidence for woody vegetation in the eastern margin of Olduvai Gorge during uppermost Bed I time. Observation and counting of 143 phytolith types (5 to >150 μ) reveal dense but heterogeneous woody cover (~ 40–90%) of unidentified trees and/or shrubs and palms associated to the freshwater springs surrounding FLK N, and more open formation (presumably ~ 25–70% woody cover) in the southeast at localities VEK, HWK W and HWK E. The paleovegetation is best described as groundwater palm forest/woodland or bushland, which current analogue may be found near Lake Manyara in similar hydrogeological context (freshwater springs near saline/alkaline lake). Re-evaluating the published pollen data based on this analogy shows that 70% of the pollen signal at FLK N may be attributed to thicket-woodland, Acacia groundwater woodland, gallery and groundwater forests; while < 30% is attributed to swamp herbage and grasslands. Micro-botanical, isotopic, and taphonomical studies of faunal remains converge on the same conclusion that the area surrounding FLK N, which attracted both carnivores and hominins in the early Pleistocene, was densely wooded during uppermost Bed I time.

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Early Pleistocene fossil wood from Olduvai Gorge, Tanzania

Quaternary International ◽

10.1016/j.quaint.2004.04.003 ◽

2005 ◽

Vol 129 (1) ◽

pp. 15-22 ◽

Cited By ~ 26

Author(s):

Marion K. Bamford

Keyword(s):

Fossil Wood ◽

Early Pleistocene ◽

Olduvai Gorge

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Geochemical “fingerprints” for Olduvai Gorge Bed II tuffs and implications for the Oldowan–Acheulean transition

Quaternary Research ◽

10.1016/j.yqres.2015.10.005 ◽

2016 ◽

Vol 85 (1) ◽

pp. 147-158 ◽

Cited By ~ 28

Author(s):

Lindsay J. McHenry ◽

Jackson K. Njau ◽

Ignacio de la Torre ◽

Michael C. Pante

Keyword(s):

High Resolution ◽

Electron Probe Microanalysis ◽

Mineral Assemblage ◽

Electron Probe ◽

Early Pleistocene ◽

Olduvai Gorge ◽

Critical Part ◽

Homo Habilis ◽

Arid Conditions ◽

Stratigraphic Position

Bed II is a critical part of early Pleistocene Olduvai Gorge, Tanzania. Its deposits include transitions from humid to more arid conditions (with associated faunal changes), from Homo habilis to erectus, and from Oldowan to Acheulean technology. Bed II (~ 1.8–1.2 Ma) is stratigraphically and environmentally complex, with facies changes, faulting, and unconformities, making site-to-site correlation over the ~ 20 km of exposure difficult. Bed II tuffs are thinner, less evenly preserved, and more reworked than those of Bed I. Five marker tuffs (Tuffs IIA–IID, Bird Print Tuff (BPT)), plus local tephra, were collected from multiple sites and characterized using stratigraphic position, mineral assemblage, and electron probe microanalysis of phenocryst (feldspar, hornblende, augite, titanomagnetite) and glass (where available) composition. Lowermost Bed II tuffs are dominantly nephelinitic, Middle Bed II tuffs (BPT, Tuff IIC) have basaltic components, and upper Bed II Tuff IID is trachytic. The BPT and Tuff IID are identified widely using phenocryst compositions (high-Ca plagioclase and high-Ti hornblende, respectively), though IID was originally (Hay, 1976) misidentified as Tuff IIC at Loc 91 (SHK Annexe) in the Side Gorge. This work helps establish a high-resolution basin-wide paleolandscape context for the Oldowan–Acheulean transition and helps link hominin, faunal and archaeological records.

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