Plio-Pleistocene synsedimentary fault compartments, foundation for the eastern Olduvai Basin paleoenvironmental mosaic, Tanzania.

摘要: Abstract Normal faults displacing Upper Bed I and Lower II strata of the Plio-Pleistocene Lake Olduvai were studied on basis facies thickness changes as well diversion transport directions across them in order to establish criteria for their synsedimentary activity. Decompacted differential thicknesses then used calculate average fault slip rates 0.05–0.47 mm/yr Tuff IE/IF interval (Upper I) 0.01–0.13 mm/yr IF/IIA section (Lower II). Considering recurrence intervals ∼1000 years, scarp heights potentially achieved values 0.05–0.47 m a maximum value 5.4 m during I, which dropped 0.01–0.13 m localized 0.72 m deposition. Synsedimentary importance form paleoecology landscapes utilized by early hominins, most traceably provably Homo habilis illustrated recurrent density compositional pattern Oldowan stone artifact assemblage variation them. Two potential relationship factors are: (1) topographies controlled sediment distribution, surface, subsurface hydrology, thus vegetation, so that resulting mosaic microenvironments paleoecologies provided variety opportunities omnivorous hominins; (2) they ensured voluminous violent pyroclastic flows from Mt. Olmoti volcano dammed conduited away Basin depocenter, when otherwise single or set ignimbrite might have filled devastated topography contained central lake body. In addition, hydraulically active may groundwater, supporting freshwater springs wetlands favoring growth trees.