Plio-Pleistocene syn-sedimentary fault compartments underpin lake margin paleoenvironmental mosaic, Olduvai Gorge, Tanzania

Stollhofen H, Stanistreet IG (2012)


Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2012

Journal

Book Volume: 63

Pages Range: 309-327

Journal Issue: 2

DOI: 10.1016/j.jhevol.2011.10.002

Abstract

Normal faults displacing Upper Bed I and Lower Bed II strata of the Plio-Pleistocene Lake Olduvai were
studied on the basis of facies and thickness changes as well as diversion of transport directions across
them in order to establish criteria for their synsedimentary activity. Decompacted differential thicknesses
across faults were then used to calculate average fault slip rates of 0.05e0.47 mm/yr for the Tuff
IE/IF interval (Upper Bed I) and 0.01e0.13 mm/yr for the Tuff IF/IIA section (Lower Bed II). Considering
fault recurrence intervals of w1000 years, fault scarp heights potentially achieved average values of 0.05
e0.47 m and a maximum value of 5.4 m during Upper Bed I, which dropped to average values of 0.01
e0.13 m and a localized maximum of 0.72 m during Lower Bed II deposition.
Synsedimentary faults were of importance to the form and paleoecology of landscapes utilized by early
hominins, most traceably and provably Homo habilis as illustrated by the recurrent density and
compositional pattern of Oldowan stone artifact assemblage variation across them. Two potential relationship
factors are: (1) fault scarp topographies controlled sediment distribution, surface, and subsurface
hydrology, and thus vegetation, so that a resulting mosaic of microenvironments and paleoecologies
provided a variety of opportunities for omnivorous hominins; and (2) they ensured that the most voluminous
and violent pyroclastic flows from the Mt. Olmoti volcano were dammed and conduited away
from the Olduvai Basin depocenter, when otherwise a single or set of ignimbrite flows might have filled
and devastated the topography that contained the central lake body. In addition, hydraulically active
faults may have conduited groundwater, supporting freshwater springs and wetlands and favoring
growth of trees.

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APA:

Stollhofen, H., & Stanistreet, I.G. (2012). Plio-Pleistocene syn-sedimentary fault compartments underpin lake margin paleoenvironmental mosaic, Olduvai Gorge, Tanzania. Journal of Human Evolution, 63(2), 309-327. https://dx.doi.org/10.1016/j.jhevol.2011.10.002

MLA:

Stollhofen, Harald, and Ian G. Stanistreet. "Plio-Pleistocene syn-sedimentary fault compartments underpin lake margin paleoenvironmental mosaic, Olduvai Gorge, Tanzania." Journal of Human Evolution 63.2 (2012): 309-327.

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