Plio-Pleistocene volcanism of Lower Bed I, Olduvai Gorge, Tanzania: transportation mechanisms, volcaniclastic sedimentation and ecological significance

点击翻译按钮获取中文摘要

The Plio-Pleistocene Bed I succession at Olduvai Gorge, Tanzania is renowned for hominin remains, rich artefacts and fossil assemblages. Tuff beds provide the basis for the stratigraphic framework and for the correlation and dating of archaeological finds. The Tuff IA to Tuff IB interval (c. 1.98-1.84 Ma), choosen for this study, is especially important from a multidisciplinary perspective: (a) It provides the earliest record of Homo habilis in the Gorge, (b) it records the earliest antiquity of Human technology, known as Oldowan culture, (c) it is associated with several important occupation floors , and (d) it includes dated Palaeo-lake Olduvai sequences that have records of orbital forcing across the Plio-Pleistocene boundary. The tuff beds themselves provide important archives of (e) the correlation between the eastern and the yet poorly studied western Olduvai Basin, (f) a change from bimodal basaltic-rhyolitic to trachytic-phonolitic compositons, (g) the occurrence of flow-stripping/decoupling effects when pyroclastic flows crossed synsedimentary active faults, (h) the interaction of volcanic systems with the ecologically attractive eastern lake margin zone, and (i) the relative importance of volcanic effects versus regional climate influences on flora and fauna.A detailed dataset is to be developed using high resolution sedimentological logging, facies, petrographic and geochemical analysis. Lateral correlations and process-oriented facies analyses across palaeo-Lake Olduvai will be the critical aim of this research, allowing a thorough understanding of the complex interactions between the volcanics and the ecology of the lake. The project integrates data on palaeoenvironments, palaeoclimate, synsedimentary tectonism and volcanism with hominin land use models contributed by palaeoanthropologists and archaeologists of the multidisciplinary OLAPP research group. OLAPP trenches excavated over the next few years will provide an exceptional opportunity for combined sedimentological, volcanological and palaeoecological studies at an extremely high resolution (mm to cm scale).